Category: CBSE Class 9

Chapter 6 Tissues Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Tissues Class 9 Important Questions and Answers Science Chapter 6

Very Short Answer Questions

Question 1.
Name the tissue present in soft parts of the plants like pith and cortex. (CCE 2010)
Answer:
Parenchyma

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2.
Where is apical meristem found ? (CCE 2010)
Answer:
At the tips of main stem, main root and their branches.

Question 3.
State one function of parenchyma. (CCE 2010)
Answer:
Storage of food.

Question 4.
Which is the function of xylem ?
(CCE 2010)
Answer:
Transport of sap (water + minerals).

Question 5.
What is the function of phloem ? (CCE 2010)
Answer:
Translocation of food.

Question 6.
Identify the part marked ‘B’ in the diagram. (CCE 2013)

Answer:
Epidermal cell.

Question 7.
State the function of epidermal cells of roots. (CCE 2013)
Answer:
Absorption of water and minerals from soil.

Question 8.
Name the protein present in the muscles which is respon¬sible for movement. (CCE 2013)
Answer:
Myosin (moves over actin during contraction of muscle fi¬bre).

Question 9.
Name the tissue present under the skin and arranged in a pattern of layers. (CCE 2013)
Answer:
Muscular tissue.

Question 10.
Which meristem is responsible for transformation of stem of a plant into trunk when it grows into a tree ? (CCE 2013)
Answer:
Lateral meristem.

Question 11.
Name two elements of water conducting tissue which are re-sponsible for conduction. (CCE 2013)
Answer:
Tracheids and vessels, collectively called tracheary elements.

Question 12.
Name the chemical substance which gets deposited in the walls of sclerenchyma. (CCE 2013)
Answer:
Lignin.

Question 13.
Identify the part marked ‘X’ in the diagram. (CCE 2014)
Answer:
Lumen.

Question 14.
Write any one characteristic of meristematic tissue. (CCE2014)
Answer:
Immature, thin-walled compactly ar¬ranged cells capable of division.

Question 15.
State the role oflarge air cavities present in parenchyma of aquatic plants.
(CCE 2014)
Answer:
Storage of metabolic gases (CO₂, O₂) and providing buoyancy.

Question 16.
Name the complex permanent tissue in plants in which the materials can move in both directions. (CCE2014)
Answer:
Phloem.

Question 17.
Name the type of tissue found in respiratory tract. (CCE 2014)
Answer:
Ciliated columnar epithelium.

Question 18.
State two functions ofthe adipose tissue. (CCE 2015)
Answer:

1. Storage of fat
2. Insulation
3. Cushions around organs
4. Body contours (rounding off).

Question 19.
Name the tissue which is responsible for increase in girth of stem and root. ( CCE 2015)
Answer:
Lateral meristem (vascular cambium and cork cambium).

Question 20.
Name the tissue that covers most of the organs and forms a barrier to keep different body systems separate. Write its one important function. (CCE 2016)
Answer:
Epithelium. Function. Protection by surface epithelium of skin from drying up, microbes, chemicals and injury.

Question 21.
Water hyacinth floats on water surface. Why ? (CCE 2016)
Answer:
Presence of aerenchyma and large air cavities in petioles.

Short Answer Questions (2 marks)

Question 1.
Identify the type of plant tissue given Label parts A and B. Where in the stem of a plant would you find this tissue ?
(CCE 2010, 2011, 2013)

Answer:
(a) Phloem. Outer side of vascular strand.
(b) A – Sieve tube cell.
B – Companion cell.

Question 2.
Differentiate between aerenchyma and chlorenchyma.
Answer:

Question 3.
(a) Identify the region of the stem marked A in the diagram and the type of simple permanent tissue found in this region
(b) Mention any two characteristic features of the cells found in this tissue. (CCE 2010)
Answer:
(a) A-Epidermis. The permanent tissue forming the epidermis is parenchyma.
(b) Characteristic

Features:

1. Cells are elongated and com-pactly arranged without any intercellular spaces.
2. Presence of a layer of non- cellular cuticle on the outer surface for protection and reduction of water loss.

Question 4.
List two characteristics of cork cells which help them to function as protective tissue. (CCE 2010, 2012)
Answer:

1. Suberin: Cork cells are impermeable to water vapours due to deposition of suberin over their cells.
2. Dead Cells: Cork cells are dead, filled with tannins, resins and air.

Question 5.
Why does growth of a plant occur in specific regions ? Where are the following found
(a) Intercalary meristem
(b) Lateral meristem? (CCE 2010)
Answer:
Meristem. Plants possess a special tissue or meristem for growth. It occurs at specific regions like apices, nodal areas and sides. Accordingly growth occurs only in those areas where meristematic tissue or meristem is present, viz., api¬ces, nodal regions and girth.
(a) Intercalary Meristem. It occurs above or below the nodes and the base of leaves.
{b) Lateral Meristem. It occurs on the sides, both in stem and root.

Question 6.
Name the connective tissue which helps is the repair of tissues. State where this tissue is found. Mention one more » fonction. (CCE 2010,2011,2012)
Answer:
Areolar tissue (a connective tissue).
Location: It occurs inside organs, around blood vessels, muscles and nerves, below skin (subcutaneous tissue) and joining various structures like muscles with skin.
Other Function: Filling, packing and covering organs.

Question 7.
List any four salient features of meristematic tissue.
(CCE 2010, 2011, 2012)
Answer:

1. Cells: Cells are small, spherical or polygonal with thin elastic wall.
2. Intercellular Spaces: They are absent.
3. Cell Contents: Nucleus is large. Cytoplasm is dense while vacuoles are absent.
4. Activity: The cells have high anabolic rate. They grow and divide repeatedly.

Question 8.
Which elements of xylem

1. Help in transport of water and minerals,
2. Store food and
3. Provide mechanical support. (CCE 2010, 2011)

Answer:

1. Transport: Vessels and tracheids.
2. Food Storage: Xylem parenchyma
3. Mechanical Support: Xylem fibres, tracheids and ves-sels.

Question 9.
Draw diagram of a neuron showing nucleus and cell body/dendrite, axon, nerve endings.
(CCE 2010, 2011, 2012)
Answer:

Question 10.
(a) In which connective tissue, matrix contains salts of calcium and phosphorus ?
(b) Which connective tissue is present in ear ?
(c) Which connective tissue connects two bones ?
(d) Which connective tissue is found in bone marrow ?
(CCE 2010, 2011)
Answer:
(a) Bone
(b) Cartilage
(c) Ligament (dense, yellow fibrous connective tissue)
(d) Areolar tissue.

Question 11.
Name four types of elements of phloem.
(CCE 2010, 2011)
Answer:

1. Sieve tube cells
2. Companion cells
3. Phloem Paren-chyma
4. Phloem fibres.

Question 12.
Name the tissue that smoothens bone surfaces at the joints. Describe its structure with the help of a diagram.
(CCE 2010, 2011)
Answer:
Cartilage. It has a covering of fibrous connective tissue called perichondrium. Blood supply is restricted to it. Internally there is a layer of cartilage forming cells or chondroblasts. Then there is a solid but flexible matrix of protein-sugar complex chondrin. Matrix contains lacunae having 1 -4 living cartilage cells called chondrocytes.

Question 13.
Name the simple permanent tissue which
(a) forms the basic packing tissue
(b) Provides flexibility in plants.
(CCE 2010, 2011)
Answer:
(a) Basic Packing Tissue: Parenchyma,
(b) Flexibility: Col- lenchyma.

Question 14.
In a temporary mount of leaf epidermis, we observe small pores.
(a) What are the pores present in leaf epidermis called ?
(b) How are these pores beneficial to the plant ?
(CCE 2011, 2012, 2015)
Answer:
{a) The pores found in the leaf epidermis are stomata.
{b) The epidermal pores or stomata are the sites of gaseous exchange and transpiration.

Question 15.
What are the two components of blood ? Why is blood considered a type of connective tissue ?
(CCE 2011, 2012)
Answer:
(a) Components. Plasma and blood cells.
(b)
(i) Blood is considered connective tissue as it contains cells suspended in a fluid matrix,
(ii) Further, it connects all parts of the body receiving and providing materials every where.

Question 16.
What is the chemical substance that makes the cells of sclerenchyma hard ? Mention where the tissue is likely to be present. (CCE 2011)
Answer:
(a) Lignin
(b) Around vascular bundles, hypodermis of monocot stem, bundle caps, hard covering of seeds and nuts, husk of coconut.

Question 17.
List any two differences between the structure and location of striated and unstriated muscles. (CCE 2011)
Answer:

Question 18.
List any two differences between striated and cardiac muscles with respect to their structure and location. (CCE 2011)
Answer:

Question 19.
State one function each of
(a) Areolar tissue
(b) Cuboidal epithelium. (CCE 2011, 2013)
Answer:
(a) Areolar Tissue: Binding, packing and covering of body organs besides providing materials for repair of injury.
(b) Cuboidal Epithelium: Stratified epithelium provides protection while simple one takes part in absorption, excretion, secretion and forming germinal layer.

Question 20.
(a) Mention the location of apical meristem in plants.
(b) Name the tissue responsible for movement of the body. (CCE 2011)
Answer:
(a) Tips of stems, roots and their branches
(b) Muscle tissue.

Question 21.
Write the function of bone, cartilage, ligament and tendon.
(CCE 2011, 2012)
Answer:
Bone: It forms supporting framework of body and protects vital organs like brain, heart and lungs.
Cartilage: It provides support, frictionless movement and flexibility to various body parts.
Ligament: It connects a bone to another bone and provides for movement at the joints.
Tendon: It attaches muscle to bone for movement of body parts.

Question 22.
(a) State two important functions of areolar tissue.
(b) Why are skeletal muscles known as striated muscles ?
(CCE 2011, 2013)
Answer:
(a) (i) Binding, packing and covering of body parts.
(ii) Providing materials for repair of injury.
(iii) Connecting skin with underlying muscles.
(b) Due to presence of alternate light and dark bands.

Question 23.
(a)
(i) Name the process by which meristematic tissue changes into permanent tissues.
(ii) Name the simple permanent tissue which contains chlorophyll in it.
(b) Aquatic plants float in water. Give reason for this act.
(CCE 2011)
Answer:
(a)
(i) Differentiation.
(ii) Chlorenchyma.
(b) Aerenchyma, that stores gases, provides buoyancy to aquatic plants and help them float over water.

Question 24.
(a) In the diagram of meristematic tissue in the plant body given here, identify the type of meristematic tissue found in the regions marked ‘A’ and ‘B’ of a stem,
(b) State one function of each. (CCE2011, 2012)

Answer:
(a) A – apical meristem.
B — lateral meristem.
(b) Function:
A – increase in length (stem, root).
B – increase in girth (stem, root).

Question 25:
(a) Give the other name of dividing cells in plants.
(b) In which part of plants, apical meristem is present ? Also mention its function. (CCE 2011)
Answer:
(a) Meristematic cells (meristematic tissue).
(b) Apices or growing points of stems, roots and their branches. Apical meristem takes part in growth in length.

Question 26.
A horse and a mango tree are both complex living organisms with specialised yet different tissue systems to perform the basic life processes. Give the reasons for possessing different tissues to perform similar functions. (CCE2012)
Answer:

1. Support: In Mango which is fixed, the supportive tissue is dead and requires little maintenance. In horse, the supportive tissue is organised to provide mobility.
2. Growth: Mango has to discard older organs as it does not have an excretory system. It, therefore, continues to grow throughout life with the help of meristems. Horse has an excretory system. It does not discard old structures. Therefore, it stops growing after attaining maturity.

Question 27.
Write two basic structural differences between parenchyma and collenchyma. (CCE 2012)
Answer:

1. Shape: Parenchyma cells are isodiametric while collenchyma cells are elongated,
2. Wall: It is thin in parenchyma and unevenly thickened (generally at corners) in collenchyma.
3. Intercellular Spaces: They occur in parenchyma but are negligible in collenchyma.

Question 28.
(a) Voluntary muscles are also known as skeletal muscles. Justify.
(b) Give two structural characteristics of these voluntary muscles. (CCE 2012)
Answer:
(a) Voluntary muscles are also known as skeletal muscles as they are usually attached to bones and take part in their movements as per our will.
(b) Structural Characteristics.
(i) Presence of alternate dark bands,
(ii) Multinucleate nature.

Question 29.
Given is the diagram showing longitudinal section of parenchymatous tissue. Label the parts M, N, O and P in the given diagram. (CCE 2012)

Answer:
M- chloroplast.
N – nucleus.
O – cytoplasm.
P – intercellular space.

Question 30.
The epidermis in desert plants is covered by a waxy coating. Name the substance which constitutes the coating. State three advantages of this coating. (CCE 2012)
Answer:
Coating or cuticle is made of cutin and wax.
Advantages:

1. Strength: Coating provides strength to epidermis,
2. Protection: It protects the living surface cells against abrasive action of wind,
3. Transpiration: The thick coating reduces transpiration.

Question 31.
List any two functions of epithelial tissue in human body.
(CCE 2012)
Answer:
(i) Protection: Being surface layer, epithelium protects the underlying structures from injury, microbes, toxins and desiccation.
(ii) Exchange: It takes part in exchange of gases in lungs (between alveoli and blood capillaries) and exchange of gases and materials in tissues (between blood capillaries and tissue fluid).

Question 32.
List four functions of blood.
Answer:

1. Transport: Blood transports gases, nutrients, hormones and waste materials to various parts of the body.
2. Heat: It distributes heat throughout the body.
3. Tissue Fluid: It forms tissue fluid from its plasma.
4. Immunocytes: Blood possesses immunocytes for fighting foreign microbes.

Question 33.
State two differences between chlorenchyma and parenchyma. (CCE 2012)
Answer:

Question 34.
Write two locations of
(i) Simple squamous epithelium
(ii) Cuboidal epithelium. (CCE 2012)
Answer:
(i) Simple Squamous Epithelium: Alveoli, blood capillaries.
(ii) Cuboidal Epithelium: Germinal epithelium, Kidney tubules.

Question 35.
Name the tisue that makes husk of coconut. Write three characteristics of this tissue. (CCE 2012)
Answer:
Sclerenchyma.
Three Characteristics:

1. Long narrow spindle-shaped cells,
2. Thick lignified wall with pits,
3. Dead cells with narrow lumen.

Question 36.
(a) Name the connective tissue which connects two bones.
(b) Name the connective tissue present in external ear.
(CCE 2012)
Answer:
(a) Ligament,
(b) Cartilage.

Question 37.
List two points of difference between parenchyma and sclerenchyma.
Answer:

Question 38.
List two points of difference between parenchyma and collenchyma tissues. (CCE 2012)
Answer:

Parenchyma	Collenchyma
1.      Shape. Cells are isodiametric. 2.      Wall. Cell wall is thin. 3.       Strength. Parenchyma provides turgidity to softer organs. 4.       Occurrence. It forms the packing tissue of all plant organs.                        ‘	Cells are elongated. Cell wall is unevenly thickened generally over the corners. It provides both mechanical strength as well as flexibility. It occurs hypodermally in dicot stems and leaves only.

Question 39.
Name the simple permanent tissue which
(i) Forms the basic packing tissue
(ii) Provides flexibility in plants. (CCE 2012)
Answer:
(i) Parenchyma,
(ii) Collenchyma.

Question 40.
What is tissue ? Jutify that blood is a tissue. Identify the meristematic tissues which are located at
(i) Growing tip of stem of a plant
(ii) Base of leaves or internodes of twigs. (CCE 2012, 2013)
Answer:
Tissue: It is a group of cells having common origin similar or related structure and a common function.
Blood as Tissue: Blood is a complex of matrix and cells that performs the function of transport with all the contained cells derived from bone narrow.
(i) Apical meristem.
(ii) Intercalary meristem.

Question 41.
What is apical meristem ? Where is it located ? State its functions. (CCE 2012)
Answer:
Apical meristem is apical tissue where cells continue to divide producing daughter cells which grow out to form different types of mature cells.
Location. It occurs at the tip of stem, root and their branches.
Functions:

1. It brings about growth in length,
2. Part of stem apical meristem is left out to produce axiallary buds and intercalary meristem.

Question 42.
(a) Identify the tissue present over eye lid.
(b) Name the tissue that carries signals from various parts of the body to brain. (CCE 2012)
Answer:
(a) Stratified squamous epithelium over outer surface (like skin) and stratified columnar epithelium in conjunctiva.
(b) Nervous tissue made up of neurons.

Question 43.
Name the tissue that
(a) Connects muscle to bone in humans
(b) Forms inner lining of alveoli
(c) Stores fat in our body
(d) Transports water and minerals in plants
(e) Present in veins of leaves. (CCE 2012)
Answer:
(a) Tendon
(b) Squamous epithelium
(c) Adipose tissue
(d) Xylem
(e) Complex tissues xylem and phloem.

Question 44.
Identify the location of the following tissues.
(a) Tendon
(b) Cuboidal epithelium
(c) Alveolar tissue
(d) Aerenchyma plant tissue. (CCE 2012)
Answer:
(a) Tendon: Between muscle and bone,
(b) Cuboidal Epithelium: Germinal epithelium, Kidney tubules.
(c) Areolar tissue: a connective tissue.
(d) Aerenchyma: Aquatic plants.

Question 45.
How does matrix of bone differ from matrix of cartilage ?
(CCE 2012)
Answer:

Question 46.
Name the tissue which helps in transportation of oxygen that we inhale to various parts of our body. Write the composition of this tissue. (CCE 2012)
Answer:
Blood Composition: Plasma or matrix – 55%, Blood cells – 45%. Plasma has 90 – 92% water, 8 – 10% organic and inorganic substances. Blood cells are of two types, haemoglobin containing red blood corpuscles (RBCs) and colourless white blood corpuscles (WBCs). Blood platelets are cell fragments present in blood.

Question 47.
Distinguish between tendon and ligament. Write one characteristic of each. (CCE 2012, 2013)
Answer:
Tendon is an inelastic cord of dense white connective tissue between muscle and bone while ligament is an elastic cord of dense yellow connective tissue between two bone ends.
Characteristic of Tendon: It contains parallel bands of white collagen fibres with rows of flat, elongated fibroblasts in between them.
Characteristic of Ligament: It has abundant yellow elastin fibres, bundles of white collagen fibres arranged variously and scattered fibroblasts.

Question 48.
Growth in plants is restricted to certain regions. Give reason for this fact. Mention two growth regions in plants.
(CCE 2012)
Answer:
In plants growth is restricted to certain regions because they are
(i) Attached, requiring supportive vertical tissue which is mostly made of dead cells,
(ii) Continued growth as older parts have to be shed or become dead since there is no regular excretory system.

1. Apical meristem at tips of stem, root and their branches.
2. Lateral meristem.

Question 49.
Name the hardest connective tissue you have studied. What is its function ? (CCE 2013)
Answer:
Bone: It forms supporting framework of body and protects vital organs like brain, heart and lungs.

Question 50.
What is cuboidal epithetial tissue ? What is its function ? (CCE 2013)
Answer:
Definition: It is an epithelial tissue which is made of compactly arranged cells which appear squarish in V.S. and polygonal in surface view.
Function: Stratified epithelium provides protection while simple one takes part in absorption, excretion, secretion and forming germinal layer.

Question 51.
Name the following tissues :
(a) Connective tissue found between skin and muscles.
(b) Tissue which connects two bones,
(e) Epithelial tissue which forms lining of kidney tubules,
(d) Tissue which is present in the veins of leaves.
(CCE 2013)
Answer:
(a) Areolar tissue
(b) Ligament
(c) Cuboidal epithelium
(d) Complex vascular tissue (xylem and phloem).

Question 52.
Give one word for
(a) Group of cells of similar structure and designed to give highest efficiency of function
(b) Process of taking up a permanent shape, size and function,
(c) Animal tissue connecting muscles to bones
(d) Kidney-shaped cells enclose stomata. (CCE2013, 2014)
Answer:
(a) Simple tissue
(b) Differentiation
(c) Tendon
(d) Guard cells.

Question 53.
Mention the differnt components of blood.

Answer:
a — plasma
b—red blood corpuscles (erythrocytes)
c—white blood carpuscles (leucocytes)
d—blood platelets (thrombocytes).

Question 54.
(a) On what basis is meristematic tissue classified ?
(b) Mention two characteristics of this tissue.
(c) Which amongst the meristems is called cambium ?
(CCE 2014, 2016)
Answer:
(a) On the basis of position —apical (tip of stem, root and their branches), intercalary (above or below nodes and leaf bases) and lateral (peripheral inside stem and root.
(b) Characteristics:

1. Cells: Cells are small, spherical or polygonal with thin elastic wall.
2. Intercellular Spaces: They are absent.
3. Cell Contents: Nucleus is large. Cytoplasm is dense while vacuoles are absent.
4. Activity: The cells have high anabolic rate. They grow and divide repeatedly.

(c) Cambium: Lateral meristem is called cambium. It is of two types, vascular cambium and cork cambium Gphellogen).

Question 55.
Which parts of our body are composed of nervous tissue ?
Name the cells that make up the nervous tissue.
(CCE 2012)
Answer:
(a) Brain, spinal cord and nerves are made of nervous tissue.
(b) Neurons or nerve cells constitute the nervous tissue

Question 56.
Write the location and function of collenchyma tissue in plants. (CCE 2014)
Answer:
Location: It occurs in hypodermis of herbaceous dicot stems, leaf midribs and leaf stalks.
Function: Collenchyma provides both mechanical strength and flexibility. Being living outer tissue. It may also help in photosynthesis and storage.

Question 57.
Draw diagram of phloem tissue and label on it all the three elements of phloem. (CCE 2014, 2016)
Answer:
Draw and label (except phloem fibre)

Question 58.
Name the type of tissue and its function present in the lining of kidney tubules. (CCE 2014)
Answer:
Epithelial cuboidal tissue. Secretion and absorption.

Question 59.
How is stratified squamous epithelium tissue different from simple squamous tissue ? (CCE 2015, 2016)
Answer:

Question 60.
Determine the location of the following tissues :

1. Unstriated muscle fibres,
2. Cuboidal epithelium.
3. Adipose tissue,
4. Striated muscle fibres.(CCE2015)

Answer:

1. Unstriated Muscle Fibres: Inside visceral organs of the body like gastrointestinal tract, blood vessels, bronchi, urinary bladder, iris, etc.
2. Cuboidal Epithelium: Germinal layer, kidney tubules, salivary mammary and pancreatic ducts, thyroid vesicles,
   Function: Gametes from germinal epithelium.
3. Adipose Tissue: Below skin, cushion around heart, kidneys, eye ball, in between body organs.
4. Striated Muscle Fibres: In limbs attached to bones, neck, face, bodywall, tongue, pharynx, diaphragm, upper part of oesophagus.

Question 61.
Give one word for the following :

1. Group of cells with similar structure and designed to give highest efficiency of function,
2. The process of taking up permanent shape, size and function,
3. Animal tissue connecting muscle to bones,
4. Kidney shaped cells that enclose stomata. (CCE 2015)

Answer:

1. Tissue
2. Differentiation
3. Tendon
4. Guard cells.

Question 62.
Name the muscular tissue which is present in the iris of  the eye. What is the shape of these cells ? (CCE 2016) ;
Answer:
Smooth or unstriated muscle fibres. Spindle shaped. :

Question 63.
Write the names of connective tissues—a, b, c and d.

Answer:
a— blood,
b—areolar tissue,
c—ligament,
d-—tendon.

Question 64.
Mention the different components of blood in the following | diagram

Answer:
a— plasma,
b—erythrocytes,
c—leucocytes,
d—blood platelets.

Question 65.
Differentiate between simple tissue and complex tissues in
Answer:

Question 66.
What is the function of sieve tube cells and how are they ! designed to carry out their function ? (CCE 2016)
Answer:
Function. Translocation of food (organic nutrients).
Design. The cells are vacuolate, nonnucleate and placed end to end in the form of tube called sieve tube. The septa between the sieve tube cells are porous (called sieve plates) for rapid transport.

Question 67.
Name the tissue in animals that carries out similar function as the following tissues do in plants :
(i) Epidermis
(ii) Vascular bundles. Also write their function.
(CCE 2016)
Answer:
(i) Epidermis: Epithelium in animals. Function. Protection from drying up, microbes, chemicals and injury.
(ii) Vascular Bundles: Blood vascular system. Function, Translocation of materials from source to individual cells and passage of materials given out by cells to the place of disposal.

Short Answer Questions (3 marks)

Question 1.
In the given figure

(a) Identify the tissue,
(b) In-fer the characteristic features of these cells,
(c) Suggest any two parts of the plant where such cells are present.
(CCE 2010)
Answer:
(a) Parenchyma.
(b) Characteristics.

1. Thin-walled living cells.
2. The cells have a large central vacuole and a peripheral cytoplasm which sends strands into the central vacuole.

(c) Location.

1. Cortex and pith of stem and root.
2. Major part ofleaves, flowers and fruits.

Question 2.
(a) Draw a labelled diagram of a neuron with three/four labellings.
(b) Identify the tissue which is made of these cells.
(c) Name one organ which is made of this tissue.
(CCE 2010, 2011, 2012, 2015)
Answer:
(a)

(b) Nervous tissue,
(c) Brain.

Question 3.
Observe the given figure

(a) Identify the tissue,
(b) Infer the charac-teristic features of these cells.
(c) Specify any two parts of the plant where such cells are present.
(CCE 2010, 2011)
Answer:
(a) Sclerenchyma.
(b) Features

1. Thick walled cells,
2. Empty dead cells,
3. No intercellular spaces.

(c) Location

1. Hypodermis of monocot stems,
2. Around the vascular bundles and inside the vascular tissues.

Question 4.
(a) Draw adipose connective tissue.
(b) Mention one region of the body where this tissue is present and state one function of this tissue. (CCE 2010, 2012)
Answer:
(a)

(b)

1. Location: Subcutaneous region of the body,
2. Function: Insulation.

Question 5.
Name the tissue responsible for flexibility in plants. How would you differentiate it from other permanent tissues ?
(CCE 2010, 2011)
Answer:
Collenchyma provides flexibility in plants.
Collenchyma differs from other permanent tissues in having irregular wall thickenings, generally at the corners.

Question 6.
(a) Draw labelled diagram of striated muscles.
(b) Mention any two characteristic features of the cells that form the above muscular tissue. (CCE 2010, 2011)
Answer:
(a)

(b) Features:

1. Presence of light and dark bands,
2. Several oval nuclei present peripherally.

Question 7.
What is connective tissue ? State its any two basic components. Differentiate between ligament and tendon.
(CCE 2010, 2011)
Answer:
Connective Tissue: It is a fundamental animal tissue having abundant matrix with scattered living cells that takes part in connecting, binding, packing and supporting different structures of animal body.
Basic Components
(i) Abundant matrix
(ii) Scattered living cells.
Differences between Ligament and Tendon

Tendon	Ligament
1.     Nature. It is tough and inelastic. 2.     White Fibres. Tendon contains parallel bundles aof white collagen fibres. 3.     Yellow Fibres. Yellow elastin fibres are absent. 4.     Fibroblasts. They occur in rows. 5.     Function. It connects a muscle to a bone.	It is strong but elastic. Bundles of white collagen fibres are arranged in various directions. Yellow elastin fibres occur in good number. Fibroblasts lie scattered. It joins a bone with another bone.

Question 8.
(a) Identify the given figures.

(b) State in brief their structure,
(c) Describe the role performed by the two.
(CCE2010, 2011)
Answer:
(a) Tracheid, vessel.
(b) Tracheid. It is an elongated lignified dead cell with wide lumen and pointed end walls.
Vessel: It is a long multicellular tubular structure having many short lignified dead cells with wide lumen and broad rup¬tured end walls arranged in a linear sequence.
Role: Both tracheids and vessels take part in transport of sap (water and mineral salts) alongwith providing mechanical strength.

Question 9.
List any six characteristics of parenchyma tissue.
(CCE2010, 2011, 2012, 2013)
Answer:

1. Type: k is a living, simple permanent tissue.
2. Cell Walls: The cell wall is thin and unlignified.
3. Cell Shape: Cells are isodiamatric, oval, rounded or po-lygonal.
4. Intercellular Spaces: Intercellular spaces are abundant so that cells are loosely packed.
5. Storage: The tissue stores nutrients and water in its cells.
6. Modifications: The tissue gets modified to form epidermis, chlorenchyma and aerenchyma.

Question 10.
From the accompanying diagram

(a) Identify the tissue
(b) Infer the characteristic features of these cells.
(c) Specify the function of the tissue
(d) Name any part of the plant where these cells are present.
(CCE2010, 2011, 2012)
Answer:
(a) Collenchyma
(b)

1. Irregular Thickening: Cells possess irregular wall thickenings, generally at the corners,
2. Intercellar Spaces:They are absent.
3. Living Simple Tissue: It is living simple tissue having large central vacuoles in its cells.

(c) Function: The tissue provides both flexibility and me-chanical strength.
(d) Location: It occurs in hypodermis of herbaceous dicot stems, leaf stalks and leaf midrib.

Question 11.
(a) Name the following structures of a neuron :

1. Single long part which arises from cell body
2. Part of neuron which bears many short branched parts.

(b) What is nerve ?
(c) Name two involuntary muscles.
(CCE2010, 2011)
Answer:
(a)

1. Axon
2. Cell body bearing dendrons and dendrites.

(b) Nerve: It is a fibrous structure formed by aggregation and linking of neurons or nerve cells that transmits electrical sig-nals between central nervous system and body tissues.
(c) Involuntary Muscles:

1. Smooth or unstriated muscles
2. Cardiac muscles.

Question 12.
How is meristematic tissue classified on the basis of its loca¬tion ? Draw a well labelled diagram to show the location of meristematic tissue in the plant body. (CCE 2010)
Answer:
On the basis of location, meristematic tissue or meristem is of three types – apical, intercalary and lateral.

Question 13.
Which permanent tissue
(a) Forms husk of coconut
(b) Stores nutrients and water in stems and roots
(c) Is irregularly thickened at the corners. (CCE 2010)
Answer:
(a) Sclerenchyma
(b) Parenchyma
(c) Collenchyma.

Question 14.
Give the location and function of the following tissues :
(a) Cartilage
(b) Areolar tissue
(c) Adipose tissue.
(CCE 2011, 2012, 2013)
Answer:
(a) Cartilage:

1. Location: Nose, ear, trachea, bronchi, larynx, bone ends.
2. Function: Providing support and elasticity to nose, ear, trachea, bronchi, larynx. Smoothening and protecting bone ends at the joints.

(b) Areolar Tissue:

1.  Location: Subcutaneous tissue between skin and muscles, inside bone marrow, binding packing and covering tissue of various body organs including blood vessels and nerves.
2. Function: Binding, packing and covering of body organs, and providing materials for repair of injuries.

(c) Adipose Tissue:

1. Location: Below skin, cushion around heart, kidneys, eye ball, in between body organs.
2. Function: Storage of fat, shock absorption and insulation.

Question 15.
Give one reson for the following statements :
(a) Blood is called connective tissue.
(b) Muscles are able to contract and relax to bring about movements
(c) Muscles of heart are called involuntary muscles.
(CCE 2011)
Answer:
(a) Blood:

1. Like other connective tissues, blood consists of living cells scattered in an abundant matrix. The matrix is liquid or plasma in blood.
2. Blood circulates throughout the body, receiving and providing materials to all tissues and organs of the body. It thus connects all parts of the body.

(b) Muscles: Muscles possess contractile myofibrils made of protein filaments. Their contraction and relaxation produce movements.
(c) Muscles of Heart: They show rhythmic contraction and relaxation throughout life. They are not under the control of will.

Question 16.
(a) Name the connective tissue that is found between skin and muscles.
(b) Draw its diagram and label any three parts.
(CCE 2011, 2012)
Answer:
(a) Areolar tissue.
(b)

Question 17.
Show the diagrammatic representation of the location of intercalary meristem and lateral meristem in plant. Name the meristem which is responsible for increase in girth of root. (CCE 2011 )
Answer:
(a)

(b) Lateral meristem

Question 18.
Define the term tissue. Differentiate between simple and permanent tissues in plants. Name the tissue which
(a) allows aquatic plants to float
(b) provides flexibility to plants.
(CCE 2011)
Answer:
Tissue: Tissue is a group of related cells that have a common origin and perform a common function.
Differences:

Simple Tissues	Complex Tissues
1. Cells: A simple tissue is formed of only one type of cells.	A complex tissue is made of more than one type of cells.
2. Activity: All the cells perform the same function.	The different cells perform different fractions of a function.
3. Types: There are three types of simple plant tissues— . parenchyma, collenchyma and sclerenchyma.	There are two types of complex plant tissues— xylem and phloem.
4. Function: They form primary structure of the plant.	They form transport system of the plant.

(a) Tissue for Floating: Aerenchyma
(b) Tissue for Flexibility: Collenchyma.

Question 19.
(a) Explain how bark/cork of a tree is formed.
(b) How does it act as protective tissue ?
(CCE 2011, 2012)
Answer:
(a) Bark is the outer dead tissue. It is mostly made of cork. It develops from outer secondary lateral meristem called phellogen or cork cambium. Cells formed on the outer side become suberised, dead and filled with tannin. They constitute cork. Cork is compact and several layers in thickness. Its outer part cracks and peels off at times.
(b) Function As Protective Tissue:

1. Bark is made of compact, dead, ’empty’, impermeable, tannin and resin containing cells which repel microbes and animals,
2. It is water proof
3. It is shock proof,
4. It provides insulation.

Question 20.
(a) Name the liquid matrix of blood,
(b) What does it contain ?
(c) List any two functions of blood.
(CCE 2011, 2012)
Answer:
(a) Plasma.
(b) It consists of water (92%), salts, proteins, nutrients (glucose, amino acids, fatty acids, vitamins), hormones and excretory products,
(c) Functions.

1. Transport of gases, nutrients, hormones and waste materials,
2. Distribution of heat.

Question 21.
Mention the type of tissue which
(a) Enables the plant to transport food materials from leaves to other parts of its body.
(b) Helps in the growth of girth of stem,
(c) Helps in the transport of water from root to other parts.
(d) Provides support to plants and also stores food.
(CCE 2011)
Answer:
(a) Phloem
(b) Lateral meristem (cambium)
(c) Xylem
(d) Parenchyma.

Question 22.
Draw the diagram of smooth muscle and cardiac muscle and label the parts. (CCE 2011)
Answer:

Question 23.

1. What type of tissue is bone ?
2. What is hard matrix made of ?
3. Write the function of ligaments and tendon.
   (CCE 2011)

Answer:

1. Bone is a skeletal connective tissue
2. Calcium and magnesium carbonate and phosphate
3. Ligament connects two bones while tendon connects a muscle to a bone.

Question 24.
Why is parenchyma called a permanent tissue ? Name two special types of parenchyma. Mention their specific roles in plants. (CCE 2011)
Answer:
Parenchyma is called permanent tissue as its cells are mature, unable to divide and have attained a permanent shape, size and function.

1. Chlorenchyma. Manufacture of food
2. Aerenchyma. Buoyancy to aquatic plants.

Question 25.
(a) Draw diagram of a muscle. Label in it

1. Spindle shaped nucleus
2. Striation

(b) List any two characteristics of this muscle. (CCE 2011)
Answer:
(a)

(b) Characteristics,

1. Long cylindrical cells with blunt ends,
2. Many peripheral nuclei.

Question 26.
What is meristematic tissue ? State its different types. Show their location in a diagram of a plant body. (CCE 2011)
Answer:
Meristematic tissue is a tissue of small thin-walled immature cells that have the ability to divide and form new cells. Location wise there are three types of meristematic tissues or meristams-apical, intercalary and lateral.

Question 27.
(a) Name the fat storing tissue of our body.
(b) Describe its structure and function with the help of a diagram. (CCE 2011, 2013)
Answer:
(a) Adipose tissue.
(b) Structure. It is a connective tissue in which there are large fat storing cells or adipocytes. Matrix is jelly like. Fibres and cells of connective tissue are also present.
Function:

1. Storage of fat.
2. Adipose tissue functions as a cushion around vital organs. It acts as an insulator.
   

Question 28.
What are the three main functions of areolar tissue ?
(CCE 2011, 2013)
Answer:

1. Packing of organs
2. Covering of organs
3. Providing materials for repair of injury.

Question 29.
Make a table to show the differences between striated, unstriated and cardiac muscles on the basis of their structure and location in the body. (CCE 2011)
Answer:

Question 30.
Write one function of each of the following tissues and also name the chemicals present in them :
(a) Sclerenchyma
(b) Collenchyma
(c) Cork cells. (CCE 2011)
Answer:
(a) Sclerenchyma. Function. Providing mechanical strength. Chemical. Lignin.
(b) Collenchyma. Function. Providing strength with flexibility. Chemical. Pectocellulose.
(c) Cork Cells. Function. Protection of internal plant tissues. Chemical. Suberin (with tannin and resin).

Question 31.
Write the term for the following tissues :
(a) That joins muscle to bone
(b) Fat reservoir of our body
(c) Supporting, filling the space inside the organs and helps in repair of tissues. (CCE 2012)
Answer:
(a) Tendon
(b) Adipose tissue
(c) Areolar tissue.

Question 32.
Label the figure and give one function of each part labelled a, b and c.(CCE 2012, 2013)

Answer:
a. Apical Meristem: Growth in length.
b. Intercalary Meristem: Growth in intenodes and leaves, bending of lodged shoots.
c. Lateral Meristem: Growth in girth.

Question 33.
(a) State one point of difference between xylem and phloem,
(b) Draw a neat diagram of xylem vessel and a tracheid. (CCE 2012)
Answer:
(a) Xylem takes part in translocation of sap (water and minerals) while phloem translocates food materials in the plant.
(b) Draw a labelled diagram given in question 8 above.

Question 34.
(a) Draw a labelled diagram of a tissue that transmits stimulus in our body,
(b) How does this tissue enables animals to move rapidly in response to stimuli ?
Answer:
(a)

(b) Nervous system is specialised to receive stimulus and provide a response to the same by activating skeletal muscles to perform the quick movements.

Question 35.
(a) Uma started walking fast when she noticed that some unknown faces are following her. Name the type of tissues which facilitated the movement of her leg bones in response to the stimulus.
(b) Draw diagram of any of the above mentioned two tissues and label any two parts.
Answer:
(a) Striated muscles and tendons, ligaments.
(b)

Question 36.
State one distinguishing feature and one similarity between two types of transporting tissues in plants. (CCE 2012)
Answer:
Transporting Tissues : Xylem (transports water and minerals) and phloem (transports food or nutrients). Similarity. Both are complex tissue, each made up of four types of cells.
Dissimilarity: Conducting channels of phloem or sieve tubes are made of living cells while conducting channels of xylem or tracheids and vessels are made of dead and empty cells.

Question 37.
Identify the simple permanent tissue and mention the location :
(a) Cells have irregular wall thickenings
(b) Tissue with large air cavity
(c) Cells are long, narrow and dead.
(CCE 2012)
Answer:
(a) Collenchyma: Hypodermis of herbaceous dicot stems, leaf stalks and leaf midrib.
(b) Aerenchyma: Stems, leaves and roots of aquatic plants.
(c) Sclerenchyma: Hypodermis of monocot stem, bundle caps, around and inside vascular bundles.

Question 38.
Identify the animal tissues from the given description and also mention their location in the human body. Tissue a. Cells are filled with fat globules and the tissue acts as an insulator. Tissue b. Has cylindrical branched cells and the tissue shows rhythmic contraction and relaxation throughout life. (CCE 2012)
Answer:
(a) Adipose Tissue: Below skin and around important organs.
(b) Cardiac Muscles: Wall of heart.

Question 39.
Write the location and one function of each
(a) Cuboidal epithelium
(b) Glandular epithelium
(c) Columnar epithelium. (CCE 2012)
Answer:
(a) Cuboidal Epithelium :

1. Location: Germinal layer, kidney tubules, salivary mammary and pancreatic ducts, thyroid vesicles,
2. Function: Gametes from germinal epithelium.

(b) Glandular Epithelium :

1. Location: Skin (sweat and oil glands), alimentary canal (digestive glands),
2. Function: Secretion of enzymes and excretion of wastes.

(c) Columnar Epithelium :

1. Location: Lining of stomach and intestine,
2. Function: Absorption in intestine.

Question 40.
Mention three characteristic features and three functions of xylem. (CCE 2012, 2013)
Answer:
Characteristic features,

1. It consists of four types of elements—tracheids, vessels, xylem parenchyma and xylem fibres.
2. Only xylem parenchyma is living. The other three are dead and lignified.
3. Tracheids and vessels are tracheary elements for which they have wide lumen and thin areas at places.

Functions,

1. Xylem conducts sap (water and mineral salts) through its tracheary elements,
2. It provides mechanical strength to the plant.
3. Xylem parenchyma stores food and helps in sideways conduction of water.

Question 41.
Show the diagrammatic representation of the location of intercalary meristem and lateral meristem in plant. Name the meristem which is responsible for

1. Increase in girth of root
2. Increase in length of roots. (CCE 2012)

Answer:

Label the two meristems.

1. Lateral meristem
2. Apical meristems.

Question 42.
Explain in brief any three roles of epidermis in plants.
(CCE 2012)
Answer:

1. Protection: Epidermis, being outer covering, protects the internal structures and prevents the entry of pathogens ‘ and pests.
2. Water Loss: Cuticular covering of epidermis reduces the rate of water loss from exposed surface.
3. Stomata: Stomata present in the epidermis regulate gaseous exchange and transpiration.

Question 43.
Make a labelled diagram to highlight two differences between striated and cardiac muscles. Write one function of striated muscles in our body. (CCE 2012)
Answer:
(a)


(b) Striated muscles being voluntary and attached to bones help in voluntary body movements including locomotion

Question 44.
Complete the following flow chart

Answer:
(a) Squamous
(b) Columnar
(c) Smooth
(d) Kidney tubules and ducts of salivary glands
(e) Attached to bones
(f) Wall of heart.

Question 45.
Name any three connective tissues. Give any one function of each. (CCE 2012)
Answer:

1. Areolar Tissue: Packing, binding, covering and repair.
2. Bone: Bony endoskeleton forms supportive framework of body.
3. Blood: It transports nutrients, metabolic wastes, gases and hormones from one part to another inside the body.

Question 46.
Name the type of epithelial tissue that lines

1. Oesophagus
2. Respiratory tract
3. Kidney tubules
4. Inner lining of intestine
5. Blood vessels
6. Ducts of salivary glands. (CCE 2012)

Answer:

1. Stratified squamous epithelium
2. Ciliated columnar epithelium
3. Cuboidal epithelium
4. Columnar epithelium
5. Squamous epithelium
6. Cuboidal epithelium.

Question 47.
(i) Draw a labelled diagram of longitudinal section of sclerenchyma
(ii) Name any two regions in the plant where this tissue is present. (CCE 2012)
Answer:
(i)

(ii) Hypodermis of monocot stem, bundle cap of young dicot stem, around and inside vascular bundles.

Question 48.
(a) Name four different types of epithelial tissue,
(b) List two functions of epithelial tissue. (CCE 2012)
Answer:
(a) Squamous, cuboidal, columnar, glandular.
(b)

1. Protection: Surface epithelium present over skin and lining of mouth protects the underlying tissues from chemicals, injury and desiccation,
2. Secretion: Glandular epithelium produces secretions like tears, mucus, gastric, juice, intestinal juice, etc.

Question 49.
Name and differentiate the type of meristematic tissues on the basis of their function. (CCE 2012)
Answer:

1. Growth in length of stem and root – apical meristem.
2. Growth in internodes and leaves – intercalary meristem.
3. Growth in girth of stem and root – lateral meristem.

Question 50.
(a) Write two differences between tendon and ligament.
(b) List any two regions of the body where cartilage is present. (CCE 2012)
Answer:
(a)

Tendon	Ligament
1.     Nature. It is tough and inelastic. 2.     White Fibres. Tendon contains parallel bundles aof white collagen fibres. 3.     Yellow Fibres. Yellow elastin fibres are absent. 4.     Fibroblasts. They occur in rows. 5.     Function. It connects a muscle to a bone.	It is strong but elastic. Bundles of white collagen fibres are arranged in various directions. Yellow elastin fibres occur in good number. Fibroblasts lie scattered. It joins a bone with another bone.

(b) Tip of nose, pinna.

Question 51.
(a) Which element of phloem comprises dead cells ?
(b) Give one function each of tracheids and vessels and xylem parenchyma,
(c) Draw a diagram of xylem
parenchyma and label nucleus. (CCE 2012)
Answer:
(a) Phloem or bast fibres,
(b)

1. Tracheids and vessels – transport of sap
2. Xylem parenchyma – lateral transport of sap.

(c)

Question 52.
Write difference amongst striated muscles, smooth muscles and cardiac muscles on the basis of their shape and number of nuclei?
Answer:

Question 53.
Name the plant tissue which is associated with the conduction of water in the plant body. Why is this tissue called complex tissue, (CCE 2012)
Answer:

1. Xylem.
2. Xylem is called complex tissue because it is made of more than one type of cells.
3. Components: Tracheids, vessels, xylem fibres and xylem parenchyma.

Question 54.
List three differences between striated/limb muscles and smooth/stomach muscles. (CCE 2012, 2013)
Answer:

Question 55.
(a) Why are complex tissues called so ?
(b) Write names of complex tissues.
(c) State the functions of these tissues.
(CCE 2013)
Answer:
(a) Complex Tissues. They are permanent plant tissues which are made of more than one type of cells which work together to perform a particular function,
(b) There are two types of complex tissues, xylem and pholem.
Functions:

1. Transport of sap (water + minerals).
2. Translocation of food.

Question 56.
Draw a diagram of smooth muscle fibre and label any three parts. Give one function of smooth muscles.
(CCE 2013)
Answer:

Function: Sustained involuntary contraction activity as in peristalsis.

Question 57.
(a) Name the tissue which joins :
(i) Muscle to bones
(ii) Bones to bones
(b) Which of the two is
(i) More elastic
(ii) Stronger ? (CCE 2013)
Answer:
(a) (i) Tendon
(ii) Ligament
(b) (i) Ligament
(ii) Tendon.

Question 58.
Animal tissues are different from plant tissues. State reason.
(CCE 2013, 2014)
Answer:

1. Mobility: Plants are stationary. They have more of dead supportive tissues for mechanical strength. Animals are mobile. Most of their tissues are living, requiring more energy for maintenance.
2. Growth: Plants continue to grow throughout life while animals stop growing after becoming mature. Plants have meristematic tissue which is absent in animals.
3. Structural Organisation: Animals have more complex strucmral organisation due to higher level of specialisation.
   Plants have simpler organisation.

Question 59.
Write one term for the following tissues
(a) that joins muscle to bone
(b) fat reservoir of our body
(c) supporting, fills the space inside the organs and helps in repair of tissues. (CCE 2013)
Answer:
(a) Tendon
(b) Adipose tissue
(c) Areolar tissue.

Question 60.
Name the tissue found in the following locations,
(a) Haversian canal
(b) Chondrocyte
(c) Eosinophils. Give one function of each of these. (CCE 2013, 2015)
Answer:
(a) Haversian Canal. Bone. Forms supporting framework of body.
(b) Chondrocyte. Cartilage. Support with flexibility (as in pinna).
(c) Eosinophils. Blood. Transport of nutrients, metabolic j wastes, gases, hormones, etc.

Question 61.
Draw a well labelled diagram of phloem tissue.
(CCE 2013)
Answer:

Question 62.
Name the following and give one characteristic of each :
(a) Living tissue that provides mechanical support in plants.
(b) Highly specialised cells for being stimulated and then transmitting the stimulus very rapidly within the body of animais,
(c) Animal tissue with elongated cells and contractile proteins responsible for movement. (CCE 2013, 2015)
Answer:
(a) Collenchyma: Irregular thickening of pectocellulose generally at the corners.
(b) Neurons: Tree-like branching, have cell body with dendrites, axon with terminal arborisations,
(c) Muscle fibre: Cylindrical multinucleate cells with light and dark bands.

Question 63.
Name the permanent tissue which
(a) Forms husk of coconut
(b) Gives flexibility to the plant,
(c) Are loosely packed cells with presence of chlorophyll. (CCE 2013)
Answer:
(a) Sclerenchyma
(b) Collenchyma
(c) Chlorenchyma.

Question 64.
(a) Name the muscle :
(i) Which is present exclusively in the heart
(ii) Which is attached to the bones and helps in voluntary movement. )
(b) Write the structural differences between them
(c) Draw their neat and labelled diagram. (CCE 2013)
Answer:
(a)
(i) Cardiac
(ii) Striated or skeletal
(b)

(c)

Question 65.
Identify the type of tissues in the following :
(a) Vascular bundle
(b) Inner lining of intestine
(c) Lining of kidney tubule
(d) Iris of eye
(e) Muscles of heart
(f) Bronchi of lungs. (CCE 2013)
Answer:
(a) Vascular tissues, xylem and phloem.
(b) Columnar epithelium
(c) Cuboidal epithelium
(d) Smooth muscle
(e) Cardiac muscle
(f) Smooth muscles, cartilage, ciliated columnar epithelium.

Question 66.
(a) Why do sclerenchyma cells have a narrow lumen ?
(b) Where are these tissues present and why ?
(CCE 2014)
Answer:
(a) Due to excessive thickening and lignification of wall and degeneration of protoplasmic contents.
(b) Sclerenchyma occurs as hypodermis in monocot stem, around vascular bundles, inside vascular tissues, hard covering of seeds, etc., for mechanical strength and protection.

Question 67.
(d) Mention different types of blood cells.
(b) Which substances are transported by blood.
(CCE 2014)
Answer:
(a) Blood Cells. Three types.

1. Biconcave enucleate coloured red blood corpuscles (erythrocytes, RBCs).
2. Nucleated, colourless, white blood corpuscles capable of changing shape (leucocytes, WBCs).
3. Nonnucleated small colourless cell fragments called blood platelets.

(b) Transport. Blood transports nutrients (e.g., glucose, amino acids, fatty acids), metabolic gases (02, C02), metabolic wastes (e.g., urea, uric acid), hormones, etc.

Question 68.
Differentiate between xylem and phloem tissues.
(CCE 2014, 2016)
Answer:

Xylem	Phloem
I. Conduction. It conducts water and minerals.	Phloem conducts organic solutes or food materials.
2. Direction. Conduction is mostly unidirectional.	Conduction can be bidirectional.
3. Channels. Conducting channels or tracheary elements are tracheids and vessels.	Conducting channels are sieve tubes.
4. Components. Xylem consists of tracheids, vessels,xylem parenchyma and xylem fibres.	Phloem consists of sieve tubes, companion cells, phloem parenchyma and phloem fibres.
5. Dead/Living Parts. Three of the four elements of xylem are dead (viz., tracheids, vessels and fibres). Only xylem parenchyma is living.	Three of the four elements are living (viz., sieve tubes,companion cells and phloem parenchyma). Only phloem/fibres are dead.
6. Mechanical Strength. In addition to conduction, xylem provides mechanical strength to the plant.	There is little mechanical function of phloem.

Question 69.
Establish the relationship between the structure, function and location in each case :
(a) Bone
(b) Areolar tissue
(c) Striated muscle. (CCE 2014, 2015)
Answer:
(a) Bone

1. Structure: It is hard connective tissue having a matrix of collagenous protein ossein and mineral matter, mostly of calcium and phosphorus laid down in lamellae around Haversian canals, Living osteocytes are stellate and occur in branched fluid-filled lacunae.
2. Function: Framework of body, movement and protection to vital organs.
3. Location: Inside the body as endoskeleton.

(b) Areolar Tissue: It is a simple connective tissue that possesses a jelly-like matrix, both white and yellow elastin fibres, fibroblasts, mast cells, plasma cells, macrophages and immunocytes.
Location: Inside and outside organs and tissues and as subcutaneous tissue.
Functions:

1. Binding: Packing and Covering. Areolar tissue functions as binding, packing and covering tissue around and inside various body organs,
2. Repair: Areolar tissue provides materials for repair of injuries.

(c) Striated Muscle:

1. Structure: Long, cylindrical cells with alternate light and dark bands and many oval peripheral nuclei,
2. Function: Voluntary body movements including locomotion.
3. Location: In limbs attached to bones, neck, face, bodywall, tongue, pharynx, diaphragm, upper part of oesophagus.

Question 70.
State the location and function of columnar epithelium. When and how is it modified ? Write the function of this modified tissue. (CCE 2014)
Answer:
(a) Location: Lining of stomach and intestine,
Function: Absorption in intestine.
(b) Modification
(i) Microvilli or tiny finger like projections on free surface (as in intestine) for increasing absorptive surface
(it) Cilia in respiratory tract and oviducts for producing slow pushing of materials.

Question 71.
Differentiate between different types of simple permanent tissues.
Answer:

Question 72.
Write two similarities and four differences between striated and cardiac muscles. (CCE 2014)
Answer:
(a) Similarities.
(i) Both are cylindrical cells with broad ends,
(ii) They contain striations or alternate light and dark bands.
(b) Differences

Question 73.
Differentiate between bone and cartilage with respect to structure, function and location. (CCE 2014)
Answer:

Question 74.
Classify permanent tissues in plants. (CCE 2014)
Answer:
Permanent tissues are of two types, simple (three in number)and complex (two in number).

Question 75.
Describe the structure, function and location of nervous tissue. (CCE 2014)
Answer:
Structure: Nervous tissue consists of neurons or nerve cells surrounded by special connective tissue cells. Each neuron consists of a nucleated cell body, small branched afferent dendrites and a long fibre-like efferent axon with terminal branches having knobs or boutons.
Function: Nervous tissues is specialised to pick up sensations, rapidly transmit the impulses, integrate and respond to the same.
Location: It occurs in brain, spinal cord and nerves.

Question 76.
Write six functions of the epithelial tissue.
(CCE 2015)
Answer:

1. Protection of underlying tissues from drying up, microbes, chemicals and injury.
2. Absorption in intestine.
3. Excretion in uriniferous tubules.
4. Exchange of gases in alveoli
5. Secretion by glandular epithelium.
6. Formation of gametes by germinal epithelium.

Question 77.
Explain the basic characteristics for classification of permanent tissues in plants. (CCE 2015, 2016)
Answer:
Basic characteristics for classification of permanent tissues are simple or complex nature and types of their specialisation. Simple Permanent Tissues. The tissues are made up of one type of cells. Depending upon their living or dead nature and thickening, simple permanent tissues are of 3 types :

1. Parenchyma: Thin walled, living.
2. Collenchyma: Uneven thickening of pectocellulose, living.
3. Sclerenchyma: Thick walled, lignified, dead.

Complex Permanent Tissues. The tissues are made up of more than one type of cells. They are of two types.

1. Xylem: Consists of tracheids, vessels, fibres and parenchyma,
2. Phloem: Consists of sieve tubes, companion cells, parenchyma and fibres.

Question 78.

1. What type of tissue is blood ?
2. What are the types of muscle fibres ?
3. Write the functions of ligaments and tendons. (CCE 2015)

Answer:

1. Connective tissue,
2. Unstriped (smooth), striped (striated) and cardiac,
3. Ligament: Connecting bone to bone and allowing movement including rotational. Tendon. Connecting muscle to bone for body movements.

Question 79.
Give one important functional difference amongst the muscle tissues and draw a labelled diagram of the muscle tissue which never shows fatigue. (CCE 2015)
Answer:

1. Muscle tissues are of three types – striated, smooth and cardiac.
2. Striated (= skeletal) muscle brings about voluntary movements of body parts, e.g., movement of arms.
3. Smooth (Unstriated) muscle performs involuntary movements like peristalsis for passage of food in the alimentary canal.
4. Cardiac muscle performs involuntary non-fatigued movement of heart in pumping blood to all body parts.

Question 80.
Complete the following flow diagram : (CCE 2015)

Answer:
a – Permanent tissue.
b – Intercalary
c – Lateral
d – Complex
e – Sderenchyma
f – Phloem.

Question 81.
(a) Name the animal tissue which is present in the larynx,
(b) Write the chemical constituents of this tissue,
(c) What function does this tissue perform ? (CCE 2016)
Answer:
(a) Tissue Present in Larynx. Cartilage,
(b) Chemical Constituents. Its matrix is made of protein sugar complex called chondrin.
(c) Function. Providing both support and flexibility besides showing little wear and tear.

Question 82.
State the location and function of columnar epithelium. Where and how is it modified ? Write the function of this modified tissue. (CCE 2016)
Answer:
Location: Simple columnar epithelium occurs in the lining layer of stomach, intestine and their glands. Modified columnar epithelium called pseuddstratified epithelium occurs in the nasal and genital tracts. Stratified columnar epithelium forms covering layer of epiglottis.
Functions:

1. Absorption: As lining layer of intestine, columnar epithelium is specialised to absorb nutrients.
2. Mucus: Goblet cells, which are modfied columnar cells, produce mucus.
3. Glandular Epithelium: It is a component of most glandular epithelia.
4. Protection: Being a surface layer, it provides protection to underlying tissues.

Question 83.
(a) Name the following tissues :
(i) The tissue which gives flexibility to plants,
(ii) Tissue which gives support to the plants and also stores food.
(b) Write two structural differences between the above two tissues.
(c) In desert plants the epidermis has a thick waxy coating. Why ? (CCE 2016)
Answer:
(a)
(i) Collenchyma
(ii) Parenchyma.
(b)

(c) Waxy coating or cuticle (cutin + wax) also provides strength to epidermis, protection against abrasive action of wind, attack by microbes.

Question 84.
Write one important function of
(a) Xylem
(b) Phloem
(c) Meristematic tissue. (CCE 2016)
Answer:
(a) Xylem: Transport of sap.
(b) Phloem: Translocation of food (organic nutrients),
(c) Meristematic Tissue: Cell division, producing cells for growth and differentiation.

Question 85.
Name the tissue associated with the following :
(a) Haversian Canal
(b) Chondrocyte
(t) Eosinophils. Give one function of each of these. (CCE 2016)
Answer:
(a) Haversian Canal. Bone. Endoskeleton.
(b) Chondrocyte. Cartilage. Parts of endoskeleton as ends of long bones, support for softer organs, (c) Eosinophils. Blood. Transport and immunity.

Question 86.
Answer the following :

1. Draw a labelled diagram of smooth muscle
2. Differentiate between parenchyma and collenchyma
3. Mention the constituents of blood.
4. Name the epithelial tissue which has hair like projections on the outer surface
5. Name the tissue that stores fat in the body. (CCE 2016)

Answer:

1. 
2. 
3. Constituents of Blood: Plasma and blood cells. Blood cells are of three type—RBCs, WBCs and platelets,
4. Ciliated: Ciliated Columnar and ciliated cuboidal.
5. Adipose tissue.

Question 87.
(a) Mention two functions of stomata
(b) Which tissue surrounds stomata ? (CCE 2016)
Answer:
(a) Functions of Stomata:

1. Gaseous Exchange: Stomata are sites where exchange of gases (carbon dioxide and oxygen) occurs between the plant interior and external environment.
2. Transpiration: Major part of transpiration occurs through stomata. Transpiration removes excess water and keeps plant surfaces cool even in bright sun.
3. Regulation: They regulate both gaseous exchange and transpiration.

(b) Epidermis.

Question 88.
(a) Blood is called fluid connective tissue. State reason.
(b) Name the various components of blood.
(c) State the main function of blood. (CCE 2016)
Answer:
(a) Blood as Fluid Connective Tissue:

1. Blood is considered connective tissue as it contains cells suspended in a fluid matrix,
2. Further, it connects all parts of the body receiving and providing materials every where.

(b) Components of Blood: Plasma or matrix – 55%, Blood cells – 45%. Plasma has 90 – 92% water, 8 – 10% organic and inorganic substances. Blood cells are of two types, haemoglobin containing red blood corpuscles (RBCs) and colourless white blood corpuscles (WBCs). Blood platelets are cell fragments present in blood.
(c) Main Function of Blood:
Transport: Blood transports gases, nutrients, hormones and waste materials to various parts of the body.

Long Answer Questions

Question 1.
(a) What is ligament ? Mention its function.
(b) What is areolar tissue and where is it formed ? Give its two functions. (CCE 2010, 2012)
Answer:
(a) Ligament: It is dense, cord-like fibrous connective tissue that binds a bone with another bone. Function. Because of its elasticity, ligament allows bending and rotational movements over a joint.
(b) Areolar Tissue: It is a simple connective tissue that possesses a jelly-like matrix, both white and yellow elastin fibres, fibroblasts, mast cells, plasma cells, macrophages and immunocytes.
Location: Inside and outside organs and tissues and as subcutaneous tissue.
Functions:

1. Binding: Packing and Covering. Areolar tissue functions as binding, packing and covering tissue around and inside various body organs,
2. Repair: Areolar tissue provides materials for repair of injuries.

Question 2.
(a) What is stratified squamous epithelium. State its functions.
(b) Name the type of tissue whose cells are filled with fat globules. State its functions. (CCE 2010, 2012, 2013)
Answer:
(a) Stratified Squamous Epithelium. It is a multilayered epithelial tissue whose basal layer lying in contact with basement membrane is capable of adding new cells to the outer layers.
Functions: It provides protection to underlying tissue from abrasion, mechanical stresses and irritating chemicals.
(b) Adipose tissue.
Functions:

1. Storage of fat.
2. Formation of shock absorbing cushions around important organs.
3. Formation of insulation layer below the skin to protect from loss of body heat,
4. Providing shape to body parts.

Question 3.
(a) Name four components of phloem.
(b) What is meristematic tissue ? State its different types. Show their locations in diagram of a plant body. Give classification of meristems. (CCE 2010)
Answer:
(a)

1. Sieve tube cells
2. Companion cells
3. Phloem Paren­chyma
4. Phloem fibres.

(b) On the basis of location, meristematic tissue or meristem is of three types – apical, intercalary and lateral.
Classification: Primary and secondary. Primary Meristems. Apical, intercalary Secondary Meristems. Lateral meristems (vascular cambium, cork cambium)

Question 4.
(i) Define tissue. What is utility of tissues in multicellular organisms ?
(ii) Are plants and animals made of same types of tissues ? If no, then write the points of difference. (CCE 2013)
Answer:
(i) Tissue is a group of related cells that have a common origin and perform a common function.
Utility of Tissues:

1. Division of Labour: Tissues bring about division of labour in multicellular organisms. It increases efficiency.
2. Higher Organisation: Tissues become organised to form organs and organ systems.
3. Individual Cells: Work load of individual cells has decreased.
4. Higher Survival: Because of division of labour, higher efficiency and organisation, the multicellular organisms have high survival.

(ii) Tissues in Plants and Animals. Plants and animals are not made of same type of tissues.
Differences:

Plant Tissues	Animal Tissues
1. Abundance. Dead supportive tissues are more abundant as compared to living tissues.	Living tissues are more common as compared to dead tissues.
2. Maintenance Energy. They require less maintenance energy.	Animals require more maintenance energy.
3. Basic Nature. There is differentiation of meristematic and permanent tissues.	Such a differentiation is absent.
4. Meristematic Tissue. Due to its activity plants continue to grow throughout life.	It is absent. Animals do not show growth after reaching maturity. Reparative growth is, however, present.
5. Organisation. It is simple.	Organisation is complex with the development of more
6. Purpose. Tissue organisation is towards stationary habit.	specialised and localised organs and organ systems. Tissue organisation is towards high mobility.

Question 5.
(a) Analyse the reason behind the following statements :

1. Epidermis is thicker in desert plants though it is usually single layered
2. Presence of waxy layer (secreted by spidermis) on the outer surface of plants.

(b) Discuss the cell arrangement which supports the fact that epidermis is a protective tissue. (CCE 2013)
Answer:
(a)

1. Thick epidermis is a device to provide extra protection to desert plants against excessive transpiration and loss of turgidity.
2. Waxy coating or cuticle (cutin + wax) also provides strength to epidermis, protection against abrasive action of wind, attack by microbes.

(b) Epidermis forms a complete covering having closely packed elongated cells with no intercellular spaces.

Question 6.
Identify the following muscular tissues and draw their diagrams :
(a) This tissue is mostly attached to bones and helps in body movements.
(b) This tissue is found in the iris of eye and bronchi of lungs.
(c) This tissue contracts and relaxes rapidly and rhythmically throughout life. (CCE 2013)
Answer:
(a) Striated muscle.

(b) Smooth muscle.

(c) Cardiac muscle.

Question 7.
Name a connective tissue which is the hardest. What makes it so hard ? List any three important functions of this tissue. (CCE 2013)
Answer:
Bone: Bone is made hard by the deposition of carbonates and phosphates of calcium and magnesium in its matrix.

Functions,

1. Attachment: Connective tissue binds different structures of the body, e.g., bone with bone, muscle with bone, muscle with skin.
2. Packing: It forms the packing material in different organs.
3. Various organs of the body are covered by protective sheaths of connective tissue.
4. Connective tissue forms shock absorbing cushions around several organs, e.g., eye, heart, kidneys.
5. Skeletal connective tissue (bones, cartilages) forms supportive framework of the body.
6. Vascular tissue (fluid connective tissue) forms an internal transport system of the body.
7. A number of cells present in the connective tissue provide protection against microbes and toxins.
8. Storage: Fat is stored in connective tissue called adipose tissue.
9. Formation of Blood Cells: Red bone marrow is a connective tissue specialised to form blood cells.
10. Components of connective tissue are involved in repair of injuries.

Question 8.
(a) Draw a neat diagrams of transverse section of parenchyma tissue and label four parts on it.
(b) Write any two differences between parenchyma and collenchyma. (CCE 2013)
Answer:
(a)

(b)

Question 9.
The growth of plant occurs in specific regions.
(i) Name the tissue which is responsible for this growth,
(ii) State the different types of this tissue,
(iii) Write one function of each of the above mentioned tissue. (CCE 2014)

Answer:
(i) Tissue: The tissue responsible for growth in specific regions of the plant is called meristematic tissue or meristem.
(ii) Types: Depending upon the region of occurrence, meristems are of three types—apical, intercalary and lateral. Apical meristem occurs over the tips of stem, root and their branches. Intercalary meristem occurs at leaf bases and above or below stem nodes. Lateral meristem is peripheral in stem and root. It has two types, vascular cambium and cork cambium.
(iii) Function:

1. Apical Meristem. Growth in length of stem and root,
2. Intercalary Meristem. Elongation of internodes, upward bending of lodged stems.
3. Lateral Meristem. Growth in girth of stem and root and formation of cork or bark on their outside for protection.

Question 10.
Draw a labelled diagram of section of phloem. Name the four types of elements found in phloem. With respect to conduction, what is the main difference between xylem and phloem. (CCE 2014)
Answer:

Four Elements. Sieve tubes, companion cells, phloem parenchyma and phloem fibres.
Differences in Conduction:

Xylem	Phloem
1. Conduction. Xylem conducts sap (water + minerals)	1. It conducts organic solutes or nutrients.
2. Direction : Conduction is mostly unidirectional, upwardly from roots to stem tips and leaves.	2. Conduction is often bidirectional from leaves to roots and stem tips.

Question 11.
Based upon their location and function differentiate amongst the three types of meristematic tissues. Draw a diagram to show the location of the three tissues in a plant. (CCE 2014)
Answer:
Types: Depending upon the region of occurrence, meristems are of three types—apical, intercalary and lateral. Apical meristem occurs over the tips of stem, root and their branches. Intercalary meristem occurs at leaf bases and above or below stem nodes. Lateral meristem is peripheral in stem and root. It has two types, vascular cambium and cork cambium.
Function:

1. Apical Meristem. Growth in length of stem and root,
2. Intercalary Meristem. Elongation of internodes, upward bending of lodged stems.
3. Lateral Meristem. Growth in girth of stem and root and formation of cork or bark on their outside for protection.
   

Question 12.
Complete the following table for plants.

Answer:
A—xylem.
B—phloem.
C—vessels.
D— tracheids.
E—xylem fibres.
F—xylem parenchyma.
G—sieve tubes.
H—companion cells.
I—phloem, parenchyma.
J-phloem fibres.

Question 13.
(a) Show a diagrammatic representation of the location of lateral meristem and intercalary meristem in plant body.
(b) Name the meristem responsible for increase in girth of root or stem.
(c) Write two difference between meristematic and permanent tissues in a tabular form. (CCE 2014)
Answer:
(a)

(b) Lateral meristem.
(c)

Meristematic Tissue	Permanent Tissue
1. Nature. The cells are small, isodiametric and undifferentiated.	The cells are large, differentiated with different shapes.
2. Spaces. Intercellular spaces are absent.	Intercellular spaces are often present.
3. Vacuoles. They are nearly absent.	Large central vacuole occurs in living permanent cells.
4. Nucleus. It is large and prominent.	Nucleus is less conspicuous.
5. Wall. Cell wall is thin.	Cell wall is thin or thick.
6. Divisions. The cells undergo regular divisions.	The cells do not normally divide.
7. Metabolism. Rate of metabolism is high.	Metabolic rate is comparatively slower.
8. Life. The cells are living.	The cells may be living or dead.
9. Function. It takes part in growth.	It provides protection, support, conduction, photosynthesis, storage, etc.

Question 14.
(a) Draw diagram of neuron and label the following points on it

1. Single long part of nerve cell
2. Short branched parts
3. Nucleus
4. Cell body.

(b) Name two tissues whose combination enables animals to move rapidly in response to stimuli. (CCE 2014)
Answer:
(a)

1. Axon
2. Dendrons.

(b) Nervous and muscular.

Question 15.
(a) Explain the formation of complex permanent tissues in plants. Mention the two types of complex tissues and write their functions.
(b) How simple permanent tissues are different from complex permanent tissues ? (CCE 2014)
Answer:
(a) Terrestrial plants being large and fixed not only require supportive tissues but also conducting tissues. Conducting tissues are complex. They have both supportive and conducting elements. The two types of complex plant j tissues are xylem and phloem.
Functions:
Xylem—Transport of sap (water + minerals).
Phloem —Translocation of food.
(b) Differences:

Simple Tissues	Complex Tissues
1. Cells: A simple tissue is formed of only one type of cells.	A complex tissue is made of more than one type of cells.
2. Activity: All the cells perform the same function.	The different cells perform different fractions of a function.
3. Types: There are three types of simple plant tissues— . parenchyma, collenchyma and sclerenchyma.	There are two types of complex plant tissues— xylem and phloem.
4. Function: They form primary structure of the plant.	They form transport system of the plant.

Question 16.
(a) Define epithelial tissue.
(b) Name the type of epithelial tissue found in the following j organs. Also draw the diagram of each tissue :

1. Skin
2. Inner lining of intestine
3. Ducts of salivary glands, (CCE 2014)

Answer:
(a) Epithelial tissue or epithelium is unilayered or multilayered animal tissue of compacdy arranged cells that overlies a basement membrane and forms a covering over external and internal surfaces of body parts.
(b)

1. Skin: Stratified squamous epithelium.
   
2. Inner Lining of Intestine: Simple columnar epithelium, (but no cilia)
3. Ducts of Salivary Glands: Stratified cuboidal epithelium.

Question 17.
(a) Draw a neat diagram of transverse section ot collenchyma tissue and label any four parts on it.
(b) Write two differences between parenchyma and collenchyma tissue. (CCE 2014)
Answer:
(a)

(b)

Question 18.
Draw a labelled diagram of unstriated muscle tissue and mention its occurrence, features and functions. (CCE 2014)
Answer:

Occurrence. Inside visceral organs of the body like gastrointestinal tract, blood vessels, bronchi, urinary bladder, iris, etc.
Features:

1. Spindle shaped, unbranched,
2. Contractile myofibrils present but do not form striations,
3. A single central nucleus.

Functions: They perform sustained involuntary contractions without getting fatigued.

Question 19.
Complete the following table : (CCE 2015)

Answer:
Husk of coconut : Tissue – Simple. Types of Tissue – Sclerenchyma. Cells – Dead. Main function – Mechanical strength / protection.
In leaf stalk below epidermis : Tissue – Simple. Type of Tissue – Collenchyma. Cells – Living. Main function – Mechanical strength with flexibility.

Question 20.
Name the tissue whose cells are highly specialized for being stimulated and then transmitting the stimulus from one place to another within the body. Mention three organs in our body which are composed of this tissue. What are the cells of this tissue called ? Name two tissues in animals the combination of which enables animals to move rapidly in response to stimuli. (CCE 2015)
Answer:

1. Tissue: Nervous tissue
2. Organs: Brain, Spinal cord, Nerves
3. Cells: Neurons
4. Tissues for Mobility: Skeletal tissues, Muscular tissue.

Question 21.
Analyse the significance of specialised epithelial tissue present in the following :
(a) Ciliary columnar epithelium in respiratory tract
(b) Stratified squamous epithelium in skin
(c) Cuboidal epithelium in kidney tubules
(d) Columnar epithelium in inner lining of intestine
(e) Squamous epithelium in lining of oesophagus.
(CCE 2016)
Answer:
(a) Ciliary Columnar Epithelium in Respiratory Tract. Pushing out the trapped dust particles and microbes.
(b) Stratified Squamous Epithelium in Skin. Protection from injury, abrasion, irritating chemicals and entry of germs.
(c) Cuboidal Epithelium in Kidney Tubules. Secretion and reabsorption.
(d) Columnar Epithelium in Intestine. It is specialised to absorb nutrients.
(e) Squamous Epithelium in Oesophagus. Protection against abrasion, microbes and toxins.

Question 22.
Name two simple permanent tissues which have living cells. Write two distinguishing features of each. Mention their location and functions. (CCE 2016)
Answer:
Simple Permanent Tissues with Living Cells. Parenchyma, Collenchyma.
Parenchyma
Features:

1. Thin-walled nearly isodiametric
2. Cells are loosely packed with intercellular spaces.

Location:

1. In all parts of the plant body (stem, root, leaves, flowers, fruits, seeds),
2. Mesophyll of leaves.

Functions:

1. Storage of food,
2. Providing turgidity or rigidity to soft parts by remaining turgid.
3. Chlorenchyma as seat of photosynthesis.
4. Aerenchyma having large air cavities for providing buoyancy,
5. Epidermis forming external covering of softer plant parts.

Collenchyma
Features: The cells possess uneven thickenings of pectocellulose.
Location: Below epidermis in herbaceous dicot stems, leaf stalks and midribs.
Functions:

1. It is living mechanical tissue which provides both mechanical strength and flexibility
2. The tissue allows growth,
3. It takes part in storage,
4. It may contain chloroplasts and take part in photosynthesis.

Question 23.
(a) Show the diagrammatic representation of location of lateral meristem and intercalary meristem in plant body
(b) Name the meristem responsible for increase in girth of < root or stem,
(c) Write two differences between meristematic and permanent tissues in a tabular form. (CCE 2016)
Answer:
(a)

(b) Lateral meristem (mainly vascular cambium).
(c)

Meristematic Tissue	Permanent Tissue
1. Nature. The cells are small, isodiametric and undifferentiated.	The cells are large, differentiated with different shapes.
2. Spaces. Intercellular spaces are absent.	Intercellular spaces are often present.
3. Vacuoles. They are nearly absent.	Large central vacuole occurs in living permanent cells.
4. Nucleus. It is large and prominent.	Nucleus is less conspicuous.
5. Wall. Cell wall is thin.	Cell wall is thin or thick.
6. Divisions. The cells undergo regular divisions.	The cells do not normally divide.
7. Metabolism. Rate of metabolism is high.	Metabolic rate is comparatively slower.
8. Life. The cells are living.	The cells may be living or dead.
9. Function. It takes part in growth.	It provides protection, support, conduction,photosynthesis, storage, etc.

Question 24.
(a) Draw a neat diagram of transverse section of collenchyma tissue and label on it any four parts,
(b) Write , any two differences between parenchyma and collenchyma.
(CCE 2016)
Answer:
(a)

(b)

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 6 Tissues are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Chapter 10 Gravitation Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Gravitation Class 9 Important Questions and Answers Science Chapter 10

VERY SHORT ANSWER QUESTIONS

Based on gravitation and Newtons law of gravitation

Question 1.
What do you mean by gravitation ? (CBSE 2012)
Answer:
The force of attraction between any two particles in the universe is called gravitation.

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2.
State Universal law of gravitation.

Or

How is the force of attraction dependent on the masses of objects and distance between them ?
(CBSE 2014)
Answer:
Each object on the universe attracts other object with a’ force known as gravitational force. The force of attraction between two objects is directly proportional to

1. the product of masses of the objects and
2. inversely proportional to the square of distance between them. That is,
   

Question 3.
The distance between two particles is decreased. Will the gravitational force between them increase or decrease ?
Answer:

So, gravitational force (F) increases when the distance (r) between two particles decreases. r

Question 4.
An iron ball exerts a force F on the rubber ball. How much force, the rubber ball will exert on the iron ball ?
Answer:
The rubber ball also exerts the same force F on the iron ball.

Question 5.
Define Universal gravitational constant (G).
Answer:
Universal gravitational constant is defined as the force of attraction between two objects of unit masses separated by unit distance.

Question 6.
Write down the unit of ‘G’ in S.I.
Answer:
Nm² kg^-2.

Question 7.
What is the value of ‘G’ ?
Answer:
G = 6.673 x 10^-11 N m² kg^-2.

Question 8.
The value of G = 6.673 x 10^-11 Nm² kg^-2 on the surface of the earth. What is the value of G on the surface of the moon ? (CBSE Sample Paper; CBSE 2011, 2013, 2014)
Answer:
The value of G on the surface of the moon
= value of G on the surface of the earth (i.e., 6.673 x 10^-11 Nm² kg^-2).

Question 9.
The gravitational force between two objects on the earth is 2 N. What will be the gravitational force between these two objects on the surface of the moon ?
Answer:
Same force i.e. 2 N.

(∴ F and G has the same value on the surface of earth and on the surface of moon).

Question 10.
State one phenomena related to universal law of gravitation.
Answer:
The atmosphere of earth is possible due to this law.

Question 11.
Name the force which is responsible for the revolution of planets around the sun. (CBSE 2015)
Answer:
The gravitational force of attraction between the planet and the sun. This force provides the necessary centripetal force to the planet to move in a circular orbit around the sun.

Question 12.
Name the force which is responsible for the revolution of moon around the earth.
Answer:
The gravitational force between the earth and the moon provides the centripetal force to the moon to move in a circular path around the earth.

Question 13.
The earth is acted upon by the gravitational force of attraction due to the sun. Then why does the earth not fall towards the sun ?
Answer:
Gravitational force of attraction on the earth due to the sun provides the necessary centripetal force to the earth to move around the earth. Hence, earth does not fall towards the sun.

Question 14.
State two factors on which gravitational force between two objects depends.
Answer:

1. Mass of the objects,
2. distance between them.

Question 15.
The gravitational force between two objects is F. How will the force change when the distance between them is reduced to 1/4 th ?
Answer:

Question 16.
Is the force of gravity stronger on a piece of iron than on a piece of wood if both have the same mass ?
(CBSE 2015)
Answer:
No. Force of gravity on a piece of iron is equal to the force of gravity on a piece of wood because F = mg.

Question 17.
When a stone is thrown vertically upwards, its velocity is continuously dedfeased. Why ? (CBSE 2015)
Answer:
When a stone is thrown vertically upwards, a force called gravitational force pulls the stone continuously in the downward direction. Hence, velocity of the stone is decreased continuously.

Based on free fall and acceleration due to gravity

Question 18.
The factor associated with the motion of an object are : Force, velocity, acceleration and momentum. Out of these four factors which one remains constant for all bodies large or small, undergoing a free fall.
(CBSE 2013, 2015)
Answer:
Acceleration of a freely falling object remains constant as it does not depend on the mass of the object.

Question 19.
Two objects of masses and M2 are dropped in vacuum from a height above the surface of earth (Mt> M2). Which one will fall the ground first, and why ?
Answer:
Both objects will fall on the ground simultaneously as the acceleration (known as acceleration due to gravity) with which an object falls towards the earth is constant irrespective of the mass of the object.

Question 20.
When an object is dropped from a height, it accelerates when it falls down. Name the force which accelerates the object.
Answer:
Gravitational force between object and earth (i.e., gravity).

Question 21.
State the type of motion shown by a freely falling stone. (CBSE 2015)
Answer:
Uniformly accelerated motion.

Question 22.
Write the expression for the acceleration due to gravity. GM
Answer:

Question 23.
What is the SI unit of acceleration due to gravity (g) ?
Answer:
m s^-2.

Question 24.
What is the value of acceleration due to gravity on the surface of earth ?
Answer:
g = 9.8 m s^-2

Question 25.
What is the value of acceleration due to gravity on the surface of moon ?
Answer:
g = 1.6 m s^-2 on the surface of moon.

Question 26.
What is the direction of acceleration due to gravity ?
Answer:
Towards the centre of the earth.

Question 27.
What will be the direction of acceleration due to gravity if the body is thrown vertically upward ?
Answer:
The direction of acceleration due to gravity is always towards the centre of the earth i.e. in the downward direction.

Question 28.
Is value of ‘g’ same at all ‘places on the earth ? Give reason for your answer. (CBSE 2011)
Answer:
No.

Since polar radius (distance of pole from the centre of earth) is less than the equatorial
radius, therefore, the value of ‘g is more at poles than at equator.

Question 29.
Where is the value of ‘g’ equal to zero on earth ?
Answer:
At the centre of the earth.

Question 30.
An object of mass 2 kg falls with an acceleration of 9.8 m s^-2 towards the ground. With what acceleration will an object of mass 4 kg fall ?
Answer:
9.8 m s^-2. This is because acceleration due to gravity is independent of the mass of the object.

Based on mass and weight of a body

Question 31.
Define mass of a body. (CBSE 2010, 2012)
Answer:
Mass of a body is defined as the quantity of matter contained in the body.

Question 32.
What is the SI unit of mass ? (CBSE 2012)
Answer:
SI unit of mass is kilogram (kg).

Question 33.
Is mass of a body a scalar or a vector physical quantity ?
Answer:
Mass is a scalar physical quantity.

Question 34.
The mass of a body at the equator is 20 kg. What will be the mass of this body at the poles ?
Answer:
20 kg.

Question 35.
Define weight of a body. (CBSE 2012)
Answer:
The force with which a body is attracted by the earth is known as the weight of the body.

Question 36.
Write a relation between the mass and weight of the body. (CBSE 2013)
Answer:
W = mg

Question 37.
State the SI unit of weight. (CBSE 2012)
Answer:
S.I. unit of weight is newton (N).

Question 38.
What is the weight of an object at the centre of earth ?
Answer:
Zero.

Question 39.
The weight of a body on the earth is 60 N. What is the weight of the body on the moon ? (CBSE 2013)
Answer:
Weight of the body on the moon = (1/6) x 60 N=10 N.

Question 40.
Define 1 kg weight and express it in Newton.
Answer:
Force is said to be 1 kg weight if it produces acceleration equal to 9.8 m s^-2 in a body of 1 kg mass.
1 kg wt = 1 kg x 9.8 ms^-2 = 9.8 N

Question 41.
What is the mass of an object whose weight is 196 N ?
Answer:

SHORT ANSWER QUESTIONS

Based on gravitation and newtons law of gravitation

Question 1.
State Newtons law of gravitation. Write the mathematical equation for Newton’s law of gravitation.
(CBSE 2010, 2011, 2014, 2015)
Answer:
According to this law, the force of attraction between two particles or bodies is

1. directly proportional to the product of their masses and
2. inversely proportional to the square of the distance between these particles or bodies

Relation between gravitational force between two bodies and the distance between them.
Consider two bodies A and B having masses m₁ and m₂ respectively. Let the distance between these bodies be r (Figure 6).

According to the law of gravitation, the force of attraction (F) or force of gravitation between these bodies is directly proportional to (i) product of masses of bodies
i.e.,                                           F ∝ m₁m₂                                                                      …(1)
and (ii) inversely proportional to square of distance between bodies.

Eqn. (3) gives the magnitude of gravitational force between two interacting bodies of masses m₁ and m₂ separated by a distance V.

Question 2.
Why is Newton’s law of gravitation known as universal law of gravitation ? (CBSE 2012)
Answer:
This is because this law is applicable to all the objects or particles in the universe.

Question 3.
Why is G called universal constant ? (CBSE 2010, 2011, 2013, 2014)
Answer:
Because the value of G = 6.673 x 10^-11 Nm² kg^-2 is same at all positions in the universe.

Question 4.
How does the gravitational force between two bodies change if the distance between them is tripled ? Explain. (CBSE 2010, 2011)
Answer:
Gravitational force between two bodies is given by

Thus, the gravitational force between the bodies becomes 1/9 th times its original value.

Question 5.
State the source of centripetal force that a planet requires to revolve around the sun. On what factors does that force depend ? Suppose this force suddenly becomes zero, then in which direction will the planet begin to move if no other celestial body affects it ?
Answer:
Gravitational force of attraction between the sun and the earth is the source of the centripetal force that a planet requires to revolve around the sun.
It depends on

1. the masses of the sun and the planet and
2. distance between the sun and the planet. If this force suddenly becomes zero, the planet begins to move in a straight line along the tangent at the point on the circular path of the planet around the sun because of inertia of motion.

Question 6.
Mention any two phenomena which will successfully be explained on the basis of Universal law of gravitation.
Answer:

1. Existence of earth’s atmosphere
2. Revolution of planets around the sun.

Question 7.
The moon is acted by the gravitational pull of earth, still it does not fall onto the earth. Explain, why ?
(CBSE 2012, 2013)
Answer:
The gravitational pull of earth on the moon provides the necessary force to the moon to move around the earth. Therefore, moon does not fall on the earth.

Question 8.
What is the cause of ocean tides ?

Or

Name the type of force which is responsible for the formation of tides in the sea. (CBSE 2014)
Answer:
The earth exerts a large gravitational pull on the moon. According to Newton’s third law of motion, moon also exerts the same large gravitational pull on the earth. This large gravitational pull or force on the earth . due to moon causes ocean tides.

Question 9.
An apple attracts the earth and the earth also attracts the apple towards its centre. Then, why only apple falls towards the earth but earth is not moved towards the apple ?
(CBSE Sample Paper; CBSE 2010, 2011)

Or

A stone and the earth attract each other with an equal and opposite force, why then we see only the stone falling towards the earth, but not the earth rising towards the stone. (CBSE 2013)
Answer:
The gravitational forces acting on both the apple and the earth (or a stone and earth) are equal in accelaration produced in the apple or stone is very large and the acceleration produced in the earth magnitude. Since, the mass of the apple or stone is very small as compared to the mass of the earth, so the
is negligible. That is why, the motion of the earth is not noticed.

Based on free fall and acceleration due to gravity

Question 10.
Two boys drop a sheet of a paper from the top of the tower. One boy dropped his sheet of paper as such
but the second boy dropped it by changing it in the form of a ball. Which sheet of paper reaches the ground first and why ? Assume that air resistance is not negligible. (CBSE 2010, 2014)
Answer:
When a body falls through air, the air resistance or force of friction due to air opposes its motion. Since the surface area of sheet of paper is more than the surface area of the paper when it is in the form of a ball. Thus, the opposition offered by air to the paper sheet is more than the opposition offered to the ball shaped sheet. Hence, the sheet changed into the ball shape reaches the ground earlier than the paper sheet.

Question 11.
Study the diagrams below.

A sheet of paper and a crumpled paper are thrown down from the same height and time is noted. Answer the following questions :
(a) Will the time taken to reach the bottom of the container be the same for the sheet of paper and crumpled paper ? Why ? Explain giving reason.
(b) What will happen in case (ii) ?
Answer:
(a) Since the area of a sheet of paper is more than the area of the paper crumpled into a small, therefore, a sheet of paper will experience a large opposing force due to air than the ball, while falling down. Hence, a sheet of paper falls slower than one that is crumpled into a ball.
(b) Both will take same time to reach the bottom as there is no air resistance.

Question 12.
Derive an expression for the acceleration due to gravity. (CBSE 2010, 2011, 2012, 2013, 2014)

Or

How is the value of ‘g’ on the earth related to the mass of the earth and its radius. Derive the expression.
(CBSE 2015)
Answer:
Consider a body of mass m near the surface of the earth (Figure 11). The force acting on the body is the gravitational force of the earth. The magnitude of the gravitational force acting on the body due to the earth is given

where, M = mass of the earth
R = radius of the earth
[Here, height of the body from the surface of the earth is neglected as compared to the radius of the earth because R = 6400 km is very large.]


This gravitational force (F) produces acceleration equal to ‘g in the body of mass m. So according to Newton’s second law of motion, which is the expression for the acceleration due to gravity.
Eqn. (3) shows that acceleration due to gravity does not depend on the mass of the object or body. Thus, all objects hollow or solid, big or small should fall at the same rate.

Question 13.
Suppose a planet exists whose mass and radius both are half of those of earth. Calculate acceleration due to gravity on the surface of this planet. lg on the surface of the earth = 9.8 m s^-2. (CBSE  2010, 2012)
Answer:

Question 14.
What is the difference between ‘g and ‘G’ ?
Answer:

Acceleration due to gravity (g)	Universal gravitational constant (G)
1. The acceleration produced in a body falling freely under the action of gravitational pull of the earth is known as acceleration due to gravity.	The gravitational force between two bodies of unit masses separated by a unit distance is known as universal gravitational constant.
2. The value of ‘g’ is different at different points on the earth.	The value of ‘G’ is same at every point on the earth.
3. The value of ‘g’ decreases as we go higher from the surface of the earth or as we go deep into the earth.	The value of ‘G’ does not change with height and depth from the surface of the earth.
4. The value of ‘g’ at the centre of the earth is zero.	The value of ‘G’ is not zero at the centre of the earth or anywhere else.
5. The value of is different on the surfaces of different heavenly bodies like the sun, the moon, the planets.	The value of ‘G’ is same throughout the universe.
6. The value of ‘g’ on the surface of the earth is 9.8 m s-2	The value of G = 6.673 x10-11 Nm2 kg-2, throughout the universe.

Question 15.
Why is the value of lg variable on the surface of earth ?
Answer:

The earth is oval shaped. The distance (R) of equator of earth from the centre of earth is greater than the distance of poles from the centre of earth. Hence, value of ‘g is different at equator and poles.

Question 16.
Give reasons :

1. The mass is constant everywhere whereas weight keeps changing.
2. The value of ‘g’ keeps changing as we move away from the earth whereas value of ‘G’ remains constant all over the universe.

Answer:

1. Mass is a quantity of matter contained in a body and remains constant everywhere. Weight = mg. Since value of ‘g’ changes from place to place, so weight keeps on changing from one place to another place.
2. The value of ‘g with height is given by
   
   where h is the height from the surface of earth. As h increases, value of ‘g’ decreases. On the other hand, G is universal constant and its value remains constant all over the universe.

Question 17.
Where is the acceleration due to gravity minimum and maximum on the surface of the earth ? (CBSE 2015)
Answer:
Acceleration due to gravity on the surface of earth is given by

Since equatorial radius (R_E) is greater than the polar radius (R_P) of the earth, therefore, acceleration due to gravity is minimum at the equator and maximum at the poles.

Based on Mass and weight of a body

Question 18.
State the factors on which weight of a body depends. (CBSE 2012)
Answer:
Since, weight, W = mg. So weight of a body depends on

1. mass of the body and
2. acceleration due to gravity (g) at the given place.

Question 19.
Why is the weight of a body less at equator than at poles ? (CBSE 2012, 2013, 2014)
Answer:
Weight, W = mg. Since the value of ‘g’ is less at equator than at poles, so weight of a body is less at equator than at poles.

Question 20.
Why is the weight of a man less on the surface of the moon than on the surface of the earth ?
Answer:
W = mg. Since value of ‘g’ on the moon is 1/6 times the value of ‘g’ on the earth. So weight of a body on moon is 1/6 times the weight of the body on earth.

Question 21.
Why is the weight of an object less on a mountain than at sea level ?
Answer:
Since value of g decreases as we go higher and higher, so weight (mg) of the object on the mountain is less than at the sea level.

Question 22.
Why is the weight of a body zero at the centre of the earth ?
Answer:
W = mg. Since g = 0 at centre of the earth.
∴ W = 0.

Question 23.
There are two kinds of balances i.e., a beam balance and a spring balance. If both the balances give the same measure of a given body on the surface of the earth, will they give the same measure on the surface of the moon ? Explain.
Answer:
Beam balance measures the mass of a body. Since mass of a body remains constant so the beam balance will give the same measures on the surface of the earth and on the surface of the moon.
On the other hand, spring balance measures the weight of a body. Weight of a body W = mg. It means, weight of a body depends upon the value of ‘g’. Since value of ‘g on the moon = 1/6 times the value of ‘g’ on the earth, so the spring balance shows 1/6 th times the weight of the body on the earth at the surface of the moon.

Question 24.
A bag of sugar weighs W at some place on the equator. Will it weigh same or more or less when taken to Antarctica ? Explain.
Answer:

Equatorial radius is more than the polar radius, so the value of ‘g’ at pole is more than the value of ‘g’ at the equator. Hence, the sugar bag will weigh more at Antarctica (or poles).

Question 25.
A body of mass 10 kg is taken to the centre of earth. What will be its mass and weight there ?
Answer:
Mass remains the same. That is, mass of body at the centre of earth = 10 kg.
Weight of body at the centre of earth, W = mg = 10 x 0 = 0 (∴ g at the centre of earth = 0).

Question 26.
Gravitational force on an imaginary planet is 6 times stronger than the gravitational force of the earth. Determine the value of acceleration due to gravity and weight of an object of mass 50 kg on that planet.
Answer:
mg_p = 6 mg_e
∴ g_p = 6 g_e = 6 x 9.8 = 58.8 ms^-2
Weight of object on planet = mg_p = 50 x 58.8 = 2940 N.

Question 27.
Find the weight of a 80 kg man on the surface of moon ? What should be his mass on the earth and on the moon ? (g_e = 9.8 m/s², g_m = 1.63 m/s²).
Answer:
Weight of man on moon = mg_m = 80 x 1.63 = 130.4 N
Mass of an object does not change, when taken to moon from earth. Therefore, mass of man on earth and moon is same i. e., 80 kg.

Question 28.
An object has mass 1 kg and weight 1.67 N on moon. Calculate its weight and mass on earth (g_e =10 m s^-2).
Answer:
Mass of object on earth = mass of object on moon = 1kg.
Weight of object on moon = (1/6) x weight of object on earth
Weight of object on earth = 6 W_m = 6 x 1.67 = 10.02 N

Question 29.
Find the weight of an object at a height 6400 km above the earth’s surface. The weight of the object at the surface of earth is 20 N and radius of earth is 6400 km.
Answer:

Question 30.
A force of 20 N acts upon a body of weight 9.8 N. What is the mass of the body and how much is its acceleration ( g = 9.8 m s^-2)?
Answer:
W = mg =9.8 N

LONG ANSWER QUESTIONS

Question 1.
(a) State Universal law of gravitation. Write the expression for the gravitational force between the earth and an object lying on the surface of the earth.
(b) Gravitational force plays an important role in nature. Justify this statement.

Or

State universal law of gravitation. Derive an expression for gravitational force between two bodies.
(CBSE 2012)
Answer:
Definition of universal gravitational constant (G)

If m₁ = 1 unit, m₂ = 1 unit and r = 1 unit, then G = F Thus, universal gravitational constant (G) is defined as the force of attraction between two bodies of unit masses separated by a unit distance.
Units of universal law of gravitation:

Characteristics of Gravitational force

1. Gravitational force between two bodies or objects does not need any contact between them. It means, gravitational force is action at a distance.
2. Gravitational force between two bodies varies inversely proportional to the square of the distance between them. Hence, gravitational force is an inverse square force.
3. The gravitational forces between two bodies or objects form an action-reaction pair. If object A attracts object B with a force F₁ and the object B attracts object A with a force F₂ (Figure 7), then
4. Gravitational force between two small bodies is very small. On the other hand, gravitational force between two large bodies (say the sun and the earth) is large.
5. Gravitational force between two objects is always attractive in nature.

Question 2.
What do you understand by free fall ? Derive an expression for the acceleration due to gravity. Write the factors on which “acceleration due to gravity” depends.
Answer:
Definition of Free Fall
The falling body on which only force of gravitation of the earth acts is known as freely falling body and such fall of a body is known as free fall. A freely falling body has constant acceleration equal to acceleration due to gravity (g), irrespective of its mass.

Thus, all bodies irrespective of their masses fall down with constant acceleration.
Motion of a freely falling body is uniformly accelerated motion.
Consider a body of mass m near the surface of the earth (Figure 11). The force acting on the body is the gravitational force of the earth. The magnitude of the gravitational force acting on the body due to the earth is given

where, M = mass of the earth
R = radius of the earth
[Here, height of the body from the surface of the earth is neglected as compared to the radius of the earth because R = 6400 km is very large.]


This gravitational force (F) produces acceleration equal to ‘g in the body of mass m. So according to Newton’s second law of motion, which is the expression for the acceleration due to gravity.
Eqn. (3) shows that acceleration due to gravity does not depend on the mass of the object or body. Thus, all objects hollow or solid, big or small should fall at the same rate.

Question 3.
Define the terms “mass” and “weight”. Write their SI units. Distinguish between mass and weight.
Answer:

Mass	Weight
The quantity of matter contained in a body is called the mass of the body.	The force with which the earth attracts a body towards its centre is called the weight of the body.
Mass of a body remains constant.	Weight of a body changes from place to place as it depends on the value ‘g’ and ‘g’ is different at different places.
Mass of a body is never zero.	Weight of a body at the centre of the earth is zero.
Mass is a scalar quantity.	Weight is a vector quantity.
Mass is measured in kg.	Weight is measured in kg wt or N.
Mass is measured by a beam balance.	Weight is measured by a weighing machine or a spring balance.

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 10 Gravitation are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Chapter 3 Atoms and Molecules Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Atoms and Molecules Class 9 Important Questions and Answers Science Chapter 3

Question 1.
What is cation ? Give one example.
Answer:
A cation is an atom or group of atoms carrying positive charge on it.

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2.
Mention two postulates of Daltons atomic theory that explain :
(a) Law of conservation of mass.
(b) Law of constant proportions.
Answer:
(a) Law of conservation of mass: The total mass of the products in a physical change or a chemical reaction is equal to the total mass of the reactants that have combined.
(b) Law of constant proportions:  A pure chemical compound always consists of the same elements that are combined together in a fixed (or definite) proportion by mass.

Question 3.
Name the compound Al₂(SO₄), and mention the ions present in it.
Answer:
The compound is called aluminium sulphate; cation : Al³⁺ ; anion : (SO₄)^2-

Question 4.
Write the formulae and the names of the ions formed by the combination of
(i) Fe³⁺ and SO₄^2-
(ii) NH₄⁺ and CO₃^2- . (CBSE 2011)
Answer:
(i) Fe₂(SO₄), : Ferric sulphate or Fe (III) sulphate.
(ii) (NH₄)₂CO₃ : Ammonium carbonate or Ammonium(I)carbonate.

Question 5.
(a) Define ‘atomic mass unit’. How is it linked with relative atomic mass ?
(b) How do you know the presence of atoms if they do not exist independently for most of the elements ?
(CBSE 2011)
Answer:
(a) Atomic mass unit (u) is 1/12 of the mass of one atom of C-12. Relative atomic mass of the atom of an element is the average mass of the atom as compared to 1/12th of the mass of C-12 atom .

(b) Atoms of most of the elements do not exist independently. However, they combine in specific numbers to form molecules or ions which we can feel and know about their presence.
For example,
* A molecules of H₂SO₄ consists of 2 atoms of H + 1 atom of S + 4 atoms of O
* A molecules of C₁₂H₂₂O₁₁ consists of 12 atoms of C + 22 atoms of H + 11 atoms of O
* Ammonium ion (NH₄⁺) consists of 1 atom of N + 4 atoms of H

Question 6.
With the help of a labelled diagram describe an activity to demonstrate the law of conservation of mass.
(CBSE 2011)
Answer:
In order to illustrate the law of conservation of mass, let us carry the same chemical reaction in the laboratory. The procedure is quite simple. In a graduated cylinder, prepare about 10% solution of one of the reactants say barium chloride in water. For that, weigh accurately 10 gram of the sample and dissolve in water with stirring in the graduated cylinder. Add more of water so as to touch 100 mL mark. This is 10 percent solution of the reactant. Transfer a portion of this solution in a conical flask as shown in figure 3.1.

In a similar manner, prepare 10% solution of sodium sulphate also. Take a portion of this solution in a small glass tube. Place the tube carefully in the flask without disturbing it. Even a thread can be used for the purpose. Cork the flask and weigh it on a balance. Shake the flask for sometime by hand so that the two reactants mix together and react to form the products. Barium sulphate is in the form of a white precipitate. The other product sodium chloride is water soluble. Weigh the flask again and notice if there is any change in weight. No change will be noticed. This means that the mass of reactants is the same as the mass of the products and this verifies the law of conservation of mass.

Question 7.
(a) Define Avogadro’s number. Why is it also known as Avogadro’s constant ?
(b) Calculate the molar mass of Na₂O.
(c) Find the mass of 10 moles of carbon dioxide. (CBSE 2011)
Answer:
(a) Avogadro’s number is the number of particles (atoms, ions, molecules etc.) present in one mole of any substance. It is denoted either as N_A or as N_Q. The number is also called Avogadro’s constant because its value is fixed (6.022 x 10²³) irrespective of the nature of the particles.
(b) Molar mass of Na₂O = 2 x Atomic mass of Na + Atomic mass of O
= 2 x 23 u + 16 u = 62 u
(c) Mass of 10 moles of CO₂= 10 x 44 u = 440 u.

Question 8.
(a) How many gram molecules of H₂SO₄ are present in 4.9 g of the acid ?
(b) How many atoms of hydrogen and oxygen are present in 0-15 mole of water (H₂O) ? (CBSE 2011)
Answer:
(a) Gram molecular mass of H₂SO₄ = 2 x 1 + 32 + 4 x 16 = 98 g

Question 9.
(a) Calculate the formula unit mass of Na₂SO₄
(b) What is the mass of one mole of sulphur atoms ?
(c) Convert 12 g of oxygen into mole. (CBSE 2011)
Answer:
(a) Na₂SO₄ is an ionic compound. Therefore its formula unit mass is the same as its molecular mass
= 2 x 23 + 32 + 4 x 16 = 142 u
(b) The mass of one mole of sulphur atoms = 32 u.
(c) 32 g of sulphur = 1 mol

Question 10.
(a) Define atomic mass unit.
(b) Distinguish between molecular mass and molar mass.
Answer:
(a) Atomic mass unit (u) is 1/12 of the mass of one atom of C-12. Relative atomic mass of the atom of an element is the average mass of the atom as compared to 1/12th of the mass of C-12 atom.
(b) Molecular mass of a substance expressed in grams is known as its moles mass. This means that molecular mass is expressed in units ‘u’ while molar mass is expressed in units ‘grams’.

Question 11.
What is meant by the term chemical formula ? Write the chemical formula of calcium oxide. Calculate its formula unit mass. (Atomic mass of Ca = 40 u, O = 16 u).
Answer:
Molecule represents a group of two or more atoms (same or different) chemically bonded to each other and held tightly by strong attractive forces. Molecules are represented in terms of symbols of constituting atoms and it is known as chemical formula.
Chemical formula of calcium oxide = CaO.
Formula unit mass = Atomic mass of Ca + Atomic mass of O = (40 + 16) = 56 u.

Question 12.
Name a non-metal which is tetratomic. (CBSE 2012)
Answer:
The non-metal is phosphorus. It exists as molecule and is tetratomic.

Question 13.
Name the cation and anion which constitute the molecule of magnesium oxide. (CBSE 2012)
Answer:
The formula of magnesium oxide is MgO. The cation and anions which constitute the molecule are Mg²⁺ and O^2- ions.
The percentage of three elements calcium , carbon and oxygen in a sample of calcium carbonate is given as : Calcium = 40% ; Carbon = 12.0% ; Oxygen = 48%

Question 14.
If the law of constant proportion is true, what weights of these elements will be present in 1.5 g of another sample of calcium. Carbonate ?
(Atomic mass of Ca = 40 u, C = 12 u, O = 16 u). (CBSE 2012)
Answer:
We have learnt that according to the law of constant proportions, the percentages of the elements present in different samples of a pure substance always remain the same. This means that in the second sample of calcium carbonate, the ratio of the different elements present will remain the same or will remain unchanged. Thus,

Question 15.
An element has valency 3. Write the formula of its oxide. (CBSE 2012)
Answer:
The valency of oxygen is 2 while that of element E is 3. The formula of the oxide of the element is : E₂O₃.

Question 16.
Calculate formula unit mass of Al₂(SO₄)₃. (CBSE 2012)
Answer:
Formula unit mass of Al₂(SO₄)₃ (Aluminium sulphate)
= (2 x Atomic mass of Al) + (3 x Atomic mass of S) + (12 x Atomic mass of O)
= (2 x 27) + (3 x 32) + (12 x 16)
= (54 + 96 + 192) = 342 u.

Question 17.
(a) State six postulates of Dalton’s atomic theory.
(b) A 0.24 g sample of compound of carbon and oxygen on analysis was found to contain 0.096 g of carbon and 0.144 g of oxygen. Find the percentage composition of the compound by weight. (CBSE 2012)
Answer:
(a) The important features of the Dalton’s Atomic Theory are listed :

1. Every matter is made up of very small particles known as atoms.
2. Atoms are the ultimate particles of matter and cannot be further sub-divided into smaller particles.
3. Atoms can neither be created nor destroyed during a physical change or a chemical reaction.
4. All atoms of a particular element are identical in all respects. This means that they have same mass, size and also same chemical properties.
5. Atoms of different elements have different masses, sizes and also chemical properties.
6. Atoms are the smallest particles of matter which can take part in chemical combination.
7. Atoms of the same or different elements combine in small whole number ratios to form molecules of a compound.

Question 18.
(a) Find the mass of 10 moles of sodium sulphite (Na₂SO₄).
(b) Calculate the number of molecules in 8 g of oxygen gas.
(c) Convert 22 g of CO₂ into moles.
Answer:

Question 19.
How many grams of sodium will have the same number of atoms as 6 grams of magnesium ?
(Given Na = 23 u, Mg = 24 u) ? (CBSE 2012, 2016)
Answer:

Question 20.
Calculate the mass of 1.2044 x 10²³ molecules of O₂ (Atomic mass of O = 16 u).
Answer:
6.022 x 10²³ (N_A) molecules of O₂ have mass = 32 u

Question 21.
With the help of an activity, show that there is no change in mass when a chemical change (chemical reaction) takes place. (CBSE 2013)
Answer:
The mass can neither he created nor destroyed in a physical change or a chemical reaction.
In other words, the mass remains unchanged or conserved in a chemical reaction. The law is also known as the Law of Indestructibility of Matter.
Explanation : Let us try to analyse as to what happens in a chemical reaction. To understand the same, let us consider a chemical reaction between barium chloride and sodium sulphate. When the solutions of these reactants prepared separately in water are mixed, the following chemical reaction takes place :

Barium chloride + Sodium sulphate  ———– > Barium sulphate + Sodium chloride (white precipitate)

Question 22.
How are given mass, molar mass and number of moles related to each other ? (CBSE 2013)
Answer:
No. of moles = Mass/Molar mass.

Question 23.
(a) Define polyatomic ions. Write an example.
(b) Calculate the formula unit mass of CaCO₃(Atomic mass of C = 12 u, Ca = 40 u, O = 16 u)
(c) Calculate the molecular mass of the following :
(i) HNO₃
(ii) CH₃COOH
Atomic mass of H = 14, N = 14 u, O = 16 u, C = 12 u) (CBSE 2013, 2015)
Answer:
(a) Polyatomic ions are the ions representing a group of atoms which carry either positive or negative charge. For example, SO₄^-2 ion.
(b) Formula unit mass of CaCO₃ = (1 x Atomic mass of Ca) + (1 x Atomic mass of C) + (3 x Atomic mass of O)
= 4 (1 x 40 u) + (1 x 12 u) + (3 x 16 u) = 100 u .
(c) Molar mass of HNO₃ = (1 x Atomic mass of H) + (1 x Atomic mass of N) + ( 3 x Atomic mass of O)
= (1 x 1 u) + (1 x 14 u) + (3 x 16 u) = 63 u.
Molecular mass of CH₃COOH = (2 x Atomic mass of C) + (4 x Atomic mass of H) + (2 x Atomic mass of O) .
= (2 x 12 u) + (4 x 1 u) + (2 x 16 u) = 60u

Question 24.
What do you understand by 1 amu ? (CBSE 2013)
Answer:
1 amu (or lu) is l/12th of the mass of one atom of carbon taken as 12.

Question 25.
Write the molecular formulae of all the compounds that can be formed by the combination of the following ions : Cu²⁺, Na⁺, Fe³⁺, Cl^–, SO₄^-2 (CBSE 2013)
Answer:
In this case, the compounds can be formed by the combination of cations and anion. Therefore, the molecular formulae of different compounds are :
CuCl₂, CuSO₄, NaCl, Na₂SO₄, FeCl₃, Fe₂(SO₄)₃.

Question 26.
What are chemical reactions according to the Law of conservation of mass ? (CBSE 2013)

Answer:
According to law of conservation of mass, chemical reactions involve only the exchange of partners in the reactants to form products. That is why, there is no change in mass.

Question 27.
Write any five features of Dalton’s atomic theory. (CBSE 2013)
Answer:
The important features of the Dalton’s Atomic Theory are listed :

1. Every matter is made up of very small particles known as atoms.
2. Atoms are the ultimate particles of matter and cannot be further sub-divided into smaller particles.
3. Atoms can neither be created nor destroyed during a physical change or a chemical reaction.
4. All atoms of a particular element are identical in all respects. This means that they have same mass, size and also same chemical properties.
5. Atoms of different elements have different masses, sizes and also chemical properties.

Question 28.
What is atomicity of an element ? Give two examples. (CBSE 2013)
Answer:
The atomicity of an element is the number of atoms present in one molecule of the element. For example,
Atomicity of oxygen in O₂ = 2
Atomicity of oxygen in O₃ = 3.

Question 29.
Write the chemical formulae of the following :
(a) Magnesium sulphate
(b) Calcium oxide
(c) Sodium sulphide
(d) Aluminium phosphate
(e) Potassium chloride
(f) Calcium carbonate. (CBSE 2013)
Answer:
(a) MgSO₄
(b) CaO
(c) Na₂S
(d) Al₂(PO₄)₃
(e) KCl
(f) CaCO₃.

Question 30.
A compound XH is formed by the combination of an element X with hydrogen. Find the valency of the element. State the formula of the compound formed by the combination of
(a) X with nitrogen
(b) X with oxygen. (CBSE 2014)
Answer:
In the compound XH, the valency of element X is 1.
(a) The valency of nitrogen is 3.
The valency of element X is 1.
The formula of the compound = NX₃
(b) The valency of oxygen is 2.
The valency of element X is 1.
The formula of the compound = OX₂

Question 31.
Calculate the number of molecules of SO₂ present in 44 g of it.
Answer:

Question 32.
Write the Latin names of sodium and iron.
Answer:
Latin name of sodium (Na) = Natrium
Latin name of iron (Fe) = Ferrum.

Question 33.
Write the formula and names of the compounds formed by the following ions.
(a) Potassium ion and iodide ion.
(b) Sodium ion and sulphide ion.
(c) Aluminium ion and phosphate ion.
Answer:
The compounds are :
(a) KI (Potassium iodide)
(b) Na₂S (Sodium sulphide)
(c) AlPO₄  (Aluminium phosphate)

Question 34.
Calculate formula unit mass of Na₂CO₃.10H₂O.
Answer:
Formula unit mass of Na2CO3.10H2O
= 2 x Atomic mass of Na + Atomic mass of C + 3 x Atomic mass of O + 10 x Molecular mass of H₂O
= 2 x 23 + 12 +3 x 16 + 10 x 18 = 286 u.

Question 35.
Calculate the number of molecules of sulphur (S₈) present in 128 g of sulphur.
Answer:

Question 36.
Calculate the number of oxygen atoms present in 120 g of nitric acid.
Answer:

Question 37.
What do you understand by the word ‘mole’ ? (CBSE 2015)
Answer:
A mole denotes Avogadro’s number of particles i.e., 6.022 x 10²³. These may be electrons, protons, neutrons, atoms, ions etc.

Question 38.
In a chemical reaction, 10.6 g of sodium carbonate reacted with 12 g of ethanoic acid. The products obtained were 4.4 g of carbon dioxide, 16.4 g of sodium ethanoate and 1.8 g of water.
(a) Write a word equation, clearly showing the reactants and products as given above.
(b) Also show that this data is in agreement with the law of conservation of mass. (CBSE 2015)
Answer:
(a) The word equation for the chemical reaction is :

(b) Mass of reactants = (10.6 + 12) = 22.6 g
Mass of products = (16.4 + 4.4 +1.8) = 22.6 g
Since the mass of reactant species is equal to the mass of the product species, the data illustrates the law of conservation of mass.

Question 39.
What is the name given to the number of 6.022 x 10²³ particles ? (CBSE 2015)
Answer:
It is called Avogadro’s number and is denoted by the sign N_A or N_Q.

Question 40.
Write the chemical names of the following compounds :
(a) K₂SO₄
(b) Mg₃(PO₄)₂
(c) NH₄Cl
(d) ZnS
(e) Na₃N
(f) AgBr (CBSE 2015)
Answer:
(a) Potassium sulphate
(b) Magnesium phosphate
(c) Ammonium chloride
(d) Zinc sulphide
(e) Sodium nitride
(f) Silver bromide.

Question 41.
How did Berzelius assign symbols to the elements ? (CBSE 2016)
Answer:

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 3 Atoms and Molecules are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Chapter 2 Is Matter Around Us Pure Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Is Matter Around Us Pure Class 9 Important Questions and Answers Science Chapter 2

Question 1.
List the two conditions essential for using distillation as a method for separation of the components from a mixture. (CBSE 2011)
Answer:

1. The components of the mixture must be miscible with each other.
2. In case, both the miscible components are liquids, they must differ in their boiling point by more than 25°C.

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2.
Water is a compound and not a mixture. Justify the statement giving two reasons. (CBSE 2010, 2011)
Answer:

1. The two elements hydrogen (H) and oxygen (O) are combined chemically to form water (H₂O) which boils at a fixed temperature.
2. The properties of water are altogether different from the constituting elements. For example, molecular hydrogen (H₂) is combustible and molecular oxygen (O₂) supports cumbustion. But water (H₂O) extinguishes fire.

Question 3.
(a) Write one property of suspension.
(b) Identify solute and solvent in 80% solution of ethyl alcohol with water. (CBSE 2012)
Answer:
(a) Suspension is of heterogeneous nature. The solid particles represent one phase while the liquid in which these are present, represents the other phase.
(b) Water present in smaller amount is solute. Ethyl alcohol present in excess is solvent.

Question 4.
(a) Classify Brass and Diamond as element and mixture.
(b) How is a chemical change different from a physical change ? (CBSE 2011)
Answer:
(a) Brass is a homogeneous mixture also called alloy. The constituents are Cu and Zn.
Diamond is an element. It is an allotropie form of carbon.
(b) In a chemical change, a new substance is formed as a result of chemical reaction. No new substance is formed in a physical change.

Question 5.
Why particles in a true solution cannot be seen with a naked eye ? (CBSE 2011)
Answer:
Particle size in a true solution is less than 10^-9 m or 1 nm. The particles are too small to scatter the beam of light and therefore, cannot be seen with naked eye.

Question 6.
(a) Identify the heterogeneous mixture from the following :
Air, soda water, soap solution, brass.
(b) Write two components of a colloidal solution. Give an example. (CBSE 2011)
Answer:
(a) Soap solution is a heterogeneous mixture while the rest are of homogeneous nature.
(b) The two components of a colloidal solution are dispersed phase and dispersion medium. For example, a colloidal solution of starch in water (Starch acts as dispersed phase and water as the dispersion medium).

Question 7.
Distinguish between elements and compounds with one example of each. (CBSE 2010)
Answer:
An element cannot be broken into simpler or smaller constituents but a compound can be broken as a result chemical reaction or by passing electric current (electro-chemical reaction). For example, sodium (element), sodium chloride (compound).

Question 8.
Suggest a suitable separation technique for the following :
(a) Mercury and water.
(b) Coloured components from blue ink,
(c) Ammonium chloride and potassium chloride
(d) Mixture of alcohol and water.
(CBSE 2010, 2011)
Answer:
(a) The separation can be done by the use of separating funnel. Mercury forms the lower layer (heavier) and water the upper layer (lighter).
(b) The separation can be done with the help of chromatography.
(c) Process of sublimation can be used. Ammonium chloride collects as the sublimate while potassium
chloride remains in the dish. .
(d) Process of fractional distillation can be used. Alcohol (ethyl alcohol) with lower boiling point (78°C or 351 K) gets distilled leaving behind water with higher boiling point (100°C or 373 K) in the distilla¬tion flask.

Question 9.
A solution contains 60 g of sugar in 480 g of water. Calculate the concentration of solution in terms of mass by mass percentage of the solution. (CBSE 2010, 2012)
Answer:

Question 10.
Identify the dispersed phase and dispersion medium in the following examples of colloids :
{a) Fog
(b) Cheese
(c) Coloured gem stone. (CBSE 2011)
Answer:
(a) Fog : Liquid (water drops) acts as dispersed phase and gas (air) as the dispersion medium.
(b) Cheese : Solid (fat) acts as the dispersed phase and water (liquid) as the dispersion medium.
(c) Coloured gem stone : Solids act as the dispersed phase as well as the dispersion medium.

Question 11.
Differentiate between simple distillation and fractional distillation.  (CBSE 2011, 2016)
Answer:
(a) In fractional distillation, a fractionating column is used while no such column is needed in simple distillation.
(b) Simple distillation can be used to separate two miscible liquids differing in their boiling points by more than 25°C. In case, the difference is less’than this, fractional distillation is used.

Question 12.
Define a solution. If 10 mL of H₂SO₄ are dissolved in 90 mL of water, calculate the concentration of solution. (CBSE 2011)
Answer:
For the definition of solution,
Volume of H₂SO₄ (solute) = 10 mL
Volume of water (solvent) = 90 mL
Volume of solution = (90 +10) mL

Question 13.

1. Why is crystallisation technique better than evaporation ?
2. Write any two physical properties each of metals and non-metals.
3. Name the technique used to separate butter from curd. (CBSE 2010, 2011)

Answer:

1. Both these techniques are used to separate the solid substances from their solutions. But crystallisation is considered better because during evaporation certain solids may decompose or some of them like sugar get charred when the solution is evaporated completely to dryness. As a result of crystallisation, even the shapes of the crystals donot change.
2. 1. Metals have a shining surface known as lustre.
   2. Metals are malleable and ductile.
   3. Non-metals are mostly poor conductors of electricity.
   4. Non-metals are generally soft.
3. Butter can be separated from curd by the process of centrifugation. This is usually done by churning
   which is very common as well as convenient.

Question 14.
Define distillation. What type of mixtures can be separated by distillation ? Draw a labelled diagram of the apparatus used for fractional distillation. (CBSE 2010, 2011)
Answer:
For the definition of distillation, The process of distillation, also called simple distillation can be used :

1. to separate two miscible liquids which differ in their boiling point temperature by 25°C or more.
2. to purify an impure liquid containing soluble non-volatile impurities.
   For the labelled diagram of the apparatus used for fractional distillation,
   

Question 15.
(a) 110 g of a solute are present in 550 g of solution. Calculate the concentration of solution.
(b) Give any three points of difference between true solution, colloidal solution and suspension.
(CBSE 2011)
Answer:

(b)

Question 16.
State one instance where water undergoes a physical change and one in which it undergoes a chemical change.
(CBSE 2010)
Answer:
Physical change : Evaporation of water or freezing of water Chemical change : Electrolysis of water.

Question 17.
You are given a mixture of sand, water and mustard oil. How will you separate the components of this mixture ? Explain with the help of different separation methods involved in it. (CBSE 2010, 2011, 2016)
Answer:
The separation of the components from this heterogeneous mixture can be done in the following steps. Step I. Filter the mixture through a glass funnel.

Water and mustard will be collected as filtrate while sand particles will remain on the filter paper as residue.
Step II. Now transfer the mixture of water and mustard oil to a separating funnel and proceed as discussed in section. Water will form the lower layer in the funnel while mustard oil the upper layer. Separate the two layers.

Question 18.
Sudha tested the solubility of four salts X, Y, Z and T at different temperatures and collected the following data. (Solubility refers to the amount in grams dissolved in 100 g of water to give a saturated solution.)

Answer the following questions from the table
(i) Which salt has the highest and lowest solubility at 323 K ?
(ii) A student prepared a saturated solution of X at 323 K and then added 25 g water to it. What mass of X must be added to again make the solution saturated ?
(iii)The solubility of which salt is least affected by increase in temperature ?
(iv) What mass of ‘T’ would be required to make saturated solution in 200 g of water at 290 K ?
(CBSE 2011)
Answer:

Question 19.
State which of the following solutions exhibit Tyndall effect :
Starch solution, Sodium chloride solution, Tincture of iodine, Air.
Answer:

1. Tyndall effect is shown both by starch solution and air which are heterogeneous mixtures and have the capacity to scatter beam of light as it passes through them.
2. Sodium chloride solution and tincture of iodine (iodine crystals dissolved in ethyl alcohol) are both homogeneous in nature and donot exhibit any Tyndall effect.

Question 20.
Identify colloids from the following :
Copper sulphate solution, milk, smoke, muddy water, butter, sugar solution, face cream, lemonade.
(CBSE 2012)
Answer:
Colloids : milk, smoke, muddy water, butter, face cream, lemonade.

Question 21.
List any three differences between true solution and suspension. (CBSE 2012)
Answer:

Question 22.
12 mL of dettol is added to a beaker containing 500 mL of water and is stirred. State four observations that you make. (CBSE 2012)
Answer:
When dettol is added to a beaker containing of water, the following observations are made.

1. An emulsion is formed which is of colloidal nature.
2. The colour of emulsion is milky.
3. It gives characteristic smell of dettol.
4. The solution can pass through a filter paper.

Question 23.
Properties of a compound are different from its constituents, while a mixture shows the properties of its constituent elements. Justify this statement taking the example of iron and sulphur. (CBSE 2012)
Answer:
Take a small amount of the material from dish [A] in a glass tube and add a few drops of dilute hydrochloric acid to it. A colourless and odourless gas will evolve accompanied by brisk effervescence. This is hydrogen gas which can be confirmed by performing certain tests.
In a similar manner, add a few drops of the same acid to the material taken from the dish B. Immediately a gas with the smell similar to rotten eggs will evolve. It is hydrogen sulphide gas.
Conclusion: From the observations listed above, we conclude that in the china dish [A], both iron filings and powdered sulphur are in the form of a mixture. In the dish [B], a chemical reaction has resulted upon heating and the black mass of iron sulphide is formed. It is a compound.
Iron + Sulphur ———- > Iron sulphide

Question 24.
Give one example in which physical and chemical changes take place. (CBSE 2012)
Answer:
It is illustrated by burning of candle. One such example is the burning of candle. The wax present in the candle changes to liquid state. This means that the change is of physical nature. At the same time, the constituents carbon and hydrogen present in wax react with oxygen of air to form new substances. This means that a chemical reaction or change is also taking place.

Question 25.
(a) Enumerate any two differences between simple distillation and fractional distillation.
(b) Draw a labelled diagram showing the process of fractional distillation. (CBSE 2012)
Answer:
(a)

1. Simple distillation can be used if the liquids to be separated differ in their boiling points by more than 25°C. If the difference is less, than fractional distillation can be used.
2. A fractionating column is needed for fractional distillation but not for simple distillation.

(b) For process of fractional distillation,

Question 26.
On dissolving chalk powder in water, a suspension is obtained. Give any four reasons to support the fact that mixture so obtained is a suspension only. (CBSE 2012)
Answer:
It is supported by the following reasons

1. White particles of chalk powder can be seen with naked eye.
2. The particles can be separated by ordinary filter paper.
3. Upon shaking, a white turbidity reappears in solution.
4. Light cannot pass through the suspension which shows that it is of opaque nature.

Question 27.
(a) Crystallization is a better technique than evaporation. Give one reason to justify the statement.
(b) Draw a labelled diagram to show the process of separation of two immiscible liquids. (CBSE 2012)
Answer:
(a) Crystallisation technique is always better than evaporation due to the following reasons.

1. Some solids may decompose and some substances like sugar may get charred during direct heating.
2. Some minute impurities of particles may still be associated in the solution obtained upon filtration. They will be present in the solid residue left after evaporation. In crystallisation, the crystals obtained are always pure.
3. Direct heating or evaporation does not give crystals. Only a solid residue is left in the dish.

(b) The separation can be done by the use of separating funnel.

Question 28.
When a solution is said to be saturated ? How can you change a saturated solution to an unsaturated solution without adding any more solvent to it ? Explain in brief. (CBSE 2012)
Answer:
A solution is said to be saturated if it has the maximum amount of the solute dissolved in a given amount of the solvent at a given temperature.
Saturated solution can also be made unsaturated by increasing the temperature provided the process of dissolution of the solid solute is of endothermic nature i.e., it is accompanied by the absorption of heart.

Question 29.
Name the type of colloids in each of the following giving an example of each.

Answer:

Question 30.
How are colloids different from suspensions ? . (CBSE 2013, 2016)
Answer:

1. In a suspension the particles settle as precipitate when it is allowed to remain undisturbed for sometime.
2. Colloidal solutions are of heterogeneous nature. They consist of two phases known as dispersed phase and dispersion medium.

Question 31.
Identify the colloids from the following :
Soda water, milk, sponge, clouds, mixture of alcohol and water, jelly. (CBSE 2013)
Answer:
Colloids : Soda water, milk, sponge, clouds, jelly.

Question 32.
How will you separate a mixture of common salt, camphor and iron filings ? Describe the process.
(CBSE 2013)
Answer:
Iron filings are first separated with the help of a magnet. Camphor is separated from the remaining mixture with the help of sublimation process leaving behind common salt.

1. In a colloidal solution, the particle size is such (1 nm to 100 nm), that these particles scatter the light rays as they fall on them. Because of scattering, the path of the light as well as the particles become visible. But in a true solution, the particle size is so small (less than 1 nm) that these particles are not in a position to scatter the light. Therefore, true solution does not show any Tyndall effect.
2. In dirty clothes, the dust particles are sticking on the oil drops present. Simple water cannot remove these oil drops from the clothes because water and oil as such do not form a stable emulsion. Soap plays the role of emulsifier and helps in forming a stable emulsion between the two. In other words, it helps in mixing oil and water. This means that soap helps in removing these oil drops along with the dirt sticking to them. The dirty clothes get washed by soap solution.

Question 33.
Give an example each for a mixture having following characteristics :

1. Two or more coloured constituents soluble in a solvent.
2. Two immiscible liquids.
3. One of the components changes directly to the gaseous state.
   Suggest a suitable method to separate the components of these mixtures. (CBSE 2013)

Answer:

1. Sulphur (a yellow solid) and iodine (a violet crystalline solid) are both soluble in carbon disulphide (CS₂) solvent. Separation can be done by sublimation. Iodine sublimes on heating while sulphur does not.
2. Turpentine oil and water. Separation can be done with a separating funnel.
3. Ammonium chloride and common salt. Ammonium chloride directly changes to vapour state (sublimes).

Question 34.
Give an example for each of following :

1. Solid-liquid homogeneous mixture
2. Gas-Gas homogeneous mixture
3. Liquid—Liquid heterogeneous mixture. (CBSE 2013)

Answer:

1. Mixture of sodium chloride in water.
2. Air: It is a homogeneous mixture of number of gases.
3. Emulsion of oil and water.

Question 35.
List any two properties of metals which make them suitable to be used as :

1. Utensils for cooking food.
2. Wires for electrical connections. (CBSE 2013)

Answer:

1. Metals are good conductors of heat.
2. Metals are good conductors of electricity and also ductile in nature.

Question 36.
To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find the concentration in terms of mass of solution at this temperature. (CBSE 2013)
Answer:
Mass of solution = Mass of solute + Mass of solvent = (36 + 100) = 136 g.

Question 37.
Which separation techniques you will apply for the separation of the following mixtures ?

1. Oil from warter
2. Camphor from sand
3. Sodium chloride from its solution in water
4. Cream from milk
5. Metal pieces from engine oil of a car.

Answer:

1. By the use of a separating funnel.
2. With the help of sublimation technique.
3. By crystallisation technique.
4. By the use of a centrifugal machine.
5. By the use of filtration technique.

Question 38.
‘Water is considered as a compound of hydrogen and oxygen and not a mixture of hydrogen and oxygen.’ Comment on it.
Differentiate between a compound and a mixture (any three points). (CBSE 2014)
Answer:
The properties of water are altogether different from those of the constituting gases. For example, water is a liquid at room temperature whereas the constituents are in the gaseous state. Water can extinguish fire whereas hydrogen is combustible in nature, oxygen supports combustion.

Question 39.
How will you separate a mixture containing kerosene and petrol (difference in their boiling point is less than 25 K) which are miscible with each other ? Explain. (CBSE 2014)
Answer:
Both are miscible liquids. Since the difference in the boiling points is less than 25 K, the separation can be done with the help of fractional distillation technique. Petrol with less boiling point distils first leaving behind kerosene in the distillation from flask. However, it is very difficult to apply this technique since both are highly flammable liquids and a great deal of precaution is needed.

Question 40.
List two differences between a pure substance and a mixture. Give an example of each. (CBSE 2014)
Answer:

1. A pure substance is an element or compound in completely pure state while mixture may contain two or more elements/compounds.
2. Constituents from a mixture can be separated while pure substance remains as a single substance. Example : Copper (pure substance); Air (Mixture).

Question 41.
Classify the following as compund and mixture. Saline water, water, air, carbon dioxide, hydrogen chloride, milk. (CBSE 2015)
Answer:
Compound : Water, carbon dioxide, hydrogen chloride.
Mixture : Saline water, air, milk.

Question 42.
Explain the terms dilute solution, concentrated solution and saturated solution. How would you determine the solubility of a solution ? What is the effect of change of temperature on the solubility ? (CBSE 2015)
Answer:
For dilute and concentrated solutions: We have read that a binary solution has two components or constituents. These are solute and solvent. The relative amounts of the solute and solvent in the solution either by mass or by volume, represent the concentration solution. Expressing the Concentration of a Solution.
The concentration of a solution is expressed as the amount of the solute present in a given amount of the solvent or solution. It is normally expressed as mass by mass percent or as volume by volume percent.
For saturated solutions: A solution becomes saturated if the solute starts separating at the bottom of the container in which the solution is being prepared at a given temperature. A saturated solution generally becomes unsaturated upon heating
For the determination of the solubility of a solution: The solubility of a solute in a solution is always expressed with respect to the saturated solution. It may be defined as : The maximum amount of the solute which can be dissolved in 100 g (0-1 kg) of the solvent to form a saturated solution at a given temperature.
For the effect of change in temperature on the solubility: The temperature at which the process of dissolution is carried is always mentioned. This means that the solubilities of salts in solvents (generally water) are influenced by the change in temperature. Actually, the effect of temperature depends upon the heat energy changes which accompany the process.

Question 43.
Why is crystallisation better than evaporation for the separation of mixtures ? (CBSE 2015)
Answer:

1. Common salt and water. Since common salt (sodium chloride) is soluble in water, it can be separated by crystallisation. The process of distillation can also be used because sodium chloride is non-volatile and water is volatile in nature.
2. Iodine and sand. Sublimation process can be used. Iodine will sublime on heating while sand will remain unaffected.
3. Kerosene and water. The liquids are not miscible with each other. Separation can be done by using a separating funnel.

Question 44.
Sugar and sulphur. The mixture is dissolved in carbon disulphide in a beaker by stirring with a glass rod. Sulphur dissolves while sugar remains as such. On filtering, sugar separates as the residue. The filtrate upon concentration and cooling gives crystals of sulphur.
Give one example each of a mixture which shows the following characteristics.

1. A mixture of two volatile component.
2. A mixture of two volatile components with a boiling point difference less than 25 K.
3. A mixture of a volatile and a non-volatile component. (CBSE 2015)

Answer:

1. Iodine and camphor
2. Acetone (b.p. = 319 K) and ethyl alcohol (b.p. = 341 K)
3. Naphthalene and sodium chloride.

Question 45.
Differentiate between an element and a compound. Categorize the following substances into elements and compounds.
Sodium chloride, iodine, water, 24 carat gold, oxygen gas, carbon. (CBSE 2015)
Answer:
For distinction between element and compound,
Elements : Iodine, 24 carat gold, carbon.
Compounds : Sodium chloride, water, oxygen gas.

Question 46.
Air is considered to be a mixture and not a compound ? Explain. (CBSE 2015)
Answer:
Air is a homogeneous mixture of different gases which can be separated by suitable methods. Therefore, it is a mixture and not a compound.

Question 47.
Observe the apparatus shown and answer the following questions.

1. Identify the apparatus
2. Design an activity to use this apparatus to separate the mixture of mustard oil and water.
3. Write the principle involved in this process. (CBSE 2015, 2016)

Answer:

1. The apparatus is known as a separating funnel.
2. For the details of the apparatus & activity.
3. Two immiscible liquids can be separated if in case they differ in their densities. A separating funnel can be used to separate the components of an immiscible liquid mixture.

Question 48.
Compare suspension and colloidal solution on the basis of

1. type of mixture
2. particle size
3. scattering of light
4. stability. (CBSE 2015)

Answer:

1. Both are heterogeneous mixture.
2. In colloidal solution, particle size ranges between 10^-9 m to 10^-7 m whereas in suspension, the particle size is more than 10^-7m.
3. Colloidal solution has the capacity to scatter the path of light when made to pass through it whereas a suspension is unable to do so.
4. A suspension is more stable than a colloidal solution.

Question 49.
A solution contains 50 g of sugar in 450 g of water. Calculate the concentration in terms of mass by mass percentage of the solution. (CBSE 2015)
Answer:

Question 50.
What is ‘Tyndall effect’ ? Name two mixtures which show this effect. (CBSE 2015)
Answer:
For Tyndall effect, The scattering of the beam of light by the dispersed phase particles in a colloidal solution as it passes through it, is known as Tyndall effect.

1. A colloidal solution of dust particles suspended in air.
2. A colloidal solution of starch in water.

Question 51.
What is chromatography ? Write its two applications. (CBSE 2016)
Answer:
In Greek, the word ‘Kroma’ means colour and the word chromatography implies ‘writing, in colour’. Actually, this technique was initially used to separate coloured components from pigments and dyes. But now it has wide range of applications. Chromatography is of a number of types such as adsorption, thin layer, paper and gas chromatography etc. However, the paper chromatography is very simple and is commonly used in the laboratory.

Question 52.
(a) Compare metals and non-metals based on their physical properties (any four).
(b) What are metalloids ? Give two examples.
(c) Identify metals from the following :
boron, sodium, mercury, carbon. (CBSE 2016)
Answer:
(a)

(b) Semi-Metals or Metalloids: There are a few elements which possess the characteristics of both metals and non-metals. These are actually border-line elements and are known as semi-metals. Semi-metals are also called metalloids. A few common examples are : Silicon, Arsenic, Antimony and Bismuth.
(c) Sodium and mercury are metals.

Question 53.
List six physical properties of metals. Name two metals. Name a metal which is liquid at room temperature.
(CBSE 2016)
Answer:

Question 54.
Give two differences between pure substances and mixtures. Give one example of each. (CBSE 2016)
Answer:

1. A pure substance is always a single substance (element or compound). A mixture has two or more constituents.
2. A pure substance has always sharp melting or boiling point. A mixture does not have sharp melting or boiling point.
   Examples : Copper sulphate (Pure substance), Air (Mixture)

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 2 Is Matter Around Us Pure are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Chapter 5 The Fundamental Unit of Life Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

The Fundamental Unit of Life Class 9 Important Questions and Answers Science Chapter 5

Very Short Answer Questions

Question 1.
Which organelles are called

1. Power house
2. Suicide bags of the cell ? (CCE 2010, 2011, 2013)

Answer.

1. Power house of Cell-Mitochondria.
2. Suicide Bags of Cell-Lysosomes.

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2.
State two important functions of the nucleus of a cell.
(CCE 2011, 2013)
Answer:

1. Genetic Information: Nucleus contains genetic information not only for the cell but also for the whole organism.
2. Control Centre: Nucleus functions as control centre for cell metabolism and cell activities.

Question 3.
Name two cell organelles that have their own genetic material/DNA and ribosomes. (CCE 2010, 2012, 2013)
Answer:
Mitochondria, Plastids.

Question 4.
Name the plastid which stores starch, oils and protein granules. (CCE 2011, 2012)
Answer:
Leucoplasts – amyloplast for starch, elaioplast for oil and aleuroplast for protein.

Question 5.
Name the cell organelle which is able to destroy a damaged old/ and worn out cell. (CCE 2011, 2012)
Answer:
Lysosome.

Question 6.
Who discovered cells in organisms ? Give an example of unicellular organism. (CCE 2011, 2013)
Answer:
Robert Hooke (1665). Example. Amoeba, Paramoecium

Question 7.
Name the process in which diffusion takes places place through a selectively permeable membrane. (CCE 2011)
Answer:
Osmosis: It is diffusion ofwater from the side of its higher
concentration (dilute solution) to the side of its lower concentration (concentrated solution) through a semipermeable membrane.

Question 8.
Name the organelle of the cell which has membrane bound sac filled with powerful digestive enzymes. Write its any one function in the cells. (CCE 2011, 2012)
Answer:
Lysosome. Function. Intracellular digestion and disposal of worm out cell organelles.

Question 9.
State the full form of ATP. (CCE 2011)
Answer:
Adenosine triphosphate.

Question 10.
Name the cell organelle, other than mitochondria, which has its own DNA and ribosomes. (CCE 2011, 2012)
Answer:
Plastid.

Question 11.
Why do egg shells dissolve in dilute hydrochloric acid ?
(CCE 2011)
Answer:
Egg shells are made of calcium carbonate which reacts with HC1 and forms soluble calcium chloride.

Question 12.
Name the functional unit of DNA that carries genetic information. (CCE 2012)
Answer:
Gene.

Question 13.
Name the site organelle where proteins are synthesized in a cell. (CCE 2012)
Answer:
Ribosomes.

Question 14.
Name the cell organelle responsible for intracellular transport. (CCE 2012)
Answer:
Endoplasmic reticulum.

Question 15.
Name the process through which Amoeba acquires its food from external environment. (CCE 2012)
Answer:
Endocytosis.

Question 16.
Identify the cell organelle which is known as the power house of the cell. State reason. (CCE 2012, 2013)
Answer:
Mitochondrion. It is the major seat of production of ATP used as source of energy for various cell functions.

Question 17.
In what way a prokaryotic cell is different from eukaryotic cell with respect to nuclear membrane ? (CCE 2012)
Answer:
A nuclear membrane is absent in prokaryotic cell. It is present in eukaryotic cell.

Question 18.
Name the plastid involved in conversion of a green brinjal to violet. (CCE 2012)
Answer:
Non-green chromoplast.

Question 19.
Name the phenomenon of losing water by a living plant cell through osmosis. (CCE 2012)
Answer:
Exosmosis.

Question 20.
Name
(i) The cells which have changing shape,
(ii) The cells which have typical shape. (CCE 2012)
Answer:
(i) Leucocytes
(ii) Liver cell, parenchyma.

Question 21.
Identify single-celled organisms from the following : Cockroach, Chlamydomonas, Snake, Mosquito, Bacteria. (CCE 2012)
Answer:
Chlamydomonas, Bacteria.

Question 22.
Name two cell organelles having membrane envelope.(CCE 2012, 2016)
Answer:
Mitochondria (double membrane covering), lysosome (single membrane envelope).

Question 23.
Name the factor which decides the movement of water across the plasma membrane. (CCE 2012)
Answer:
Difference in the concentration of water inside the cell and outside solution.

Question 24.
State the significance of membrane biogenesis. (CCE 2012)
Answer:
It replaces the membrane depleted due to exocytosis and injury.

Question 25.
List the constituents of plasma membrane. (CCE 2012)
Answer:
Phospholipids, proteins and small carbohydrates.

Question 26.
State the reason for calling cell membrane as selectively permeable membrane. (CCE 2012)
Answer:
Cell membrane is called selectively permeable because it

1. Allows diffusion of some substances including water
2. Allows active passage of some solutes but
3. Remains impermeable to others.

Question 27.
Name two components of chromosomes. (CCE 2012)
Answer:
DNA and proteins.

Question 28.
Name two cell organelles having double membrane envelope. (CCE 2012)
Answer:
Plastids, Mitochondria.

Question 29.
Mention the difference between prokaryotes and eukaryotes in terms of nuclear region present in them. (CCE 2012)
Answer:
Genetic material is enclosed inside the nucleus in eukaryotes while it lies coiled in the cytoplasm as nucleoid in prokaryotes.

Question 30.
Name the cell organelle that detoxifies poisons and drugs in the liver of vertebrates. (CCE 2012, 2015)
Answer:
Smooth endoplasmic reticulum.

Question 31.
Name the kind of plastid which is important for photosyntheis in leaves of plants. (CCE 2012)
Answer:
Chloroplasts (green chromoplasts).

Question 32.
Name the main constituent substance present in plant cell wall and state its function. (CCE 2012)
Answer:
Cellulose. It provides mechanical strength and rigidity to the cell wall.

Question 33.
Mention the change in human red blood cells when they are placed in hypotonic salt/sugar solution. (CCE 2012)
Answer:
RBCs will continue to swell and ultimately burst.

Question 34.
When a living plant cell loses water through osmois, there is contraction of contents of the cell away from the cell wall. What is this phenomenon called ? (CCE 2012, 2015, 2016)
Answer:
Plasmolysis.

Question 35.
Identify and name the following structures
(a) The undefined nuclear region of prokaryotic cell
(b) Site of energy release inside the cell. (CCE 2012)
Answer:
(a) Nucleoid
(b) Mitochondria.

Question 36.
What would happen if an animal cell is kept in distilled water for 24 hours ? (CCE 2012)
Answer:
It will swell up and burst.

Question 37.
State the function of chromosome in a cell.(CCE 2012, 2013)
Answer:
It contains genetic information in the form of genes and takes part in equitable distribution of the same at the time of cell division.

Question 38.
The raisins added to porridge swell after some time. Name the process involved. (CCE 2013)
Answer:
Osmosis.

Question 39.
Name the factor which decides the movement of water across the plasma membrane. (CCE 2013)
Answer:
Concentration of water.

Question 40.
What is nucleoid ? (CCE 2013)
Answer:
Genetic material of prokaryotes which is devoid of a nuclear envelope and consists of a single compacted DNA molecule (equal to a single chromosome) is called nucleoid.

Question 41.
Every multicellular organism has come from a single cell. Justify this statement. (CCE 2013)
Answer:
Every multicellular organism develops from a single cell called zygote, which is formed by fusion of two types of gametes.

Question 42.
Identify the single celled organisms from the following :
Cockroach, Amoeba, Snake, Mosquito, Bacteria. (CCE 2013)
Answer:
Amoeba, Bacteria.

Question 43.
Which part of the cell is called brain of the cell ? (CCE 2013)
Answer:
Nucleus, as it controls all the activities of the cell.

Question 44.
Who discovered cells in living organisms ? Give an example of a unicellular organism. (CCE 2013)
Answer:
Leeuwenhoek (1674). Amoeba.

Question 45.
Name the process of building of cell membrane. (CCE 2014, 2015)
Answer:
Membrane biosynthesis.

Question 46.
Mention the commonly used name of cell membrane.
(CCE 2014)
Answer:
Plasma membrane.

Question 47.
What is the name given to the components of the cell ? (CCE 2014)
Answer:
Cell organelles.

Question 48.
State the role of vacuole in a plant cell. ( CCE 2015)
Answer:
Vacuole: Storage, dumping and development of osmotic concentration.

Question 49.
Pick up the odd one out of ribosomes, Golgi apparatus, mitochondria, endoplasmic reticulum (ER) and give suitable reason. (CCE 2015)
Answer:
Ribosomes. Ribosomes have no membrane covering while covering membranes occur in others.

Question 50.
Which process plays an important role in gaseous exchange between cells ? (CCE 2016)
Answer:
Diffusion.

Question 51.
Name the process by which unicellular fresh water organisms and most plant cells tend to gain water. (CCE 2016)
Answer:
Osmosis.

Question 52.
Name the cell organelle which is commonly called “suicide bag” of the cell. (CCE 2016)
Answer:
Lysosome.

Question 53.
Why do chromatin fibres organise themselves into chromosomes? (CCE 2016)
Answer:
For equitable distribution of genetic material during cell division.

Question 54.
State the site of manufacture of fat molecules in a cell.
Answer:
Surface of smooth endoplasmic reticulum.

Short Answer Questions (2 Marks)

Question 1.
(a) What is DNA ? Where is it found ?
(b) Name the functional segment of DNA. (CCE 2010, 2011)
Answer:
(a) DNA or deoxyribonucleic acid is genetic material of living beings. It occurs as part of chromatin in nucleus and as such in mitochondria and plastids.
(b) Gene.

Question 2.
Name two similarities between mitochondria and plastids.
(CCE 2010, 2011)
Answer:
Both of them possess

1. Double membrane covering
2. Their own DNA.

Question 3.
Mention any two functions of endoplasmic reticulum.
(CCE 2010, 2011, 2013)
Answer:

1. Biosynthesis: Endoplasmic reticulum is engaged in synthesis of lipids (SER) and proteins (RER).
2. Support: It provides support to cytoplasm.

Question 4.
Give function of the following organelles

1. Chloroplast
2. Nucleus
3. Ribosomes. (CCE 2010, 2011, 2012)

Answer:

1. Chloroplast: Photosynthesis,
2. Nucleus: Control of cellular activities and inheritance
3. Ribosomes: Protein synthesis.

Question 5.
State cell theory. Name the scientist who presented it. (CCE 2010)
Answer:
Cell theory states that cells are the structural and functional units of bodies of all living beings. The theory was put forward by Schleiden and Schwann ( 1839).

Question 6.
What is plasmolysis ? Give one example. (CCE 2010, 2011)
Answer:
Plasmolysis is shrinkage of protoplasm from the cell wall due to continued exosmosis when cells are placed in hypertonic solution. A peeled carrot piece placed in salt solution will contract due to plasmolysis of its cells.

Question 7.
Write the names of two cell organelles that have their own DNA and ribosomes. (CCE 2010)
Answer:

1. Plastids
2. Mitochondria.

Question 8.
What is endocytosis ? Name an organism that feeds by this method. (CCE 2010, 2011, 2013)
Answer:
Endocytosis is the bulk transfer of materials from outside to inside of a cell with the help of special vesicles developed by plasma membrane. Organism (that feeds by endocytosis). Amoeba.

Question 9.
(a) What is plasma membrane made up of ?
(b) Name the process and also explain how food and other substances enter through plasma membrane. (CCE 2010)
Answer:
(a) Plasma membrane is made of a bilayer of lipids (or phospholipids) and proteins located inside and outside the same,
(b) Food passes through plasma membrane by endocytosis. Other bulk transports also occur through it. For soluble substances, plasma membrane shows selective permeability.

Question 10.
Two Rhoeo peels were taken. One peel was put in a petridish containing cold water and the other was put in a petridish containing hot water. After a while both were transferred to hypertonic solutions. If the peels were observed under the microscope, will there be any difference in the observation of both the peels. Yes or no. Give reason for your answer.
(CCE 2010)
Answer:
Yes. There is difference. The peel placed initially in hot water does not undergo plasmolysis. Plasmolysis occurs in cells of the peel initially kept in cold water. Hot water kills the cells. Dead cells do not show osmosis.

Question 11.
Give technical term for a medium which has exactly the same concentration as the cell ? Why does the size of the cell remain the same when placed in such a solution ?  (CCE 2010)
Answer:
Isotonic solution. A cell placed in isotonic solution neither gains water nor loses water as equal amount of water passes inwardly and outwardly in it.

Question 12.
Mention two functions of Golgi apparatus. (CCE 2011)
Answer:

1. Formation of complex sugars,
2. Formation of lysosomes.
3. Storage, modification and packaging of various substances,
4. Secretion and excretion.

Question 13.
How do substances like CO₂ and water move in and out of cell? (CCE 2011)
Answer:
CO₂ moves into and out of cell though diffusion or passage from the area of its higher concentration to the area of its lower concentration across the cell membrane.
Water moves into and out of cell through osmosis or passage of water from the area of higher concentration (e.g., dilute solution) to the area of lower concentration (e.g., strong solution) across the cell membrane which acts as a semipermeable membrane.

Question 14.
(a) In which form does mitochondria release energy ? Write its full form.
(b) The inner membrane of mitochondria is deeply folded. What is the advantage of these folds ? (CCE 2011, 2012)
Answer:
(a) As ATP or adenosine triphosphate.
(b) Folding of inner membrane creates a large surface area for ATP generating reactions.

Question 15.
Where are chromosomes located in a cell ? What are they composed of ? What important information they contain ? (CCE 2011)
Answer:
Location: Nucleus.
Composition: DNA and proteins.
Information: They carry genetic information for structural and functional traits in the form of genes.

Question 16.
Preetha was observing live cells of Onion in biology laboratory. She observed cell wall, cytoplasm and nucleus clearly. Suddenly her friend who was doing chemistry experiment spilled a few drops of salt water on the slide. After some time Preetha observed the slide and found some changes,
(a) What would have been the change in the live cells of Onion peel after adding salt water ?
(b) Name the type of process.
(CCE 2011)
Answer:
(a) There was shrinkage of cytoplasm away from cell wall.
(b) Plasmolysis.

Question 17.
How can plant cells withstand much greater changes in the surrounding medium than the animal cells ?
(CCE 2011)
Answer:
Plant cells are covered by a rigid wall. The cell wall allows the plant cells to withstand changes in the surrounding medium better than animal cells.

Question 18.
Write two characteristics of prokaryotic cells. (CCE 2011)
Answer:
(i) Genetic material is equal to a single chromosome which is not organised into a nucleus,
(ii) Membrane bound cell organelles absent.

Question 19.
What are unicellur organisms ? List two examples. (CCE 2011)
Answer:
Organisms made of single cells are called unicellular organisms. Examples. Amoeba, Paramoecium.

Question 20.
Which stain is used to prepare an Onion peel slide ? Why do we need a stain to be added ? (CCE 2013)
Answer:
Safranin. The stain is added to make the cellular components clearly visible under the microscope.

Question 21.
Name the process by which
(a) Oxygen moves in and out of the cell,
(b) Water moves in and out of the cell. Differentiate between the two processes. (CCE 2013)
Answer:
(a) Diffusion
(b) Osmosis.

Question 22.
What will happen if
(a) Almonds are soaked in water.
(b) Concentrated solution of fertilizer is applied to green grass lawn. Give suitable reason in support of your answer.
(CCE 2013)
Answer:
(a) Almond will swell up due to endosmosis. There is higher concentration of water around almonds than inside them.
(b) Grass will shrivel due to exosmosis. There is higher concentration of water inside grass plants than in outer concentrated fertilizer solution.

Question 23.
Give one function each of RER and SER. (CCE 2014)
Answer:
Function of RER. Synthesis of protein for export to Golgi apparatus.
Function of SER. Synthesis of lipids.

Question 24.
Name a cell organelle which lacks membrane. Where is it prepared ? (CCE 2014)
Answer:
(i) Ribosome,
(ii) It is synthesised in the form of subunits in nucleolus part of nucleus.

Question 25.
Differentiate between eukaryotic and prokaryotic cells, based on the size and number of chromosomes. (CCE 2014)
Answer:
The genetic material of a prokaryotic cell is equal to a small histone free chromosome and is often called prochromosome. A eukaryotic cell has two to several histone supported larger chromosomes.

Question 26.
What is the importance of osmosis in :
(a) Unicellular organisms
(b) Plants ? (CCE 2015)
Answer:
Osmosis in Unicellular Organisms. Absorption of water, osmoregulation.
Osmosis in Plants. Absorption of water from soil, cell to cell movement of water.

Question 27.
Which cell organelle is known as “suicide bags” of the cell ? Why? (CCE 2015)
Answer:
Lysosomes contain digestive enzymes against all types of organic materials. If their covering membrane breaks as it happens during injury to cell, the digestive enzymes will spill over the cell contents and digest the same. As lysosomes are organelles which on bursting can kill the cells possessing them, they are called suicide bags.

Question 28.
Describe the structure of mitochondria with reference to its membrane covering. (CCE 2015)
Answer:
Structure: Mitochondria are rod or sausage shaped colourless organelles of aerobic eukaryotes that have a double membrane covering. The outer membrane is porous. The inner membrane is folded. The folds are called cristae. They bear ATP generating elementary particles. The matrix contains enzymes of Krebs cycle,

Question 29.
(a) Name the cell organelle which helps in packaging and
dispatching the material synthesised over the endoplasmic reticulum to various targets inside and outside the cell.
(b) Name and write function of cell organelle formed by the above cell organelle. ( CCE 2016)
Answer:
(a) Golgi apparatus,
(b) Lysosome: Lysosomes possess digestive enzymes which help in intracellular digestion and removal of scenescent cellular structures.

Short Answer Questions (3 Marks)

Question 1.
Write in a tabular form three differences between a plant cell and an animal cell. (CCE 2010, 2011, 2012)
Answer:

Question 2.
Classify the following as osmosis or diffusion :
(a) Aquatic animals using oxygen dissolved in water during respiration.
(b) Swelling up of raisins on keeping in water.
(c) Spreading of virus on sneezing. (CCE 2010)
Answer:
(a) Diffusion
(b) Osmosis (endosmosis)
(c) Diffusion.

Question 3.
(a) Which cell organelles are called power houses of the cell and why ? (CCE 2010, 2012)
(b) Why is ATP called energy currency of the cell ? (CCE 2010)
Answer:
(a) Mitochondrion is known as power house of the cell because it produces most of the molecules of ATP (adenosine triphosphate) which are required for providing energy for synthesis of new chemicals, mechanical and other cellular functions.
(b) ATP or adenosine triphosphate is called energy currency of the cell as it is built up when energy is available as from an * exothermic reaction and broken down to release the energy whernsver required for performing an activity or an endothermic reaction.

Question 4.
Draw a neat diagram of an animal cell and label on it the following :
Plasma membrane. Nucleus, Lysosome/RER, centriole, Lysosome. (CCE 2010, 2012)
Answer:

Question 5.
List any three functions performed by endoplasmic reticulum.
(CCE 2010)
Answer:

1. Biosynthesis: Endoplasmic reticulum is engaged in synthesis of lipids (SER) and proteins (RER).
2. Support: It provides support to cytoplasm.
3. Transport: It helps in intracellular as well as intercellular transport of substances.

Question 6.

1. State two types of plastids
2. Write one function of each. (CCE 2010)

Answer:

1. Chloroplasts and chromoplasts.
2. Chloroplasts. Photosynthesis. Chromoplasts. Providing colouration to flowers and fruits for attracting animals to perform pollination and dispersal respectively.

Question 7.
What are chromosomes ? List their two functions.  (CCE 2010)
Answer:
Chromosomes are rod-like DNA containing stainable condensed chromatin units which become visible at the time of cell division.
Functions: 

1. They carry genetic information in the form of genes arranged in a linear sequence.
2. By their replication just before cell division and equitable distribution during cell division, chromosomes maintain the hereditary content of the cells.

Question 8.
List three differences between prokaryotic and eukaryotic cells. (CCE 2010, 2011, 2012)
Answer:

Question 9.
Describe the role played by lysosomes. Why are these termed as suicide bags ? How do they perform their function ?
(CCE 2011, 2012)
Answer:
Role: Lysosomes take part in

1. Destruction of foreign particles.
2. Intracellular digestion of food
3. Digestion and removal of worn out cell organelles.

Suicide Bags: Lysosomes contain digestive enzymes against all types of organic materials. If their covering membrane breaks as it happens during injury to cell, the digestive enzymes will spill over the cell contents and digest the same. As lysosomes are organelles which on bursting can kill the cells possessing them, they are called suicide bags.
Working: Lysosomes are full of digestive enzymes. They fuse with foreign and worn out cell structures. Lysosomal enzymes bring about their digestion. The digested substances diffuse out into cell while the undigested materials are thrown out of the cell.

Question 10.
Explain your observation in the following with reason involved in the process : (a) Salt is applied to raw mango pieces (b) Dried raisins are kept in water for a few hours.
(CCE 2011)
Answer:
(a) Salt applied over raw mango pieces will kill the surface cells and prevent growth of microbes over them due to exosmosis.
(b) Raisins swell up due to endosmosis or entry of water into their cells due to osmosis.

Question 11.
Differentiate between diffusion and osmosis. Write any two examples where a living organism uses osmosis to absorb water. (CCE 2011, 2012)
Answer:
(a)

(b) Examples :
(i) Absorption of soil water by roots.
(ii) Gaining of water by guard cells during opening of stomata.

Question 12.
(a) Name the organelles which provide turgidity to the plant cell. Name any two substances which are present in it.
(b) How are they useful in unicellular organisms like Amoeba ?
(CCE 2011, 2014)
Answer:
(a) Vaculoes.

1. Water,
2. Dissolved storage and waste substances (Sugars, salts, amino acids, organic acids).

(b) In unicellular organisms vacuoles take part in

1. Osmoregulation and excretion by contractile vacuoles,
2. Digestion of food in food vacuoles.

Question 13.
Distirigush amongst hypotonic, isotonic and hypertonic solutions. (CCE 2011)
Answer:
Hypotonic solution has lower osmotic concentration and higher water concentration as compared to the cell. The cell gains water from Such external solution by osmosis. Isotonic solution is the one which has the same osmotic concentration and water concentration as that of the cell. The cell placed in such a solution will neither gain nor lose water.
Hypertonic solution has a higher osmotic concentration and lower water concentration as compared to the cell. The cell loses water to such an external solution and gets plasmolysed.

Question 14.
(a) What is osmosis ?
(b) What happens to cell when it is placed in hypotonic, isotonic and hypertonic solutions respectively ?
(c) What is plasmolysis ? (CCE 2011)
Answer:
(a) Osmosis is diffusion of water from the region of its higher concentration (pure water or dilute solution) to the region of its lower concentration (strong solution) through a semipermeable membrane.
(b)

1. Cell in Hypotonic Solution. Swells up due to endosmosis and becomes turgid.
2. Cell in Isotonic Solution. No change.
3. Cell in Hypertonic Solution. Cell contents shrink due to exosmosis or outward passage of water.

(c) Plasmolysis is shrinkage of protoplasm from the cell wall due to continued exosmosis when cells are placed in hypertonic solution. A peeled carrot piece placed in salt solution will contract due to plasmolysis of its cells.

Question 15.
State main functions of the following :
(a) Mitochondria
(b) Golgi apparatus
(c) Vacuoles. (CCE 2011)
Answer:
(a) Mitochondria,

1. Site of aerobic respiration.
2. Liberation of energy as ATP (hence power house of cells).

(b) Golgi Apparatus.

1. Formation of lysosomes.
2. Complexing, packaging, secretion and excretion of substances.

(c) Vacuoles,

1. Storage ofinorganic and organic substances.
2. Dumping ofwastes.
3. Developing osmotic concentration for absorption of water and maintenance of turgidity of cells.

Question 16.
Briefly explain the structure and function of nucleus.
(CCE 2011)
Answer:
Structure: Nucleus is oval or rounded dense cellular structure having four components :

1. A double membrane porous envelope (nuclear envelope),
2. Nuclear sap or nucleoplasm.
3. Chromatin made of threads of DNA and protein which get converted into chromesomes at the time of cell division,
4. Nucleolus, a rounded naked structure attached to chromatin and seat of ribosome formation.

Functions:

1. Nucleus controls cellular activities.
2. It contains genetic or hereditary information over its chromosomes for expression of various traits.
3. Ribosomes are formed in its nucleolus.

Question 17.
What are the two types of endoplasmic reticulum ? Mention one function of each. (CCE 2011)
Answer:
Types: There are two types of endoplasmic reticulum, smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). Rough endoplasmic reticulum bears ribosomes on its surface. The same are absent over SER.
Function of RER: Synthesis of proteins over its ribosomes.
Function of SER: Synthesis of lipids and steroids.

Question 18.
What are chromoplasts and leucoplasts ? Give an example of chromoplasts which has green pigment. ( CCE 2011)
Answer:
Chromoplasts. The coloured plastids are called chromoplasts. Leucoplasts. The colourless plastids are known as leucoplasts. Green Chromoplasts. Chloroplasts.

Question 19.
What will happen if the organisation of a cell is destroyed due to some physical or chemical influence ? (CCE 2011)
Answer:
Organisation is important for performing different functions of the cell. If organisation is destroyed, the cell will not be able to perform many of its functions. This will lead to senescence and death of the cell Bursting of lysosomes will quicken death of the cell.

Question 20.
Draw the diagram to show animal cell and label the following parts :
(a) Power house of the cell,
(b) Suicidal bag
(c) Organelle which helps in protein synthesis
(d) Organelle which helps during cell division.
(CCE 2011, 2012)
Answer:

(a) Mitochondrion
(b) Lysosome
(c) Ribosome
(d) Centriole.

Question 21.
(a) State two types of plastids. Mention the function of each.
(b) How do vacuoles help in ingestion and egestion in single celled organisms ? (CCE 2011, 2012)
Answer:
(a) Leucoplasts and chromoplasts. Leucoplast. Storage of carbohydrates, proteins and fats. Chromoplast. Photosynthesis by chloroplasts (green chromoplasts) and attractive colouration in flowers and fruits by non-green chromoplasts.
(b) During ingestion of food, the plasma membrane invaginates in contact with food particle and pinches off as small food containing vacuole called phagosome. Phagosome fuses with lysosome to form food vacuole. Digestion occurs. The digested materials pass out into cytoplasm. The vacuole containing undigested food pieces rises to the surface, fuses with plasma membrane to perform egestion.

Question 22.
What is the relationship between chromatin material and chromosomes ? (CCE 2011, 2013)
Answer:
Chromatin is an intertwined mass of thread-like DNA- protein complex that occurs in the nucleus. At the time of cell division, chromatin condenses and gets organised into chromosomes.

Question 23.
(a) Explain the phenomenon of plasmolysis.
(b) Explain how do cell walls permit cells of fungi to withstand very dilute external media without bursting.
(CCE 2011)
Answer:
(a) Plasmolysis is shrinkage of protoplasm from the cell wall due to continued exosmosis when cells are placed in hypertonic solution. A peeled carrot piece placed in salt solution will contract due to plasmolysis of its cells.
(b) Despite being present in very dilute medium, the fungal cells do not undergo unlimited swelling. Swelling stops as soon as the limit of cell wall elasticity is reached. At this time, the cell wall exerts an opposite force that prevents further entry of water.

Question 24.
List the specific functions of the following :

1. Rough endoplasmic reticulum
2. Golgi apparatus
3. Lysosomes
4. Mitochondria
5. Plastids
6. Vacuoles in unicellular organisms. (CCE 2011)

Answer:
Rough Endoplasmic Reticulum.

1. Protein synthesis,
2. Golgi Apparatus.
   1. Formation of lysosomes.
   2. Complexing, packaging, secretion and excretion of substances.
3. Lysosomes. Waste disposal, intracellular digestion,
4. Mitochondria,
   1. Site of aerobic respiration.
   2. Liberation of energy as ATP (hence power house of cells).
5. Plastids Photosynthesis (chloroplasts), storage (leucoplasts), colouration (non-green chromoplasts).
6. Vacuoles in Unicellular Organisms. Osmoregulation, excretion, ingestion, digestion and egestion.

Question 25.
Describe the structure and write any two functions of Golgi apparatus. (CCE 2011)
Answer:
Golgi apparatus is a stack of curved membrane bound flat sacs called cisternae/cisterns that bear tubules and vesicles on the sides Functions.
Golgi Apparatus:
(a) Formation of lysosomes.
(b) Complexing, packaging, secretion and excretion of substances.

Question 26.
(a) Which organelles supply energy to a cell ? In what form it is stored ?
(b) Explain the structure of this organelle,
(c) Does this organelles contain DNA ? Why ? (CCE 2011)
Answer:
(a) Mitochondria. The energy is stored in the form of ATP.
(b) Structure. Mitochondria are rod or sausage shaped colourless organelles of aerobic eukaryotes that have a double membrane covering. The outer membrane is porous. The inner membrane is folded. The folds are called cristae. They bear ATP generating elementary particles. The matrix contains enzymes of Krebs cycle,
(c) Mitochondria possess DNA and ribosomes which help them in synthesis of a number of proteins for their functioning.

Question 27.
Mention the difference between prokaryotic and eukaryotic cells regarding
(i) Nuclear region
(ii) Cell organelles
(iii) Chlorophyll. (CCE2012)
Answer:

Question 28.
(a) What is membrane biogenesis ?
(b) Explain what happens when a drop of concentrated sugar solution is placed on a rheo leaf mounted on a glass slide. Name this phenomenon. Would the same happen if riieo leafwas boiled before mounting ? Give reason for your answer. (CCE 2012)
Answer:
(a) Membrane Biogenesis. It is formation, renewal and repair of biomembrane from its constituents (lipids and proteins) synthesised over smooth and rough endoplasmic membrane and their modification by Golgi apparatus.
(b)

1. A concentrated sugar solution will cause exosmosis in cells of rheo peel mounted on a glass slide. The cytoplasm withdraws from cell wall. The phenomenon is called plasmolysis.
2. Plamolysis does not occur in cells of rheo leaf peel if the latter has been boiled before mounting. It is because boiling kills the cells. Exosmosis can occur only in living cells.

Question 29.
(a) Which cell organelle would you associate with ATP production ? How is this organelle able to make its own protein ?
(ib) A student performed an experiment by placing a de- shelled egg in a concentrated salt solution for five minutes.
What change did he observe in the egg ? Give reason for the same. (CCE 2012)
Answer:
(a) Mitochondrion. The organelle is able to synthesise some of its proteins because it has its own DNA and ribosomes.
(b) The deshelled egg placed in salt solution contracts. The contraction is caused by exosmosis.

Question 30.
(a) Where are genes located in a cell ?
(b) Name the nucleic acids that are present in animal cell. (CCE 2012)
Answer:
(a) Genes are located in the chromatin/chromosomes inside the nucleus.
(b) Animal cell has two types of nucleic acids, DNA (deoxyribonucleic acid) and RNA (ribose nucleic acid). While RNA is mostly located in the cytoplasm, DNA is present inside nculeus (smaller quantity in mitochondria).

Question 31.
(a) State and explain the process by which Amoeba obtains its food. (CCE 2012)
(b) Why is the plasma membrane called a selectively permeable membrane ? (CCE 2012)
Answer:
(a) Amoeba obtains its food through endocytosis. Part of plasma membrane coming in contact with food particle
invaginâtes, engulfs the same and is pinched off into cytoplasm as phagosome. Phagosome fuses with a lysosome to produce a food vacuole. Digestion occurs in the food vacuole. The digested materials pass out into the cytoplasm. The vacuole having undigested matter rises to the surface and performs exocytosis to throw out the undigested matter.
(b) Cell membrane is semipermeable membrane for water. It permits the entry of gases through diffusion. Ions, sugar, amino acids, etc. pass through the plasma membrane by an active process. Plasma membrane is impermeable to certain other materials. Therefore, it is selectively permeable.

Question 32.
Two beakers A and B contain plain water and concentrated sugar solution respectively. Equal number of dried raisins are kept in them for a few hours and then taken out. (t) Explain the reason for the difference in the physical appearance of raisins which were taken out of the two beakers, (it) On the basis of above observation, categorise the two solutions as hypotonic and hypertonic. (CCE 2012)
Answer:

1. Raisins placed in beaker A have swollen while those of beaker B remain shrivelled,
2. Solution (here water) in beaker A is hypotonic (as it causes entry of water into raisins) while solution in beaker B is hypertonic as no water from this solution passes into raisins.

Question 33.
(a) How is flexible nature of plasma membrane useful to Amoeba. Name the process.
(b) Plastids are able to make their own protein. Explain.
(c) Why plant cells shrink when kept in hypertonic solution.
(CCE 2012)
Answer:
(a)Flexible nature of plasma membrane is useful to Amoeba in

1. Engulfing food particles. The process is called endocytosis.
2. Formation of pseudopodia for locomotion.

(b) Plastids possess DNA and ribosomes for formation of proteins as per information present in the former.
(c) Plant cells placed in hypertonic solution shrink due to passage of a part of their contained water into outer solution due to exosmosis.

Question 34.
(a) List two roles of nucleus of a cell,
(b) Name two substances stored in the vacuoles of a plant cell.
(CCE 2012)
Answer:
(a) Roles of Nucleus,

1. Control: Nucleus controls cell metabolism and cell activities,
2. Hereditary Information: Nucleus contains all the hereditary information not only for the cell but also the whole organism.

(b) Substances in Vacuoles,

1. Water
2. Salts and some organic substances.

Question 35.
(a) Who gave the term Golgi apparatus,
(b) Name one cell organelle formed by Golgi apparatus.
(c) Write any two functions of Golgi apparatus.
Answer:
(a) Cajal (1914).
(b) Lysosome
(c)
(i) Complexing, packages, secretion and exeretion of substances,
(ii) Membrane biosynthesis.

Question 36.
Distinguish leucoplast from chromoplast based on one feature. Give an example of chromoplast present in plant cell. What is the function of chromoplast in plant cell ?
(CCE 2012)
Answer:
Leucoplast is colourless plastid while chromoplast is coloured plastid. Chromoplast present in green aerial cells of the plant is called chloroplast. It takes part in photosynthesis.

Question 37.
Differentiate between rough and smooth endoplasmic reticulum. How is endoplasmic reticulum important for membrane biosynthesis ? (CCE 2012)
Answer:
Rough endoplasmic reticulum bears ribosomes over its surfaces while the same are absent over smooth endoplasmic reticulum. The two types of endoplasmic reticulum synthesise respectively proteins and lipids that are modified and complexed by Golgi apparatus for membrane biosynthesis.

Long Answer Questions

Question 1.
(a) What are lysosomes ? Why are they called “suicide bags of a cell” ?
(b) What happens to the dry raisins when we put them in plain water for some time ? State the reason for whatever is observed. What would happen if these raisins are now placed in concentrated salt solution ? (CCE2010, 2011)
Answer:
(a) Lysosomes. They are small, single membrane bound cell organelles which contain digestive enzymes for intracellular digestion and waste disposal.
Lysosomes contain digestive enzymes against all types of organic materials. If their covering membrane breaks as it happens during injury to cell, the digestive enzymes will spill over the cell contents and digest the same. As lysosomes are organelles which on bursting can kill the cells possessing them, they are called suicide bags.
(b) Dry raisins placed in water swell up due to endosmosis or osmotic entry ofwater into them. The swollen raisins placed in concentrated salt solution will shrink in size and become wrinkled due to exosmosis or osmotic expulsion of water from them.

Question 2.
(a) Distinguish between chloroplast and leucoplast with respect to their pigments and function.
(b) How would
(i) a plant cell
(ii) an animal cell behave when placed in a hypotonic solution of sodium chloride ? Explain giving reason. (CCE 2010, 2011)
Answer:
(a)

(b) Cells placed in hypotonic solution swell up due to endosmosis or osmotic entry of water into them. Swelling is limited in plant cells as they have rigid cell walls. Due to absence of a cell wall, an animal cell will continue to swell up till it bursts.

Question 3.
(a) What is endoplasmic reticulum ?
(b) Describe its structure.
(c) Name two types of endoplasmic reticulum.
(d) What crucial role does it play in the liver cells of vertebrates ?
(e) What is membrane biosynthesis ?
(CCE 2010)
Answer:
(a) Endoplasmic reticulum is a three dimensional interconnected network of membrane lined channels that run through the cytoplasm.
(b) Structure. Endoplasmic reticulum or ER has three components,
(i) Cistemae. They are interconnected flat sacs which run parallel to one another.
(ii) Tublues. They are tube-like extensions of cisternae.
(iii) Vesicles. They are oval or rounded sacs that are connected to cisternae and tubules. Membranes of endoplasmic reticulum are similar to plasma membrane but are thinner. The channels contain a fluid endoplasmic matrix.
(c) Types. There are two types of endoplasmic reticulum, smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). Rough endoplasmic reticulum bears ribosomes on its surface. The same are absent over SER.
(d) Detoxification. SER present in vertebrate liver detoxifies poisons and drugs.
(e) Membrane Biosynthesis. It is synthesis of cell membrane from its constituent proteins and lipids synthesised over endoplasmic reticulum and complexed by Golgi apparatus.

Question 4.
(a) Differentiate between
(i) The functions of RER and SER
(ii) Plasma membrane and cell wall.
(b) What is endocytosis ? (CCE 2010)
Answer:
(a) (i)

(ii) Differences between Plasma Membrane and Cell Wall.

(b) Endocytosis is the bulk transfer of materials from outside to inside of a cell with the help of special vesicles developed by plasma membrane. Organism (that feeds by endocytosis). Amoeba.

Question 5.
(a) Differentiate between
(i) Nucleus and nucleoid.
(ii) Plant cell and animal cell,
(b) What is osmosis ?   (CCE 2010)
Answer:
(a) (i) Differences between Nucleus and Nucleoid.

(ii) Plant Cell and Animal Cell.

(b) Osmosis: Diffusion of water through a semipermeable membrane from the region of its higher concentration (dilute solution) to the region of its lower concentration (concentrated solution) is known as osmosis.

Question 6.
(a) In the given diagram, identify the parts marked B and C.
(b) What are the substances that organelle A stores ?
(c) Mention one function of organelles B and C.
(d) What are cisterns ? (CCE 2010)

Answer:
(a) B —Golgi apparatus.
C — Chloroplast.
(b) A (Central Vacuole). It stores salts, sugar, amino acids, organic acids, some proteins and waste products. Recently lysosomal enzymes have also been detected in it.
(c) Function. :
(i) B — Secretion and excretion.
(ii) C — Photosynthesis.
(d) Cisterns. They are membrane bound curved flat stacks of Golgi bodies that bear tubules and vesicles on their periphery. Similar structures also occur in endoplasmic Ans. reticulum.

Question 7.
Observe the given figure and answer the questions.
(a) What has happened to cell A and B ? Explain.
(b) Identify the type of solution into which cells A and B are placed.
(c) Name and explain the process that has taken place in cells A and B. (CCE 2010)

Answer:
(a) Cell A has become turgid while cell B has become plasmolysed (flaccid).
(b) Cell A is placed in hypotonic solution while cell B is dipped in hypertonic solution.
(c) A—Endosmosis or osmotic entry of water hasoccurred. It is because cell sap has lower concentration of water while the outer solution has higher concentration of water.
Water moves from its higher concentration to lower concentration across a semipermeable membrane.
B —Exosmosis or osmotic expulsion of water has occurred. The cell sap has higher concentration of water than the external solution. Therefore, water passes from inside the cell to the outside.

Question 8.
(a) Draw a neat and labelled diagram’ of a prokaryotic cell.
(b) Why organisms like bacteria are called prokaryotes ?
(CCE 2010)
Answer:
(a)

(b) Bacteria are called prokaryotes because their genetic material is not organised into a nucleus. Instead it lies directly inside cytoplasm as nucleoid.

Question 9.
(a) Categorise plastids based on their colour and function.
(b) Mention the strange similarity between plastids and mitochondria with reference to synthesis of their own materials. What do they synthesise ? (CCE 2010, 2012)
Answer:
(a) Plastids are of three types on the basis of their colour.

1. Colourless Plastids or Leucoplasts. Depending upon their storage product, they are of three types — amyloplasts (storage of starch), aleuroplasts (storage of proteins), and elaioplasts (storage of oil).
2. Brown-Red Plastids or Chromoplasts. They provide colouration to flowers and fruits for attracting pollinators and disseminators.
3. Green Plastids or Chloroplasts. They perform photosynthesis.

(b) Similarity Between Plastids and Mitochondria. They have their own DNA and ribosomes. Ribosomes are used to synthesise a part of proteins and enzymes required by the organelles. Rest of the materials are obtained from the cytoplasm of the cell. DNA and ribosomes make the two organelles semi-autonomous.

Question 10.
(a) What is lacking in a virus which makes it dependent on a living cell to multiply ?
(b) Expand RER and SER. Differentiate between their structure and function. (CCE 2010, 2011)
Answer:
(a) Virus does not have a metabolic machinery as it lacks cytoplasm. Therefore, it is dependent upon the metabolic machinery of a living cell for multiplication.
(b) RER: Rough endoplasmic reticulum.
SER: Smooth endoplasmic reticulum.

Question 11.
Draw a labelled diagram of an animal cell and label the following organelles :
(a) The organelle that contains powerful digestive enzymes.
(b) The organelle that has its own DNA.
(c) The organelle that forms cytoplasmic framework
(d) The organelle that helps in expelling excess water in Amoeba. (CCE 2010)
Answer:

Labelling,
(a) Lysosome
(b) Mitochondrion
(c) Endoplasmic reticulum
(d) Vacuole (Contractile vacuole in Amoeba).

Question 12.
(a) Why does nuclear membrane have pores ?
(b) Why do chromosomes contain DNA in the nucleus ?
(c) Give two roles of nucleus in the cell. (CCE 2010)
Answer:
(a) Pores in Nuclear Membrane. For allowing and controlling the exchange of materials between the nucleus and cytoplasm.
(b) Chromosomes Contain DNA in Nucleus, (i) In order to protect DNA from influence of cytoplasmic enzymes, (it) For separating transcription machinery from translation machinery.
(c)

1. Bodies of the living beings are made up of cells and their products.
2. Activities of an organism are the sum total of activities of its cells.
3. Cells develop from pre-existing cells.Viruses are an exception to cell theory.

Question 13.
(i) Draw a plant cell and label the parts which
(a) Is a dead layer and is permeable
(b) Is the kitchen of the cell
(c) Packages materials coming from endoplasmic reticulum
(d) Controls and regulates all the activities of the cell.
(ii) Identify the two structures which are present only in typical plant cell. (CCE 2013)
Answer:
(i)

(a) Cell wall
(b) Chloroplast
(c) Golgi apparatus
(d) Nucleus.
(ii) (a) Cell wall (b) Chloroplast/plastid.

Question 14.
(a) Draw a neat diagram of an animal cell and label the parts whose functions are as follows :

1. Flelps in storage, modification and packaging of products in vesicles.
2. Helps in keeping the cell clean by digesting worn out cell organelles,
3. Helps in oxidation of glucose to produce energy in the form of ATP.
4. Allows the entry and exit of some materials into and out of cells.

(b) Define nucleoid. (CCE 2014)
Answer:
(a)

1. Golgi apparatus
2. Lysosome
3. Mitochondrion
4. Plasma membrane.

(b) Nucleoid: Genetic material of prokaryotes which is devoid of a nuclear envelope and consists of a single compacted DNA molecule (equal to a single chromosome) is called nucleoid.

Question 15.
Do all cells of our body look alike in terms of shape, size and structure ? What similarities do they have ? (CCE 2015, 2016)
Illustrate by drawing diagrams of various cells present in human body. (CCE 2015)
Answer:
No. Similarities,

1. Covering of plasma membrane.
2. Presence of centrally placed nucleus.
3. Cytoplasm and different cell organelles,

e.g., Golgi apparatus, lysosomes, mitochondria, ribosomes, endoplasmic reticulum. (iv) Metabolic pathways.
Cells become differentiated to perform different functions. They also come to have different shapes and sizes, e.g., nerve cell, bone cell, fat cell, ovum, sperm, blood cells, muscle fibres.

Question 16.
Draw and label a plant cell and write one main function of the following cell organelles :
(a) Chloroplast
(b) Plasma membrane
(c) Vacuole
(d) Lysosomes. (CCE 2015)
Answer:

(a) Chloroplast. Photosynthesis.
(b) Plasma membrane. Holding the cell contents and selective^^” permeability.
(c) Vacuole. Storage, dumping and development of osmotic concentration.
(d) Lysosome. Scavenging, intracellular digestion and defence.

Question 17.
Write differences between prokaryotic and eukaryotic cells.
Draw diagram also. (CCE 2015)
Answer:

Diagrams :

Question 18.
(a) Why is the cell called structural and functional unit of life ?
(b) Explain the concept of division of labour in multicellular organisms giving an example. (CCE 2015)
Answer:
(a) Structural Unit: A living organism is made up of one or more cells. Therefore, cell is structural unit of life. Functional Unit. All life functions of an organism reside in its cells. Cells may also become specialised to perform specific functions like contraction in muscle cell or impulse transmission in nerve cell. Therefore, cells are functional units of life.
(b) Division of labour is the taking up of different functions of the system/body by different specialised components in a coordinated fashion so that the whole is benefitted without any part put to overwork. It increases efficiency. In multicellular organisms like humans there are a number of organs, tissues and cells performing different functions, e.g. contraction and movement by muscle cells, transmission of impulses by nerve cells, transport of oxygen by RBCs, protection from germs by white blood corpuscles, gamete formation by germ cells, pumping of blood by heart, extraction of wastes by kidneys, etc.

Question 19.
On the basis of number of cells living organisms are classified as unicellular and multicellular,
(a) Name two unicellular organisms
(b) What is meant by division of labour in multicellular organisms,
(c) Name one prokaryotic and one eukaryotic unicellular organism ?
(d) Every multicellular organism has come from a single cell. Justify this statement.
(e) Write one common feature between in Amoeba and white
blood cells of humans. (CCE 2015)
Answer:
(а) Amoeba, Paramecium.
(b) Division of labour is the taking up of different functions of the system/body by different specialised components in a coordinated fashion so that the whole is benefitted without any part put to overwork. It increases efficiency. In multicellular organisms like humans there are a number of organs, tissues and cells performing different functions, e.g. contraction and movement by muscle cells, transmission of impulses by nerve cells, transport of oxygen by RBCs, protection from germs by white blood corpuscles, gamete formation by germ cells, pumping of blood by heart, extraction of wastes by kidneys, etc.
(c) Bacterium (prokaryotic, e.g., Escherichia coli), Chlamydemortas (eukaryotic).
(d) Every multicellular organism develops from a single cell called zygote, which is formed by fusion of two types of gametes.
(e) Both have irregular shape and perform endocytosis.

Question 20.
(a) Draw a neat diagram of a typical plant cell and label chloroplast and plasma membrane.
(b) State main function of

1. Mitochondria
2. Chloroplast.

(c) Write two differences between a plant cell and an animal cell. (CCE 2016)
Answer:
(a)

(b) Mian Function,

1. Mitochondria: Aerobic respiration and energy release,
2. Chloroplast: Photosynthesis.

(c)

Question 21.
What is meant by osmosis ? State the following conditions :
(a) When the cell loses water and shrinks
(b) When there is no overall movement of water. How can the plant cell withstand very dilute external media without bursting.
(CCE 2016)
Answer:
Osmosis is diffusion of water from the region of its higher concentration (pure water or dilute solution) to the region of its lower concentration (strong solution) through a semipermeable membrane.
(a) Plasmolysis due to external solution being hypertonic.
(b) External solution is isotonic.

Question 22.
A plant cell placed in very dilute solution swells up, becomes turgid but further endosmosis stops due to cell wall that begins to press the protoplasm inwardly.
(a) Differentiate between rough and smooth endoplasmic reticulum,
(b) How is endoplasmic reticulum important for membrane biosynthesis ? (CCE 2016)
Answer:
(a)

(b) Membrane Biosynthesis: It is synthesis of cell membrane from its constituent proteins and lipids synthesised over endoplasmic reticulum and complexed by Golgi apparatus.

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 5 The Fundamental Unit of Life are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Chapter 1 Matter in Our Surroundings Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Matter in Our Surroundings Class 9 Important Questions Science Chapter 1

Question 1:
Answer the following questions.

1. Why is ice at 273 K more effective in cooling than water at the same temperature ?
2. Name the two gases which are supplied in compressed form in homes and hospitals.
3. What is dry ice ? (CBSE 2010, 2011)

Answer:

1. The three states of matter are : solid, liquid and gas. Out of these, the solid state is the most rigid since the particles present are very closely packed and interparticle forces are quite strong.
2. LPG (Liquid Petroleum Gas) is supplied in homes while liquefied oxygen in hospitals
3. Solid carbon dioxide (CO₂) is known as dry ice. It is so named as it does not wet a piece of paper or cloth.

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2:
CO₂ is a gas. Justify the given statement by two reasons. (CBSE 2011)
Answer:

1. CO₂ does not have a fixed volume. It can be compressed on applying pressure.
2. CO₂ does not have a fixed shape. It can take the shape of any container in which it is put.

Question 3:
What is a pure substance ? Give its one characteristic. (CBSE 2011)
Answer:
A pure substance is the one which cannot be separated into smaller parts by any physical methods. It may be either a pure element (e.g. sodium) or a pure compound (e.g. calcium carbonate).

Question 4:
What happens when you pour some acetone on your palm ? (CBSE 2010, 2011)
Answer:
Acetone is a very low boiling liquid. It immediately changes to vapours. The evaporation is an endothermic process. Acetone takes up heat energy from hand. Therefore, the palm immediately becomes cold or even numb.

Question 5:
Name SI unit of measuring temperature. The boiling point of water is 100°C under normal atmospheric pressure. Convert this temperature to SI Units. (CBSE 2011, 2016)
Answer:
SI units of temperature is Kelvin (K)
100°C = (100 + 273) = 373 K.

Question 6:
Give reasons for the following :
(a) Gases fill up completely the vessel in which they are kept.
(b) Gases exert pressure on the walls of the containing vessel. (CBSE 2011, 2012, 2014, 2016)
Answer:
(a) Particles constituting gases are very fast moving and diffuse at a fast speed. They therefore, readily fill up the vessel completely in which these are kept.
(b) Particles of gases collide against the walls of the containing vessel and impart momentum to them. This is responsible for the pressure of the gas.

Question 7:
Name three states of matter. Which state of matter is rigid and why ? (CBSE 2011, 2013)
Answer:
The three states of matter are : solid, liquid and gas. Out of these, the solid state is the most rigid since the particles present are very closely packed and interparticle forces are quite strong.

Question 8:
What is meant by particulate nature of matter ? List four characteristics of particle nature of matter.
Answer:
In order to illustrate the particle nature of matter, take some water in a glass beaker. To this add one spoon full of some salt (e.g., sodium chloride) and stir with a glass rod.
The important characteristics of the particulate nature of matter may be summed up as follows :

1. Every matter is made up of particles.
2. The particles constituting a matter are very small in size.
3. The particles have empty or vacant spaces in them known as interparticle spaces.
4. Particles are not stationary and are in a state of motion.
5. Attractive forces are present in the particles of a substance. These are called interparticle forces.
6. The particle motion increases with the rise in temperature.

Question 9:
Why do people sprinkle water on a roof after a hot summer day ? (CBSE 2011, 2016)
Answer:
Water has a large heat of vaporisation. In a hot summer day, the roof is quite hot. Water absorbs a large amount of heat from the roof for its vaporisation. The roof gets sufficiently cool and one can sleep comfortably.

Question 10:
List three characteristics of particles of matter. Describe one example for each characteristic to illustrate it.
Name the characteristics which are responsible for
(a) spreading of smell of scent in a room and
(b) water taking the shape of the vessel in which poured. (CBSE 2011)
Answer:
For the three characteristics of matter and their examples,
(a) Spreading of smell of scent in a room is because of diffusion of the gases. Scent consists of a number of sweet smelling gases or vapours.
(b) Water is a liquid and liquids take up the shape of any container in which these are kept.

Question 11:
The temperature-time graph given below shows the heating curve for pure wax. From the graph answer the following :

1. What is the physical state of the substance at the points A, B, C and D ?
2. What is the melting point of the substance ?
3. What is its boiling point ?
4. Which portions of the graph indicates that change of state is taking place.
5. Name the terms used for heat absorbed during change of states involved in above processes. (CBSE 2011)

Answer:

1. At point A : Wax is in the solid state.
   At point B : Wax has started melting and exists both in the solid as well as liquid states.
   At point C : Wax is in liquid state.
   At point D : Wax has started boiling. Therefore, it exists both in the liquid as well as gaseous states.
2. Melting point of wax = 15°C
3. Boiling point of wax = 110°C
4. The change of state (solid to liquid) is represented by the portion A₁ to B₂ (straight line).
   The change of state (liquid to gas) is represented by the portion D₁ to D₂ (straight line).
5. It is known as latent heat of fusion in case of solids and latent heat of vaporisation in case of liquids.

Question 12:
Explain which one will cause more severe burns—boiling water at 100°C or steam at 100°C. (CBSE 2011, 2012)
Answer:
In order to illustrate the particle nature of matter, take some water in a glass beaker. To this add one spoon full of some salt (e.g., sodium chloride) and stir with a glass rod.
The important characteristics of the particulate nature of matter may be summed up as follows :

1. Every matter is made up of particles.
2. The particles constituting a matter are very small in size.
3. The particles have empty or vacant spaces in them known as interparticle spaces.
4. Particles are not stationary and are in a state of motion.
5. Attractive forces are present in the particles of a substance. These are called interparticle forces.
6. The particle motion increases with the rise in temperature.

Question 13:
On suffering from high fever, which will lower your body temperature more; ice or ice cold water ?
(CBSE 2012, 2014)
Answer:
Ice will lower the body temperature more than ice cold water because latent heat of fusion of ice is quite high (335 kj kg^-1). Ice is therefore, expected to absorb more heat energy from the body and will lower the body temperature more than ice cold water.

Question 14:
Flow will you change water from gaseous state to liquid state ? Suggest a simple activity. (CBSE 2011)
Answer:
Pass the water vapours or steam through a water condenser as used in case of simple distillation. It gets condensed to form liquid water.

Question 15:
Justify that melting of wax is a physical change. (CBSE 2011)
Answer:
It can be justified in two ways :

1. No new substance is formed and there is no change in the chemical properties of wax as a result of melting.
2. When the liquid wax is cooled for sometime, it again gets solidified.

Question 16:
Ramesh took two beakers A and B containing hot water and cold water respectively. In each beaker, he dropped a crystal of copper sulphate. He kept the beakers undisturbed. After sometime what did he observe and why ? (CBSE 2011, 2012)
Answer:
In both the beakers, the solutions became blue. However, this happened at a faster rate in the beaker B which contains hot water. This change has taken place because of the process of diffusion which proceeds at a faster rate in hot water as compared to cold water.

Question 17:
Archit dropped a crystal of potassium permanganate into two beakers A and B containing hot water and cold water respectively. After keeping the beakers undisturbed for some time what did he observe and why ?
(CBSE 2012)
Answer:
Potassium permanganate crystals have purple colour. In a beaker B containing hot water, the purple colour would spread more readily as compared to the beaker A which contains in it cold water. Actually the kinetic energy of the particles increases with the rise in temperature.

Question 18:
Account for the following ;

1. When sugar crystals dissolve in water, the level of water does not rise appreciably.
2. Naphthalene balls disappear with time without leaving any solid residue.
3. A wooden table should be called a solid.
4. Dogs generally hang out their tongue in summer. (CBSE 2012)

Answer:

1. Since water is a liquid, there are intermolecular spaces. Sugar particles occupy these spaces. As a result, water
   level does not rise appreciably,
2. A pure substance is the one which cannot be separated into smaller parts by any physical methods. It may be either a pure element (e.g. sodium) or a pure compound (e.g. calcium carbonate).
3. For the three characteristics of matter and their examples,
   1. Spreading of smell of scent in a room is because of diffusion of the gases. Scent consists of a number of sweet smelling gases or vapours.
   2. Water is a liquid and liquids take up the shape of any container in which these are kept.
4. In summer, dogs get exhausted due to the loss of persipiration from their body. Since they are always running most of the time, they hang out their tongue.

Question 19:
(a) 5 mL of water was taken in a test tube and china dish separately. These samples were then kept under different conditions as below :
(i) Both the samples are kept under a fan.
(ii) Both the samples are kept inside a cup board.
State in which case evaporation will be faster ? Give reason to support your answer.
(b) How will the rate of evaporation change if above activity is carried out on a rainy day. Justify your answer.
(CBSE 2012)
Answer:
(a) Evaporation will be faster under a fan. Since fan helps in the fast movement of the air, water will get more opportunity to evaporate under a fan than inside a cup board. In this case, the outside air will not come in contact with water.
(b) On a rainy day, there is humidity in air. As a result, evaporation of water will slow down.

Question 20:
A rubber band can change its shape on stretching; will you classify it as solid or not ? Justify your answer.
(CBSE 2012)
Answer:
Yes, it can be classified as a solid. It is an elastic solid which changes its shape on stretching and regains the same when the stretching force is removed.

Question 21:
When a solid melts, its temperature remains constant. Explain. (CBSE 2012)
Answer:
The heat energy supplied once the solid starts melting is used up as latent heat of fusion. The melting point temperature of a solid gives an idea of the interparticular forces which bind the constituents in a solid. Thus, greater the melting point temperature, more will be the magnitude of intermolecular forces. For example,
Melting point temperature of sodium = 370 K
Melting point temperature of potassium = 336 K
This means that the attractive forces in atoms of sodium in the solid state of the metal are more than the forces that are present in the atoms of potassium also in the same state.

Question 22:
State one similarity and two differences between boiling and evaporation. (CBSE 2012, 2014, 2015)
Answer:
Similarity : In both evaporation and boiling, liquid changes to vapour state.
Differences :

1. Evaporation takes place from the surface while boiling occurs throughout the liquid.
2. Liquid can evaporate at all temperatures while boiling occurs only at a fixed temperature known as the boiling point temperature.

Question 23:
Draw a flow sheet diagram to illustrate interconversion of three states of matter. Name the process of each interconversion. (CBSE 2012)
Answer:
It is because of the change in interparticle spaces and inter particle forces. If a solid is to be converted into liquid, the interparticle spaces have to be increased. Similarly, if a liquid is to change to the gas, these spaces have to be further increased.

In other words, we can say that one state of a substance can be converted into the other by changing interparticle spaces.They actually change interparticle forces of attraction. Please note that the process can be reversed also under suitable conditions. This is known as interconversion of states of matter. The obvious question which strikes the minds of everybody is to how to bring about the change of state. There are two ways to achieve this.
By changing the temperature
By changing thé pressure.

Question 24:

1. You want to wear your favourite shirt in a party, but the problem is that it is still wet after a wash. Mention three steps with reason that you would take to dry it faster ?
2. It is a hot summer day. Priyanshi and Ali are wearing cotton and nylon clothes respectively. Who do you
   think would be more comfortable and why ? (CBSE 2012, 2013, 2014, 2016)

Answer:

1. 1. Squeeze the shirt with force. By doing so, some of the moisture is removed.
   2. Spread the shirt on a stand. It provides greater surface area for evaporation.
   3. Iron the shirt. Increase in temperature helps in drying the shirt.
2. Cotton clothes would be more comfortable than the nylon clothes since these are porous. Persipiration sticking to the skin can escape from the pores. Priyanshi would feel more comfortable.

Question 25:
Explain how three states of matter arise due to the variation in the characteristics of the particles.
(CBSE 2013)
Answer:
The three states of matter arise because of two characteristics

1. Interparticle spaces : These are minimum in the solid state and maximum in the gaseous state.
2. Interparticles forces of attraction : These are maximum in the solid state and minimum in the gaseous state.

Question 26:
List any two properties of liquids which are common to gases. (CBSE 2013)
Answer:

1. Both of them do not have any definite shape. They can take up the shape of the container in which these are kept,
2. Both of them show the property of diffusion. However, gases diffuse faster.

Question 27:
How is heating of sugar different from heating of ammonium chloride ? Explain your answer. (CBSE 2013)
Answer:
Sugar melts upon heating whereas ammonium chloride sublimes upon heating without leaving behind any residue.

Question 28:
To which physical state of matter, do the following statements apply ? (CBSE 2013)

1. incompressible, no fixed shape
2. incompressible, high melting point
3. compressible, no definite volume
4. incompressible, highly fluid.

Answer:

1. Liquid state
2. Solid state
3. Gaseous state
4. Liquid state.

Question 29:
A drop of ink and a drop of honey are placed in watel in different beakers. Which of the two will spread faster ? Give reason for your answer. (CBSE 2013)
Answer:
Ink drop will spread faster as compared to honey. The density of honey is more than that of ink. Therefore, particles in ink diffuse faster as compared to the particles in honey.

Question 30:
Suppose you want to convert a gas into a liquid. Which two methods can you apply ? (CBSE 2013, 2016)
Answer:

1. By increasing the pressure or by compressing the gas.
2. By lowering the temperature or by cooling the gas.

Question 31:
Describe an activity to determine the melting point of ice with a diagram. (CBSE 2013, 2016)
Answer:
We know that the melting point of ice and the freezing point of water in pure states are both zero. This means that at this temperature, both are present. Upon heating, the temperature would actually not change but heat energy supplied would be absorbed by the ice as latent heat of fusion. This would result in the melting of ice.

The temperature would remain zero degree till the whole of ice has melted. Further heating would increase the temperature of water till it starts boiling at 100°C. The curve (d) gives the correct representaton.

Question 32:
Explain why do wet clothes dry faster when we spread them out. (CBSE 2013)
Answer:
By spreading wet clothes, the surface area available for evaporation increases. Therefore, wet clothes dry faster.

Question 33:
Describe an activity to show that particles of matter have spaces between them. (CBSE 2014, 2015)
Answer:
The important characteristics of the particulate nature of matter may be summed up as follows :

1. Every matter is made up of particles.
2. The particles constituting a matter are very small in size.
3. The particles have empty or vacant spaces in them known as interparticle spaces.
4. Particles are not stationary and are in a state of motion.
5. Attractive forces are present in the particles of a substance. These are called interparticle forces.
6. The particle motion increases with the rise in temperature.

Question 34:
How will you separate a mixture of naphthalene balls powder and common salt ? Draw a neat and labelled diagram to show the process. (CBSE 2015)
Answer:
We have so far studied that upon heating, a solid initially changes to the liquid state and then to the gaseous state when the temperature is increased. The process or the change of state can be reversed when the temperature is decreased. However, there are some exceptions. Certain solids directly change to the gaseous state upon heating without passing through the liquid state. This is called sublimation. The substance obtained on cooling the vapours is known as sublimate. Sublimation may be defined as :
the change of solid directly into the gaseous state without passing through the liquid state upon heating.

Naphthalene balls, camphor, iodine, ammonium chloride are some common examples of the substances which undergo sublimation.

Question 35:
Define (a) Compressibility (b) Rigidity (c) Fluidity (CBSE 2015)
Answer:
(a) Compressibility: It is the property as a result of which the particles of any matter come closer on applying pressure.
(b) Rigidity: It is the capacity of the particles of a matter to resist a change in shape and size on applying stress.
(c) Fluidity: It is the property as a result of which particles of a matter have tendency to flow.

Question 36:
(a) Define the process of vaporisation.
(b) List four factors which affect the rate of evaporation. (CBSE 2015)
Answer:
(a) vaporisation and may be defined as the amount of heat energy that is needed to convert one kg of a liquid at its boiling point temperature into its vapour state without any rise in temperature.
Latent heat of vaporisation of water is 226 kj kg^-1. It is the amount of heat that is absorbed when one kilogram of water at its boiling point temperature (100°C) changes to vapour state without any further rise in temperature.
(b)

1. Surface area available for evaporation
2. Increase in temperature
3. Decrease in humidity
4. Increase in the speed of wind

Question 37:
State the physical state of water as the following temperatures.
(a) 373 K
(b) 300 K
(c) 200 K (CBSE 2015)
Answer:
(a) Gas or Vapours
(b) Liquid
(c) Ice.

Question 38:
Why does perspiration keep our body cool ? (CBSE 2015)
Answer:
Actually, we perspire a lot in the hot and humid weather. Since cooling is caused during evaporation, the body temperature gets lowered. We feel more comfortable. Now, cotton is of porous nature and is a good absorber of water coming out of the pores as sweat. The synthetic clothes are less porous and donot absorb sweat so quickly. As the sweat evaporates, it absorbs some energy from the body since the clothes are in contact with our skin. The temperature of the body gets lowered and we feel more comfortable. We feel less comfortable in nylon and terylene clothes during summer.

Question 39:
Tabulate three differences between boiling and evaporation. (CBSE 2015)
Answer:

Question 40:
Give reasons for the following observations

1. The smell of lighted incense stick spreads several metres away.
2. A liquid has a fixed volume but not a fixed shape.
3. Ice floats over water.
4. A wooden table is called a solid at room temperature. (CBSE 2015)

Answer:

1. This happens because of diffusion. For example, the smell of food particularly of fish being cooked in the kitchen spreads in the lobby and even in different rooms because of diffusion.
2. Liquids do not have fixed shapes and take up the shape of any container in which these are put. A liquid cannot be compressed on applying pressure. Actually, the interparticle forces in the liquids are so strong that the pressure which is applied is not in a position to overcome these. Liquids therefore keep their volume.
3. Ice (solid state) floats over water (liquid state). Both are chemically same and are made from H2O molecules. Actually, the structure of ice is more porous* as compared to that of water. Therefore, for a given mass, the volume of ice is more than that of water and its density is comparitively less. As a result, ice floats over water.
4. different containers. For example, blue crystals of copper sulphate have needle like shape which they retain whether kept in a beaker or in a china dish or placed on the palm of our hand.

Question 41:
(a) When common salt is added to water, will there be any change in volume ? Give reason.
(b) Write any one similarity between three states of matter. (CBSE 2015, 2016)
Answer:
(a) No, there will be no change in volume. The particles of common salt will occupy inter particle empty spaces present in the molecules of water. The salt will dissolve in water and there will not be any change in the level of the solution thus formed.
(b) All the three states of matter consist of particles which have specific mass.

Question 42:
Out of boiling and evaporation, which is a surface phenomenon ? Explain. (CBSE 2015)
Answer:
Evaporation is a surface whereas boiling once started occurs throughout the liquid. In a liquid, the particles or molecules experience mutual forces of attraction. However, these are not stationary and have some kinetic energy at all temperatures. The particles of a liquid are also colliding with one another and exchanging energy during the collisions. Above the liquid surface, atmosphere or air is present which is a mixture of several gases. The particles of the liquid present on the surface have a tendency to come out from the surface so that they may acquire more freedom to move and become part of the atmosphere. This is also known as randomness. To overcome the interparticle forces of attraction, they need some energy which they take up from the rest of the particles or molecules of the liquid. As a result, their temperature gets lowered and cooling is caused.

Question 43:
Define boiling point. Write down the boiling point of water on Celcius scale and Kelvin scale. (CBSE 2016)
Answer:
The boiling point temperature of a liquid may be defined as :
the temperature at which a liquid starts boiling or the liquid state of a substance changes into gaseous/vapour state.
For example, the boiling point temperature of water is 100°C or 373 K. It is interesting to note that what we have noticed in the melting of a solid, also happens in the boiling of a liquid. It means that once the liquid starts boiling, its temperature does not change although it is still being heated. The explanation is also similar. As long as the liquid has not boiled, the heat energy which is supplied increases the kinetic energy of the particles (or H2O molecules) present in the liquid. As a result, the temperature rises. Once the liquid starts boiling, the heat energy is now being used to bring about a change in state from liquid to gas or vapours. It is known as latent heat of vaporisation and may be defined as :
the amount of heat energy that is needed to convert one kg of a liquid at its boiling point temperature into its vapour state without any rise in temperature.
Latent heat of vaporisation of water is 226 kj kg-1. It is the amount of heat that is absorbed when one kilogram of water at its boiling point temperature (100°C) changes to vapour state without any further rise in temperature.

Question 44:
Liquids and gases are commonly known as fluids. Compare their properties and show that they can flow easily.
(CBSE 2016)
Answer:
Unlike solids, the liquids have fluidity and not rigidity i.e., they have tendency to flow. This is due to lesser interparticle or intermolecular forces that are present in the liquid state as compared to the solid state. However, the liquids differ in their relative fluidity. For example, water flows at a faster rate than honey because in honey, the particles are heavier and also more closely packed.
Gases have maximum fluidity and least rigidity.
Since the interparticle spaces are the maximum in the gaseous state, the attractive forces are the least. As a result, the fluidity is very large while rigidity is negligible.

Question 45:
Tabulate the differences in the states of matter on the basis of the following characteristics :

1. Rigidity
2. Kinetic energy
3. Density. (CBSE 2016)

Answer:

1. Rigidity: We have seen that rigidity is maximum in the solid state and fluidity or particle motion is negligible. In the liquid state of a substance, both these characters are
   different. The liquids are less rigid than the solids and the molecular motion is also comparatively more.
2. Kinetic energy: The kinetic energy is linked with movement of the particles from one place to the other. Since the constituents in the solid state are very closely packed, they have negligible kinetic energy. That is why solids do not flow.
3. Density: Mass occupied by a solid per unit volume and is obtained by dividing the mass of a particular solid by the volume occupied by that mass of the solid.
   The unit of density : kg/L or kg/dm³.

 

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 1 Matter in Our Surroundings are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Chapter 4 Structure of the Atom Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Structure of the Atom Class 9 Important Questions Science and Answers Chapter 4

Question 1.
J. Chadwick discovered a sub-atomic particle which has no charge but has mass nearly equal to that of a proton. Name the particle and give its location in an atom. (CBSE 2011)
Answer:
The information suggests that the particle discovered by Chadwick is neutron. It is denoted by the symbol ¹₀n. It is located in the nucleus of an atom along with proton.

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2.
If ‘K’ and ‘L’ shells of an atom are completely filled, then what would be

1. the total number of electrons in an atom and
2. its valency ? (CBSE 2011)

Answer:
According to Bohr Bury scheme, ‘K’ and ’L’ shells of an atom can have maximum of 2 and 8 electrons respectively. If these are completely filled, this means that :

1. Total number of electrons in the atom = 2 + 8 = 10
2. Valency of the atom = zero.

Question 3.
For chlorine, Z = 17, A = 35. Give the number of protons, electrons and neutrons in

1. chlorine atom
2. chloride ion. (CBSE 2011)

Answer:

1. In chlorine atom (Cl)
   Number of protons (Z) = 17
   Number of neutrons = A- Z = 35-17= 18
2. In chloride ion (CF)
   Number of protons (Z = 17)
   Number of electrons = (Z+1)=17+1 = 18
   Number of neutrons = A – Z = 35 – 17 = 18

Question 4.
List three observations of the experiment performed by Rutherford for his model of an atom.
Answer:
From the scattering experiment, Rutherford made the following observations :

1. Most of the alpha particles were able to pass through the gold foil undeflected.
2. Some of these particles were deflected by small angles.
3. A very few (one out of approximately 12000) alpha particles suffered major deflections and even came back in the same direction.

Question 5.
An atom of an element has two electrons in outermost M-shell. State its
(a) Electronic configuration
(b) Number of protons
(c) Atomic number
(d) Nature whether metal or non-metal
(e) Valency
(f) Name (CBSE 2011)
Answer:
(a) Since the atom has two electrons in outermost M-shell, this means that K and F shells are already filled. Therefore, electronic configuration is 2(K) 8(F) 2(M)
(b) Number of protons = Number of electrons = 12
(c) Atomic number = Number of protons =12
(d) The elements with two valence electrons is a metal
(e) Valency of the element = Number of outermost electrons = 2
(f) The element is magnesium (Mg)
Hydrogen has three isotopes which are written as :

Question 6.
Explain why :
(a) These isotopes have identical chemical properties.
(b) These isotopes are electrically neutral
(c) These isotopes differ in their masses. (CBSE 2011, 2016)
Answer:
(a) The isotopes have identical chemical properties because all of them have one electron in the only shell (K-shell)
(b) The isotopes are electrically neutral because each one has one proton and one electron.
(c) The isotopes differ in their masses because they differ in their mass numbers (1,2 and 3 respectively).

Question 7.
In the following table, the mass number and the atomic number of certain elements are given :

(a) Select the pair of isobars from the above table.
(b) What would be the valency of the element C listed in the above table ?
(c) Which two sub-atomic particles are equal in number in a neutral atom ? (CBSE 2011)
Answer:
(a) Elements D and E are pair of isobars since they have same mass no. = 40
(b) The electronic configuration of the element C with Z = 7 is 2, 5.
It has five valence electrons. Its valency can be either 5 or 3 (8 – 5) = 3.
(c) In a neutral atom, the number of electrons in the extra-nuclear portion is equal to the number of protons in the nucleus.

Question 8.
(a) Why are the chemical properties of the isotopes same ?
(b) Draw Bohr model for helium atom.
(c) What are the number of protons, neutrons and electrons in ⁵⁹₂₇Co and ¹⁰⁸₄₇Ag ? (CBSE 2011)
Answer:
(a) Isotopes have the same atomic number as well as the same electronic configuration. Therefore, their chemical properties are the same.
(b)

(c)

Question 9.
(a) Which popular experiment is shown in the figure ?

(b) List three observations of this experiment.
(c) State conclusions drawn from each observation of this experiment.
(d) State the model of atom suggested on the basis of the above experiment. (CBSE 2011)
Answer:
(a) Rutherford  Model
(b)  Rutherford made the following observations :

1. Most of the alpha particles were able to pass through the gold foil undeflected.
2. Some of these particles were deflected by small angles.
3. A very few (one out of approximately 12000) alpha particles suffered major deflections and even came back in the same direction.

(c) Conclusions

1. As most of the alpha particles passed through undeflected, this means that they did not come across any obstruction in their path. Thus, most of the space in an atom is expected to be empty.
2. As a few alpha particles suffered minor deflections and a very few major deflections, this means that these must have met with some obstructions in their path.
3. This obstruction must be :
   1. Very small : Only a few particles were obstructed by it.
   2. Massive : Each alpha particle has 4u mass and is quite heavy. It could easily pass through a light obstruction by pushing it aside.

(d) The main features are listed as follows :

1. An atom consists of two parts. These are nucleus and extra nuclear portion.
2. Nucleus is present in the centre of the atom and is surrounded by extra nuclear portion.
3. The radius of the nucleus of an atom is nearly 10^-15m while that of the atom is about 10^-10m. Thus, nucleus is very small in comparison to the atom.
4. The mass of the atom is mainly of the nucleus. All the protons and neutrons (discovered later on by Chadwick) are present in the nucleus.
5. The positive charge on the nucleus is because of protons present (each proton has one unit positive charge).
6. All the electrons are present in the extra-nuclear space around the nucleus.
7. The total positive charge of the nucleus due to the presence of protons is the same as that of the electrons present in the extra nuclear space. Therefore, the atom as a whole is electrically neutral.
8. Electrons present in the extra nuclear portion are not stationary. These are revolving around the nucleus at high speed following a circular path.
9. The revolving electrons do not come close to the nucleus or drawn towards the nucleus because their force of attraction towards the nucleus is balanced by the centrifugal force which is of the same magnitude. It is directed away from the nucleus

Question 10.
There are two elements ²⁶₁₃A and ²⁶₁₄B. Find the number of sub-atomic particles in each of these. What is the relation between these atoms ?
Answer:

Since the two elements have same mass number hut different atomic numbers, these are related to each other as isobars.

Question 11.
(a) In the gold foil experiment, what observations led Rutherford to conclude that
(i) Most of the space inside the atom is hollow.
(ii) The central portion of the atom is positively charged.
(iii) Volume occupied by the nucleus is very small as compared to the total volume of the atom.
(iv) Almost the entire mass of the atom concentrated at its centre.
(b) If bromine atom is available in the form of two isotopes ⁷⁹₃₅Br (49.7%) and ⁸¹₃₅Br (50.3%), calculate the average atomic mass of bromine atom. (CBSE 2014, 2016)
Answer:
(a) (i) Most of the α-particles passed through the foil undeflected.
(ii) Some α-particles (positively charged) were deflected and a few came back in the same direction. This means that there is very small, positively charged and massive portion present in the centre of the atom. This is known as nucleus.
(iii) The number of α-particles which were deflected back was very small.
(iv) Since the mass of the atom is mainly due to positively charged protons (neutrons were not known at that time), this means that the entire mass of the atom is concentrated in the centre of the atom called nucleus.
(b) % of Br isotope with mass number 79 = 49.7 % of Br isotope with mass number 81 = 50.3

Question 12.
State the postulates stated by Neils Bohr in order to overcome the objection as raised against Rutherford’s model of atom.
Answer:
The main postulates of the theory are listed :

1. In the extra nuclear portion of an atom, the electrons revolve in well defined circular paths known as orbits.
2. These circular orbits are also known as energy levels or energy shells.
3. These have been designated as K, L, M, N, O, … (or as 1, 2, 3, 4, 5, …) based on the energy present.
4. The order of the energy of these energy shells is :
   K<L<M<N<0 <…. or 1< 2< 3 < 4<5 <….
5. While revolving in an orbit, the electron is not in a position to either lose or gain energy. In other words, its energy remains stationary. Therefore, these energy states for the electrons are also known as stationary states.

Question 13.
Which of the following are isotopes and which are isobars ?
Argon, Protium, Calcium, Deuterium. Explain why the isotopes have similar chemical properties but they differ in physical properties ? (CBSE 2012)
Answer:
The symbol notations for elements are represented as follows :
¹₁H and ²₁H are isotopes while ⁴⁰₁₈Ar and ⁴⁰₂₀Ca are isobars. Since the isotopes of an element have same atomic number, they have same electronic configuration and also similar chemical properties. They have different physical properties since their mass numbers are different.

Question 14.
Explain Bohr and Bury rules for distribution of electrons into different shells.
Answer:

1. The maximum number of electrons which can be present in a particular energy shell of an atom is given by 2n². Here ‘n is the number of the energy shells or energy levels.
2. The outermost energy shell in an atom cannot have more than eight electrons even if it has a capacity to take up more electrons according to first rule.
3. It is not necessary for a given shell to complete itself before another shell starts forming. As a rule, the new shell is formed as soon as the outermost shell, acquires eight electrons.

Question 15.
The atomic number and mass number of an element are 16 and 32 respectively. Find the number of protons, electrons and neutrons in it. State its valency. Is this element a metal or a non – metal. Justify your, answer.
(CBSE 2012, 2014, 2016)
Answer:
No. of protons = Atomic number =16
No. of electrons = Atomic number =16
No. of neutrons = Mass number – Atomic number = 32-16 = 16
Electronic configuration of the element = 2, 8, 6
Valency of the element = (8 – 6) = 2
The element is a non – metal since it tends to gain electrons and not lose electrons.

Question 16.
The K and L shells of an atom are completely filled. Find the number of electrons present in it. State the name of the element. . (CBSE 2012, 2013)
Answer:
Number of electrons present : K(2), L(8) = 10. The element is neon (Ne).

Question 17.
You are given an element X. Find out
(a) Number of protons, electrons and neutrons in ‘X’.
(b) Valency of ‘X’ ,
(c) Write the chemical formula of the compound formed when ‘X’ reacts with
(i) hydrogen,
(ii) carbon.
(CBSE 2012)
Answer:
(a) Number of protons = 8
Number of electrons = 8 Number of neutrons = 16 – 8 = 8
Electronic configuration = 2, 6
(b) Valency of ‘X’ =8-6 = 2
(c) The element ‘X’ is ‘O’. The formula of the compounds with hydrogen (H) and oxygen (O) are :
(i) H₂O (ii) CO₂.

Question 18.
Define the terms (a) isotope, (b) isobar giving one example in each case. Name the element whose isotope is used in
(i) nuclear reactor,
(ii) treatment of cancer. (CBSE 2012)
Answer:
(a) Most of the elements exist in nature. An investigation of some of these have revealed that the atoms of a particular element may have different mass numbers. However, their atomic numbers are the same. These are called isotopes. Thus, isotopes may be defined as : the different atoms of the same element having same atomic number but different mass numbers.
(b)  Isobars may be defined as : the atoms belonging to the different elements with same mass numbers but different atomic numbers.
(i) U-235 isotope is used in nuclear reactor as a fuel.
(ii) Co-60 isotope is used in the treatment of cancer.

Question 19.
(a) What are canal rays ? Who discovered them ? What is the charge and mass of canal rays ?
(b) How are canal rays different from electrons in terms of charge and mass ? (CBSE 2012)
Answer:
(a) Canal rays are the rays which originate in the discharge tube experiment and move away from the anode. These are called canal rays since they seem to be flowing like a stream of water in a canal.
(b) Canal rays are basically anode rays which consist of protons. For the charge and mass of protons. For the comparison of canal rays and electrons in terms of charge and mass.

Question 20.
A certain particle X has 17 protons, 17 electrons and 18 neutrons
(i) What is the mass number of X ?
(ii) What is atomic number of X ?
(iii) What is valency of X ?
(iv) Identify the element.
Answer:
(i) Mass no. of X = No. of p + No. of n = 17 + 18 = 35
(ii) Atomic no. of X = No. of p = 17
(iii) Electronic configuration of X = 2, 8, 7
Valency of X = (8 – 7) = 1
(iv) Name of element X = Chlorine (Cl).

Question 21.
Who discovered protons ?
Answer:
Protons were discovered by Goldstein.

Question 22.
(a) The element helium has 2 electrons in its valence shell but its valency is not 2. Explain.
(b) Choose the isotopes from the following nuclei :
(i) 8p + 8n
(it) 8p + 9n
(iii) 18p + 22n
(iv) 20p + 20n (CBSE 2013)
Answer:
(a) The element helium (He) is a noble gas element (Z = 2). It has only one shell (K shell) which can have maximum of two electrons only. It therefore, does not take part in chemical combination and its valency is zero.
(b) Elements (i) and (ii) represent pair of isotopes since they have 8 protons (Atomic no. = 8)

Question 23.
What are valence shell and valence electrons ? (CBSE 2013)
Answer:
Valence shell is the outermost shell in an atom. The electrons present in it are called valence electrons.

Question 24.
Complete the following table :

Answer:

Question 25.
The total number of nucleons in the atoms of calcium and argon is 40 and the atomic numbers of calcium and argon are 20 and 18 respectively. Name the pair of these two elements and also find out the number of neutrons present in the nucleus of argon atom. (CBSE 2013)
Answer:
The elements which have same no. of nucleons but different atomic numbers are called isobars. Therefore, calcium (Ca) and argon (Ar) represent a pair of isobars.
No. of neutrons in the nucleus of Ar = 40 – 18 = 22.

Question 26.
Atom of an element has one proton, one electron and no neutron. Name the element. How will you represent it ? (CBSE 2013)
Answer:
The element is called protium or hydrogen. It is represented as j H

Question 27.
An atom has 2 electrons in M-shell. What is the atomic number of the element ? (CBSE 2014)
Answer:
K and L shells of the atom are filled and M shell has two electrons. Therefore,
Total number of electrons in the atom = 2 + 8 + 2= 12
Atomic number (Z) of the element = 12.

Question 28.
An element is represented as ¹⁶₈X. Find :
(a) The number of electrons in element X. .
(b) Mass number of an element X.
(c) The number of neutrons in element X. (CBSE 2014, 2016)
Answer:
(a) The number of electrons in element X = 8
(b) Mass number of element X = 16
(c) The number of neutrons in element X = 16-8 = 8.

Question 29.
The electronic configuration of potassium (K) is 2,8,8, 1 instead of 2,8,9 though the M shell can accommodate up to 18 electrons. Explain. (CBSE 2014)
Answer:
M-shell cannot have more than 8 electrons in case it happens to be outermost or valence shell in an atom. Therefore, the correct electronic configuration of the element potassium (K) is 2,8,8,1.

Question 30.
Show the electron distribution in magnesium atom and magnesium ion diagrammatically and also give their atomic numbers. (CBSE 2014)
Answer:
Atomic number (Z) of magnesium is 12. Its electronic distribution is 2,8,2. Magnesium ion (Mg²⁺) is formed by the loss of two electrons from the valence shell of the atom. Therefore, the electronic distribution * in the ion is 2, 8. These are shown diagrammatically as follows :

Question 31.
The composition of two atoms A and B is given :

(a) What are the mass numbers and atomic numbers of A and B ?
(b) What is the relation between the two chemical species ?
(c) Which element or elements do they represent ?
Answer:
(a) Mass number of A = 17 + 18 = 35 u
Mass number of B = 17 + 20 = 37 u
(b) The two chemical species exist as pair of isotopes since they have the same number of protons and electrons.
(c) They represent the element chlorine (Cl).

Question 32.
Write the names of three elementary particles which constitute an atom. (CBSE 2015)
Answer:
Three elementary particles which constitute an atom are ; electron (e), proton (p) and neutron (n).

Question 33.
(a) What is the relationship between two elements X and Y whose atomic numbers are 18 and 20 respectively but their mass numbers remain the same as 40 ?
(b) Are their chemical properties same or different ? Explain and support your answer.
(c) Which has more number of electrons Na or Na⁺ ? Why ? (CBSE 2015)
Answer:
(a) The elements X and Y are related to each other as isobars.
(b) Since the atomic numbers of the elements are different, their chemical properties also differ.
(c) The electronic configurations of Na and Na⁺ ion are given as follows :
Na (Z =11), K(2), L(8), M(l)
Na⁺ (Z = 11), K(2), L(8), M(-)
Na⁺ ion is formed when Na atom loses one electron. Therefore, Na atom has more electrons (11) than Na⁺ ion (10).

Question 34.
Write the electron distribution of oxygen atom. How many valence electrons does it have ? (CBSE 2015)
Answer:
Atomic number (Z) of oxygen is 8.
Electronic distribution = K(L), L(6)
Valence electrons = 6.

Question 35.
(a) Why does helium have zero valency ?
(b) Name the scientist and his experiment to prove that nucleus of an atom is positively charged.
(CBSE 2015)
Answer:
(a) Atomic number (Z) of helium is 2. Its electronic configuration is K(2). This means that its atom has completely filled shell which is the only shell it has. Therefore, valency of the element is zero.
(b) The scientist is Rutherford and the experiment is known as α-particle scattering experiment.

Question 36.
List the observations in α-particle scattering experiment which led Rutherford to make the following conclusions :
(i) Most of the space in an atom is empty,
(ii) Whole mass of an atom is concentrated in its centre.
(iii) Centre is positively charged. (CBSE 2015)
Answer:
(i) As most of the alpha particles passed through undeflected, this means that they did not come across any obstruction in their path. Thus, most of the space in an atom is expected to be empty.
(ii)  As a few alpha particles suffered minor deflections and a very few major deflections, this means that these must have met with some obstructions in their path.
This obstruction must be :

• Very small : Only a few particles were obstructed by it.
• Massive : Each alpha particle has 4u mass and is quite heavy. It could easily pass through a light obstruction by pushing it aside.

(iii) Positively charged : Alpha particles have positive charge. Since they were repelled or deflected back, the obstruction must also carry same charge i.e., positive charge, (similarly charged particles always repel each other).

Question 37.
Define isotopes. Why do isotopes have same atomic number but different mass numbers ? Explain with the help of an example. (CBSE 2015)
Answer:
Most of the elements exist in nature. An investigation of some of these have revealed that the atoms of a particular element may have different mass numbers. However, their atomic numbers are the same. These are called isotopes. Thus, isotopes may be defined as :
The different atoms of the same element having same atomic number but different mass numbers.
Please note that the difference in the mass numbers of the isotopes is because of the difference in the number of neutrons present. For example,
Hydrogen (H) exists in the form of three isotopes. These are named as :

Question 38.
Write the two postulates of Thomson’s model of an atom. What were the drawbacks in this model ?
(CBSE 2015)
Answer:

1. An atom may be regarded as a positively charged sphere in which protons are present.
2. The negatively charged electrons may be regarded as studded or embedded in this sphere.

Question 39.
(a) How many neutrons are present in C-14 isotope of carbon ?
(b) How many protons does He²⁺ ion possess ?
(c) How many electrons can be filled in the third orbit of an atom at the maximum ? (CBSE 2015)
Answer:
(a) C-14 isotope of carbon has mass number 14 and atomic number 6. In this isotope ;
No. of protons = Atomic no. = 6.
No. of electrons = Atomic no. = 6.
No. of neutrons = Mass no. – Atomic no.
= 14 – 6 = 8.
(b) He²⁺ ion (z = 2) has two protons,
(c) The third orbit of an atom can have maximum of 8 electrons.

Question 40.
Identify the most stable atom from the following. Also give the reason for your answer :

Answer:
Argon Ar₁₈⁴⁰ is the most stable atom. It is a noble gas atom with completely filled shells (2, 8, 8).

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 4 Structure of the Atom are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Chapter 9 Force and Laws of Motion Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Force and Laws of Motion Class 9 Important Questions and Answers Science Chapter 9

VERY SHORT ANSWER QUESTIONS

Based on force and inertia

Question 1.
Name the physical quantity, which changes the shape of a ball.
Answer:
Force.

More Resources

• Previous Year Question Papers for CBSE Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science

Question 2.
Define the term force. (CBSE 2011, 2012, 2014)
Answer:
A force is a physical quantity which causes or tends to cause a motion in an object at rest or changes or tends to change the direction of motion of a moving object or the shape or size of the object.

Question 3.
Define balanced forces. (CBSE 2013)

Or

State the meaning of balanced forces. (CBSE 2012)
Answer:
Two equal and opposite forces acting simultaneously on an object are known as balanced forces. The resultant force due to balanced forces is zero.

Question 4.
Define unbalanced forces. (CBSE 2013)
Answer:
Two forces of unequal magnitudes and acting in opposite directions on an object simultaneously are known as unbalanced forces. The resultant force due to unbalanced forces is non zero.

Question 5.
Name the force which is responsible for change in position or state of an object. (CBSE 2012, 2013)
Answer:
Unbalanced force.

Question 6.
A ball is moving over a horizontal smooth surface with a constant velocity. What type of forces are acting on the ball ?
Answer:
Balanced forces are acting on the ball.

Question 7.
An unbalanced force is acting on an object. List two possible effects that will be caused in the motion of object.
(CBSE 2011)
Answer:

1. Object may be accelerated or retarded,
2. Direction of motion of the object may change.

Question 8.
What do you mean by inertia ? (CBSE 2010, 2012)
Answer:
The tendency of a body to oppose any change in its state of rest or uniform motion is called inertia of the body.

Question 9.
Write the kinds of inertia. (CBSE 2012)
Answer:

1. Inertia of rest,
2. Inertia of motion
3. Inertia of direction.

Question 10.
Name the physical quantity that measures inertia. (CBSE 2010, 2012, 2015)
Answer:
Mass of the body measures its inertia.

Question 11.
On which factor does inertia depend ? (CBSE 2013, 2015)
Answer:
It depends on the mass of the object.

Question 12.
Which has more inertia : a man or a child ?
Answer:
A man has more inertia than a child.

Question 13.
Which has highest inertia : solid made of aluminium, steel and wood oÇ same shape and same volume ?
(NCERT Question Bank, CBSE 2011, 2012)
Answer:
Solid made of steel has the highest inertia because its mass is greater than aluminium and wooden solids.

Question 14.
Name the property of bodies to resist a change in their velocity. (CBSE 2012, 2013, 2014)
Answer:
Inertia.

Question 15.
In a tug of war, the rope does not move in any direction. Why ? (CBSE 2013)
Answer:
Because balanced forces act on the rope. Both the teams apply equal and opposite forces on the rope.

Question 16.
Which one has greater inertia : a stone of mass 1 kg or a stone of mass 5 kg ?
Answer:
Inertia depends on the mass of the object. A stone of mass 5 kg has greater inertia than the stone of mass 1kg.

Question 17.
What kind of force is required to accelerate the motion of an object ?
Answer:
Unbalanced force.

Question 18.
A ball is moving over a horizontal smooth surface with a constant velocity. What type of forces are acting on the ball ?
Answer:
Balanced forces.

Question 19.
Name the forces (type of forces) when their resultant force acting on a body is not zero.
Answer:
Unbalanced forces.

Question 20.
Mention any two affects of force.
Answer:

1. It changes the state of rest or motion of a body,
2. It changes the shape of the body.

Question 21.
Is force a scalar or a vector quantity ?
Answer:
Force is a vector quantity.

Question 22.
State Newtons first law of motion.
                  Or
Define the first law of motion.
                 Or
State the law of inertia.
Answer:
Everybody continues in its state of rest or uniform motion in a straight line unless some external force acts on it.

Question 23.
Which law of motion defines the force ?
Answer:
First law of motion.

Question 24.
Define momentum and give its SI unit. (CBSE 2010, 2011, 2012, 2014, 2015)
Answer:
Momentum = mass x velocity.
SI unit of momentum is kg m s^-1.

Question 25.
Name the factors on which momemtum of a body depends. (CBSE 2012, 2013, 2015)
Answer:

1. Mass of the body and
2. Velocity of the body.

Question 26.
Define momentum of a body. (CBSE 2010, 2011)
Answer:
Momentum of a body is defined as the product of the mass and velocity qf the body. Momentum of body = m x v.

Question 27.
Is momentum a scalar or a vector quantity ? (CBSE 2015)
Answer:
Momentum is a vector quantity.

Question 28.
What is the name given to the product of mass and velocity of a body ? (CBSE 2012)
Answer:
Linear momentum.

Question 29.
State Newtons second law of motion. Give its mathematical expression. (CBSE 2010, 2012, 2013)
Answer:
The rate of change of momentum of a body is directly proportional to the unbalanced force acting on it and the change in momentum takes place in the direction of the unbalanced force. F = ma.

Question 30.
Name the physical quantity which is determined by the rate of change of linear momentum.
(CBSE 2010, 2012, 2013)
Answer:
Force.

Question 31.
Define one unit of force. (CBSE 2010, 2011, 2013)
Answer:
A force is said to be unit force if it produces unit acceleration in a body of unit mass.

Question 32.
Name the unit of force in SI.
Answer:
newton (N).

Question 33.
Define SI unit of force. (CBSE 2011, 2014)
Or
Define one newton of force. (CBSE 2012)
Answer:
SI unit of force is newton. Force is said to be 1 newton if it produces 1 m s^-2 acceleration in a body of 1 kg.

Question 34.
What is the relationship between force and acceleration ? (CBSE 2012, 2013)
Answer:
F = ma, where m is the mass of a body.

Question 35.
What is the name given to the product of mass and acceleration of a body ?
Answer:
Force (∴ F = ma)

Question 36.
How much force acts on a body whose momentum is constant (i.e. p = constant) ?
Answer:
F = dp/dt. If p = constant, then no force acts on the body.

Question 37.
Calculate the force required to produce an acceleration of 2.5 m s^-2 in a body of 4 kg.
Answer:
F = ma = 4 x 2.5 = 10 N.

Question 38.
A body of mass 30 kg has a momentum of 150 kg m s^-1. Find its velocity. (CBSE 2013, 2014)
Answer:

Question 39.
An athlete always runs some distance before taking a jump. Why ?
Answer:
To gain the momentum so that he may jump higher.

Question 40.
An object is thrown vertically upward. What is its momentum at the highest point ? (CBSE 2012)
Answer:
Momentum = mass x velocity.
Since velocity of the object at the highest point is zero, so momentum of the object is zero at the highest point.

Question 41.
What will happen to the momentum of a body whose velocity is doubled ?
Answer:
Momentum = mV. Therefore, momentum of a body is doubled if its velocity is doubled.

Question 42.
Name the physical quantity whose SI unit is “newton”.
Answer:
Force.

Question 43.
Which would require a gereater force — accelerating a 1kg mass at 10 m s or a 2 kg mass at 4 m s ?
Answer:
F = ma,
F₁ = 1 x 10 = 10 N and
F₂ = 2 x 4 = 8 N
So, 1 kg mass accelerating at 10 m s^-2 requires greater force than the 2 kg mass at 4 m s^-2.

Or

Which would require a greater force — accelerating a 2 kg mass at 5 m s^-2 or a 5 kg mass at 3 ms^-2 ?
Answer:
F₁ = m₁ x a₁ =2 x 5 = 10 N,
F₂ = m₂ x a₂ = 5 x 3 = 15 N
∴ F₂ > F₁

Question 44.
If the mass of a body is doubled, what will happen to its acceleration, if the applied force remains constant ?
Answer:
a = F/m. If mass(m) is doubled, acceleration becomes half of its original value, if the applied force remains m constant.

Question 45.
State Newtons third law of motion.
Answer:
To every action, there is equal and opposite reaction.

Question 46.
State action and reaction while a person walks on a ground.
Answer:
Action : Force exerted by person on ground.
Reaction : Force exerted by ground on person.

Question 47.
Do action and reaction forces act on same body or different bodies ?
Answer:
Action and reaction act on the different bodies.

Question 48.
State action and reaction in the case when a person swims.
Answer:
Action : Force with which swimmer pushes the water in the backward direction with his hands.
Reaction : The force with which water pushes the swimmer in the forward direction.

Question 49.
State action and reaction in the case when a bullet is fired from the gun. (CBSE 2011)
Answer:
Action : Force exerted by a spring on the bullet.
Reaction : Force exerted on the gun.

Question 50.
State action and reaction when a bullet is fired from the gun.
Answer:
Force exerted on the bullet is action and the force exerted on the gun is reaction.

Question 51.
When a man jumps out from a boat to the bank of a river, the boat moves backwards. Identify the action and reaction in this situation. (CBSE 2015)
Answer:
Action = force with which the foot of the man pushes the boat in the backward direction.
Reaction = force exerted by the boat on the man.

Based on the law of conservation of momentum

Question 52.
State law of conservation of momentum. (CBSE 2010, 2012, 2013, 2015)
Answer:
The total momentum of a system remains constant if no external force acts on the system.

Question 53.
A fast moving truck loses momentum equal to 2 kg m s^-1 after colliding with a stationary car.
Will the car lose or gain momentum ?
How much momentum is lost or gained by the car if the truck comes to the rest after collision ?
Answer:
The car will gain momentum. Momentum gained by the car = 2 kg m s^-1

Question 54.
Name the principle on which a rocket works. (CBSE 2012, 2013)
Answer:
Law of conservation of linear momentum.

Question 55.
What do you mean by recoil velocity of a gun ?
Answer:
The velocity with which a gun moves backward after firing a bullet is called the recoil of the gun.

Question 56.
Is momentum a scalar or a vector quantity ? (CBSE 2015)
Answer:
Momentum is a vector quantity.

SHORT ANSWER QUESTIONS

Based on force and inertia

Question 1.
When are the forces acting on a body said to be balanced ? Give an example. What type of change can the balanced forces bring about in an object ? (CBSE 2010, 2015)
Answer:
Two forces of equal magnitude but acting in opposite directions on a body are said to be balanced forces. When we push a wall but the wall does not move at all, then balanced forces are acting on the wall. When balanced forces are -acting on an object, there is no change in the state of the object.

Question 2.
What are the changes that a force can bring about on a body?  Give examples. (CBSE 2010, 2011)

Or

Explain any three effects that can be produced by force with examples. (CBSE 2012, 2013, 2014)
Answer:
Force can change

1. the shape of the body,
2. direction of motion .of the body,
3. the speed of the body and
4. size of the body

Examples :

1. The shape of a ball lying on a floor can be changed by pressing it.
2. The direction of motion of moving ball can be changed by hitting it with a bat.
3. A ball at rest can be set in motion if force is applied on it.
4. The length of a spring tied at one end can be increased by pulling it.

Question 3.
Two balls A and B of masses m and 2m are in motion with velocities ‘2V’ and ‘V’ respectively.
Compare
(i) their inertia,
(ii) their momentum and
(iii) the force needed to stop them in the same time.
Answer:

(iii) Since momentum of both the balls is same, so same amount of force is needed to stop them in the same time.

Question 4.
Property of a body by virtue of which it opposes any change in state is called
(a) momentum
(b) energy
(c) inertia
(d) acceleration.
Answer:
(c)

Question 5.
If A and B are two bodies with masses 10 kg and 50 kg respectively, then which body has more inertia ? Also calculate the ratio of the inertia of two bodies.
Answer:
Inertia of body B is more than the inertia of body A.
body A 10 kg and body B 50 kg.
If the time taken to bring a ball to rest from a certain velocity V is reduced to half, what will be the change in values of

Question 6.
Look at the diagrams given (Figure A) and answer the following questions. In which case will the object move and in which direction ? Give reason in support of your answer.

Answer:
In case (ii) object moves in the direction of force of 25 N because in this case the net force acting on the object = 25N-15N=10N
In case (i), net force acting on the object is zero.

Question 7.
In the given experimental set-up (Figure B) a student gave the card a sharp, fast horizontal flick with a finger.

1. What will happen to the coin ?
2. Write reason for your answer.

Answer

1. The coin will fall into the glass.
2. The card will move, when a fast horizontal flick with a finger is given to it. On the other hand, coin remains at rest due to inertia of rest and hence falls into the glass.

Question 8.
State the effect of force in each of the following cases,

1. A spring is stretched,
2. A hockey player hits an incoming ball
3. A football lying on the ground is kicked.

Answer:

1. Length of spring increases and hence its shape is changed.
2. The direction of the ball is changed.
3. Football comes in motion from rest state.

Question 9.
(a) Initial and final momentum
(b) Change of momentum
(c) Rate of change of momentum.
Answer:
(a) Initial and final momentum remain the same as they do not depend on time.
(b) Change in momentum remains the same as change in momentum = Final momentum-initial momentum.
(c)

therefore, rate of change of momentum is Time taken doubled if time is reduced to half.

Question 10.
While riding on the bicycle if we stop paddling, why does the bicycle begin to slow down ?
Answer:
Bicycle begins to slow down as its motion is opposed by the unbalanced force known as force of friction between the types of bicycle and the road.

Based on Newton’s laws of motion

Question 11.
What happens when a wet piece of cloth is shaken ? (CBSE 2011)
Answer:
When a wet piece of cloth is shaken, fibres of the cloth come in motion and water droplets in the cloth fall down due to inertia of rest.

Question 12.
A person getting down from the moving bus falls in the direction of the bus. Explain, why ?

Or

A passenger has to run along with moving bus in the same direction of the bus while getting down from the bus. Explain.

Or

It is is dangerous to jump out of a moving bus. Why ? (CBSE 2011, 2013)
Answer:
As soon as the passenger gets down from a moving bus, his foot comes to rest but upper portion of his body remains in motion in the direction of the moving bus. He may fall down if he does not run along with the bus.

Question 13.
A stone tied to a string whirls in a horizontal circle. It flies off tangentially when the string breaks suddenly.
Answer:
The stone flies off tangentially due to inertia of direction of motion.

Question 14.
What happens to a person travelling in a bus when the bus takes a sharp turn ? Explain.(CBSE 2011)

Or

A passenger in a moving car slips to one side of the seat when the car takes a sharp turn. Give reason for it. (CBSE 2012)
Answer:
When car or bus takes a sharp turn, passenger slips to one side of the seat due to the inertia of motion.

Question 15.
It is difficult to balance our body when we accidendy step on a peel of banana. Explain, why ?(CBSE 2011)
Answer:
When we walk on the ground, our foot pushes the ground in the backward direction (Action). On the other
hand, ground pushes our foot in the forward direction (Reaction). This reaction of the ground helps us to move in the forward direction.
But, when our foot falls on a peel of banana, then our foot slips on the peel of banana and cannot push the ground in the backward direction. Consequently, no reaction force acts on our foot. Hence we lose the balance and fall down.

Question 16.
Why are the wheels of vehicle provided with mud gaurds ? (CBSE 2012)
Answer:
The rotating wheels of a vehicle throw out mud sticking to it tangentially due to inertia of direction. The mud
gaurds stop this mud to fall on another vehicle just moving behind the vehicle.

Question 17.
All the cars are provided with seat belts. Give reason. (CBSE 2012, 2013)
Answer:
When a car stops suddenly, driver and passengers continue to move due to inertia of motion. Hence, they may
be hurt due to the collision between them and the body of the car. Therefore, seat belts are provided to prevent their forward motion in case of an accident.

Question 18.
A heavy leather ball and a light tennis ball are kept on the floor of a moving train. When train is suddenly stopped, they are set in motion. In which direction will they move ? Which one of them will attain higher velocity ?
Answer:
They will move in the direction of the motion of the train due to inertia of motion. The mass, of leather ball is greater than that of tennis ball, so leather ball will resist more than the tennis ball to change its state of motion. Hence, tennis ball will attain higher velocity.

Question 19.
A bullet fired on a glass window makes a fine hole while a stone smashes when hits it. State the reason.
(CBSE 2015)
Answer:
A bullet fired from a gun makes a small hole in the window pane while passing through it, but the stone striking the window pane breaks it into pieces. When a bullet strikes the window pane, only a small portion of the window pane where the bullet strikes comes in motion because the bullet makes contact with the pane for a very short time due to its high speed. On the other hand, the remaining portion of the window pane remains at rest due to inertia of rest. Thus, a small hole is made by the bullet in the window pane.
The speed of the stone is very small compared to the speed of the bullet. So the stone makes contact with the window pane for longer period of time. During this-longer time, the whole window pane comes in motion and hence breaks into pieces.

Question 20.
If the net external force acting on a body is zero, then total momentum of the body is
(a) Zero
(b) Variable
(c) Constant
(d) Information not sufficient.
Answer:

Question 21.
A body of mass ‘m is moving with a velocity u. When a force is applied on it for time t, its velocity increases to ‘v’. Write expressions for
(a) Initial and final momentum,
(b) Change in momentum
(c) Rate of change of momentum. Also write SI unit for each
(CBSE 2015)
Answer:
(a) Initial momentum = mu
Final momentum = mv
(b) Change in momentum = final momentum – initial momentum = (mv – mu) = m(v – u)

SI unit of initial momentum, final momentum and change of momentum is kg m s^-1
SI unit of rate of change of momentum is kg m s^-2 or N.

Question 22.
If the time taken to bring a ball to rest from a certain velocity v is reduced to half, what will be the change in values of :
(a) Initial and final momentum
(b) Change of momentum
(c) Rate of change of momentum.
Answer:
(a) Initial and final momentum remain the same as they do not depend on time.
(b) Change in momentum remains the same as change in momentum = Final momentum – initial momentum
(c)

∴ Rare of change of momentum is doubled if time is reduced to half.

Question 23.
Derive First law of motion mathematically from the mathematical expression of Second law of motion.
Answer:
According to First law of motion, a body continues to move with uniform velocity or zero acceleration if no external force acts on it. Second law of motion is given by F= ma.
If F = 0, a = 0. This is the mathematical expression of first law of motion.

Question 24.
Why, no force is required to move an object with a constant velocity ? (CBSE 2011)
Answer:
We know, F = ma
When, velocity is constant, then acceleration, a = 0
Hence, F = 0

Question 25.
A cricket player lowers his hands while catching a fast moving ball. Explain. Why ?
(CBSE 2011, 2012, 2013)
Answer:
A cricket player lowers his hands while catching the ball.
F = dp/dt
If a player does not lower his hands while catching the ball, the time to stop the ball is very small. So a large force has to be applied to reduce the velocity of the ball to zero or to change the momentum of the ball. When a player lowers his hands, the time to stop the ball is increased and hence less force has to be applied to cause the same change in the momentum of the ball. Therefore, the hands of the player are not injured.

Question 26.
Explain, how can we walk easily on a hard and rough surface than on a slippery surface ?
Answer:
Walking of a person. When a person walks on the ground, he pushes the ground with his foot in the backward direction by pressing the ground. This push is known as action. According to Newtons third law of motion, an equal and opposite reaction acts on the foot of the person by the ground. This reaction (force) of the ground on the person pushes him forward (figure 21).
Thus, Action = force exerted on the ground by a person through his foot.

Question 27.
Two similar buses are moving with same velocity on the road. One of them is empty and the other is loaded with passengers. Which of the two will be stopped by the application of less force ? Explain.
(CBSE 2010, 2011, 2013)
Answer:
Momentum = m v. Loaded bus has greater mass than the empty bus. So loaded bus has greater momentum than the empty bus. The rate of change momentum is directly proportional to the force applied. Therefore, the empty bus will be stopped by applying less force.

Question 28.
A bullet fired from a gun is more dangerous than an air molecule hitting a person, though both bullet and air molecule are moving with same velocity. Explain.
Answer:
The momentum of a bullet is very large than the momentum of the air molecule as the mass of bullet is very large than that of air molecule. When bullet and air molecule hit a person, then the momentum transferred to person by a bullet is very large than the momentum transferred by the air molecule. Hence, large force is exerted on the person by the bullet.

Question 29.
When a force acts on an object, it accelerates ? What do you observe, when two equal and opposite forces act on an object ? (CBSE 2011)
Answer:
When two equal and opposite forces act on an object, then the net force acting on it is zero. Therefore, the object will remain at rest if it were at rest before the application of two equal and opposite forces. However, the object will continue to move with constant velocity if it were moving with constant velocity before the application of the forces.

Question 30.
Draw velocity-time graph of a moving particle on which net external force acting is zero.
Answer:
Net external force = zero. It means, acceleration (a = F/m) of the particle is zero.

In other words, particle is moving with constant velocity. Velocity-time graph of such a particle is represented by a curve AB parallel to time-axis (Figure C)

Question 31.
Draw distance-time graph of a moving object on which net external force acting is zero.
Answer:
Net external force = zero. It means, acceleration (a = F/m) of the particle is zero.

In other words, the object is moving with constant velocity. Therefore, the particle travels equal distances in equal intervals of time. Distance time graph of such an object is shown in figure D.

Question 32.
Glass wares are wrapped in straw during their transportation. Give reason.
(CBSE 2012)
Answer:
During transportation, the glass wares may break if they collide with each other in the event of jerks. When they are wrapped in straw, the force of jerk is transmitted to them through the pieces of straw in a longer period of time. Thus, the change in momentum of the glass wares takes place in a longer period of time. Therefore, a very small force is experienced by them in the event of jerks and hence they do not break.

Question 33.
When two bodies X and Y collide with each other, X exerts a force of 5 N on Y towards east direction. What
is the force exerted by Y on X ? Justify your answer stating the law. (CBSE 2012)
Answer:
Force exterted by Y on X = 5 N towards west direction as per Newton’s third law of motion.

Question 34.
Explain, how a Karate player can break a pile of tiles with a single blow of his hand. (CBSE 2012)
Answer:
A Karate player strikes the pile of tiles very fast so that change in the momentum of his hand takes place in
very small time interval. Hence, a very large force (F = dp/dt) is exerted on the pile of tiles, which is enough to break the pile of tiles.

Question 35.
Why a glass pane of a window is shattered when a flying pebble hits it ? (CBSE 2012)
Answer:
When a flying pebble hits the glass pane, its contact time with glass pane is large. During this large interval of time, it imparts its momentum to the entire glass pane, which in turn shattered.

Question 36.
A truck of mass M is moved under a force F. If the truck is loaded with an object equal to the mass of the truck and the driving force is halved, then how does the acceleration change ?
Answer:
Acceleration, a = F/m. When m is doubled and F is made half, acceleration becomes ¼ th of its initial value.

Question 37.
Why are road accidents at high speed very much worsen than accidents at low speeds ?
Answer:
When accidents at high speed occur, then large momentum is to be changed in small interval of time. Hence, large force is exerted on vehicles and they get damaged very badly as compared to when accidents occur at low speed.

Question 38.
Name the physical quanity whose unit is

1. kg m s^-2 and
2. kg m s^-1

Answer:

1. Force,
2. Linear momentum

Question 39.
Represent the following graphically :
(a) momentum versus mass, when velocity is constant
(b) momentum versus velocity, when mass is constant.
Answer:
(a)

(b)

Question 40.
Describe in brief an activity to illustrate the properly of inertia of rest.
Answer:

1. Describe an activity to demonstrate the property of inertia of rest of an object.
2. Now place a fifty paisa coin on the card board.
3. Strike the card board with a finger.

It is found that card board flies away and the coin falls into the glass. This is because, card board moves away due to the application of force of finger. However, coin remains at its position due to inertia of rest and hence falls into the glass.
This activity demonstrates the property of inertia of rest of an object. It is based on Newton’s first law of motion.

Question 41.
In the figure below, the card is flicked with a push.

(a) What do you observe in above case and why ?
(b) State the law involved in this case.
(c) What will be your observation if the above coin is replaced by a heavy five rupee coin. Justify your answer.
Answer:
(a) The coin falls into the glass. The card comes in motion due to push but coin on the card remains at rest. The coin falls into the glass due to inertia of rest.
(b) Law of inertia or First law of motion.
(c) Heavy coin will also fall into the glass. The heavy coin has more inertia than the lighter coin.

Question 42.
State Newton’s Third law of motion. Are the forces mentioned in the law balanced forces ? Why ? Will they always produce accelerations of equal magnitude ? Why ?
Answer:
For every action, there is equal and opposite reaction. Forces are not balanced forces because both the forces act on two different bodies. They do not produce the same acceleration because acceleration = ~~. Since masses (m) of both the bodies are different, so accelerations of both the bodies are different.

Question 43.
When a person hits a stone, his foot is injured. Why ? (CBSE 2011)
Answer:
When a person hits a stone, the stone exerts equal force on his foot. Due to this force, his foot gets injured.

Question 44.
According to Newton’s third law of motion, a ball falling towards earth exerts a force on the earth but the motion of earth towards the ball is not noticed. Explain why ?
Answer:
The acceleration produced in the earth is very small as its mass is very large. Hence, the motion of the earth towards ball is not noticed.

Question 45.
How a man can swim in water ?

Or

A swimmer is able to swim in a forward direction in a swimming pool only when he is pushing the water in the backward direction. Give reason for the above mentioned statement and justify the same. (CBSE 2013)
Answer:
When a swimmer pushes water in the backward direction with his hands, equal and opposite reaction by water on the man pushes him in the forward direction.

Question 46.
When a person jumps out of a boat, the boat moves backward. Explain, why ? (CBSE 2011, 2012)
Answer:
When a person jumps out of a boat, he pushes the boat in the backward direction (Action). According to Newtons third law of motion, the boat exerts an equal force (i.e. reaction) on the person in the forward direction. So, when the person jumps out of the boat, the boat moves backward (Figure 23). Thus, Action = force applied by the person on the boat through his foot. Reaction = force exerted on the person by the boat.

Question 47.
Why a boatman pushes the bank of the river with a pole to take his boat into the river ?
Answer:
A boatman pushes the river bank with a bamboo pole to take his boat into the river.
When the boatman pushes the river bank with a bamboo pole, the river bank offers an equal and opposite reaction. This reaction helps the boat to move into the river. In this case, action = force applied on the ground with a bamboo pole, and reaction = force exerted by the ground on the boat.

Question 48.
“Action and reaction are equal and opposite but even then they do not cancel each other.” Explain, why ?
(CBSE 2011)

Or

Why don’t, the forces of action and reaction cancel each other ? (CBSE 2013)
Answer:
Two equal and opposite forces can cancel each other if they act on the same body. But action and reaction do not act on the same body. Action acts on one body and the reaction acts on another body. Hence they cannot cancel each other.

Question 49.
Look at the diagram and answer the following questions :

(a) When a force is applied through the free end of the spring balance A, the reading on the spring balance A is 15 g wt. What will be the measure of the reading shown by spring balance B ?
(b) Write reasons for your answer.
(c) Name the force which balance A exerts on balance B and the force of balance B on balance A.
Answer:
(a) Reading shown by spring balance is 15 g wt.
(b) Every action has equal and opposite reaction.
(c) Force which balance A exerts on balance B is action. Force of balance B on balance A is reaction.

Question 50.
A man throws a ball weighing 500 g vertically upwards with a speed of 10 m s^-1
(i) Find its initial momentum
(ii) Find its momentum at the highest point of its flight.
Answer:

Question 51.
A person is hit harder, when he falls on a hard floor than when he falls on the heap of sand or cotton. State the reason. (CBSE 2015)
Answer:
According to Newton’s second law of motion,

When a person falls on a hard floor, his change in momentum occurs in small interval of time because he comes to rest abruptly. Hence, a large force is exerted on the person by the floor. On the other hand, when the person falls on a heap of sand or cotton, the sand or cotton yields under his weight. Therefore, the change in momentum of the person occurs in a large interval of time. Hence, less force is exerted on the person by the heap of sand or cotton.

Question 52.
Mention any two examples which can be explained on the basis of Third law of motion.
Answer:

1. Walking of a person on a road,
2. Recoil of a gun.

Based on the law of conservation of momentum

Question 53.
Why does a gun recoil backward when a bullet is fired from it ?

Or

Firing a bullet from a gun, results in recoil of gun. Give reason. (CBSE 2011)
Answer:
A gun recoils, when a bullet is fired from it to conserve the linear momentum of the gun and the bullet.

Question 54.
A gun recoils backward with small speed than the bullet moving forward. Explain why ?
Answer:
Recoil speed of gun is inversely proportional to the mass of the gun. Mass of gun is much greater than the mass of bullet. Therefore, gun recoils backward with small speed than the bullet moving forward.

Question 55.
Explain, why an inflated balloon lying on the surface of a floor moves forward when pierced with a needle.
Answer:
When balloon is pierced with a needle, air inside the balloon rushes out with certain momentum. Therefore, the balloon moves in the opposite direction to conserve the linear momentum of the balloon.

Question 56.
When a bullet is fired, it exerts an equal and opposite force on the gun, yet hurt caused by the recoil of the
gun is much less than that by a bullet ? Give reason. (CBSE 2012)
Answer:
Recoil velocity of gun is much less than the velocity of bullet. Therefore, momentum imparted by gun is very small and hence it hurts less than that of the bullet.

Question 57.
Mention two examples from your daily life which can be explained on the basis of law of conservation of momentum. (CBSE 2013)
Answer:

1. Recoil of a gun,
2. Rocket propulsion.

Question 58.
Two friends on roller skates are standing 5m apart facing each other. One of them throws a ball of 2 kg towards the other, who catches it ? How will this activity affect the positions of the two ? Explain.
Answer:
Total initial linear momentum of the two friends is zero as both are at rest. When one person throws the ball towards the other and the other catches it, then the total linear momentum of both will have to be zero as no external force acts on them. Thus both friends must move in opposite direction. Hence, the distance between both friends will increase.

Question 59.
Observe the following diagram and answer the questions given below :

Which direction does the balloon move when the thread tied to its neck is removed and why ?
State the conclusion drawn from this activity.
Answer:
When the thread tied to its neck is removed, air inside the balloon rushes to the left side and the balloon moves to right side to conserve linear momentum.
Law of conservation of linear momentum is verified.

Question 60.
A gunman gets jerk in backward direction while firing a gun. State the reason. (CBSE 2015)
Answer:
The gun recoils backward to conserve the momentum of the system (gun + bullet). The backward motion of the gun exerts a force on the gunman and hence he gets a jerk in the backward direction.

LONG ANSWER QUESTIONS

Question 1.
State Newtons second law of motion. Use this law to find the method to measure force acting on an object.
(CBSE 2010, 2011)

Or

From Newton’s second law of motion, obtain a mathematical expression for force. (CBSE 2013)
Answer:
According to this law, the change in momentum of a body per unit time (i.e. rate of change of momentum) is directly proportional to the unbalanced force acting on the body and the change in momentum takes place in the direction of the unbalanced force on the body.
∴ F ∞ dp/dt
Consider a body of mass moving with initial velocity Let a force acts on the body for time so that the velocity of the body after time is .
Initial momentum of the body, p_i = mu
Final momentum of the body, p_f = mv
Now, change in momentum of the body = p_f – p_i = mv – mu = m(v-u)

Thus, force acting on the body is directly proportional to (i) its mass (m) and (ii) its acceleration (a).
Eqn. (1) gives the mathematical form of Newtons second law of motion. The force given by eqn (1) acts on the body.
Newton’s second law of motion in vector form     
We know, force ( F ) and acceleration ( a ) are vector quantities, whereas mass ( m)  is a scalar quantity. Therefore, Newton’s second law of motion can be written in vector form as

This relation shows that the direction of force applied on the body is same as that of the acceleration produced in the body.

Question 2.
Define momentum of a body. Prove with the help of third law of motion that the total momentum of two bodies is conserved during collision provided no external force acts. (CBSE Sample Paper)
Answer:
According to the law of conservation of momentum, the total momentum of a system (or an object) remains constant if no net external unbalanced force acts on the system.
That is, momentum of a system, p = constant, if net external force acting on it is zero (i.e. F = 0).
Consider a system consisting of two bodies A and B of (say glass spheres) masses m₁ and m₂ respectively. Let these bodies are moving with velocities u₁ and u₂ as shown in figure 26. Let u₁ > u₂ Let these bodies collide with each other for a small interval of time ‘dt’. At the time of collision, body A exerts a force F on body B and body B exerts equal and opposite force (- F) on body A. Due to these forces, the momentum of the bodies changes. Let v₁ and v₂ be the velocities of body A and body B respectively after the collision.



i.e. Total momentum of the system (i.e. bodies A and B) before collision = Total momentum of the system (i.e. bodies A and B) after collision. This is the law of conservation of linear momentum.

Question 3.
From Newton’s second law of motion,

From this establish F = ma, where m is mass and a is acceleration. (CBSE 2011)
Answer:
Consider a body of mass moving with initial velocity Let a force acts on the body for time so that the velocity of the body after time is .
Initial momentum of the body, p_i = mu
Final momentum of the body, p_f = mv
Now, change in momentum of the body = p_f — p_i = mv – mu = m(v-u)

Thus, force acting on the body is directly proportional to (i) its mass (m) and (ii) its acceleration (a).
Eqn. (1) gives the mathematical form of Newtons second law of motion. The force given by eqn (1) acts on the body.
Newton’s second law of motion in vector form     
We know, force ( F ) and acceleration ( a ) are vector quantities, whereas mass ( m)  is a scalar quantity. Therefore, Newton’s second law of motion can be written in vector form as

This relation shows that the direction of force applied on the body is same as that of the acceleration produced in the body.

Question 4.
Derive the law of conservation of linear momentum.

Or

Total momentum of two bodies remains unchanged before and after the collision. Justify this statement.
(CBSE 2015)
Answer:
Let a moving ball collides with another stationary ball lying on a ground. Observe, what happens after collision. The moving ball will slow down i.e. its velocity decreases after colliding with the stationary ball. On the other hand, the stationary ball begins to move i.e. its velocity increases after collision.
Consider a system consisting of two bodies A and B of (say glass spheres) masses m₁ and m₂ respectively. Let these bodies are moving with velocities u₁ and u₂ as shown in figure 26. Let u₁ > u₂ Let these bodies collide with each other for a small interval of time ‘dt’. At the time of collision, body A exerts a force F on body B and body B exerts equal and opposite force (- F) on body A. Due to these forces, the momentum of the bodies changes. Let v₁ and v₂ be the velocities of body A and body B respectively after the collision.



i.e. Total momentum of the system (i.e. bodies A and B) before collision = Total momentum of the system (i.e. bodies A and B) after collision. This is the law of conservation of linear momentum.

Question 5.
State and verify law of conservation of momentum. (CBSE 2013)
Answer:
Consider a system consisting of two bodies A and B of (say glass spheres) masses m₁ and m₂ respectively. Let these bodies are moving with velocities u₁ and u₂ as shown in figure 26. Let u₁ > u₂ Let these bodies collide with each other for a small interval of time ‘dt’. At the time of collision, body A exerts a force F on body B and body B exerts equal and opposite force (- F) on body A. Due to these forces, the momentum of the bodies changes. Let v₁ and v₂ be the velocities of body A and body B respectively after the collision.



i.e. Total momentum of the system (i.e. bodies A and B) before collision = Total momentum of the system (i.e. bodies A and B) after collision. This is the law of conservation of linear momentum.

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 9 Force and Laws of Motion are helpful to complete your science homework.

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