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Chapter 14 Natural Resources Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Natural Resources Class 9 Important Questions and Answers Science Chapter 14

Very Short Answer Questions

Question 1.
Name any two factors responsible for the formation of soil.
(CCE 2011)
Answer:
Abiotic (sun, water, wind) and biotic (living organisms).

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.
Write full form of CFC. (CCE 2011)
Answer:
Chloro-fluoro-carbon.

Question 3.
We are lucky that ozone is not stable near to the earth’s surface. Why ? Give appropriate answer. (CCE 2011)
Answer:
Ozone occurring near the surface of the earth is a strong oxidant causing corrosion of articles, hardening of rubber, respiratory distress and internal haemorrhages. Fortunately, it is not stable forming oxygen and oxides.

Question 4.
How is biosphere a dynamic and stable system ?
(CCE 2011)
Answer:
There is a regular circulation of biogeochemicals between the different components of biosphere which also receives regular supply of energy as well that is ultimately dissipated in the form of infra-red rays.

Question 5.
Name the carbon compounds responsible for causing ozone hole in the atmosphere. (CCE 2011, 2012)
Answer:
Chlorofluorocarbons (CFCs).

Question 6.
Name the bacteria responsible for nitrification in nature.
(CCE 2011)
Answer:
Nitrosomonas (ammonia to nitrite) and Nitrobacter (oxidises nitrite to nitrate).

Question 7.
Which gas is the major component of atmosphere of Vends and Mars ? (CCE 2011)
Answer:
Carbon dioxide, 95-97%, of their atmosphere.

Question 8.
In which part of legumes, nitrogen fixing bacteria are present ? (CCE 2011, 2012)
Answer:
In their root nodules.

Question 9.
What is the function of ozone which is present in the upper level of atmosphere ?
OR
State one use of ozone. (CCE 2011, 2012)
Answer:
Ozone present in the upper layer of atmosphere or stratosphere filters out harmful high energy ultraviolet radiations (100-320 nm) liberating heat in the process that warms up the stratosphere.

Question 10.
Name any one method by which water helps in the formation of soil. (CCE 2011)
Answer:
Passing into cracks of rock, expanding on cooling causing more cracks and widening the previous ones ultimately crushing the rock to form soil particles.

Question 11.
State the role of symbiotic bacteria in nitrogen cycle in nature. (CCE 2011)
Answer:
Symbiotic bacteria live in the root nodules of legumes where they pick up molecular nitrogen from the soil air and convert the same into salts of nitrogen (e.g., ammonium) for use by the host in building amino acids and proteins.

Question 12.
Name two nitrogen compounds obtained by industrial fixation. (CCE 2011)
Answer:
Ammonia, Urea.

Question 13.
Define biogeochemical cycle. Give examples also.
(CCE 2011, 2012)
Answer:
The repeated circulation of biogenetic nutrients or biogeochemicals between the abiotic and biotic components of biosphere is called biogeochemical cycle, e.g, Carbon cycle, Nitrogen cycle, Water cycle, Phosphorus cycle.

Question 14.
Name two biologically important compounds that contain both oxygen and nitrogen. (CCE 2011)
Answer:
Proteins, nucleic acids (DNA, RNA).

Question 15.
Write two methods adopted to control pollution.
(CCE 2011)
Answer:

1. Use of CNG instead of gasoline (petrol, diesel) in automobiles,
2. Non-discharge of effluents and other pollutants into water bodies and atmosphere by the industries.

Question 16.
Name the disease that can be caused by UV radiations.
(CCE 2011)
Answer:
Skin cancer, eye cataracts.

Question 17.
Name any two water pollutants. (CCE 2011)
Answer:

1. Industrial effluents
2. Untreated sewage
3. Fertilizers, pesticides.

Question 18.
Give two causes of soil erosion. (CCE 2011)
Answer:
Deforestation, overgrazing followed by action of wind or water.

Question 19.
State one cause of depletion of ozone layer. (CCE 2011)
Answer:
Presence of chlorofluorocarbons/halons/nitrogen oxides/ chlorine.

Question 20.
What is soil erosion ? (CCE 2011)
Answer:
Removal of unprotected top soil as through the agency of wind or water is called soil erosion.

Question 21.
Name two factors that make soil/weathering of rocks.
(CCE 2011, 2012)
Answer:
Sun and water.

Question 22.
Mention causes of global warming. (CCE 2011)
Answer:

1. Increased concentration of green house gases (e.g, CO₂)
2. Deforestation.

Question 23.
What is the importance of green house gases present in the atmosphere ? (CCE 2011, 2012)
Answer:
Green house gases do not allow the infra-red rays coming out of earth to escape but to reflect the same to earth making it warm (average temperature 15°C) and suitable for living beings to live comfortably on earth.

Question 24.
Write two biotic components of biosphere ?
(CCE 2011, 2012)
Answer:
Plants, animals, decomposers.

Question 25.
How is oxygen replenished in nature ? (CCE 2011)
Answer:
By photosynthesis.
6CO₂ + 6H₂O ———-> C₆H₁₂O₆ + 6O₂.

Question 26.
How is average temperature of earth made steady ?
(CCE 2011)
Answer:
Air/atmosphere/green house gases do not allow increase in day temperature and slow down escape of heat during the night.

Question 27.
List any two causes of increase in concentration of CO₂ in the atmosphere. (CCE 2011, 2012)
Answer:

1. Increasing use of fossil fuels,
2. Reduction in vegetation cover.

Question 28.
‘Pesticides reduce soil fertility.’ Give two reasons for your answer. (CCE 2011)
Answer:

1. Pesticides kill soil organisms and, therefore, reduce the decomposition of organic matter so that there is lesser release of minerals from the same,
2. Decrease in soil organisms like earthworms decreases soil aeration.

Question 29.
What are resources available on earth for life to exist ?
(CCE 2011)
Answer:
Air, water, solar energy, minerals, soil.

Question 30.
Give the name of two air pollutants. (CCE 2011)
Answer:
(i) Suspended particulate matter (SPM).
(ii) Pollutant gases like SO₂, nitrogen oxides, methane, carbon monoxide, hydrogen sulphide.

Question 31.
Why is air called breath of life ? (CCE 2011)
Answer:
Air is called breath of life as life cannot exist without air which not only forms a protective transparent envelope or atmosphere around the earth but also provides oxygen (for respiration) and CO₂ (for photosynthesis) with a mechanism for their renewal.

Question 32.
How is CO₂ fixed in the atmosphere ?
(CCE 2011, 2012)
Answer:
CO₂ is being withdrawn continuously from atmosphere by photosynthetic activity of autotrophs. It is returned in nearly equal amount through respiration and combustion.

Question 33.
Which part of solar radiation is absorbed by ozone layer ?
(CCE 2011)
Answer:
Very high energy ultraviolet rays (100 – 320 nm) are absorbed by ozone layer.

Question 34.
What are the constituents of soil ? (CCE 2011)
Answer:
Rock or soil particles (45%), organic matter (humus, 5%), air (25%), water (25%) and different types of microbes (variable).

Question 35.
What is smog ? (CCE 2011)
Answer:
Smog is dark brown or greyish smoky mist that is formed in cold weather due to presence of suspended particles of unburnt carbon, oxides of nitrogen or sulphur in the air. It is suffocating and harmful causing irritation to eyes, nose and lungs besides injuring several internal organs.

Question 36.
Name the group of plants which contain nitrogen fixing bacteria in their root nodules. (CCE 2011, 2012)
Answer:
Legumes.

Question 37.
Name the winds which bring rain in India. (CCE 2011)
Answer:
South-west monsoon and north-east monsoon.

Question 38.
List any two factors that determine the soil type.
(CCE 2011)
Answer:

1. Size of soil particles
2. Amount of humus/air/water.

Question 39.
Why do lichens not occur in Mumbai whereas they occur in Manali and Ooty ? (CCE 2011)
Answer:
Lichens are very sensitive to air pollution which is quite heavy in Mumbai while air pollution is nearly absent in Manali and Ooty.

Question 40.
What are biodegradable pollutants ? (CCE 2011)
Answer:
Pollutants which can be broken down through the agency of micro-organisms are called biodegradable pollutants, e.g., garbage, sewage.

Question 41.
Give the major source of minerals present in the soil.
(CCE 2011)
Answer:
Rocky matter.

Question 42.
Name two industrial air pollutants. (CCE 2011)
Answer:

1. Suspended particulate matter (SPM).
2. Oxides of nitrogen and sulphur.

Question 43.
How are winds formed ? (CCE 2011, 2012)
Answer:

1. Uneven heating of earth’s surface,
2. Differences in heating and cooling of land and water bodies.

Question 44.
Write two methods adopted to control air pollution.
(CCE 2011)
Answer:

1. Electronic precipitators,
2. Scrubbers.

Question 45.
Name any two green house gases. (CCE 2012, 2013)
Answer:
Carbon dioxide, Methane.

Question 46.
Define the term ‘global warming’ in context to increase in carbon dioxide content of the atmosphere. (CCE 2012)
Answer:
Global warming is the rise in temperature of the surface of earth and its immediate atmosphere due to increase in concentration of green house gases, especially CO₂.

Question 47.
What is ozone hole ? (CCE 2012)
Answer:
It is an area of excessive thinning out of ozone in the stratosphere from where high energy UV rays freely pass over to earth, e.g., over Antarctica in spring.

Question 48.
What are CFCs ? (CCE 2012)
Answer:
CFCs are chlorofluorocarbons which have been used extensively in aerosol propellents, refrigerants, formation of foams, spray agents, etc. They are strong ozone depleting substances (ODS).

Question 49.
Name the atmospheric gas that leads to global warming .
(CCE 2012)
Answer:
Carbon dioxide.

Question 50.
Suggest a way of bringing underground water to the surface of earth. (CCE 2012)
Answer:
By means of tube wells, dug wells, hand pumps.

Question 51.
State the percentage of nitrogen gas in the atmosphere.
(CCE 2012)
Answer:
78%.

Question 52.
Mention any one effect of increase in the amount of green house gases in the atmosphere. (CCE 2012)
Answer:
Rise in temperature (global warming).

Question 53.
“Water is essential for life”. Justify the statement.
(CCE 2012)
Answer:
Water is solvent, reaction medium and transport medium of biomolecules constituting living matter.

Question 54.
The large scale deforestation should be stopped. List two reasons to justify. (CCE 2012)
Answer:
Large scale deforestation should be stopped immediately as it is

1. Raising CO₂ concentration in the atmosphere resulting in global warming.
2. Causing floods and soil erosion.

Question 55.
Name the compounds responsible for hole in ozone layer of atmosphere. (CCE 2012)
Answer:
Chlorofluorocarbons, halons, carbon tetrachloride, methyl bromide, methyl chloroform, nitrogen oxides, chlorine.

Question 56.
Name any two pollutants produced by burning of coal and petroleum. (CCE 2012)
Answer:
Suspended particulate matter (SPM), pollutant gases (e.g., sulphur dioxide, nitrogen oxides), hydrocarbons.

Question 57.
Mention two factors that influence the pattern of winds.
(CCE 2012)
Answer:

1. Difference in heating and cooling of land and water bodies.
2. Rotation of earth.
3. Inclination to sun.

Question 58.
List two human activities that would lead to air pollution.
(CCE 2012)
Answer:

1. Burning of fossil fuels.
2. Gaseous emissions from industries.

Question 59.
Name two free living nitrogen fixing bacteria.
(CCE 2012)
Answer:
Azotobacter, Beijerinkia.

Question 60.
Name the process by which carbon is incorporated into life forms like plants. (CCE 2012)
Answer:
Photosynthesis.

Question 61.
Name the organism sensitive to SO₂ in air. (CCE 2012)
Answer:
Lichens

Question 62.
Why do plants need nitrogen ? (CCE 2012)
Answer:
For building up amino acids, proteins, nucleotides, nucleic acids, enzymes, alkaloids and some vitamins.

Question 63.
Name any two physical agents that cause weathering of rocks. (CCE 2012)
Answer:
Atmospheric changes (heating-cooling, wetting-drying, frostraction),- mechanical forces (abrasion by sand, rain, hail,
rolling stones, wave action).

Question 64.
What is the conversion of ammonia to nitrates called ?
(CCE 2012)
Answer:
Nitrification.

Question 65.
List two activities of man which lead to environmental pollution. (CCE 2012)
Answer:

1. Burning of fossil fuel
2. Passage of sewage or municipal water into water bodies.

Question 66.
Name two chemicals present in living organisms having carbon, hydrogen and oxygen as main constituents.
(CCE 2012)
Answer:
Carbohydrates, fats. They are food articles which function as storage and source of energy.

Question 67.
Frozen water between cracked rocks causes the cracks to widen. How? (CCE 2013)
Answer:
Frozen water occupies more volume than liquid water. It exerts a large mechanical force on sides of rock cracks which, therefore, widen.

Question 68.
What does hydrosphere consist of ? (CCE 2013)
Answer:
Hydrosphere or water component of earth includes all the water present in, on and around the earth.

Question 69.
State any one difference between oxygen and ozone.
(CCE 2013)
Answer:
Oxygen is diatomic (O₂) while ozone is triatomic (O₃)

Question 70.
Name two elemental forms of carbon found on the earth ?
(CCE 2013)
Answer:
Graphite, Diamond.

Question 71.
State the percentage of nitrogen gas in the atmoshpere.
(CCE 2013)
Answer:
78%

Question 72.
Name the poisonous gas formed from oxygen gas in the atmosphere ? (CCE 2013)
Answer:
Ozone.

Question 73.
What is meant by the term biosphere ? (CCE 2013)
Answer:
Part of earth which supports life is called biosphere.

Question 74.
Name the factor responsible for rainfall patterns in India.
(CCE 2013)
Answer:
South-west monsoon and to a smaller extent north-east monsoon.

Question 75.
Name the stages of the life cycle of aquatic animals which are affected by change in temperature. (CCE 2014)
Answer:
Egg (hatching), larvae and young animals.

Question 76.
Write the name of triatomic molecule of oxygen.
(CCE 2014)
Answer:
Ozone (O₃).

Question 77.
State the temperature range on the surface of moon.
(CCE 2014)
Answer:
-190°C (dark period) to 110°C (light period).

Question 78.
Mention the direction in which air flows at night in coastal areas. (CCE 2014)
Answer:
From land to sea.

Question 79.
Alongwith the natural resources available on the earth, what else is required to meet the basic requirement of all life forms on the earth ? (CCE 2014)
Answer:
Solar energy.

Question 80.
Name the gas produced when glucose molecules breakdown using oxygen. (CCE 2014)
Answer:
Carbon dioxide (CO₂).

Question 81.
Name two natural resources available on earth.
(CCE 2014)
Answer:

1. Renewable, exhaustible, e.g., forests,
2. Non-renewable exhaustible, e.g., fossil fuels.

Short Answer Questions (2 Marks)

Question 1.
Mention two ways of fixing carbon dioxide.
(CCE 2011)
Answer:

1. Photosynthesis, also called carbon assimilation, by autotrophic plants,
2. Formation of shells and components of skeleton in marine animals.

Question 2.
How temperature/sun and water help in soil formation ?
(CCE 2011, 2013)
Answer:

1. Temperature: Rocks expand on being heated up in the sun and contract on cooling during night. This alternate heating and cooling produces cracks that ultimately break up rocks into smaller pieces and particles.
2. Water: Water entering cracks causes the cracks to widen on being frozen resulting in more cracks and breaking of rocks. Water carrying suspended particles flowing over the rocks corrodes the surface of the latter removing more particles that collect to form soil.

Question 3.
Give reason for the following :
(i) We are lucky that ozone is not stable near the earth’s surface,
(ii) The combustion of fossil fuels increases the amount of suspended particles in air. (CCE 2011)
Answer:
(i) Ozone occurring near the surface of the earth is a strong oxidant causing corrosion of articles, hardening of rubber, respiratory distress and internal haemorrhages. Fortunately, it is not stable forming oxygen and oxides.
(ii) Combustion of fossil fuels is never one hundred percent complete. A lot of unburnt carbon particles or hydrocarbons come out in fumes or exhausts and form suspended particles in the air.

Question 4.
(i) Why is water necessary for all living organisms ? Mention any two points in support of your answer.
(ii) Water is known as “wonder liquid”. Justify this statement by giving any two reasons.
(CCE 2011, 2012)
Answer:
(i) Necessity of Water:

1. Component: Water is a major component (60-90%) of living matter and is a general solvent for various biochemicals which also react in the medium of water.
2. Transport: Water is a medium of transport in the body of living organisms.
3. Buffer: It also functions as a temperature buffer.

(ii) A Wonder Liquid: Water is liquid between 0° and 100°C. It forms solid ice below 0°C and vapours above 100°C. It becomes available at far off places as rain, rivers and springs. Underground water is source of fresh water at many places.

Question 5.
(i) Define the term smog,
(ii) Name two types of diseases caused by regularly breathing the polluted air.
(CCE 2011)
Answer:
(i) Smog is dark brown or greyish smoky mist that is formed in cold weather due to presence of suspended particles of unburnt carbon, oxides of nitrogen or sulphur in the air. It is suffocating and harmful causing irritation to eyes, nose and lungs besides injuring several internal organs.
(ii) Diseases. Pneumoconiasis, Asthma, Bronchitis, damage to liver, kidneys and cancer.

Question 6.
What is green house effect ? How is it caused ?
(CCE 2011, 2012, 2014)
Answer:
Green house effect is keeping an area warm by allowing the solar radiations to pass in but preventing long waves to escape due to presence of radiatively active gases and glass panes.
Certain gases present in the atmosphere of the earth provide a green house effect over earth, keeping it warm with an average temperature of 15°C, e.g., C02, methane, chlorofluoro-carbons, nitrous oxide.

Question 7.
Give the chemical formula of Ozone ? What is its role in atmosphere ? (CCE 2011)
Answer:
O₃. Ozone is good ozone in stratosphere where it filters out very harmful ultraviolet radiations (100-320 nm) coming from sun. It is bad ozone near the surface of earth because of its highly oxidising nature.

Question 8.
(a) Why do terrestrial forms require fresh water ?
(b) Give two examples where fresh water can be found in the frozen form on earth. (CCE 2011)
Answer:
(a) The osmotic concentration of terrestrial forms is low. They can neither store nor eliminate high amounts of dissolved salt present in sea water. Therefore, they require fresh water.
(b) Ice caps over poles, Glaciers.

Question 9.
(a) What is soil erosion ? State any one way by which it can be prevented.
(b) What is humus ? What is the role of earthworms in increasing the quantity of humus. (CCE 2011)
Answer:
(a) Soil Erosion: Removal of unprotected top soil as through the agency of wind or water is called soil erosion.
Soil erosion can be prevented by covering the soil with vegetation.
(b) Semidecayed organic matter present in the soil is called humus. Earthworms bring about fragmentation of organic remains and add humus and mineral rich worm castings in the soil.

Question 10.
What is atmospheric fixation of nitrogen ? (CCE 2011)
Answer:
It is the formation of oxides of nitrogen from atmospheric dinitrogen (N2) in the presence of energy from electric storms, lightning and high energy ultraviolet rays. Nitrogen oxides dissolve in rain water as nitrous and nitric acids. They pass down to soil and water bodies forming nitrites and nitrates.

Question 11.
The heaps of solid waste are a menace. Give two reasons.
(CCE 2011)
Answer:
Solid waste is discarded solid material dumped over soil, e.g., municipal waste, industrial waste, mining waste.

1. Municipal and industrial waste often gives a strinking bad smell.
2. Toxic chemicals present in the solid waste often seep into ground water making the same unfit for human consumption.
3. It makes the area of earth useless and infertile.

Question 12.
How is addition of undesirable substances and change in temperature affect the water life ? (CCE 2011, 2013)
Answer:

1. Undesirable Substances: Fertilizers, pesticides, industrial effluents, municipal waste water when passed into water bodies cause eutrophication that later on kills most of the aquatic life due to depletion of oxygen and presence of toxic chemicals.
2. Temperature: A change in temperature affects oxygen concentration. A high temperature reduces O₂ content which reduces the rate of decomposition of organic matter, causes asphyxiation of aquatic animals, non-hatching of eggs and killing of larvae.

Question 13.
Name two measures that can be taken to reduce water pollution. (CCE 2011)
Answer:

1. Treatment of municipal waste water before discharging it into water body.
2. Treatment of industrial effluents before passing it into municipal sewers or water body.

Question 14.
(i) What is the role of atmosphere in climate control ?
(ii) What is the percentage of nitrogen and oxygen in the air ? (CCE 2011)
Answer:
(i) Atmosphere helps to maintain the climate of a place (which depends upon inclination and air currents) by acting as temperature buffer, preventing rise of temperature during the day and excessive cooling during the night. For this, the atmosphere is a bad conductor of heat.
(ii) Nitrogen – 78%, Oxygen – 21%.

Question 15.
Mention any two human activities which are responsible for water pollution. (CCE 2011)
Answer:

1. Runoff of fertilizers and pesticides applied to crop fields.
2. Passage of municipal waste water and industrial effluents into water bodies.

Question 16.
Differentiate between biodegradable and non- biodegradable pollutants. (CCE 2011)

Biodegradable Pollutants	Non-biodegradable Pollutants
1. Nature. They are biological in origin which can be degraded by decomposer microo-rganisms.	1. They are non-biological in origin which cannot be degraded by micro-organisms.
2. Accumulation. They do not accumulate	2.They tend to accumulate and even show biomagnification.
Ex. Cowdung, Garbage,Sewage.	Ex. Plastic, Mercury,DDT.

Answer:
Biodegradable Pollutants Non-biodegradable

Question 17.
(a) Name the process that returns oxygen to the atmosphere.

(b) Write the condition responsible for poor visibility in cold weather. (CCE 2011)
Answer:
(a) Photosynthesis is the metabolic process that brings about carbon assimilation and releases oxygen, energy
(b) In cold weather, water vapours condense over suspended particulate matter (dust, unburnt carbon) present in the air resulting in foggy conditions and poor visibility.

Question 18.
List two measures of conserving soil fertility.
(CCE 2011)
Answer:
Conservation of soil fertility is the maintenance of ability of the soil to support crops and vegetation. It is carried out by

1. Crop rotation
2. Green manuring
3. Regular addition of farmyard manure.

Question 19.
What causes acid rain ? Mention any damage caused by it on living organisms. (CCE 2011)
Answer:
Acid rain is rainfall with a pH of less than 5. It is caused by the excess emission of SO₂ and nitrogen oxides. The gases dissolve in water forming nitric acid and sulphuric acid. Acid rain causes chlorosis, defoliation, stunting and dieback of plants. It causes skin and lung irritation. Marble structures, metallic articles, jewellary, textiles and paintings are also spoiled by acid rain.

Question 20.
Which symbiotic life forms can grow on stones and help in formation of soil ? Write the mode of their action for making soil from rocks. (CCE 2011)
Answer:
Lichens are dual or composite forms which can grow on bare rocks and bring about biological weathering. The lichens secrete organic acids over the rock surface corroding the same and producing small crevices. Later on, the crevices grow into cracks producing soil.

Question 21.
Explain the role of atmosphere as a blanket. List the factors deciding the rainfall pattern. (CCE 2011)
Answer:

1. Atmosphere as Blanket: Atmosphere is a bad conductor of heat. It does not allow over heating during daytime or excessive cooling during night. Instead, it helps to maintain the average temperature of the earth.
2. Factors Deciding Rainfall Patterns :
   1. Availability of water vapours,
   2. Areas of low pressure or depression
   3. Prevailing wind
   4. Condensation of water vapours.
   5. Direction of mountains.

Question 22.
How do forests play an important role in maintaining water cycle ? (CCE 2011)
Answer:
Forests, being large areas of vegetation, transpire a large amount of water in the vapour form. The water vapours being lighter, rise in the air, cool down and form tiny water droplets around air borne particles producing clouds. In contact with cold air, clouds produce rain. Rain falling over a forest area mosdy percolates into the soil from where the same is absorbed by the forest plants.

Question 23.
What are green houses ? (CCE 2011)
Answer:
Green houses are enclosures with glass panes which allow the solar radiations to pass inwards but prevent the escape of infra-red heat waves. As a result, green houses remain warm. They are useful in growing tropical plants in colder areas.

Question 24.
List any four activities you think would lead to air pollution. (CCE 2011)
Answer:

1. Excessive use of fossil fuels like coal and petroleum.
2. Deforestation,
3. Smoke from industries,
4. Smoke from automobiles,
5. Mining activities.

Question 25.
What is top soil ? Mention any two factors that decide which plants will thrive on that soil. (CCE 2011)
Answer:
Top soil is the upper mineral and humus rich layer of soil that supports vegetation.
Factors:

1. Depth of top soil,
2. Nutrient and humus content of soil,
3. Soil particles,
4. Soil pH.

Short Answer Questions (3 Marks)

Question 1.
(a) “The flow of energy is unidirectional whereas the biogeochemical transfer is cyclic.” Explain why.
(b) Justify the statement, “The nitrogen cycle is supposed to be an ideal cycle in the biosphere.” (CCE 2011)
Answer:
(a) Energy is regularly entering the biosphere from the sun. It is trapped by the producers from where it passes to herbivores and then to carnivores. The energy present in organic remains passes into decomposers. At every step of this transfer there is a lot of dissipation of energy which ultimately leaves the biosphere.
Biogeochemicals are components of biosphere which neither came from outside nor are lost. They are picked / up by producers, passed to consumers and returned to producers by the activity of decomposers. Therefore, flow

(b) Amount of nitrogen remains almost constant in the atmosphere as well as soil. No nitrogen is lost. It is because a part of nitrogen is being fixed regularly in the atmosphere while an equal part of nitrogen is being added to atmosphere through denitrification. Nitrogen salts are also undergoing biogeochemical cycling.

Question 2.
List any three ways to control soil pollution. (CCE 2011)
Answer:

1. Minimum or no use of chemical fertilizers, insecticides and pesticides.
2. Dumping of solid wastes only in sanitary fill.
3. Proper disposal of garbage in composting, biogas plants and incineration.

Question 3.
“It is necessary to conserve natural resources.” Explain.
(CCE 2012)
Answer:
Natural resources (e.g., air, water, soil, forests, minerals, fossil fuels) are earth resources which are being used by human beings for meeting their requirements. However, due to their indiscriminate and excessive use, there is already shortage of these resources and causing harm to our welfare. Therefore, there is an urgent requirement of their conservation by controlling their use and measures to increase their availability through

1. Rain water harvesting.
2. Afforestation and reforestation along with controlled grazing and cutting.
3. Restoration of soil fertility and prevention of soil erosion.
4. Reuse, recycling and substitution of minerals.
5. Judicious use of fossil fuels and finding of alternate sources of energy.

Question 4.
(a) What are different ways in which water gets polluted ?
(b) How does it affect life forms ? (CCE 2012)
Answer:
(a) Water pollution is caused by passage of

1. Untreated or partially treated sewage.
2. Runoff from argicultural fields treated with fertilizers and pesticides.
3. Passage of untreated industrial effluents and hot water.
4. Oil spills.

(b) Water pollution causes :

1. Spread of water borne diseases (e.g., typhoid, cholera, jaundice)
2. Eutrophication or nutrient enrichment followed by algal blooms, death of aquatic animals and organic loading leading to foul smell and taste.
3. Industrial effluents having toxic chemicals causing diseases as minamata disease, itai itai disease, plumbism, methaemoglobinemia, fluorosis, black foot disease, cancer.

Question 5.
(a) How is soil formed ?
(b) What is soil erosion ?
(c) Write two steps to control soil erosion. (CCE 2012)
Answer:
(a) Soil Formation. Soil is formed by weathering (pulverisation) of rocks through physical (sun, water, air), chemical (hydration, oxidation, reduction) and biological (lichens, mosses, herbs) factors followed by humification.
(b) Soil Erosion: Removal of unprotected top soil as through the agency of wind or water is called soil erosion.
(c) Control of Soil Erosion,

1. Afforestation.
2. Wind breaks.
3. Step cultivation on hills.

Question 6.
(a) List the causes that affect life forms found in water bodies in various ways.
(b) Name the element present in coal other than carbon that releases harmful gases during combustion of coal.
(CCE 2012)
Answer:
(a) Water pollutants like untreated sewage, industrial effluents, fertilizer and pesticide rich run off from agricultural fields. .
(b) Sulphur, producing sulphur oxides (e.g., S02) during combustion of coal.

Question 7.
(a) What are the two different states in which water is formed during the water cycle ?
(b) What is the major source of fresh water in the city/town/village where you live ?
(c) Do you know of any activity which may be polluting this water source ? (CCE 2012)
Answer:
(a) Water vapours, liquid water.
(b) The major source of fresh water is ground water in my locality. It is pumped out by tube wells.
(c) It is being polluted by leaching of heavy metals e.g., Nickel from industrial effluents.

Question 8.
How is ‘soil formation different from ‘soil erosion ? Write two factors responsible for each one of them. (CCE 2012)
Answer:
Soil formation (Paedogenesis) is formation of soil from rocky crust of earth while soil erosion is removal of top soil. Factors for Soil Formation: Sun (heating and cooling), water (wetting and drying, freezing, abrasion).
Factors for Soil Erosion. Absence of vegetation cover, heavy rain or strong wind.

Question 9.
(a) “An increase in temperature of water bodies would lead to water pollution”. Explain.
(b) Suggest any two methods to prevent water pollution.
(CCE 2012)
Answer:
(a) Increase in Temperature: A change in temperature affects oxygen concentration. A high temperature reduces O₂ content which reduces the rate of decomposition of organic matter, causes asphyxiation of aquatic animals, non-hatching of eggs and killing of larvae.
(b) Prevention of Water Pollution:

1. Sewage: Only fully treated sewage water should be allowed to pass into water body.
2. Industrial Effluents: They should not be allowed to flow into water body without treatment.

Question 10.
(a) Ozone is poisonous and is found in the upper atmosphere of earth. Yet the world is worried about its depletion. Explain why ?
(b) Write any two methods to control ozone layer depletion.
Answer:
(a) Ozone present in the upper layer of atmosphere or stratosphere filters out harmful high energy ultraviolet radiations (100-320 nm) liberating heat in the process that warms up the stratosphere.
(b)

1. Replacing chlorofluorocarbons and halons with ozone friendly chemicals.
2. Use of jet fuel with little nitrogen.

Question 11.
(a) What are various components of soil.
(b) “Fertilizers and pesticides lead to soil pollution.” List two reasons to justify the statement. (CCE 2012, 2013)
Answer:
(a) Soil consists of mineral matter (45%), organic matter (5%), air (25%), water (25%) and variable number of soil organism. Mineral matter consists of gravel (size 2-10 mm), sand (0.02-2.0 mm), silt (0.002-0.02 mm) and clay (below 0.002 mm) Organic matter is in semidecayed form and is called humus.
(b) Both fertilizers and pesticides cause soil pollution by

1. Killing or inhibiting the growth of soil micro- organisms.
2. Destruction of soil crumbs.
3. Their passage into crops and ground water causing toxic effects over humans and animals (e.g., producing methaemoglobin).

Question 12.
Name four main processes that are part of water cycle in nature. (CCE 2012)
Answer:

1. Vaporisation
2. Cloud formation
3. Rain
4. Infiltration and run-off.

Question 13.
What is smog ? List any two harmful effects of smog.
(CCE 2012)
Answer:
(a) Smog is dark brown or greyish smoky mist that is formed in cold weather due to presence of suspended particles of unburnt carbon, oxides of nitrogen or sulphur in the air. It is suffocating and harmful causing irritation to eyes, nose and lungs besides injuring several internal organs.
(b) Harmful Effects,

1. Allergy, asthma, bronchitis and suffocaton in human beings and animals.
2. Silvering, glazing and necrosis in plants.

Question 14.
Explain the formation of sea breeze and land breeze in coastal areas. (CCE 2012)
Answer:
Sea Breeze. It is flow of cooler breeze from sea towards the land during the day time. During day time, land gets heated faster. Air above land heats up, rises and creates an area of low pressure. Air above sea is cooler and has higher pressure. It moves towards land.
Land Breeze. During night, land cools rapidly while sea water remains warmer. Air above sea is warmer, rises and develops low pressure. Air above land is cooler and has higher pressure. It flows towards sea.

Question 15.
State any two sources of water pollution. Which type of pollution affects the breeding of aquatic animals.
(CCE 2012)
Answer:
Sources of Water Pollution,

1. Sewage
2. Fertilizers and pesticides
3. Industrial effluents.

Temperature: Increase or decrease of temperature of water body affects breeding of most aquatic animals. A high temperature reduces the amount of oxygen dissolved in water.

Question 16.
(a) How does the atmosphere act as a blanket.
(b) The moon which is about the same distance from the sun as that of earth but still there is no atmosphere on moon. (CCE 2012)
Answer:
(a) Atmosphere as Blanket: Atmosphere is a bad conductor of heat. It does not allow over heating during daytime or excessive cooling during night. Instead, it helps to maintain the average temperature of the earth.
(b) Moon Has No Atmosphere: Atmosphere is maintained by gravity and circulation of its components. Moon has only 1/6 gravity as compared to earth. It does not hold any atmosphere. There is no living organisms which can produce and utilise camponents of atmosphere.

Question 17.
Name the constituents of abiotic component of the biosphere. Explain their major role in biosphere. (CCE 2012)
Answer:
Air, water and soil.

1. Air/Atmosphere: It functions as a blanket, source of O₂ and CO₂, medium of dispersal, formation movement and precipitation of water vapours.
2. Water: Water is a component of living beings (60-90%), solvent, transport medium, reaction medium for biomolecules, temperature buffer and bringing turgidity to living cells.
3. Soil: It provides anchorage, water and minerals to plants, a place for microorganisms to dispose off organic remains and release of minerals.

Question 18.
(a) What is soil pollution ? What factors are responsible for it ?
(b) Suggest two methods of preventing or reducing soil pollution. (CCE 2012)
Answer:
(a) Soil Pollution. It is adverse alteradon in the soil caused by removal or addition of substances which reduce its fertility and quality.
(b) Factors. Addition of raw manure, excess fertilizers, pesticides, faulty irrigation and dumping of wastes as well as industrial effluents.
(c) Control of Soil Pollution.

1. Minimum or no use of chemical fertilizers, insecticides and pesticides.
2. Dumping of solid wastes only in sanitary fill.
3. Proper disposal of garbage in composting, biogas plants and incineration.

Question 19.
Write one appropriate word for statements (1—3) given below and briefly explain them.

1. The process by which carbon is incorporated into life forms.
2. The process by which nitrates are converted into free nitrogen.
3. The cyclic flow of nutrients like nitrogen and oxygen between nonliving environment and living organisms.
   (CCE 2012)

Answer:

1. Photosynthesis: CO₂ is taken up by plants from their environment and changed into organic form. Energy is taken from sun. Hydrogen is taken from water.
2. Denitrification: Some bacteria present in water-logged soils take oxygen from nitrates for their activity. This changes nitrates into gaseous nitrogen.
3. Biogeochemical Cycling: Biogeochemicals or nutrients are taken up by organisms for their structure and functioning. They are released later on when organic remains are decomposed. The same are picked up again by the organisms.

Question 20.
(a) Name two elemental forms in which carbon occurs.
(b) Name any two forms in which carbon is found in combined state with other elements in nature.
(c) Briefly explain how it can be said that all life forms are based on carbon containing molecules. (CCE 2012)
Answer:
(a) Elemental Forms. Diamond, Graphite.
(b) Combined State. Carbon dioxide, Carbohydrate.
(c) Life Forms. All life forms contain protoplasm, energy storing and energy liberating organic substances and enzymes for catalysing various metabolic reactions. All these are organic substances made of carbon, e.g, proteins, enzymes, carbohydrates.

Question 21.
(a) What is the role of bacteria in nitrogen cycle ?
(b) What happens to nitrate once it enters the plant ?
(CCE 2012)
Answer:
(a) Role of Bacteria,

1. Biological nitrogen fixation, e.g., Azotobacter, Rhizobium.
2. Decomposition, ammonification and nitrification, e.g., Bacillus ramosus, Nitrosomonas, Nitrobacter.
3. Denitrification, e.g., Pseudomonas.

(b) Nitrogen Assimilation. Nitrate absorbed by plants is first reduced to ammonia level. Ammonia combines with organic acids to produce amino acids from which proteins and nucleotides are formed.

Question 22.
Give reason :
(a) Presence of high levels of suspended particles in the air is harmful.
(b) A sudden change in the temperature of water body is dangerous for aquatic life.
(c) The process of nitrogen fixation does not take place in the presence of oxygen. (CCE 2012)
Answer:
(a) Some of the suspended particles present in the air enter our lungs, reach alveoli and cause pulmonary ailments like asthma, bronchitis, emphysema, lung fibrosis, pneumoconiosis.
(b) Change in temperature changes the amount of oxygen dissolved in water and disturbs the breeding of aquatic animals.
(c) The enzyme for nitrogen fixation called nitrogenase is sensitive to oxygen as it is specialized to combine hydrogen with nitrogen.

Question 23.
What makes the biosphere dynamic but stable ?
(CCE 2012)
Answer:
The composition of atmosphere, the extent of hydrosphere and lithosphere remain stable in the biosphere. It is because of regular circulation of their constituents among different components and between biotic and abiotic parts of the biosphere. The phenomenon is called biogeochemical cyclling.

Question 24.
Design an activity to show how convective currents are set up in the air and what is the nature of these currents ?
(CCE 2012)
Answer:
Demonstration of Convectic Currents
Apparatus: A beaker or wide mouthed bottle, a candle, box of matches, incense stick (agarbatti).
Working: Fix a burning candle in a beaker or wide mouthed bottle. Light an incense stick. Take it first to edge of the beaker, then half way towards middle and finally above the candle flame.
Results: When kept near the edge, smoke from incense stick will move towards the flame. This will also occur when it is halfway towards the flame. However, when the incense stick is kept above the flame, the smoke will rise up. In all cases smoke flows towards the area of low air pressure.

During night, reverse flow of air occurs. Land cools down rapidly. Air over it becomes cooler. Sea water cools slowly. Air above it is hotter with lower air pressure as compared to air pressure over land. Therefore, cooler air present over land moves towards sea.
Factors Influencing Movements of Air. Depending upon the difference in energy levels and air pressure, there occurs diverse type of atmospheric phenomena like breeze, wind, storm, thunderstorm, monsoon rains, cyclones, etc. The factors controlling these phenomena are

1. Uneven heating of land in different parts of earth
2. Differences in heating and cooling of land and water.
3. Barrier of mountains
4. Rotation of earth.

Question 25.
State two consequences of global warming. (CCE 2012)
Answer:

1. Melting of polar ice and glaciers will raise the water level of sea submerging many low level coastal areas.
2. Atmosphere will shrink due to cooling caused by reduced passage of long wave radiations.
3. Tropics will be converted into arid areas while floods will occur in higher latitudes.

Question 26.
Explain the role of atmosphere in keeping climate control.
(CCE 2012)
Answer:
Atmosphere helps in maintaining the climate of an area by retaining the heat over the area as it is a temperature buffer. There is neither excessive heating during day nor excessive cooling during night. The average temperature of a place remains steady as per inclination of the area towards sun.

Question 27.
Mention the importance of soil. How is it depleted? Write two ways to replenish soil. (CCE 2012)
Answer:
(a) Soil provides anchorage, minerals and water to terrestrial plants. It is also residence of microorganisms involved in decomposition of organic remains and release of minerals.
(b) Soil Depletion. It occurs through soil erosion, water logging and salination.
(c) Replenishment of Soil. Providing a vegetation cover, correction of water logging and salination, crop rotation and contour bunding.

Question 28.
Explain the following terms :

1. Ammonification
2. Nitrification
3. Biosphere.
   (CCE 2012)

Answer:

1. Ammonification: It is breakdown of proteins and deamination of amino acids to release ammonia.
2. Nitrification: It is oxidation of ammonia released through ammonification to form nitrites and nitrates.
3. Biosphere: It is living mande of earth comprising lower atmosphere, lithosphere and hydrosphere where living beings are present.

Question 29.
How has industrialisation led to air pollution ? Explain in three points. (CCE 2012)
Answer:

1. Processing industries release a lot of air pollutants (e.g., cotton dust, iron mill dust, flour mill dust, cement industries, asbestos industry) that cause pneumoconiosis and other pulmonary problems.
2. Fuel. Industries consume coal and other fossil fuels which send out smoke, pulluting gases and hydrocarbons,
3. Chemical industries send out toxic chemicals into air that have a harmful effect on plants, animals and humans,

Question 30.
How is smog formed ? What does it indicate ? (CCE 2012)
Answer:
Smog is opaque fog which is formed due to noncirculation of air that results in accumulation of suspended particulate matter, pollutant gases, hydrocarbons and water vapours.
It indicates high level of pollution in the area due to industries and vehicular traffic.

Question 31.
Two similar plastic trays filled with soil and manure are taken. In tray A mustard seeds are sown and watered for 4-5 days until they germinate into seedlings and the seedlings grow into small plants. Watering of the tray A is stopped for the next 2-3 days and the small plants are allowed to grow. Trays A and B are placed over a brick in a tilted position. Now both the trays are watered with equal amount of water using a water can.
(a) Name the natural phenomenon indicated by tray B.
(b) Less of water flowing out is indicated by tray A. Give reason.
(c) Why is the top layer of soil considered the most important layer ? (CCE 2012)

Answer:
(a) Run off, which is high in soil not covered by vegetation.
(b) Most of the water is absorbed by soil as the latter is porous due to presence of plants. Run off is little.
(c) Top soil is important because it contains humus, air and decomposer microorganisms. Roots of most plants are restricted to it.

Question 32.
Explain the role played by lichens, moss and trees in the soil formation. (CCE 2012)
Answer:

Soil is formed through two processes of weathering and humification.
It is pulverisation of rocks or breaking of rocks into fine particles. There are three types of weathering — physical (atmospheric changes and mechanical forces), chemical and biological. Sun, water, wind and living organisms perform them.

1. Sun: It causes expansion of rocks by heating. Cooling causes their contraction. Different parts of rocks expand and contract at different rates. Uneven expansion and contraction produces cracks leading to fragmentation of rocks.
2. Water:
   1. Wetting and Drying: Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks.
   2. Frost Action: Water seeping in cracks would swell up and exert a great pressure if it freezes due to low temperature. The rock would undergo fragmentation.
   3. Abrasion: Running water carrying rock fragments would break and grind rocks occurring in the pathway. Rain and hail also cause rock breaking.
3. Wind: Dust and fine sand carried by wind cause abrasion of the rock surface when wind strikes the same.
4. Living Organisms: Lichens secrete chemicals to dissolve minerals from the rock surface. This produces crevices where dust collects. Mosses grow there. They cause deepening of crevices and development of small cracks. Roots of short lived plants widen these cracks. Roots of larger plants cause fragmentation of rocks by entering the cracks and growing in size.

Question 33.
How are clouds formed and bring us rain ? Explain briefly. (CCE 2012)
Answer:
Clouds are wet air masses that float in the direction of prevailing wind. They develop when water vapours are formed in large number. There is evaporation from the surface of water bodies and wet areas due to their heating during the daytime. Plants also give out water vapours in transpiration while animals do so in exhaled air and perspiration. Air also heats up during daytime. The hot air along with water vapour rises up. At a height, air expands and becomes cool. Cooling causes the water vapours to condense. Suspended particles of dust and other materials function as nuclei around which water vapours condense. When a large wet air mass collects, cloud is formed.
Clouds move along the prevailing direction of wind. Wherever they meet cool air or high mountains, further condensation of water droplets change the same into rain.

Question 34.
How do modern farming practices bring about conversion of fertile soil to barren soil ? Explain briefly (CCE 2012)
Answer:

1. Clean Tilling: The exposed top soil layer gets dried and it is blown away by wind.
2. Fertilizers: They are chemical formulations which are added to soil in order to provide specific nutrients to crop plants.
3. Pesticides: They are broad spectrum formulations which are. used to kill pests and weeds. Some of these pesticides are slow to degrade. They undergo biomagnification and prove harmful to higher forms of life, e.g., chlorinated hydrocarbons.
4. Excessive Irrigation: Faulty irrigation causes water logging and soil salination. Both of them reduce crop yield drastically.
   Therefore, indiscriminate use of fertilizers, pesticides and faulty irrigation can turn fertile crop fields into barren areas. It is important to adopt sustainable practices like organic farming and sprinkler irrigation.

Question 35.
What is soil ? How is it formed ? State the major factor that decides the structure of soil. What role does it play ?
(CCE 2012, 2013)
Answer:
Soil: It is upper weathered and mineral containing part of earth’s crust which supports plant life and contains numerous organisms and organic remains.
Soil Formation: Soil is formed by weathering (pulverisation) of rocks through physical (sun, water, air), chemical (hydration, oxidation, reduction) and biological (lichens, mosses, herbs) factors followed by humification.
Major Factor: Average particle size determines the structure of soil, e.g., clayey, loam, sandy. Soil particles determine j mineral availability, soil hydration and soil aeration.

Question 36.
Geeta visited her relatives living in a village. She found that many villagers were suffering from water borne disease like cholera and jaundice. She also noticed that the pond in the village used as a water source did not have any aquatic plants and animals.

1. What could be the reason for mass illness ?
2. Write two reasons for the pond to have been devoid of life. (CCE 2013)

Answer:

1. Reason for Mass Illness. Contamination of pond water with sewage,
2. Reasons for Absence of Aquatic Plants and Animals,
   1. Loading of water with sewage could cause increased activity of decomposers which deplete the pond of its dissolved oxygen.
   2. Absence of oxygen kills all the aquatic animals and plants.

Question 37.
Rajesh lived in a village which was pollution free. He visited j an industrial city during winter and found the visibility very poor. Many children were showing signs of allergy. What could have been the reason. Suggest any two ways which could have helped to improve the situation.
(CCE 2013)
Answer:
The industrial city was engulfed in smog. Smog contains components (e.g., smoke particles, S02, H2S, hydrocarbons, etc) which are injurious to human beings, causing allergy, suffocation and irritation.

1. Switch over from coal-fired engines to gasoline and electric engines in industries,
2. Tall chimneys and passing the smoke through precipitators and scrubbers,
3. Strict enforcement of pollution control norms over vehicles.

Question 38.
(a) Where is the ozone layer found ?
(b) What is ozone hole and how is it caused ?
(c) State its harmful effects.
(CCE 2013, 2014)
Answer:
(a) Ozone layer is ozone (O₃) rich upper part of atmosphere called stratosphere. It lies at a height of 23-25 km above equator and 11-16 km above poles.
(b) Ozone Hole. Ozone hole is area of excessive thinning of ozone in the stratosphere. It is mostly found over Antarctica and to a lesser extent over north pole during their spring times. Cause. Ozone depletion occurs due to certain chemicals called ozone depleting substances (ODS), e.g., chlorofluorocarbons (CFCs), halons, nitrogen oxides, chlorine. They react with 03 and change it to oxygen state,
(c) Harmful Effects. Thinning of ozone layer results in passing very high energy ultraviolet rays (100—320 nm) to the earth. They cause skin cancer, harm eye sight, weaken immune system, cause harmful mutations and reduce crop yield.

Question 39.
Describe the structure of a simple glass house mentioning the climatic conditions in which they are used. Name any two green house gases. (CCE 2013)
Answer:
Green house is an enclosure having glass panes in the direction where solar radiations fall inside. Green houses are built in cold climates for growing tropical plants even in winters. It is because the interior of glass house remains warm because glass panes (and water vapours, CO₂ in the enclosure) allow solar radiations to enter but prevent passage of heat waves to the outside.
Green House Gases (GHGs). CO₂, methane (CH₄).

Question 40.
What are the two forms of oxygen found in the atmo¬sphere ? Write one importance of each. (CCE 2013)
Answer:
Diatomic oxygen (O₂) and triatomic ozone (O₃). Importance,

1. Oxygen is essential for respiration and combustion,
2. Ozone present in stratosphere protects earth from harmful short wave ultraviolet radiations (100-320 nm).

Question 41.
Draw carbon cycle in nature. (CCE 2013)
Answer:

Question 42.
Your school is less than a kilometre from your house. Your neighbourhood friend who attends the same school, comes to the school by a car every day.
How do you think he can contribute towards reduction of air pollution ? Write any three suggestions. (CCE 2013)
Answer:

1. My friend can join a car pool for school.
2. He can go to school in school bus.
3. Since the distance is small, my friend can go to school by foot or on bicycle.

Question 43.
What are CFCs ? Why are they harmful ? (CCE 2013)
Answer:
CFCs are chlorofluorocarbons that have been in use as aerosol propellents, refrigerants, shaving foams, formation of foam sheets and mattresses, spray agents, etc. They pass into stratosphere and release chlorine. Chlorine destroys ozone molecules and convert them into oxygen. As a result ozone present in stratosphere gets depleted resulting in passage of harmful UV radiations on earth.

Question 44.
List any three human activities that you think would lead to increase in carbon dioxide content of atmosphere.
(CCE 2013)
Answer:

1. Large scale deforestation that reduces assimilation of CO₂ in photosynthesis,
2. Combustion of fossil fuels in thermal plants, industries, transport etc. is throwing large amounts of CO₂ into the atmosphere.
3. Biomass or wood burning.

Raj at and five of his friends went for a picnic with a lot of food stuffs and game items to Gorewara lake from where the drinking water supply for the city is done. As they were playing, they saw a fish entangled in the twigs and injured itself. They helped to free it, nurtured it and put it back in water. Before leaving, they put all the left-over food in water.

Question 45.
Answer the following questions.

1. What would have happened had they not saved the fish ?
2. What do you think about their act of throwing the food into water ?
3. Mention one way in which you will help your city authorities to cope with such problem. (CCE 2013)

Answer:

1. The fish would have died. Saving and nurturing an animal is an act of love for nature.
2. The act of throwing the left-over food in the lake is bad as it increases the organic loading of lake and can cause its eutrophication.
3. To install two types of bins on the shore of the lake for placing left-overs by the visitors.

Question 46.
In coastal areas what is the direction of flow of air during the day ? Explain why ? (C. C.E. 2014)
Answer:
Sea Breeze: It is flow of cooler breeze from sea towards the land during the day time. During day time, land gets heated faster. Air above land heats up, rises and creates an area of low pressure. Air above sea is cooler and has higher pressure. It moves towards land.

Question 47.
What is the percentage of oxygen found in the atmosphere ?
Name two compounds of oxygen found in nature. Name any three processes in which oxygen is used up in atmosphere. (C.C.E. 2014)
Answer:
21% (20-94%). Diatomic O₂(oxygen) and triatomic O₃(ozone).
Uses:

1. Respiration in most organisms,
2. Combustion of fossil fuels,
3. Formation of oxides,
   e.g., nitrogen oxides during atmospheric fixation of nitrogen,
4. Decomposition of organic matter.

Question 48.
State three factors influencing wind movements which re-sult in diverse atmospheric phenomena. (C.C.E. 2014)
Answer:
Winds are basically caused by heating of air in certain parts. The hot air rises upwards. This creates an area of low pressure. Cooler air from adjacent higher pressure areas passes into this area. This creates wind. The factors which control movement of winds in different directions in different parts of the earth are

1. Uneven heating of land in different parts of earth
2. Differences in heating and cooling of land and water.
3. Barrier of mountains
4. Rotation of earth.

Question 49.
Explain the biological processes in nitrogen cycle.
(C.C.E. 2014)
Answer:
Biological processes in nitrogen cycle are :

1. Biological Nitrogen Fixation: A number of free living and symbiotic bacteria and blue-green algae are capable of picking up of atmospheric nitrogen and converting it into ammonia that combines with organic acids to form amino acids. Rhizobium is the common symbiotic bacterium that occurs in the nodules of legume roots.
   
2. Nitrogen Assimilation: It is carried out by plants. Plants pick up nitrates or ammonium ions from their medium. Nitrate or nitrite is first changed into ammonium state. Ammonium ions combine with organic acids to form amino acids. Amino acids give rise to proteins and nucleotides. Nucleotides produce nucleic acids. Enzymes are derived from proteins.
   
3. Decomposition: Organic remains undergo decay and decomposition through the agency of decomposers. It releases carbon dioxide.
4. Denitrification: It is the process of reduction of nitrates into gaseous nitrogen which escape into atmosphere. Denitrification is caused by bacteria present in water logged soils, g., Pseudomonas aeruginosa.

Question 50.
How is percentage of carbon dioxide maintained in the atmosphere ? Mention one human activity which adds carbon dioxide in the atmosphere. (C. C.E. 2014)
Answer:
Percentage of carbon dioxide is maintained in the atmosphere by its consumption in photosynthesis (carbon assimilation) being almost equal to its liberation in respiration and combustion.
However, with increasing use of fossil fuels, more carbon dioxide is being added to the tmosphere than its withdrawal.

Question 51.
Draw a labelled diagram of‘oxygen cycle’ occurring in nature. (C.C.E. 2014)
Answer:

Question 52.
Write the composition of soil. On what basis is the type of soil decided ? (C. C.E. 2014)
Answer:
Soil Composition: Soil consists of mineral matter (45%), organic matter (5%), air (25%), water (25%) and variable number of soil organism. Mineral matter consists of gravel (size 2-10 mm), sand (0.02-2.0 mm), silt (0.002-0.02 mm) and clay (below 0.002 mm) Organic matter is in semidecayed form and is called humus.
Type of Soil: Average particle size determines the structure j of soil, e.g., clayey, loam, sandy. Soil particles determine j mineral availability, soil hydration and soil aeration.

Question 53.
(a) What is the outermost layer of the earth called ?
(b) How is it important to life forms ?
(c) Name the factors that help in the formation of soil from rocks. (C. C.E. 2014)
Answer:
Answer:
(a) Lithosphere.
(b) Upper crust of earth forms soil which provides anchor¬age, water and minerals, to terrestrial plants. Aquatic organ¬isms also depend upon soil for supply of minerals.
(c) Soil is formed through two processes of weathering and humification.
Weathering
It is pulverisation of rocks or breaking of rocks into fine particles. There are three types of weathering — physical (atmospheric changes and mechanical forces), chemical and biological. Sun, water, wind and living organisms perform them.

1. Sun: It causes expansion of rocks by heating. Cooling causes their contraction. Different parts of rocks expand and contract at different rates. Uneven expansion and contraction produces cracks leading to fragmentation of rocks.
2. Water:
   1. Wetting and Drying: Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks.
   2. Frost Action: Water seeping in cracks would swell up and exert a great pressure if it freezes due to low temperature. The rock would undergo fragmentation.
   3. Abrasion: Running water carrying rock fragments would break and grind rocks occurring in the pathway. Rain and hail also cause rock breaking.
3. Wind: Dust and fine sand carried by wind cause abrasion of the rock surface when wind strikes the same.
4. Living Organisms: Lichens secrete chemicals to dissolve minerals from the rock surface. This produces crevices where dust collects. Mosses grow there. They cause deepening of crevices and development of small cracks. Roots of short lived plants widen these cracks. Roots of larger plants cause fragmentation of rocks by entering the cracks and growing in size.

Humification
Partially decomposed organic matter or humus mixes with weathered rock particles to form soil. Humus helps in formation of soil crumbs which are essential for maintaining proper hydration and aeration of soil.

Question 54.
(a) State the reason for the following :
(t) Excess burning of coal causes green house effect,
(it) Soil is a mixture.
(iii) Temperature ranges from -190° C to 110°C on the surface of the moon. (C.C.E. 2014)
Answer:
(a) Excess burning of coal adds lot of CO₂ to the atmosphere. Carbon dioxide is a green house gas which allows the solar radiations to strike the earth’s surface but prevents the escape of long wave radiations from the earth’s atmosphere.
(b) Soil is a Mixture. Soil consists of particles (sand, silt, clay and humus) which do not get dissolved in water, neither they react with one another.
(c) Moon does not have an atmosphere. Its surface heats up to 110°C when solar radiations strike it. In the absence of solar radiations, the surface temperature of moon dips to -190°C.

Question 55.
State the different ways by which atmospheric nitrogen can be fixed into oxides of nitrogen. Explain in brief.
(C.C.E. 2014)
Answer:
Atmospheric Nitrogen Fixation: In the presence of lightning (energy and pressure), electric storm and high energy ultraviolet rays, small amounts of nitrogen and oxygen of the air react to form nitrogen oxides. The latter dissolve in rain water to form nitric and nitrous acids. They pass down to soil and water bodies forming nitrites and nitrates.

1. Industrial Nitrogen Fixation: Nitrogen is made to combine with hydrogen under high temperature and pressure to form ammonia. Ammonia is often changed further to urea because the latter is less toxic.
2. Nitrogen Assimilation: It is carried out by plants. Plants pick up nitrates or ammonium ions from their medium. Nitrate or nitrite is first changed into ammonium state. Ammonium ions combine with organic acids to form amino acids. Amino acids give rise to proteins and nucleotides. Nucleotides produce nucleic acids. Enzymes are derived from proteins.
   
3. Decomposition: Organic remains undergo decay and decomposition through the agency of decomposers. It releases carbon dioxide.
4. Denitrification: It is the process of reduction of nitrates into gaseous nitrogen which escape into atmosphere. Denitrification is caused by bacteria present in water logged soils, g., Pseudomonas aeruginosa.

Question 56.
Describe how lichens and big trees influence the formation of soil.
Answer:
Living Organisms: Lichens secrete chemicals to dissolve minerals from the rock surface. This produces crevices where dust collects. Mosses grow there. They cause deepening of crevices and development of small cracks. Roots of short lived plants widen these cracks. Roots of larger plants cause fragmentation of rocks by entering the cracks and growing in size.

Question 57.
Mention six combined forms in which oxygen is found on the earth’s crust. (C. C.E. 2014)
Answer:
Carbonate, silicon oxides, sulphate, nitrate, phosphate, metal oxides.

Question 58.
Explain the following terms :
(i) Nitrogen Fixation
(ii) Nitrification
(iii) Denitrification. (C. C.E. 2014)
Answer:
(i) Nitrogen Fixation: It is conversion of inert gas into bio¬logically acceptable form. Nitrogen fixation is carried out abiologically in the atmosphere (through lightning, electric storms, UV radiations) and biologically by certain bacteria and cyanobacteria (= blue-green algae).
(ii) Nitrification : Conversion of ammonia to nitrites and nitrites to nitrates by bacteria.
(iii) Denitrification: Conversion of nitrates to gaseous nitrogen by bacteria.

Long Answer Questions (5 Marks)

Question 1.
(i) Make neat and labelled sketch of nitrogen cycle in nature.
(ii) Describe in brief the role of nitrogen fixing bacteria and lightning in fixing nitrogen. (CCE 2011, 2014)
Answer:
(i)

(ii)
(a) Nitrogen Fixing Bacteria (Biological Nitrogen Fixation). They live both freely (e.g., Azotobacter) as well as symbionts (e.g., Rhizobium in root nodules of legumes). The bacteria pick up nitrogen gas (N₂) from soil atmosphere, reduce it to ammonia (NH₃), then forming amino acids and proteins.
(b) Lightning (Physical Nitrogen Fixation). By its energy, it helps to combine a small quantity of nitrogen with oxygen of the atmosphere forming nitrogen oxides. The latter dissolve in rain water and enter the soil producing nitrite and nitrate.

Question 2.
(i) Draw a neat labelled sketch of carbon cycle in nature.
(ii) What is green house effect ? How does CO₂ cause global warming in the atmosphere ?
(CCE 2011, 2012, 2013)
Answer:
(i)

(ii) Green house effect is keeping an area warm by allowing the solar radiations to pass in but preventing long waves to escape due to presence of radiatively active gases and glass panes.
CO₂ is a green house gas. It permits the solar radiations to pass through and reach the surface of the earth. Infra-red (heat) waves emitted by the earth are, however, not allowed to pass out by CO₂. They are reflected back to earth. This causes global warming.

Question 3.
(a) Mention the two forms of oxygen found in the atmosphere,
(b) Name the form of oxygen, absorbing UV radiations.
(c) Draw flow diagram of oxygen cycle. (CCE 2011)
Answer:
(a) O₂, O₃
(b) O₃
(c)

Question 4.
Many human activities lead to increasing levels of pollution of air, water bodies and soil. “Isolating these activities to specific and limited areas would not help in reducing pollution.” Justify the statement giving at least five reasons. (CCE 2011, 2012)
Answer:
It is often suggested that all polluting units be asked to shift outside the city limits, so that there is not much effect on the residential area. This is, however, of not much help as

1. Burning of fossil fuels lead to acid rain which spreads over large areas killing vegetation, water bodies and causing harm to human beings and their assets.
2. Polluting units add green house gases into the atmosphere. They have global warming effect.
3. A number of air pollutants pass into stratosphere causing depletion of protective ozone layer.
4. Passage of sewage into water bodies makes the water unfit for consumption as it becomes a source of many water borne diseases. There is scum, foul odour and bad taste.
5. Dumping of industrial effluents over the soil causes many of the toxic chemicals and heavy metals to slowly percolate down and get mixed with ground water.

Question 5.
(a) Mention three processes in which oxygen is used up from the atmosphere and the only process in which it is returned to the atmosphere.
(b) Describe briefly two processes by which carbon dioxide is returned back to the atmosphere.
(CCE 2011, 2012)
Answer:
(a)

1. Consumption of Oxygen.
   1. Respiration
   2. Combustion
   3. Atmospheric fixation of nitrogen.
2. Return of Oxygen. Photosynthesis,

(b) Return of CO₂.

1. Respiration
2. Combustion.

Question 6.
(a) With the help of a well sketched diagram, explain water cycle in nature.
(b) How is green house effect related to global warming ? Explain. (CCE 2011, 2012)
Answer:
(a)

Water evaporates from the wet surfaces and plants (transpiration). The water vapours being light rise in the air, getting cooled and condensed over dust particles forming clouds. Clouds move along air currents, , cooling further and undergoing precipitation.
(b) Green house effect is keeping an area warm by allowing the solar radiations to pass in but preventing long waves to escape due to presence of radiatively active gases and glass panes.
Green house effect is shown by a number of radiately active gases, also called green house gases (GHGs), e.g., CO₂, methane, chlorofluorocarbons, nitrous oxide. The gases allow the solar radiations to pass through and reach the surface of earth. However, heat waves (infra-red rays) coming from hot surfaces of earth are unable to pass out of the atmosphere as the higher concentration of green house gases reflect most of them back to earth. This raises the temperature of the earth. The phenomenon is called global warming.

Question 7.
(a) In coastal area, wind current moves from sea towards the land during the day but during night it moves from land to sea. Discuss the reason.
(b) How are CFCs harmful for the environment and living beings ? (CCE 2011, 2012)
Answer:
(a)

1. During day, warmer land heats up the air above it which rises and creates an area of low pressure. Air above sea remains comparatively cool. It has a higher pressure and, therefore, cooler air moves towards the land,
2. During night, land becomes cooler quickly while sea water remains comparatively warmer. Low air pressure area develops over sea. Cooler air from land, will therefore, flow towards sea.

(b) CFCs passing into stratosphere split up to release active chlorine under the impact of UV radiations. Chlorine catalyses the breakdown of ozone into oxygen. Depletion of ozone will allow more UV rays to pass down to earth causing skin cancers, blindness and weakening of immune system.

Question 8.
(a) What do you understand by ozone layer depletion ?
(b) What is air pollution ? How does air pollution affect animal and plant life ? (CCE 2011)
Answer:
(a) Ozone Layer Depletion: Ozone hole is formed during spring time over antarctica and to a small extent over north pole. Thinning of ozone layer or ozone hole increases the passage of harmful ultravoilet rays to earth. This has increased incidence of skin cancers, defective eye sight, reduced immunity, increased number of mutations and reduced crop yield in southern countries of southern hemisphere.
(b) Air Pollution: It is the addition of substances, gases and chemicals into the air that has the harmful effect on human beings, human assets, plants and animals. The major sources of air pollution are combustion of fossil fuels, industrial processes and agricultural burning. Air pollutants include suspended particulate matter (SPM), gases (e.g., sulphur dioxide, nitrogen oxides, carbon monoxide, hydrogen sulphide, methane, ammonia) and vapours of unburnt hydrocarbons. They also produce two harmful environmental products of acid rain and smog.
Effect on Animal Life. Respiratory disorders, allergies, eye and throat irritation, haemorrhages, frequent diarrhoea, reduced appetite and weakening of bones.
Effect on Plant Life. Chlorosis, necrosis, water soaked areas, defoliation and die back.

Question 9.
How do clouds form in the sky ? Draw the biogeochemical cycle involved in it. What are the different states in which water is found in the water cycle ?
(CCE 2011)
Answer:
(a) Clouds are wet air masses that float in the direction of prevailing wind. They develop when water vapours are formed in large number. There is evaporation from the surface of water bodies and wet areas due to their heating during the daytime. Plants also give out water vapours in transpiration while animals do so in exhaled air and perspiration. Air also heats up during daytime. The hot air along with water vapour rises up. At a height, air expands and becomes cool. Cooling causes the water vapours to condense. Suspended particles of dust and other materials function as nuclei around which water vapours condense. When a large wet air mass collects, cloud is formed.
(b)

(c) States of Water,

1. Gaseous state – as vapour,
2. Liquid state – as rain, flowing water, water bodies, underground or soil water.
3. Solid state – as snow in cooler areas like polar regions, mountain tops, winter in subarctic and temperate areas.

Question 10.
(a) Draw a labelled diagram to show oxygen cycle in biosphere,
(b) Name the major process through which oxygen is returned to the atmosphere
(c) Enlist the various processes by which atmospheric oxygen and oxygen dissolved in water is consumed.
(CCE 2011)
Answer:
(a)

(b) Photosynthesis,
(c)

1. Respiration (consumes both atmospheric oxygen and oxygen dissolved in water),
2. Combustion.
3. Decomposition.

Question 11.
(a) Describe briefly any two processes involved in the cycling of N₂ in the environment.
(b) What is nitrogen fixation ? Why do plants need to fix nitrogen ? (CCE 2011)
Answer:
(a) Processes Involved in Cycling of N₂ :

1. Nitrogen fixation,
2. Nitrogen assimilation
3. Decomposition
4. Denitrification.

(b) Nitrogen Fixation: It is conversion of inert nitrogen gas (N₂) into biologically acceptable forms like NH₃, NO₂, NO₃. Plants need nitrogen fixation because they cannot absorb and utilise nitrogen gas.

Question 12.
(a) What are biogeochemical cycles ?
(b) Why is circulation of water necessary in the environment ? Discuss any two human activities which are disturbing water cycle.
(CCE 2011)
Answer:
(a) The repeated circulation of biogeochemicals or biogenetic nutrients between abiotic and biotic components of the environment is called biogeochemical cycling, e.g., CO₂ cycle, N₂ cycle, Water cycle, O₂ cycle.
(b)

1. Circulation of water is necessary because land biota needs fresh water while the major reservoir of water is ocean. Land is regularly losing water through evaporation, flowing of rivers and ground water to the oceans. Therefore, land must receive fresh water regularly in the form of rain and snow.
   1. Excessive withdrawal of ground water.
   2. Polluting water bodies through sewage, industrial effluents, fertilizers and pesticides.

Question 13.
(a) Describe the role of photosynthesis and respiration in carbon cycle.
(b) What is meant by biogeochemical cycle ? Name two essentials which are transferred between different components of the biosphere. (CCE 2011)
Answer:
(a) (i) Photosynthesis. It assimilates CO₂ and forms organic food like glucose and starch, proteins and fats. Organic food with its contained energy is passed from producers to herbivores and then to carnivores in the ecosystem.
(ii) Respiration. It oxidises glucose and other organic compounds-for releasing energy for body activities. CO₂ is liberated.
(b) Biogeochemical Cycle: The repeated circulation of biogeochemicals or biogenetic nutrients between abiotic and biotic components of the environment is called biogeochemical cycling, e.g., CO₂ cycle, N₂ cycle, Water cycle, O₂ cycle.
Biogeochemicals and Energy: Biogeochemicals are picked up by plants and made part of organic matter which also incorporates chemical energy during the process of photosynthesis. From plants, the biogeochemicals and energy contained in organic food pass into animals which feed on plants. Animals are eaten by other animals. The biogeochemicals and energy contained in organic matter pass into them. However, the whole of energy is not passed on the higher trophic levels. Energy is dissipated at every step of its transfer. Organic wastes and dead bodies of all organisms are acted upon by decomposers to release biogeochemicals back into abiotic environment.

Question 14.
(a) Fill in A, B, C, D and E
(b) What will happen if step A does not occur ?
(c) What is the role of nitrogen fixing bacteria in the biosphere ?
(d) Name two biologically important compounds that contain both oxygen and nitrogen. (CCE 2011)
Answer:
(a)
A – ammonification.
B – ammonia.
C – nitrites.
D – nitrates.

(b) Absence of Step A. No breakdown of proteins to release ammonia.
(c) Role of Nitrogen Fixing Bacteria. They add a lot of usable form of nitrogen in the soil which become available to plants for synthesis of organic matter.
(d) Nucleic acids (DNA and RNA) and proteins.

Question 15.
(a) What do the blanks 1, 2, 3, 4 and 5 in the given cycle stand for ?
(b) Name two natural and one man-made process by which CO₂ returns to the atmosphere
(c) CO₂ is necessary for plants but it is also a pollutant. Justify your answer.
(CCE 2011)

Answer:
(a)
1. – organic compounds (plants).
2. – Organic compounds (animals)
3. Inorganic carbonates (shells)
4. – carbonates in water.
5. – Limestone,
(b) Natural Processes of Return of CO₂.

1. Respiration,
2. Decay and decomposition. Man-made Process of Return of C02. Combustion

(c) Besides being essential for photosynthesis, carbon dioxide is a green house gas. Upto 350 ppm, it is both a good raw material as well as essential for keeping the earth warm. However, when its concentration rises (as presently it is 400 ppm), it becomes pollutant because it results in global warming. The latter is quite dangerous because it will melt polar ice, raise the water level of oceans and submerge several coastal areas and islands.

Question 16.
(a) Why step farming is common in hills ?
(b) How is acid rain causing harm to ‘Taj Mahal’
(c) Name two leguminous plants which can fix nitrogen. (CCE 2011)
Answer:
(a) Step Farming in Hills. In hills, slope is divided into a number of flat fields. The process is called terracing or step farming. It helps in slowing down the flow of water, increasing water absorption by soil and decreasing soil erosion.
(b) Acid rain contains small quantities of sulphuric acid and nitric acid. They have a corrosive action on marble
(calcium carbonate) forming calcium sulphate and calcium nitrate that peels off. Taj Mahal being made of marble with specific engravings will lose its charm due to acid rain corrosion.
(c) Gram, Pea, Groundnut.

Question 17.
(a) How does energy enter the biosphere ?
(b) In the following biogeochemical cycle, name and define the process marked as (X), (Y) and (Z).
(c) What compounds of nitrogen cause air pollution and how are they released in air ? (CCE 2011)

Answer:
(a) Energy enetering the biosphere comes from sunlight. It is picked up by green plants (with the help of chlorophyll) and changed into chemical energy during photosynthesis when organic matter is built up.
6CO₂ + 6H₂O + Energy  ————> C₆H₁₂O₆ + 6O₂
(b) (X) – Nitrogen Fixation.
(Y) – Ammonification.
(Z) – Denitrification.
(c) Oxides of nitrogen cause air pollution. Most of them are released during combustion of fossil fuels.

Question 18.
(a) The circulation of carbon is important in nature. Give reasons for your answer,
(b) Explain any two processes involved in the cycling of nitrogen in the environment.
(CCE 2011, 2012)
Answer:
(a) Carbon is an essential component of all organic substances. However, its concentration in the atmosphere is very small. Therefore, circulation of carbon is important for the continuation of life on earth. Organic substances are formed from CO₂ during the process of photosynthesis. Organic matter passes from plants to animals, animals to animals and ultimately to decomposers. It is regularly consumed in respiration by all living beings which releases CO₂. CO₂ is also released during decomposition of organic matter.
(b)

1. Nitrogen fixation,
2. Nitrogen assimilation
3. Decomposition involving ammonification and nitrification,
4. Denitrification.

Question 19.
(a) Explain two major processes that maintain CO₂ percentage in the atmosphere,
(b) Draw carbon cycle.
(c) Mention two steps involved in carbon cycle.
(CCE 2011)
Answer:
(a) The two main process that maintain CO₂ percentage in the atmosphere are photosynthesis (withdrawal of CO₂) and respiration (release of CO₂).
(b)

(c) Steps,

1. Photosynthesis. It withdraws CO₂ from environment and incorporates carbon into organic food along with energy.
2. Passage. Organic food synthesised by plants becomes available to herbivores. From herbivores, it passes to carnivores.
3. Respiration. Organic food not only builds up the body of organisms but also becomes substrate for respiration wherein it releases CO₂ back into environment.
4. Combustion. It is burning of organic matter including fossil fuels. Combustion releases CO₂.
5. Decay and Decomposition. Organic remains are acted upon by decomposers. The process releases CO₂.
6. Long Term Withdrawal and Return. Seepage of CO₂ rich water forms carbonate rocks like limestone. Carbonate also gets incorporated inside shells and skeleton of animals.
   Large scale burying of organic life inside earth produces fossil fuels. Weathering of carbonate rocks and burning of fossil fuel release locked CO₂ back to environment.

Question 20.
(a) Name any four carbon containing molecules which are essential to life forms.
(b) Mention the three processes in which oxygen is used up from the atmosphere and the only process in which it is returned to the atmosphere. (CCE 2011, 2012)
Answer:
(a) Proteins, Fats, Carbohydrates, Nucleic acids (DNA, RNA).
(b) Use Up of Oxygen. Respiration, Combustion, Atmospheric fixation of nitrogen, Return of oxygen. Photosynthesis.

Question 21.
Explain nitrogen cycle with the help of labelled diagram.
Name four processes which occur during nitrogen cycle.
(CCE 2012)
Answer:

Nitrogen occurs as inert gas (N₂) in atmosphere (78% of total). A part of it is converted into useful compounds of nitrogen by atmospheric fixation, biological fixation and industrial fixation. The same are absorbed by plants and assimilated to form protoplasmic substances. Animals obtain the same from plants. Organic remains are acted upon by decomposers to release ammonia from which nitrite and nitrate are formed through activity of other groups of microbes. The same are picked up by plants again. A part of nitrate present in water-logged soils is changed to gaseous nitrogen by denitrifying bacteria.
Processes:

1. Nitrogen fixation.
2. Nitrogen assimilation.
3. Decomposition.
4. Denitrification.

Question 22.
(a) Name the gas which is used in the process of photosynthesis.
(b) Complete the cycle (as given in question 15) and explain. (CCE 2012)
Answer:
(a) CO₂.
(b)
1 – organic compounds (plants).
2 – Organic compounds (animals)
3- Inorganic carbonates (shells)
4 – carbonates in water.
5 – Limestone,
CO₂ present in atmosphere is picked up by photoautotrophs in their photosynthesis.
They form organic substances. Animals obtain the same from plants. Respiration of living beings and decomposition of organic matter return CO₂ back to atmosphere. A part of carbon passes , into earth as carbonate forming limestone.
Some animals also form shells from their carbonaceous materials. Both the processes take out a part of CO₂ from the cyclic pool.

Question 23.
(a) Draw a schematic diagram of nitrogen cycle in nature.
(b) Explain how the nitrogen molecules are converted into nitrates and nitrites by

1. Biological process,
2. Physical process.
   (CCE 2012, 2014)

Answer:
(a)

(b)

1. Biological Process. N₂ is fixed biologically by some free living (e.g, Azotobacter) and symbiotic (e.g., Rhizobium) prokaryotes to produce ammonia which is immediately fixed into amino acids from which proteins, nucleotides and other compounds are formed. After death of the organism, the proteins are decomposed to release ammonia (ammonification). Ammonia is oxidised to nitrite {e.g., Nitrosococcus) and then nitrate (e.g., Nitrobacter) in the process of nitrification.
2. Physical Process. Ligthing, electric storm and high energy ultra-violet rays help combine small quantity of nitrogen with oxygen to form nitrogen oxides. The latter dissolve in rain water to produce nitrite and nitrate.

Question 24.
(a) Write any two uses of carbon dioxide gas.
(b) List the importance of oxygen gas and ozone gas present in the atmosphere.
(c) How atmosphere of earth differ from that of Mars and Venus ?
(d) Mention the percentage of earth covered by H₂O.
(CCE 2012)
Answer:
(a) Uses of CO₂.

1. It is raw material for photosynthesis.
2. Being a major green house gas, it keeps the earth comfortably warm for living beings.

(b)

1. Importance of Oxygen. It is essential for respiration and combustion.
2. Importance of Ozone. Ozone is harmful in trophosphere where it is unstable. It is useful in stratosphere where it forms a shield to protect the earth against very harmful high energy UV radiations.

(c)

		Atmosphere over Earth	Atmosphere over Venus and Mars
1.	Nitrogen and Oxygen.	It contains nitrogen and oxygen.	The two are absent
2.	Carbon Dioxide.	Carbon dioxide content is little (0-03%).	Carbon dioxide is the major component of atmosphere forming 95-97%.
3.	Water Vapours.	The atmosphere contains water vapours which form a component of water cycle.	The atmosphere does not contain water vapours. Living beings, being absent, have no role in
4.	living Beings.	Composition of atmosphere is maintained by living beings.	determining composition of atmosphere.

(d) 75%.

Question 25.
(a) Increased loading of nutrients in the water body results in algal bloom. How is it harmful to aquatic life ?
(b) What is acid rain ? Name the two gases which causes acid rain.
(c) List any two harmful effects of air pollution.
(CCE 2012)
Answer:
(a) Increased loading of nutrients in the water body results in eutrophication stimulating the growth of photoautorophic organisms, especially algae. The algae grow in such abundance as to cover the whole water surface. The phenomenon is called algal bloom. It shades the submerged plants which die. Decomposers become active but pick up most of the oxygen dissolved in water. Depletion of oxygen kills the animals, further increasing organic loading. Ultimately, anaerobic breakdown of organic matter begins which produces sulphides that form scum and sludge in the water body. Blue-green algae often invade such waters and release toxins.
(b) Acid rain is rainfall having a pH of less than 5. It is caused by dissolution of two gases, SO₂ and nitrogen oxides, in rain water.
(c) Harmful Effects of Air Pollution,

1. Suspended particulate matter or SPM causes asthma, bronchitis and allergic cold.
2. Pollutant gases cause irritation in eyes, throat and lungs, damage liver, kidneys, spleen and nervous system.
3. Hydrocarbons and some gases cause cancer.

Question 26.
(a) Name any four cycles in nature that form part of biogeochemical cycling.
(b) Name any four sources of fresh water.
(c) How does energy enter biosphere ?
(d) Name one natural and one man made process by which carbon dioxide returns to atmosphere.
Answer:
(a) Water cycle, nitrogen cycle, carbon cycle, oxygen cycle.
(b) Sources of Fresh Water,

1. GroundWater: It is brought to the surface through water pumps, dug wells, tube- wells, etc.
2. Water Reservoirs: They store run off and rain water.
3. Rain: It brings fresh water every where that can be stored.
4. Rivers: They develop through melting of snow and formation of springs in the catchment areas. Rivers supply fresh water all through their passage to sea.

(c) Energy enters the biosphere through trapping of solar energy by photcautotrophs during the process of photosynthesis.
(d)

1. Natural Process Respiration
2. Man-Made Process. Combustion.

Question 27.
(a) How is gaseous nitrogen fixed by the plants ?
(b) Mention one difference between nitrogen fixation and nitrification.
(c) Mention the percentage of oxygen content in the atmosphere.
(d) Name three combined forms of oxygen in which it is found. (CCE 2012)
Answer:
(a) Plants can fix gaseous nitrogen only with the help of certain bacteria and blue-green algae, e.g, Rhizobium inside root nodules of legumes.
(b) Nitrogen fixation is conversion of inert gaseous nitrogen into biologically usable salts of nitrogen (e.g., nitrite, nitrate, ammonia) by physical and biological methods. Nitrification is conversion of ammonia (released during decomposition of proteins) into nitrates with the help of certain bacteria (e.g., Nitrosococcus, Nitrobacter).
(c) 21%
(d) Carbon dioxide, sulphur dioxide, nitrogen oxides.

Question 28.
(a) Explain the biological and physical methods of nitrogen fixation.
(b) (i) Complete the nitrogen cycle by labelling ‘X’ and ‘Y in the biogeochemical cycle shown.
(ii) Explain the part marked ‘X’. (CCE 2012)

Answer:
(a) Nitrogen Fixation: It is conversion of inert gaseous nitrogen into usable form.

1. Biological Nitrogen Fixation: It is carried out by free living (e.g., Azotobacter) and symbiotic (e.g., Rhizobium) bacteria. They pick up free nitrogen gas from soil air and convert it into ammonia state. The latter is used to change organic acids into amino acids.
2. Physical Nitrogen Fixation: (Atmospheric Nitrogen Fixation). In the presence of lightning, electric storm and high energy UV rays, small amounts of nitrogen and oxygen combine to form nitrogen oxides. They dissolve in rain water and pass down to earth as nitrites and nitrates.

(b) Y-Ammonification.
X-Denitrification
(ii) Denitrification: Some bacteria present in water-logged soils take oxygen from nitrates for their activity. This changes nitrates into gaseous nitrogen.

Question 29.
(a) Observe the diagram. When the incense stick is kept near the edge of the mouth of beaker, in which direction will the smoke flow ? Give reason.
(b) What role does the sun play in formation of soil ?
(CCE 2012)

Answer:
(a) The incense will flow towards the flame because it is creating an area of low air pressure due to hot air rising upwards.
(b) Soil is formed through two processes of weathering and humification.
Weathering
It is pulverisation of rocks or breaking of rocks into fine particles. There are three types of weathering — physical (atmospheric changes and mechanical forces), chemical and biological. Sun, water, wind and living organisms perform them.

1. Sun: It causes expansion of rocks by heating. Cooling causes their contraction. Different parts of rocks expand and contract at different rates. Uneven expansion and contraction produces cracks leading to fragmentation of rocks.
2. Water:
   1. Wetting and Drying: Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks.
   2. Frost Action: Water seeping in cracks would swell up and exert a great pressure if it freezes due to low temperature. The rock would undergo fragmentation.
   3. Abrasion: Running water carrying rock fragments would break and grind rocks occurring in the pathway. Rain and hail also cause rock breaking.
3. Wind: Dust and fine sand carried by wind cause abrasion of the rock surface when wind strikes the same.
4. Living Organisms: Lichens secrete chemicals to dissolve minerals from the rock surface. This produces crevices where dust collects. Mosses grow there. They cause deepening of crevices and development of small cracks. Roots of short lived plants widen these cracks. Roots of larger plants cause fragmentation of rocks by entering the cracks and growing in size.

Humification
Partially decomposed organic matter or humus mixes with weathered rock particles to form soil. Humus helps in formation of soil crumbs which are essential for maintaining proper hydration and aeration of soil.

Question 30.
(a) Complete the given oxygen cycle.
(b) State four forms in which oxygen is found in the earth’s crust.
(c) Give an example where oxygen does not support life activities. (CCE 2012)

Answer:
(a) Organic molecules, Respiration, Photosynthesis.
(b) Carbonate, sulphate, nitrate, metal and silicon oxides.
(c) Anaerobic organisms and deep water forms, e.g, Clostridium botulinum.

Question 31.
“Urbanisation and industrialisation are mainly responsible for increase in environment pollution”. Justify this statement and suggest ways and means to check it. (CCE 2012)
Answer:
Urbanisation and industrialisation generate a lot of pollutants:

1. Sewage: A lot of sewage is generated in urban areas. It contains organic matter and several pathogens.
2. Industrial Effluents: They are produced by most industries like dyeing units, electroplating units, paper mills, leather processing units, sugar mills, chemical industries, etc. Like sewage , the industrial effluents are disposed off by passing into a water body.
3. Fossil Fuels: Homes, industries, automobiles and thermal plants are burning fossil fuels that produce SPM, pullutant gases and hydrocarbon vapours.
4. Processing Industries: They generate pollutant particulate matter like cotton dust, coal dust, iron dust, asbestos, etc.
5. Garbage and Trash: They are wastes of residential and commercial areas.

Control

1. Sewage Treatment: It removes most of the organic matter and kills the pathogens.
2. Effluent Treatment: It removes toxic chemicals.
3. Garbage: It can be used to produce manure or generate biogas and manure.
4. Trash: It is partly recycled and partly dumped in land fills.
5. Electrostatic Precipitators: They remove suspended particles.
6. CNG: Use of CNG in vehicles reduces air pollution by automobiles.

Question 32.
(a) Define air pollution. What are the visible indications of air pollution ?
(b) Define acid rain,
(c) Mention any two adverse effects of acid rain. (CCE 2013)
Answer:
(a) Air Pollution: It is addition of particulate matter, gases and vapours into the air that have an adverse effect on humans, animals, vegetation and human assets.
Visible Indications of Air Pollution,

1. Occurrence of suspended particulate matter (SPM).
2. Common occurrence of asthma, bronchitis and allergic cold in the residents,
3. Irritation in eyes, throat and lungs.
4. Occurrence of smog during winter causing suffocation and uneasiness.

(b) Acid Rain: Sources of Fresh Water,

1. GroundWater. It is brought to the surface through water pumps, dug wells, tube- wells, etc.
2. Water Reservoirs. They store run off and rain water.
3. Rain. It brings fresh water every where that can be stored.
4. Rivers. They develop through melting of snow and formation of springs in the catchment areas. Rivers supply fresh water all through their passage to sea.

(c) Adverse Effects of Acid Rain:

1. Corrosion and pitting of marble and limestone structures,
2. Killing of vegetation and aquatic life.

Question 33.
(a) Give a schematic representation of oxygen cycle in nature,
(b) State the importance of oxygen cycle in nature.

Or

Explain in how many ways O₂ is used up from the atmosphere and how it returns back to the atmosphere.
(CCE 2013, 2014)
Answer:
(a)

(b) Importance,

1. It keeps the oxygen concentration of the atmosphere nearly constant,
2. It makes regular supply of oxygen to all organisms for respiration, human beings for combustion, microorganisms for decay and atmosphere for fixation of some nitrogen,
3. Oxygen is being regularly added to the atmosphere and aquatic habitats by photosynthetic activity of producers.

Question 34.
(a) In which layer of earth is water available ?
(b) Name the abiotic components of the biosphere.
(c) Name the gas which forms 95-97% of the atmosphere on Mars.
(d) At night which one is warmer, air over sea or air over land ?
( Answer:
(a) Water. It occurs in hydrosphere part of earth which extends from on, in and above earth.
(b) Abiotic Components of Biosphere. Air, water and soil.
(c) CO₂
(d) Over sea as water cools down slowly as compared to land.
(e) Coal, petroleum.

Question 35.
(a) How is soil formed ?
(b) Name the four main processes that are part of the water cycle in nature,
(c) Name two compounds formed by nitrogen and oxygen in the nitrogen cycle. (CCE 2013)
Answer:
(a) Soil is formed through two processes of weathering and humification.
Weathering
It is pulverisation of rocks or breaking of rocks into fine particles. There are three types of weathering — physical (atmospheric changes and mechanical forces), chemical and biological. Sun, water, wind and living organisms perform them.

1. Sun: It causes expansion of rocks by heating. Cooling causes their contraction. Different parts of rocks expand and contract at different rates. Uneven expansion and contraction produces cracks leading to fragmentation of rocks.
2. Water:
   1. Wetting and Drying: Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks.
   2. Frost Action: Water seeping in cracks would swell up and exert a great pressure if it freezes due to low temperature. The rock would undergo fragmentation.
   3. Abrasion: Running water carrying rock fragments would break and grind rocks occurring in the pathway. Rain and hail also cause rock breaking.
3. Wind: Dust and fine sand carried by wind cause abrasion of the rock surface when wind strikes the same.
4. Living Organisms: Lichens secrete chemicals to dissolve minerals from the rock surface. This produces crevices where dust collects. Mosses grow there. They cause deepening of crevices and development of small cracks. Roots of short lived plants widen these cracks. Roots of larger plants cause fragmentation of rocks by entering the cracks and growing in size.

Humification
Partially decomposed organic matter or humus mixes with weathered rock particles to form soil. Humus helps in formation of soil crumbs which are essential for maintaining proper hydration and aeration of soil.
(b) Water Cycle Processes.

1. Vaporisation
2. Cloud formation
3. Rain
4. Infiltration and run-off.

(c) Nitrogen oxides (e.g., nitrate), proteins.

Question 36.
(a) Write names of two biologically important compounds that contain both oxygen and nitogen.
(b) (i) Give a schematic representation of nitrogen cycle.
(ii) Name the main processes involved in it. (CCE 2013)
Answer:
(a) Nucleic acids, Proteins.
(b) (i)

(ii) Main Processes: Processes Involved in Cycling of N₂ :

1. Nitrogen fixation,
2. Nitrogen assimilation
3. Decomposition
4. Denitrification.

Question 37.
(a) List any two human activities which would lead to an increase in CO₂ content of air.
(b) Draw a schematic diagram of carbon cycle in nature. (CCE 2013)
(a)

1. Increased combustion of fossil fuels
2. Deforestation,

(b)

Question 38.
(a) Expand CFC.
(b) Mention one important function of ozone,
(c) What is green house effect ?
(d) Name one green house gas. (CCE 2013)
Answer:
(a) CFC-Chlorofluorocarbon.
(b) Ozone. Filtering harmful high energy ultraviolet
radiations in the atmosphere,
(c) Green House Effect: Green house effect is keeping an area warm by allowing the solar radiations to pass in but preventing long waves to escape due to presence of radiatively active gases and glass panes.
(d) Green House Gas. Carbon dioxide.

Question 39.
(a) What is soil pollution ?
(b) What are the various factors that decide which plants will thrive on a particular kind of soil.
(c) Explain any two factors that cause soil erosion.
(CCE 2013)
Answer:
(a) Soil Pollution: It is adverse alteradon in the soil caused by removal or addition of substances which reduce its fertility and quality.
(b) Soil Factors Controlling Plants Thriving Over It.
Top soil is the upper mineral and humus rich layer of soil that supports vegetation.
Factors:

1. Depth of top soil,
2. Nutrient and humus content of soil,
3. Soil particles,
4. Soil pH.

(c) Soil Erosion,

1. Absence of vegetation cover,
2. Heavy rain, fast run off or strong wind.

Question 40.
(a) What percentage of elemental oxygen is found in earth’s atmosphere and by which process oxygen is returned back to atmosphere.
(b) Represent oxygen cycle that is operating in nature diagrammatically. (CCE 2013)
Answer:
(a)

1. 21%
2. Photosynthesis.

(b)

Question 41.
What is biogeochemical cycle ? Draw flow chart of nitrogen cycle in nature. (CCE 2013)
Answer:
Biogeochemical Cycle: The repeated circulation of biogeochemicals or biogenetic nutrients between abiotic and biotic components of the environment is called biogeochemical cycling, e.g., CO₂ cycle, N₂ cycle, Water cycle, O₂ cycle.
Nitrogen Cycle.

Question 42.
(a) With the help of a neat labelled, diagram, depict the cycling of carbon in nature.
(b) Mention two ways in which carbon dioxide is fixed in nature. (CCE 2013)
Answer:
(a)

(b)

1. Photosynthesis by photoautotrophs
2. Animals for building their endoskeleton and shells.

Question 43.
What is meant by air pollution ? Explain any three human activities that cause air pollution. Mention any two harmful effects of air pollution. (C. C.E. 2014)
Answer:
Definition: Air pollution is addition of particulate matter, gases and vapours into the atmosphere that have an adverse effect on humans, animals, vegetation and human assets.
List any three human activities that you think would lead to air pollution.

1. Burning of fossil fuels in industries, vehicles and thermal plants.
2. Processing industries like textiles, asbestos, flour
3. Stone crushing.

Harmful Effects: 
Effect on Animal Life: Respiratory disorders, allergies, eye and throat irritation, haemorrhages, frequent diarrhoea, reduced appetite and weakening of bones.
Effect on Plant Life: Chlorosis, necrosis, water soaked areas, defoliation and die back.

Question 44.
(a) Why is the atmosphere essential for life ?
(b) Explain how does atmosphere act as a blanket.
(C.C.E. 2014)
Answer:
(a)

1. Oxygen: Atmosphere contains oxygen which is essential for combustion and respiration of most organisms.
2. Carbon Dioxide: Atmosphere provides carbon dioxide for photosynthesis of plants.
3. Protection: Atmosphere filters out lethal cosmic rays and high energy ultraviolet rays.
4. Temperature Buffer: Atmosphere does not allow daytime temperature to rise abnormally nor does it allow night time temperature to fall down drastically. This provides favourable temperature for the living organisms.
5. Other Functions: Air currents help in dispersal of spores and other dissemules. Water cycle operates through atmosphere and produces rain to replenish fresh water over land.

(b) Atmosphere or air is a bad conductor of heat. It, therefore, functions as a blanket.

1. It does not allow sudden increase in temperature during the daylight hours when sun shines overhead.
2. There is no sudden cooling during night. Atmosphere slows down the escape of heat to the outer space from the area of earth under darkness.
3. Atmosphere maintains the average temperature of the earth fairly steady not only during the day but throughout the year.

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 14 Natural Resources 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 12 Sound Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Sound Class 9 Important Questions and Answers Science Chapter 12

VERY SHORT ANSWER QUESTIONS

Based on waves and sound

Question 1.
What is sound ?
Answer:
Sound is a form of energy which produces the sensation of hearing in our ears.

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.
What does wave transfer ?
Answer:
Wave transfers energy.

Question 3.
What is a mechanical wave ?
Answer:
A waves that are characterised by the motion of particles of a medium are called mechanical waves. These waves require material medium for their propagation.

Question 4.
What is a transverse wave ? (CBSE 2011)
Answer:
If the particles of the medium vibrate about their mean positions at right angles to the direction of propagation of the disturbance, then the wave is called transverse wave. Light is a transverse wave.

Question 5.
Differentiate between crest and trough. (CBSE 2013)
Answer:
The highest point on the elevation of the medium through which transverse wave travels is called crest.
The lowest point on the depression of the medium through which transverse wave travels is called trough.

Question 6.
What is a longitudinal wave ? (CBSE 2011)
Answer:
If the particles of a medium vibrate or oscillate to and fro about their mean positions along the direction of propagation of the disturbance, then the wave is called longitudinal wave. Sound wave is a longitudinal wave.

Question 7.
Name a wave which does not require a material medium for its propagation. (CBSE 2012)
Answer:
Electromagnetic wave.

Question 8.
What do you understand by the terms “compression” and “rarefaction” ? (CBSE 2012)
Answer:
A region of high pressure of a medium when sound wave travels through it is called compression. A region of low pressure of a medium when sound wave travels through it is called rarefaction.

Question 9.
What happens to the medium through which sound travels ?
Answer:
A medium is divided into the regions of high pressure or high density and regions of low pressure or low density called compressions and rarefactions respectively.

Question 10.
Define time period. (CBSE 2011, 2013, 2017)
Answer:
Time Taken by two consecutive compressions or rarefactions to cross a fixed point is called time period.

Question 11.
State SI unit of time period.
Answer:
second(s)

Question 12.
What do you understand by the frequency of a sound wave ? (CBSE 2011)
Answer:
The number of compressions or rarefactions crossing a point in one second is called the frequency of a sound wave.

Question 13.
State SI unit of frequency compressions or rarefactions crossing a point, hertz (Hz).
Answer:

Question 14.
Write relation between time period (T) and frequency (v).
Answer:

Question 15.
What do you understand by the wavelength of a sound wave ? (CBSE 2015, 2017)
Answer:
Distance between two successive compressions or successive rarefactions is called wavelength of a sound wave.

Question 16.
State SI unit of wavelength. (CBSE 2012)
Answer:
metre (m).

Question 17.
State the meaning of the term “amplitude with reference to a wave. Mention its SI unit. (CBSE 2013)
Answer:
Maximum displacement of a particle of the medium from its mean position when wave travels through the medium. It SI unit is metre.

Question 18.
What type of wave is represented by density-distance graph ? (CBSE 2011)
Answer:
Longitudinal wave.

Question 19.
Name the physical quantity whose unit is ‘hertz’. (CBSE 2015)
Answer:
Frequency.

Question 20.
What do you understand by the pitch of a sound ? (CBSE 2012)
Answer:
Pitch of a sound is the characteristic of sound that depends on the frequency received by a human ear.

Question 21.
Name the physical quantity which determines the pitch of a sound.
Answer:
Frequency of a sound wave.

Question 22.
Write factor on which pitch of a sound depends ? (CBSE 2011, 2012)
Answer:
Pitch of a sound depends on the frequency of the wave.

Question 23.
What do you understand by the loudness of a sound ? (CBSE 2012)
Answer:
Amplitude of the vibrating body determines the loudness of the sound. Large is the amplitude of vibration, large is the loudness of the sound produced.

Question 24.
What do you mean by the intensity of sound ? (CBSE 2011)
Answer:
Sound energy per unit time per unit area is known as the intensity of sound.

Question 25.
Write the S.I. unit of intensity of sound.
Answer:
Js^-1 m² or Wm^-2.

Question 26.
Out of which of the following media, the speed of sound is maximum : solid, liquid, gas.
Answer:
The speed of sound is maximum in solid medium.

Question 27.
Draw diagram to represent sound of high pitch and (b) low pitch, of the same loudness. (CBSE 2011, 2012)
Answer:

Question 28.
Name the physical quantity which determines the loudness of a sound.
Answer:
Amplitude of the vibrating body.

Question 29.
Define the characteristic “timbre” or “quality” of a sound. (CBSE 2012, 2015)
Answer:
Quality or timbre is a characteristic of a sound which enables us to distinguish between two sounds of some loudness and pitch.

Question 30.
Speed of sound is more on hotter day. Explain. Why ? (CBSE 2013)
Answer:
Speed of sound increases with increase in temperature.

Based on Reflection of sound

Question 31.
What is an echo ? (CBSE Sample Paper 2010, 2011, 2012, 2015)
Answer:
Echo is a repetition of sound due to the reflection of original sound by a large and hard obstacle.

Question 32.
What should be the minimum distance between the source of sound and the obstacle to hear an echo ?
(CBSE 2011)
Answer:
17 metres.

Question 33.
Give one application where principle of echo is utilised. (CBSE 2011)
Answer:
Hearing aid.

Question 34.
Give example of multiple echoes. (CBSE 2014)
Answer:

1. Rolling of thunder,
2. Whispering galleries.

Question 35.
What do you understand by the reverberation ? (CBSE 2011, 2012, 2013)
Answer:
The penomenon of prolongation of original sound due to the multiple reflection of sound waves even after the source of sound stops producing sound is called reberberation.

Question 36.
What is reverberation time ?
Answer:
The time interval during which original sound appears to prolong.

Question 37.
What are infrasonic waves ? (CBSE 2012, 2013)
Answer:
The waves of frequency less than 20 Hz are called infrasonic waves.

Question 38.
What are ultrasonic waves ?  (CBSE 2012, 2013)

                             Or

What is ultrasound ? (CBSE 2012, 2015, 2017)
Answer:
The waves of frequency greater than 20,000 Hz are called ultrasonic waves or ultra sound.

Question 39.
What type of waves are produced by bats ?
Answer:
Ultrasonic waves.

Question 40.
State one important use of ultra sounds in industries.
Answer:
Ultra sounds are used to find faults and cracks in metals.

Question 41.
State two important uses of ultrasounds for medical purpose. (CBSE 2011, 2012, 2013, 2014)
Answer:

1. Diagnosing the diseases in human body
2. To analyse the development of an unborn child.

Question 42.
If 20 waves are produced per second, what is the frequency in Hertz ? {CBSE 2011)
Answer:
Frequency = 20 Hz.

Question 43.
What is echocardiography ? {CBSE 2012)
Answer:
It is the technique to construct the image of heart using ultrasonic waves.

Question 44.
Echoes can’t be heard in a small room. Explain. (CBSE 2013)
Answer:
The minimum distance between source of sound and the obstacle! to hear an echo should be 17m.

Question 45.
Therefore, echoes can’t be heard in a small room.

                                    Or

Write the hill form of “SONAR”. (CBSE 2011, 2015)

                                    Or

What is the acronym of SONAR ? (CBSE 2012)
Answer:
SONAR stands for Sound Navigation And Ranging.

Question 46.
What is the basic principle on which SONAR works ? (CBSE 2011, 2016)
Answer:
SONAR works on the principle of reflection of waves (i.e. echo).

Question 47.
Write one application of SONAR. (CBSE 2011, 2012)
Answer:
It is used to measure the depth of a sea.

Question 48.
What is the function of a detector in a SONAR ? (CBSE 2011)
Answer:
It detects the echo received to find the time taken by the wave to reach the SONAR from the bed of sea.

SHORT ANSWER QUESTIONS

Based on waves and sound

Question 1.
Mention the types of mechanical waves. Identify the type which can be produced in solids, liquids and gases. (CBSE 2015)
Answer:
Types of mechanical waves :

1. Transverse wave,
2. Longitudinal wave

Longitudinal wave can be produced in solids, liquids and gases.

Question 2.
Describe an activity to show that sound waves need medium to travel. (CBSE 2011, 2012)
Answer:
Sound Needs a Medium to Travel:
We have learnt that sound travels from one place to another place when the energy is transferred from one particle to another particle of a medium like air or gas, liquid, solid etc. It means, sound needs a material medium for its propagation. In other words, sound cannot travel through vacuum.
Demonstration to show that sound waves cannot travel through vacuum:
Put an electric bell inside a closed glass jar connected with a vacuum pump. Initially, air from the jar is not taken out. Connect the electric bell with a battery (Figure 10). It rings and the sound produced is heard by us.

Now start evacuating the air from a glass jar using a vacuum pump, we will hear less and less sound, i.e. the loudness of the sound decreases. When there is no air in the glass jar, we do not hear sound. This activity demonstrates that sound waves require material medium (in this case air) for its propagation.

Question 3.
Sound cannot travel through vacuum. How will you demonstrate this fact ?
Answer:
Demonstration to show that sound waves cannot travel through vacuum:
Put an electric bell inside a closed glass jar connected with a vacuum pump. Initially, air from the jar is not taken out. Connect the electric bell with a battery (Figure 10). It rings and the sound produced is heard by us.

Now start evacuating the air from a glass jar using a vacuum pump, we will hear less and less sound, i.e. the loudness of the sound decreases. When there is no air in the glass jar, we do not hear sound. This activity demonstrates that sound waves require material medium (in this case air) for its propagation.

Question 4.
Write any three differences between transverse and longitudinal waves. (CBSE 2012, 2013)
Answer:

Transverse Wave	Longitudinal Wave
1. In transverse wave propagation, the particles of the medium vibrate about their mean or equilibrium position at right angles to the direction of the propagation of the wave.	In longitudinal wave, particles of the medium vibrate about their equilibrium position along the direction of the propagation of the wave.
2. When transverse wave travels through a medium, the shape of the medium changes.	When longitudinal wave travels through a medium, medium is divided into the regions of high and low pressures.
3. Traverse wave can travel in solids and on the surface of liquids.	Longitudinal waves can travel in solids, liquids and gases.

 Question 5.
Show that v = λv, where symbols have usual meanings.

                                                 Or

Establish relationship between speed of sound, its wavelength and frequency.
(NCERT Question Bank,CBSE 2012)
Answer:
Let the time period of a vibrating body be T. It means, the vibrating body completes one oscillation in time T. One oscillation of a body is represented by a wave of wavelength λ as shown in figure 15.


Thus, speed of wave= wavelength x frequency
Note : The speed of a mechanical wave (i.e. sound wave) is constant in a given medium. If sound of large frequency is produced by a vibrating body, then the wavelength of this sound wave will be small, so that speed = wavelength x frequency is constant
The speed of a sound wave differs only when the sound wave goes from one medium to another medium.

Question 6.
Sounds of same loudness and pitch but produced by different musical instruments like a violin and flute are distinguishable. Explain, why ? (CBSE 2012)

                                                                      Or

In an orchestra, violin and flute are played at the same time but still these are distinctly recognizable. Name the characteristic that makes it possible. (CBSE 2012)

                                                                      Or

Name the characteristic of sound that helps us to distinguish a note played on a sitar and a violin.
(CBSE 2012)
Answer:
This is due to the quality or timbre of sound waves.

Question 7.
A vibrating body produces sound. However, no sound is heard when a simple pendulum oscillates in air.
Explain the reason. (NCERT Question Bank)
Answer:
Sound is heard only if the body vibrates with a frequency more than 20 Hz and less than 20,000 Hz. The pendulum oscillates or vibrates with a frequency less than 20 Hz. Hence, no sound is heard when the pendulum vibrates or oscillates in air.

Question 8.
A boy strikes one end of a long iron pipe with a stone. Another boy who keeps his ear close to the other end of the pipe heard two sounds in a short interval of time. Explain, why? (CBSE 2011)
Answer:
When a boy strikes an iron pipe, sound is produced. The sound waves travel through air and the pipe. Since speed of sound in iron is greater than the speed of sound in air, so the sound travels faster through iron pipe than air. Hence, another boy hears two sounds, one travelling through iron pipe and the other travelling through the air.

Question 9.
Sound travels faster in summer season than in winter season. Explain, why ?
Answer:
This is because, speed of sound increases with increase in temperature.

Question 10.
Why is the speed of sound greater in solids than in gases ?
Answer:
This is because particle of solids are closer than the particles of gases.

Question 11.
Draw a graph for a wave representing wave distrubance and time for a sound changing from low pitch to
high pitch, keeping amplitude of the sound same. (CBSE Sample Paper; 2011)
Answer:

Question 12.
Waves of frequency 100 Hz are produced in a string as shown in figure. Give its :
(a) amplitude,
(b) wavelength
(c) velocity
(CBSE 2011, Similar CBSE 2014, 2015)

Answer:
Here, v = 100 Hz
(a) Amplitude = 5 cm
(b) Wavelength = distance between two successive crests or troughs = 20 cm.
(c) Velocity, u = vλ = 100 Hz x 0.2 m = 20 m s^-1

Question 13.
State the factors on which speed of sound depends. (CBSE 2011, 2012)
Answer:
Speed of sound depends on :

1. nature of medium and
2. temperature of the medium.

Speed of sound in solids is greater than in liquids and speed of sound in liquids in greater than in gases. Speed of sound increases with the increase in temperature of the medium and it decreases with the decrease in temperature of the medium.

Question 14.
The sound of an explosion on the surface of a lake is heard by a boatman 100m away and a diver 100m
below the point of explosion. Of the two presons mentioned (boatman or diver) who would hear the sound first ? And why ? {CBSE 2011, 2015)
Answer:
Since velocity of sound in water is more than the velocity of the sound in air, so the diver in the water will hear the sound of explosion earlier than the boatman.

Based on Reflection of sound

Question 15.
State two conditions for echo to be heard. (CBSE Sample Paper 2010, 2011, 2012, 2015)
Answer:
Echo can be heard if

1. the minimum distance between the source of sound and the obstacle is 17 m.
2. the obstacle is rigid and hard.

Question 16.
The reverberation time of a hall used for speeches should be very short. Explain why?
Answer:
If the reverberation time of a hall is long, then the multiple echoes will interfere with the original sound. Hence nothing will be heard distinctly. For this reason, the reverberation time of the hall should be very short.

Question 17.
Explain, how can you demonstrate the reflection of sound.
Answer:
When a sound wave travelling in a medium bounces back to the same medium after striking the second medium (which is solid), reflection of sound wave is said to take place. The reflection of sound wave is similar to the bouncing back of a rubber ball after striking a wall or the surface of a floor.
Just like light, sound is reflected by the solid and liquid surfaces. The reflection of sound obeys the laws of reflection. The laws of reflection of sound are as follows :

1. Incident angle = Reflected angle and
2. The incident direction of sound, reflected direction of sound and the normal to the point of incidence all lie in the same plane.

Question 18.
Describe multiple echoes. Write any two of their important applications. (CBSE 2011)
Answer:
When a sound wave is reflected many times by an obstacle, multiple echoes are heard. Multiple echoes are heard in whispering galleries.

Question 19.
State the laws of reflection of sound. (CBSE 2011)
Answer:

1. Incident angle = reflected angle of sound wave
2. Incident direction of sound, reflected direction of sound and the normal to the point of incidence all lie in the same plane.

Question 20.
Why we cannot hear an echo in a small room ? (CBSE 2011, 2012)
Answer:
To hear an echo, the minimum distance between the source of sound and the obstacle reflecting sound
waves must be 17m. However, the size of the room (i.e. the distance between two opposite walls) is less than 17m. Hence, we cannot hear an echo in a small room.

Question 21.
Mention one advantage and one disadvantage of reverberation. (CBSE 2013)
Answer:
A certain amount of reverberation improves the quality of sound of orchestral and choral music. However,
excessive reverberation makes the speech or music indistinct.

Question 22.
Draw a diagram showing laws of reflection followed by sound waves and label the following :
Incident wave, Reflected wave, Angle of incidence and Angle of reflection. (CBSE 2013)
Answer:

Based on ultra sound, sonar and human ear

Question 23.
Explain how ultra sound is used to clean spiral tubes and electronic components ? (CBSE 2011, 2014)
Answer:
The spiral tubes are dipped in a liquid. The ultrasonic waves are passed through this liquid. These waves force the dirt or any other impurity out from the spiral tube and hence the tube is cleaned.

Question 24.
Waves of special frequencies are used for cleaning hard to reach places.
(a) Name the waves
(b) What is the frequency of these waves ?
(c) Explain how do these waves perform this work. (CBSE 2015)
Answer:
(a) Ultrasonic waves
(b) Frequency of ultrasonic waves is greater than 20,000 Hz and less than or equal to 10⁷ HZ.
(c) The spiral tubes are dipped in a liquid. The ultrasonic waves are passed through this liquid. These waves force the dirt or any other impurity out from the spiral tube and hence the tube is cleaned.

Question 25.
Give three medical uses of ultrasound. (CBSE 2014)
Answer:

1. Diagnosing diseases in human body,
2. To study the development of an unborn baby
3. In echocardiography.

Question 26.
Why do we hear sound produced by the humming bees while the sound of vibrations of pendulum is not heard ? (CBSE 2011, 2013, 2015, 2016)
Answer:
Humming bees produces waves of frequency greater than 20 Hz, which are audible to us. On the other hand, frequency of vibration of pendulum is less than 20 Hz, which is not audible to us.

Question 27.
List three points which an engineer should use while designing an auditorium. (CBSE 2013)
Answer:

1. Reverberation time should be small (or short).
2. The ceiling of the auditorium should be curved.
3. The ceiling of the auditorium should be made up of sound absorbing material.

Question 28.
A man fires a rifle in front of a cliff and hears the echo after 3 seconds. Calculate the distant of man from the cliff if velocity of sound in air is 340 m/s. (CBSE 2013)
Answer:
Time taken by sound to travel a distance between man and cliff, t = 3/2 = 1.5 s.
∴ Distance of man from the cliff, S = vt = 340 x 1.5 = 510 m.

Question 29.
A detector installed on a ship receives an ultrasonic signal sent to underwater object after v seconds of its transmission. If the speed of sound in water is ‘v’ what is the depth of object. (CBSE 2015)
Answer:
Time taken by the signal to reach detector from the depth of object = t/2.
Speed of signal in water = v
∴ Depth of the object = vt/2.

Question 30.
What is ultra sound ? Explain how defects in a metal block can be detected using ultra sound.
(CBSE 2011, 2012)
Answer:
The waves of frequency range greater than 20,000 Hz and equal to 10⁷ Hz are known as ultrasound.
A beam of ultrasound is thrown on the metal block under investigation. The picture of the metal block produced by the reflected ultrasound is taken on the screen or the monitor of the computer. The position of the crack or fault in the metal block can be detected by analysing the picture.

Question 31.
How is the pressure variation in a sound wave amplified in human ear ? (CBSE 2011)

                                                                 Or

How does the ear drum of human ear vibrate ? (CBSE 2012)
Answer:
The sound wave in the form of high pressure (compressions) and low pressure (rarefactions) reach the ear drum. When sound waves fall on ear drum, it begins to vibrate. The vibrations produced by the ear drum are amplifed by the three ossicles (i.e. hammer, anvil and the stirrup) in the middle of the ear.

LONG ANSWER QUESTIONS

Question 1.
Describe with the help of a diagram, how compressions and rarefactions are produced in air near a source of sound.
Answer:
When a body vibrates, then the particles of the medium (say air) around the vibrating body are set into vibrations. The particles of the medium which are very close to the vibrating body are pushed away from the body. These particles of the medium strike against the neighbouring particles. Hence the number of particles of the medium in the region where the displaced particles strike against the neighbouring particles is large. This region is known as  compression (C).
Since pressure is directly proportional to the number of particles, so the compression is a region of high pressure or high density. When the vibrating body moves backward, a region of emptiness known as rarefaction (R) or a region of low pressure or low density is created. The displaced particles of the medium rebound into the region of low pressure or rarefaction. At the same time, compression is followed outwards.
Therefore, when a body vibrates to produce sound, compressions and rarefactions follow one another as the sound travel through the medium away from the vibrating body. Thus, propagation of sound can be visualised as the propagation of pressure variations or density variations in the medium.
Figure 9 represents the regions of compressions (or high pressures) and rarefactions (or low pressures) as the sound propagates in the medium.

Question 2.
What is reflection of sound ? State laws of reflection of sound.
Answer:

When a sound wave travelling in a medium bounces back to the same medium after striking the second medium (which is solid), reflection of sound wave is said to take place. The reflection of sound wave is similar to the bouncing back of a rubber ball after striking a wall or the surface of a floor.
Just like light, sound is reflected by the solid and liquid surfaces. The reflection of sound obeys the laws of reflection. The laws of reflection of sound are as follows :

1. Incident angle = Reflected angle and
2. The incident direction of sound, reflected direction of sound and the normal to the point of incidence all lie in the same plane.

Question 3.
Give five practical applications of reflection of sound.
Answer:

1. Megaphone is a device used to address public meetings. It is a horn-shaped. When we speak through megaphone, sound waves .are reflected by the megaphone. These reflected sound waves are directed towards the people (or audience) without much spreading (Figure 20).
   
2. Hearing Aid: Hearing aid is used by a person who is hard of hearing. It is an electronic device which is designed to amplify sound for the wearer to make the speech understandable. The microphone of hearing aid converts sound into electrical signals. These signals are amplified by the amplifier and then fed to the speaker. The speaker converts electrical signal to sound and then feed it into the ear as a narrow beam of sound waves. This narrow beam of sound waves fall on the diaphragm of the ear. Hence, the diaphragm of the ear vibrates with large amplitude. Therefore, the hearing power of the person is improved.
3. Sound waves from the speaker are reflected by the sound board and these reflected waves are directed towards the people (or audience).
   Sound boards. Sound boards are curved surfaces (concave) which are used in a big hall to direct the sound waves towards the people sitting in a hall. The speaker is (i.e. source of sound) placed at the focus of the sound board as shown in figure 21.
   
4. Stethoscope: Stethoscope is a device used by doctors to listen the sound produced by heart and lungs. The sound produced by heart beat and lungs of a patient reaches the ears of a doctor due to multiple reflection of sound (Figure 22).
   
5. Ceilings of concert halls are curved. The ceilings of concert halls and auditoriums are made curved. This is done so that the sound reaches all the parts of the hall after reflecting from the ceiling of the hall as shown in figure 23.
   
   Moreover, these ceilings are made up of sound absorbing materials to reduce the reverberation.

Question 4.
Give five practical applications of ultrasonic waves. (CBSE 2011)

                                               Or

Explain the technique of ultrasonography. (CBSE 2016)
Answer:
Ultrasonic waves have number of uses :

1. For Communication
   1. Ultrasonic waves are used to establish underwater communication.
   2. Ultrasonic waves are used to determine the depth of a sea. It is done with the help of a SONAR.
2. Industrial uses
   1. Ultrasonic waves are used for cleaning the hidden parts of an instrument. The process is known as ultrasonic cleaning. The instrument or device whose hidden parts are to be cleaned is dipped in a liquid. The ultrasonic waves are passed through this liquid. These waves forces the dirt or any other impurity out from the parts of the instrument which otherwise cannot be approached directly.
   2. Ultrasonic waves are used for welding plastic. Two plastic surfaces are pressed against each other. Then ultrasonic waves are allowed to fall at a point where plastic surfaces are in contact. These waves produces heat energy. This heat energy binds the two plastic surfaces together.
   3. Ultrasonic waves are used to find faults and cracks in metals. Ultrasonic waves are thrown on a metal under investigation. The beam of ultrasonic waves reflected by the metal is investigated. The intensity of the ultrasonic waves reflected from the fault or a crack is different from the intensity of the waves reflected from the other part of metal. Thus, the position of the fault or a crack in the metal can be easily located. In fact, the picture of the metal produced by the reflection of ultrasonic waves is taken on the screen or the monitor. By analysing this picture, the position and size of the crack or fault in the metal is detected.
3. Medical uses
   1. Ultrasonic waves are used for diagnosing the diseases in human body. Different parts of the body like bone, fat, muscles and liquid have different reflective properties. Ultrasonic waves are allowed to fall on the portion of the body of a patient to be diagnosed. These waves are reflected back by the different parts (like bones, tissues, liquids and muscles etc.) of that portion of the body in different manners. The varying echoes are recorded for analysing that part of the body.
      The method used for diagnosing the different part of a human body with the help of the ultrasonic waves is known as ultrasonography.
   2. Ultrasonic waves are used to kill bacteria in liquids. Thus, the liquids like milk can be preserved for a longer period of time.
   3. Ultrasonic waves are also used to study the development of an unborn child. Any abnormality in the growth of an unborn child can be detected by the observing the picture taken by ultrasound.
   4. Echocardiography. It is medical diagnostic technique in which ultrasonic waves are used to construct the image of heart.

Question 5.
Write the full name of SONAR. How will you determine the depth of a sea using echo ranging ?
(CBSE 2011, 2012)

                                              Or

Explain the working of SONAR. (CBSE 2014)
Answer:
SONAR stands for Sound Navigation and Ranging.
It is a device which is used in the ships to locate rocks, icebergs, submarines, old ships sank in sea etc. It is also used to measure the depth of a sea.
Principle: It is based on the principle of the reflection of sound wave (i.e. echo).
Determination of the Depth of a Sea using Sonar
A beam of ultrasonic waves from the transmitter of a SONAR fitted on the ship is sent towards the bottom of the sea (Figure 25).

This beam is reflected back from the bottom of the sea and is received by the receiver or detector of the SONAR on the ship.
The time taken by the ultrasonic waves to go from the ship to the bottom of the sea and then back to the ship is noted. Let it be V seconds. Therefore, the time taken by the ultrasonic waves to go from the ship to the bottom of

The method of finding the distance of object using echo is called echo­ranging. While, the method of finding the depth of the sea using echo is called echo-depth ranging. In this case, SONAR is called fathometer.

Question 6.
Explain by drawing a diagram, how the human ear works.

                                                       Or

Explain how human ear works in the transmission of sound waves to the brain. (CBSE 2011, 2013)

                                                       Or

Draw labelled diagram of auditory part of human ear and explain how the human ear works. (CBSE 2012)
Answer:
The human ear is divided into three parts— the external ear, the middle ear and the inner ear (Figure 26).

We shall discuss only the auditory aspect of the ear and not its detailed structure.
The external ear which we see is known as Pinna. This part collects the sound and sends it to the auditory canal.
The sound in the form of compressions (high pressure) and rarefaction (low pressure) reaches the ear drum or tympanum. When the compressions and rarefactions strike the ear drum, the ear drum begins to vibrate. These vibrations are transmitted across the middle ear by the three ossicles (the hammer, the anvil and the stirrup). The vibrations produced by the eardrum are amplified (i.e., their amplitude is increased) by the hammer, anvil and the stirrup.
The amplified vibrations are then transmitted to the cochlea. Cochlea is a coiled and fluid filled tube having the sense organ of hearing. The movement of the fluid in the cochlea due to the vibrations stimulates the auditory nerve. The impression (in the form of electrical signals) is carried by the auditory nerve to the brain. This impression is interpreted as sound by the brain.

Question 7.
Explain the technique of ultrasonography.
Answer:
Ultrasonics or Ultrasound
The waves of frequency greater than 20,000 Hz are known as ultrosonic waves or ultrasound. The frequency of ultrasonic wave is greater than 20,000 Hz and equal to 10⁷ Hz. These waves are not audible to a human ear but they can be heard by animals and birds.
Bats can produce ultrasonic waves by flapping their wings. They can also detect these waves. The ultrasonic waves produced by the bats after reflection from the obstacles like buildings guide them to remain away from the obstacles during their flights. Hence, they can fly during night without hitting the obstacles. Bats also catch their prey during night with the help of ultrasonic waves. The ultrasonic waves produced by a bat spread out. These waves after reflecting from a prey say an insect reach the bat. Hence, the bat can easily locate its prey (Figure 24).

Dolphins also produce ultrasonic waves. Dolphins can also detect the ultrasonic waves. They catch their prey like a fish due to their ability to detect the ultrasonic waves reaching them after reflecting’ from a fish.

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 12 Sound 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 8 Motion Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Motion Class 9 Important Questions and Answers Science Chapter 8

VERY SHORT ANSWER QUESTIONS

Based on Motion of an object along a straight line

Question 1.
What do you understand by the motion of an object ?
Answer:
An object is said to be in motion if its position change:, with time.

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.
What is a reference point ?
Answer:
A fixed point with respect to which the given object changes its position.

Question 3.
Is it possible that the train in which you are sitting appears to move while it is at rest ?
Answer:
Yes. The train at rest in which we are sitting appears to move when we look at another train moving parallel to the track on which our train is standing.

Question 4.
Define the term “distance”. –
Answer:
The length of actual path travelled by an object in the given time is called the distance travelled by the object.

Question 5.
Is distance a scalar or a vector quantity ?
Answer:
Distance is a scalar quantity’.

Question 6.
Define the term “displacement”.
Answer:
The shortest distance between the initial and final positions of the object in a particular direction.

Question 7.
Is displacement of an object a scalar or a vector quantity ?
Answer:
Displacement is a vector quantity.

Question 8.
Under what condition is distance and the magnitude of the displacement equal ?
(CBSE 2010, 2013, 2014, 2015)
Answer:
Distance and magnitude of the displacement are equal if an object moves along a straight line in one direction.

Question 9.
A particle is moving in a circle of diameter 5 m. What is its displacement when it completes 1 ~ revolutions ?
Answer:
After 1 revolution, particle is diametrically opposite to its initial position. Therefore, its displacement = diameter of the circle = 5 m.

Question 10.
What do you mean by uniform motion ? (CBSE 2010, 2012)
Answer:
The motion of an object is uniform motion if it travels equal distances in equal intervals of time along a straight line.

Question 11.
What is non-uniform motion ? (CBSE 2012)
Answer:
The motion of an object is non-uniform if it travels unequal distances in equal intervals of time.

Question 12.
Give one example of non-uniform motion. (CBSE 2012)
Answer:
A bus moving on a hilly road or on a zig-zag road.

Question 13.
What is the shape of the path of a body when it is in uniform motion ?
Answer:
Straight line.

Based on Speed and Velocity

Question 14.
Define the term “speed”.
Answer:
The distance travelled by an object per unit time is known as speed of the object.

Question 15.
State SI unit of speed.
Answer:
metre/second (ms^-1)

Question 16.
Is speed a scalar or a vector quantity ?
Answer:
Speed is a scalar quantity.

Question 17.
Define uniform speed.
Answer:
The speed of an object is said to be uniform speed if it travels equal distances in equal intervals of time.

Question 18.
Define average speed. (CBSE 2012)
Answer:
Average speed is the ratio of the total distance travelled by an object to the total time taken by it.

Question 19.
What does speedometer of an automobile measure ?
Answer:
Speedometer of a vehicle measures its instantaneous speed.

Question 20.
Define the term “velocity”.
Answer:
Velocity is defined as the ratio of the displacement of an object to the time taken by it.

Question 21.
What do you understand by a uniform velocity ?

Or

When is a body said to have uniform velocity ? (CBSE 2011, 2012, 2013)
Answer:
Velocity of an object is uniform if it has equal displacements in equal intervals of time.

Question 22.
What do you understand by a non-uniform velocity ?

Or

When is a body said to have non-uniform velocity ? (CBSE 2011)
Answer:
Velocity of an object is non-uniform if it has unequal displacements in equal intervals of time.

Question 23.
Define average velocity.
Answer:
Average velocity is the ratio of the total displacement of an object to the total time taken by it.

Question 24.
Is velocity a scalar or a vector quantity ?
Answer:
Velocity is a vector quantity.

Question 25.
An object starts with initial velocity u and attains final velocity V. The velocity is changing at a uniform rate.
What is the formula for calculating average speed in this situation ? (CBSE 2011)
Answer:

Question 26.
A physical quantity measured is -10 m s^-1. Is it a speed or velocity ?
Answer:
It is velocity because velocity can be positive or negative. On the other hand, speed is always positive.

Question 27.
What is the numerical ratio of average velocity to average speed of an object when it is moving along a straight path ? (CBSE 2014)
Answer:
In this case, both are equal, so ratio is 1.
Based on Acceleration

Question 28.
Define acceleration of a body.
Answer:
Acceleration is defined as the change in velocity per unit time.

Question 29.
State SI unit of acceleration.
Answer:

Question 30.
Is acceleration a scalar or a vector quantity ?
Answer:
It is a vector quantity.

Question 31.
Why does (second)² in the unit of acceleration ?
Answer:
change in velocity change in displacement

Question 32.
Name the physical quantity that corresponds to the rate of change of velocity.
Answer:
Acceleration.

Question 33.
What do you mean by positive acceleration ? (CBSE 2013, 2015)
Answer:
When the change in velocity of a body takes place in the direction of motion of the body, then the acceleration is positive.

Question 34.
Give one example of positive acceleration.
Answer:
The acceleration of a body is positive, when it falls from certain height.

Question 35.
What do you mean by negative acceleration ? (CBSE 2015)
Answer:
When the change in velocity of a body takes place in a direction opposite to the direction of motion of the body, then the acceleration is negative.

Question 36.
Give one example of retardation or negative acceleration. (CBSE 2013)
Answer:
When the velocity of a train decreases before entering the platform.

Question 37.
When do you say that a body is in uniform acceleration ? (CBSE 2010, 2013)

Or

Define uniform acceleration. (CBSE 2010, 2013, 2014, 2015)
Answer:
When the velocity of a body changes by an equal amount in equal intervals of time, then the body is in uniform . acceleration.

Question 38.
When do you say that a body has non-uniform acceleration ? (CBSE 2013)
Answer:
When the velocity of a body changes by unequal amount in equal intervals of time, then the body is in non¬uniform acceleration.

Question 39.
Give an example of a motion in which the acceleration is in the direction of motion.
Answer:
When a body (say a ball) falls from the roof of a house, then the acceleration of the body is in the direction of motion.

Question 40.
Give an example of a motion in which the acceleration is against the direction of motion.
Answer:
When a ball rolling over a horizontal surface slows down due to the force of friction between the ball and the horizontal surface, then acceleration is against the direction of motion.

Or

When a body is thrown upward, then the acceleration is against the direction of motion of the body.

Question 41.
What is the acceleration of a body moving with uniform velocity in a straight line ? (CBSE 2014)
Answer:

Since velocity is uniform, so change in velocity = 0. Hence, acceleration of body = 0.
Based on distance-time and velocity-time graphs

Question 42.
Draw a distance-time graph for an object at rest.

Question 43.
What will you say about the motion of a body if its distance-time graph is a straight line having a constant angle with time axis ? (CBSE 2010)
Answer:
If distance-time graph is a straight line having a constant angle with time axis, then the distance travelled by the body increases in equal amount in equal intervals of time. It means, the motion of the body is a uniform motion.

Question 44.
If the displacement-time graph for a particle is parallel to time axis, how much is the velocity of the particle.
(CBSE 2013)
Answer:
Velocity is zero as there is no change in displacement with time.

Question 45.
What does the slope of a velocity-time graph represent ?
(CBSE 2010, Term I)
Answer:
It represents the acceleration of the body.

Question 46.
Figure shows the displacement-time graph of four children A, B, C and D. Which child has the highest velocity ? (CBSE 2010, 2012, 2013)

Answer:
Velocity = Slope of displacement – time graph.
Since slope of displacement-time graph for the child B is greater than all other children. Hence, child B has the highest velocity.

Question 47.
What can you say about the motion of a body if its velocity-time graph is a straight line parallel to time axis ?
(CBSE 2012)
Answer:
When velocity-time graph of the motion of a body is a straight line parallel to time axis, then the velocity of the body does not change with time. So the body is said to move with constant velocity.

Question 48.
Name the physical quantity measured by the area occupied below velocity-time graph for uniform motion.
(CBSE2012, 2014)
Answer:
Magnitude of displacement of the body = area under v-t graph.

Question 49.
Plot velocity-time graph of a body moving with constant or uniform velocity. (CBSE 2012, 2014)
Answer:

Question 50.
Velocity-time graph of a body is shown in figure A.

What conclusion can be drawn about the type of motion ? (CBSE 2010, 2011, 2012)
Answer:
Motion of the body is uniform motion.

Question 51.
Velocity-time graph of a body is shown in figure B.

What conclusion can be drawn about the velocity of the body from this graph ?
(CBSE Sample Paper 2010, 2011)
Answer:
Body is moving with constant velocity = 4 m s^-1.

Based on circular motion

Question 52.
Define circular motion. (CBSE 2011, 2012)
Answer:
The motion of a body moving around a fixed point in a circular path.

Question 53.
State the meaning of uniform circular motion.
(CBSE 2010, 2012, 2013, 2014, 2015)
Answer:
The circular motion of a body having constant speed is called uniform circular motion.

Question 54.
Give an example of a uniform circular motion. (CBSE 2014)
Answer:
A cyclist travelling with constant speed on a circular path.

Question 55.
Is uniform circular motion accelerated motion ?
(CBSE 2012, 2013)
Answer:
Uniform circular motion of a body is accelerated because its direction of motion changes continuously although its speed is constant.

Question 56.
If the acceleration of the particle is constant in magnitude but not in direction, what type of path does the particle follow.
Answer:
Circular path.

Question 57.
Why is the motion of an athlete moving along the circular path an accelerated motion ?
Answer:
The direction of motion of the athlete is changing continuously, so his velocity is also changing continuously. Due to change in velocity along the circular path, his motion is accelerated motion.

SHORT ANSWER QUESTIONS

Based on motion of an object along a straight line

Question 1.
Can a body exist in a state of absolute rest or of absolute motion ? Explain with example. (CBSE 2015)
Answer:
A state of rest or state of motion is not absolute but it is a relative term. A body at rest in one frame of reference
may be in motion in other frame of reference. For example, a passenger sitting in a moving bus is at rest with respect to the bus or other co-passengers. However, the same passenger is in motion with respect to a person standing on a road side. Thus, rest and motion are relative terms.

Question 2.
Distinguish between distance and displacement. (CBSE 2010, 2012, 2013)
Answer:

Distance	Displacement
1. Distance is the length of the actual path travelled by an object in a given interval of time.	1. Displacement is the shortest distance between the initial and final positions of a moving object in a particular direction.
2. Distance travelled by an object depends upon the shape of the path followed by the object in going from initial position to the final position. Distance travelled by an object in a given interval of time is always positive. Distance is a scalar quantity.	2. The displacement of an object between initial and final positions of the object does not depend upon shape of the path followed by it. Displacement of an object in a given interval of time may be positive, negative or zero. Displacement is a vector quantity.

Question 3.
Mention two differences between speed and velocity. (CBSE 2013, 2015)
Answer:

Speed	Velocity
1. Distance travelled by an object per unit time is known as its speed.	The distance travelled by an object in a particular direction (i.e. displacement) per unit time is known as its velocity.
2. Average speed of a moving object cannot be zero.	Average velocity of a moving object can be zero.
3. Speed tells how fast an object moves.	Velocity tells how fast an object moves and in which direction it moves.
4. Speed is a scalar quantity.	Velocity is a vector quantity.
5. Speed of an object is always positive.	Velocity of an object can be positive or negative.

Question 4.
Give one example each to differentiate between uniform acceleration and non-uniform acceleration.
(CBSE 2010, 2012)
Answer:
Object has uniform acceleration if its velocity changes by an equal amount in equal intervals of time. For example, motion of an object falling freely from the top of a building.
On the other hand if velocity of an object changes by an unequal amount in equal intervals of time, then it has non-uniform acceleration. For example, the motion of a bus on a hilly track or on a circular track.

Question 5.
Differentiate acceleration from velocity.
Answer:

Acceleration	Velocity
1.      Acceleration of an object is defined as the change in velocity of the object per unit time. 2.       SI unit of a acceleration is m s-2.	1.     Velocity of an object is defined as the change in displacement of the object per unit time. 2.      SI unit of velocity is m s-1.

Based on distance-time and velocity-time graph

Question 6.
What kind of motion of a body is represented by the graphs shown in figure C ?

Answer:
(a) Body is at rest because its distance does not change with time.
(b) Body has uniform motion and then comes to rest.

Question 7.
Explain the differences between the two graphs shown in figure E.

Answer:
Graph (a) shows that body starts from rest and then accelerates uniformly.
Graph (b) shows that body starts with some initial velocity (≠0) and then accelerates uniformly

Question 8.
Four speed-time graphs are shown in figure F :

Which graph represents the following cases ?
(a) A ball thrown vertically upwards and returning to the hand of the thrower.
(b) A body decelerating to a constant speed and then accelerating.

Answer:
(a) Graph (a)
(b) Graph (d).

Question 9.
What do the graphs (I and II) shown in figure G indicate ?

Answer:
Graph I indicates that a body has certain initial speed and then its speed decreases to zero. In other words, this graph shows the retarded motion of a body.
Graph II shows that a body first retards and then accelerates.

Question 10.
A person travelling in a bus noted the timings and the corresponding distances as indicated on the km stones.
(a) Name this type of table.
(b) What conclusion do you draw from this table ?
Answer:
(a) The table gives distance-time data.

Time	Distance
8:00 am	10 km
8:15 am	20 km
8:30 am	30 km
8:45 am	40 km
9:00 am	50 km

(b) As the bus is travelling equal distances in equal intervals of time, so the motion of the bus is uniform motion.

Question 11.
The distance-time graph of trains are given in figure L.

The trains start simultaneously in the same direction.
(i) How much ahead of A is B when the motion starts ?
(ii) What is the speed of B ?
(iii) When and where will A catch B ?
(iv) What is the difference between the speeds of A and B ?
(v) Is the speed of both the trains uniform or non-uniform ? Justify your answer.
Answer:
(i)

(iii) After 2 hours, A catches B. A catches B at Q i.e. 150 km from origin O.
(iv) Speed = slope of distance – time graph. Since slope of distance – time graph for A is greater than that of B, therefore, speed of A is greater than the speed of B.
(v) Speed of both the trains is uniform.

Question 12.
In a long distance race, the athletes were expected to take four rounds of the track such that the line of finish was same as the line of start. Suppose the length of the track was 200 m.

1. What is the total distance to be covered by the athletes ?
2. What is the displacement of the athletes when they touch the finish line ?
3. Is the motion of athletes uniform or non-uniform ?

Answer:

1. Total distance to be covered in four rounds = 4 x length of track = 4 x 200 = 800 m.
2. Since initial and final positions of athletes are same, so displacement of athletes = 0.
3. Motion of athletes is non-uniform as they cover unequal distances in equal intervals of time.

Question 13.
Draw a velocity-time graph for an object in uniform motion. Show that the area under the velocity-time graph gives the displacement of the object in the given time interval.
Answer:
Velocity-time graph for an object in uniform motion is shown in figure M.

Question 14.
Which of the two bodies A and B in the following graph is moving with higher speed and why ?
(CBSE 2015)

Answer:
Speed of a body = slope of distance-time graph.
Since slope of distance-time graph for body B is greater than the slope of distance-time graph for body A. Therefore, body B is moving with higher speed than body A.

Question 15.
Which of the two bodies A and B in the following graph is moving with a greater acceleration and why ?
(CBSE 2015)

Answer:
Acceleration of a body = slope of V — t graph. Since slope of V — t graph for body B is greater than the slope of V – t graph for body A, therefore, body B is moving with a greater acceleration than the body A.

Based on equation of motion

Question 16.
State three equations of motion. Which of them describes :
(i) velocity-time relation
(ii) position-time relation ?
(CBSE 2013, 2015)
Answer:

Question 17.
Write any two equations of motion for a body having uniform acceleration.
Answer:

Based on circular motion

Question 18.
What is uniform circular motion ? How is uniform circular motion regarded as an accelerated motion ? Explain. (CBSE 2010, 2011)
Answer:
Circular motion of a body having constant speed is known as uniform circular motion.
When a body has uniform circular motion, its velocity changes due to the continuous change in the direction of its motion. Hence, the motion of the body is accelerated motion.

Question 19.
What is the difference between uniform motion in a straight line and uniform circular motion ?
(CBSE 2010, 2012, 2013)
Answer:

Uniform motion in a straight line	Uniform motion in a straight line
1. The direction of motion of an object does not change.	1. direction of motion of an object changes continuously.
2. If an object moves with constant velocity, acceleration of the object is zero.	2. uniform circular motion, object moves with constant speed but its direction of motion changes continuously. Therefore, velocity of an object having uniform circular motion changes. Hence, the motion.

Question 20.
An object is moving with uniform speed in a circle of radius r. Calculate the distance and displacement
(a) When it completes half the circle,
(b) When it completes full circle,
(c) What type of motion does the object possess ?
Answer:
(a) When object completes half the circle,
distance travelled by the object = ½ x circumference of the circle = ½ x 2πr
= πr. Displacement of the object = 2r  (∴ object is just at opposite position from its original position).
(b) Distance travelled by the object = circumference of the circle = 2πr. Displacement of the object = zero (∴ object’s initial and final positions are same).
(c) Since the direction of motion of the object changes continuously in the circle, hence its velocity changes and its motion is accelerated motion.

LONG ANSWER QUESTIONS

Question 1.
Draw velocity-time graph for an uniformly accelerated object. Using velocity-time graph, derive v = u + at.

Or

Derive the equation of motion V = u + at using graphical method. (CBSE 2011, 2013, 2015)
Answer:
Derivation of First Equation of Motion From Velocity-Time Graph (Equation for Velocity-time Relation)
The velocity-time graph of a uniformly accelerated motion of the body having initial velocity (u) is shown in figure .
The velocity-time graph is a straight line AB.

Question 2.
Draw velocity-time graph for an uniformly accelerated object. Using velocity-time graph, derive S = ut + ½ at² .
(CBSE 2010, 2011, 2013, 2015)

Or

From velocity-time graph of a body, derive equation for “position-time” relation (II equation of motion) for a body. (CBSE 2012)
Answer:

Question 3.
Draw velocity-time graph for an uniformly accelerated object. Using velocity-time graph, derive v² – u² = 2aS.
(CBSE 2010, 2011, 2013)
Answer:

Question 4.
Write the three equations for the uniformly accelerated motion. Also derive the second and third equations
by graphical method. (CBSE 2013)
Answer:
Derivation of First Equation of Motion From Velocity-Time Graph (Equation for Velocity-time Relation)
The velocity-time graph of a uniformly accelerated motion of the body having initial velocity (u) is shown in figure 28.
The velocity-time graph is a straight line AB.

Question 5.
An object starts a linear motion with velocity ‘u’ and with acceleration ‘a’ It acquires a velocity ‘v’ in time ‘t’.
(i) Draw its velocity-time graph
(ii) Obtain 1st equation of motion, v = u + at for velocity time relation using this graph. (CBSE 2013)
Answer:
(i)

(ii)
Derivation of First Equation of Motion From Velocity-Time Graph (Equation for Velocity-time Relation)
The velocity-time graph of a uniformly accelerated motion of the body having initial velocity (u) is shown in figure 28.
The velocity-time graph is a straight line AB.

Hope given Previous Year Question Papers for CBSE Class 9 Science Chapter 8 Motion 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 7 Diversity in Living Organisms Class 9 Science Important Questions with Answers PDF will help you in scoring more marks in your exams.

Diversity in Living Organisms Class 9 Important Questions and Answers Science Chapter 7

Very Short Answer Questions

Question 1.
Give technical term : A flowering plant whose embryo possesses a single cotyledon. (CCE 2011)
Answer:
Monocot.

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.
Name the kingdom: A unicellular eukaryotic aquatic organism. (CCE 2011)
Answer:
Protista.

Question 3.
Rewrite the scientific name correctly

1. panthera tigris
2. Periplaneta Americana. (CCE 2012)

Answer:

1. Panthera tigris
2. Periplaneta americana.

Question 4.
Name the term used for

1. Left and right halves of the body having the same design
2. Animals where tissues develop from three germinal layers. (CCE 2012)

Answer:

1. Bilateral Symmetry
2. Triploblastic.

Question 5.
State the phylum to which Centipede, Scorpion and Prawn belong. (CCE 2012)
Answer:
Arthropoda.

Question 6.
State the phylum to which Liverfluke and Planaria belong.
(CCE 2012)
Answer:
Platyhelminthes.

Question 7.
State the phylum to which Antedon (Feather Star) and Asterias (Star Fish) belong. (CCE 2012)
Answer:
Echinodermata.

Question 8.
State the system in poriferans that helps in circulating water throughout the body to bring in food and oxygen.
(CCE 2012)
Answer:
Canal system.

Question 9.
What is the common feature between bryophytes and frogs ? (CCE 2012, 2013)
Answer:
Both are amphibians with bryophytes living in moist cool habitats and frogs living both on land and water.

Question 10.
Shyam knew the correct name of Mango but did not follow the conventions while writing it and wrote it as Mangifera Indica. Rewrite the scientific name as per conventions. (CCE 2012)
Answer:
Mangifera indica.

Question 11.
Name the group of plants which produces seeds but not fruits. (CCE 2012)
Answer:
Gymnosperms ( = Gymnospermae).

Question 12.
Give reason why blue green algae are classified alongwith bacteria and placed in kingdom monera. (CCE 2012)
Answer:
Blue-green algae are prokaryotic like bacteria.

Question 13.
Mention the location and function of notochord.(CCE 2012)
Answer:
It lies dorsally, ventral to nerve cord, and provides attachment to muscles.

Question 14.
Write difference between bryophytes and pteridophytes. (CCE 2012)
Answer:
Bryophytes are non-vascular cryptogams with dominant gametophyte while pteridophytes are vascular cryptogams with dominant sporophytic plant body.

Question 15.
Name the kingdom having organisms with holes or pores all over the body. (CCE 2012)
Answer:
Animalia (phylum porifera).

Question 16.
How would you call the symbiotic relationship between fungi and certain blue-green algae ? (CCE 2012)
Answer:
Lichen.

Question 17.
Name an organism whose heart is two-chambered. (CCE 2012)
Answer:
Fish.

Question 18.
Explain the term symbiosis. (CCE 2012, 2013)
Answer:
Symbiosis is mutually beneficial obligatory relationship between two organisms, e.g, lichen.

Question 19.
Name the phylum of animal kingdom to which parasitic worms causing diseases such as filarial worm, round worm belong. (CCE 2012)
Answer:
Nemathelminthes.

Question 20.
Name one reptile with four chambered heart. (CCE 2012)
Answer:
Crocodile.

Question 21.
Write the scientific name of common frog. (CCE 2012)
Answer:
Rana tigrina.

Question 22.
Name animal phylum which exclusively has free living marine animals. (CCE 2012)
Answer:
Echinodermata.

Question 23.
Name one mammal that lays eggs. (CCE 2012)
Answer:
Echidna.

Question 24.
Write the name of phylum to which Hydra and Sea Anemone belong. (CCE 2012)
Answer:
Coelenterata (Cnidaria).

Question 25.
Name the phylum to which Sycon and Euplectella belong.
(CCE 2012)
Answer:
Porifera.

Question 26.
Name an organism which is called saprophyte. Why is it called so ? (CCE 2012)
Answer:
Rhizopus. The organism is called saprophyte because it obtains nourishment from organic remains.

Question 27.
What is the habitat of poriferans ? (CCE 2012)
Answer:
Aquatic, sedentary, attached to solid substratum, mostly in sea but a few fresh water forms as well.

Question 28.
Which is the lowermost category in the hierarchy of classification of groups of organisms ? (CCE 2012, 2013)
Answer:
Species.

Question 29.
In the hierarchy of classification

1. which grouping will have smallest number of organisms with a maximum number of common characteristics and
2. which will have the largest number of organisms. (CCE 2011, 2012)

Answer:

1. Species
2. Kingdom.

Question 30.
Name a division of plants which can be classified as cryptogamae. (CCE 2012)
Answer:
Thallophyta/Bryophyta/Pteridophyta.

Question 31.
Write one difference between echinodermata and chordata.
(CCE 2012)
Answer:
In echinoderms a notochord is absent while the same is present in chordates.

Question 32.
In which Kingdom would you place an organism which is multicellular and without cell wall ? (CCE 2012)
Answer:
Animalia.

Question 33.
Write the name of a species belonging to coelenterata which lives in colonies. (CCE 2012)
Answer:
Obelia, Coral.

Question 34.
Write the two words that constitute binomial nomenclature.(CCE 2012)
Answer:
Genus (generic name) and species (specific epithet).

Question 35.
To which group in the hierarchy of classification saprophytes belong ? (CCE 2012)
Answer:
Saprophytes mosdy belong to kingdom fungi.

Question 36.
Name the phylum to which turtle and king cobra belong.
(CCE 2012)
Answer:
Chordata ( Class Reptilia).

Question 37.
Name the phylum to which Leech and Earthworm belong.
(CCE 2012)
Answer:
Annelida.

Question 38.
Name the phylum to which Octopus and Unio/Pila belong.
(CCE 2012, 2013)
Answer:
Mollusca.

Question 39.
Write one point of difference between radial and bilateral symmetry. (CCE 2012, 2013)
Answer:
In radial symmetry body can be divided into two equal halves by any vertical plane passing through central axis while in bilateral symmetry body is divisible into two equal halves by only midsagittal plane.

Question 40.
Mention three animal phyla that possess true coelom. (CCE 2012)
Answer:
Annelida, Arthropoda, Chordata.

Question 41.
Identify the given specimen and write its characteristic features. (CCE 2012)

Answer:
Moss (Funaria): It has leaf like and stem-like structures. The plant is a gametophyte bearing rhizoids and dependent sporophyte.

Question 42.
In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic ? (CCE 2013)
Answer:
Protista.

Question 43.
Explain the term angiosperm. (CCE 2013)
Answer:
Angiosperms are seed plants in which the seeds are produced inside fruits and the sporophylls are aggregated to form flowers.

Question 44.
Poriferans have holes or pores all over the body that lead to a system that helps in circulating water to bring in food and oxygen. Name the system. (CCE 2013)
Answer:
Canal system.

Question 45.
Which division amongst plants has the simplest organisms? (CCE 2013)
Answer:
Thallophyta.

Question 46.
Write two points of difference between Protozoa and Porifera. (CCE 2014)
Answer:

1. Protozoa are unicellular while Porifera are multicellular.
2. Protozoa are moslty motile. Porifera are sedentary in the mature state.

Question 47.
Where are seeds of gymnosperms formed ? (CCE 2014)
Answer:
On the megasporophylls found in female cones.

Question 48.
Why is it difficult to classify bacteria ? Give two reasons.
(CCE 2014)
Answer:

1. Bacteria are microscopic,
2. There are limited differences in structure and functions.

Question 49.
Relate the given plant with its division in the scheme of classification (CCE 2014)

Answer:
Spermatophyta-Angiospermae- Dicotyledoneae.

Question 50.
Name the substance which makes the cell wall of fungi.
(CCE 2014)
Answer:
Chitin (=fungus cellulose), a complex carbohydrate.

Question 51.
What do you understand by diploblastic ? Give one example of an organism which is diploblastic. (CCE 2015)
Answer:
Diploblastic are animals having two germinal layers, ectoderm and endoderm, e.g. Sycon.

Question 52.
An amoeba and a worm are very different in their body design. State the basic difference between them.
(CCE 2015)
Answer:
Amoeba is a unicellular organism while worm is a multicellular organism.

Question 53.
Arrange the following groups from lower to higher level : Genus, Class, Division, Family, order. (CCE 2015)
Answer:
Genus – Family – Order – Class – Division.

Question 54.
Pick the odd one from the following :
(a) Amoeba, Sponge, Euglena, Frog,
(b) Snail, Slug, Squid, Snake. (CCE 2015)
Answer:
(a) Sponge
(b) Snake.

Question 55.
How many chambers do most of the reptiles have in their heart ? Name one reptile which has four chambered heart.
(CCE 2015)
Answer:
Incomplete four chambers. Complete four chambers occur in crocodile.

Question 56.
A pore bearing organism like creature ‘A’ belongs to phylum ‘B’ of kingdom animalia. Identify ‘A’ and ‘B’.(CCE2016)
Answer:
A—Sponge.
B—Porifera.

Question 57.
What are lichens ? (CCE 2017)
Answer:
Licherns are dual organisms which have been formed by permanent symbiotic association between an alga and a fungus.

Question 58.
What is symbiotic relationship ? Give an example.
(CCE 2017)
Answer:
Symbiosis is mutually beneficial obligatory relationship between two organisms, e.g, lichen.

Short Answer Questions (2 marks)

Question 1.

1. Write one main characteristic feature that differentiates gymnosperms from angiosperms.
2. Give one example each of a gymnosperm and an angiosperm. (CCE 2011, 2013)

Answer:

1. Gymnosperms possess naked seeds while angiosperms contain seeds enclosed inside the fruit.
2. Example of Gymnosperm. Pinus. Example of Angiosperm. Mango.

Question 2.
(i) Identify the class of animals having the following characteristics features :
(a) Warm blooded animals that lay eggs and have four chambered heart and a covering of feathers.
(b) Cold blooded animals having scales and they breathe through lungs.
(ii) Give an example of an animal belonging to each of these classes. (CCE 2011)
Answer:
(i)
(a) Aves
(b) Reptilia
(ii) Example of Aves. Pigeon. Example of Reptilia. Snake.

Question 3.
What are the four main characteristics of chordates ? (CCE 2011,2012,2013, 2014)
Answer:
Presence of

1. Notochord which in higher forms is transformed into cranium and vertebral column,
2. Dorsal Hollow Nerve Cord. In higher chordates, it is transformed into brain and spinal cord.
3. Pharyngeal Gill Slits. Present at some stage of life cycle,
4. Post-anal tail.

Question 4.
(a) Give one characteristic difference between primitive and advanced organisms.
(b) Name the phylum to which the following are included :

1. Spider
2. Cockroach
3. Prawn
4. Housefly. (CCE 2011)

Answer:
(a) Primitive organisms have simple basic body design while advanced organisms have more complex body structure with specialisations.
(b) Arthropoda.

Question 5.
What is binomial nomenclature ? Who introduced it ? (CCE 2011, 2012, 2013)
Answer:
Binomial nomenclature is a scientific system of poviding distinct and proper names to organisms where each name consists of two words, generic and specific epithet. It was introduced by Carolus Linnaeus (1751).

Question 6.
(a) What are the two adaptive features of birds ?
(b) What is the scientific name of Ostrich ? (CCE 2011)
Answer:
(a) Adaptive Features of Birds,

1. Body covered by feathers,
2. Fore limbs modified into wings.

(b) Ostrich. Struthio camelus.

Question 7.
(a) List two features which differentiate chordates from non-chordates.
(b) In which phylum will you place the organisms which have

1. Calcareous spines on their body,
2. Presence of holes or pores all over the body. (CCE 2011 )

Answer:
(a) Chordate Features.

1. Occurrence of notochord that is transformed into cranium and vertebral column in higher chordates.
2. Presence of dorsal hollow nerve cord above the notochord which in higher chordates is transformed into brain and spinal cord.

(b)

1. Echinodermata.
2. Porifera.

Question 8.
How do saprophytes get their food ? Give two examples of saprophytes. (CCE 2011)
Answer:
Saprophytes are organisms that feed on organic remains by the process of external digestion.
Examples. Mushroom, Rhizopus.

Question 9.
Characters of some organisms are given. Identify their group and give an example of each
(a) Single-celled, eukaryotic and photosynthetic.
(b) The body is divided into segments, may be unisexual or hermaphrodite. (CCE 2011, 2012)
Answer:
(a) Protista – diatoms.
(b) Annelida – Nereis, Pheretima.

Question 10.
(a) How many chambers do the heart of fish, amphibians and mammals have ?
(b) Name the classes of vertebrates which lay eggs with shells. (CCE (2011)
Answer:
(a)

1. Heart of Fish – Two chambered.
2. Heart of Amphibians – Three chambered.
3. Heart of Mammals – Four chambered.

(b) Reptilia, Aves.

Question 11.
List the major divisions in kingdom plantae. Write the characteristic features of any one of them. (CCE (2011)
Answer:
Divisions of Kingdom Plantae. Thallophyta, Bryophyta, Pteridophyta, Spermatophyta (Gymnosperms, Angiosperms).
Characteristic Features of Bryophyta.

1. Absence of vascular tissues.
2. Simple vegetative structure.
3. Amphibians.
4. Plant body gametophyte.
5. Sporophyte parasitic over gametophyte.
6. Sex organs are multicellular and’jacketed.
7. An embryo stage present in the life cycle.

Question 12.
(a) Explain binomial nomenclature. What are its conventions ?
(b) Name the scientist who has given it.
(c) Write its advantage. (CCE 2011, 2012, 2016)
Answer:
(a) Binomial nomenclature is a scientific system of providing distinct and proper two word name to each and every organism.
Conventions.

1. It consists of two words, first generic (like noun) and second specific (species).
2. Generic name has first letter capital while specific word begins with small letter.
3. Both are derived from latin language or are latinised.
4. They are printed in italics or are underlined separately in hand-written form.

(b) Binomial nomenclature was given by Carolus Linnaeus (1751).
(c) Advantage:

1. It is universal, being the same in all languages and conntries.
2. It is distinct and sepcific with no two organisms having the same name.

Question 13.
Why is there a need for classification and systematic naming of living organisms ? (CCE 2011, 2012)
Answer:
Need for Classification. A good system of classification is required for

1. Identification of organisms.
2. Study of organisms of other regions.
3. Study of whole range of organisms, choosing one or a few from each group.
4. Find similarities and dissimilarities, relationships and evolutionary trends.

Need for Systematic Naming. It is scientific naming of groups and subgroups and arranging them in a hierarchy with each taxon having some characteristics of its own.
This helps in locating the position of an organism.

Question 14.
Why bryophytes are called the amphibians of the plant j kingdom? (CCE2011, 2013)
Answer:
Bryophytes are called amphibians of plant kingdom as they live in moist, damp and shady places. A layer of water is required on the soil surface for

1. Sexual reproduction.
2. Protection from transpiration and hence desiccation
3. Supply of water to all parts in the absence of vascular tissues.

Question15.
Some reptiles live in water and yet lay eggs with tough covering unlike the amphibians. Why ? (CCE 2011)
Answer:
Reptiles evolved over land where hard shelled eggs occur for protecting the embryo surrounded by extra-embryonic membranes. Some reptiles went back into aquatic habitats, However, they did not lose their hard shelled eggs which are usually laid over the banks of water bodies.

Question 16.
(a) Define cryptogams.
(b) Name the division of plant kingdom having amphibian plants. (CCE 2011, 2012)
Answer:
(a) Cryptogams. They are seedless lower plants where reproductive organs are inconspicuous requiring an external water for fertilization.
(b) Bryophyta.

Question 17.
Bats can fly. Still they are placed in mammals. Why ? (CCE 2011)
Answer:
Bats are

1. Viviparous giving birth to young ones.
2. They possess mammae for feeding the young ones.
3. The body is covered by hair.

Question 18.
How are fungi

1. Similar and
2. dissimilar to plants ? (CCE 2011)

Answer:
Similarity. Presence of cell wall. Dissimilarity. Presence of chitin in cell wall (instead of cellulose) and glycogen (instead of starch) as reserve food.

Question 19.
How do thallophytes and pteridophytes differ from each other ? Write two differences. (CCE 2011)
Answer:

1. Thallophytes are the simplest plants with little differentiation while pteridophytes have a well differentiated body design.
2. Reproductive organs are single celled with no embryo stage in thallophytes. In pteridophytes the reproductive organs are multicellular and jacketed with an embryo stage being present in the life cycle.

Question 20.
(a) What is biodiversity ? (CCE 2013)
(b) List three/four features of vertebrates.
(CCE 2011, 2012)
Answer:
(a) Biodiversity. It is the occurrence of different types of organisms and their variants adapted to different environmental conditions and formation of different types of communities.
(b) Features ofVertebrates.

1. Notochord replaced by cranium and vertebral column,
2. Dorsal nerve cord transformed into brain and spinal cord.
3. Presence of paired gill pouches replaced by lungs in land animals.
4. A chambered ventral heart is present.

Question 21.
Give reasons for each of the following :
(a) “Blue-green algae are placed in Monera and not in Plantae”.
(b) “Bryophytes and pteridophytes grow in moist and shady places.” (CCE 2011)
Answer:
(a) Blue-green algae are prokaryotes. They are, therefore, placed in Monera. Plantae includes eukaryotes.
(b) Bryophytes and pteridophytes occur in moist and shady places as they require a film of water over the surface of soil for the liberation and passage of sperms to the archegonia.

Question 22.
(a) Write any two important features that are present in all chordates.
(b) Mention one difference between triploblastic and diploblastic animals. (CCE 2011)
Answer:
(a) Chordate Features.

1. Occurrence of notochord that is transformed into cranium and vertebral column in higher chordates.
2. Presence of dorsal hollow nerve cord above the notochord which in higher chordates is transformed into brain and spinal cord.

(b) Difference Between Triploblastic and Diploblastic Animals. Triploblastic animals have three germ layers (ectoderm, mesoderm and endoderm), while diplablastic animals have only two germ layers (ectoderm and endoderm).

Question 23.
Write two peculiar characters of sponges. (CCE 2011)
Answer:

1. Occurrence of a canal system and two types of pores.
2. Presence of flagellated collar cells or choanocytes.

Question 24.
(a) Give one difference between lizards and snakes.
(b) Name the type of nutrition in fungi. (CCE 2011)
Answer:
(a) Lizards have limbs and fixed jaw with limited gape while snakes are limbless with movable jaws for wide gape.
(b) Fungi have heterotrophic absorptive nutrition (saprophytic, parastic).

Question 25.
How can we say that Sea Horse is a fish while Jelly Fish is not a fish but a coelenterate ? (CCE 2011)
Answer:
Jelly Fish (Aurelia) is a diploblastic animal with tissue level organisation, a single opening and tentacles with nematoblasts like coelenterates.
Sea Horse (Hippocampus) possesses fins and gills covered by operculum like other bony fishes.

Question 26.

1. Which group of plants is known as flowering plants ?
2. On the basis of seed, how a maize plant is different from a pea plant ? (CCE 2011)

Answer:

1. Angiosperms (angiospermae).
2. Seed of Maize has a single cotyledon (monocotyledoneae) while the seed of Pea has two cotyledons (dicotyledoneae).

Question 27.
(a) What are saprophytes ?
(b) Name the kingdom to which they belong.
(c) What is the cell wall of fungi made of ? (CCE 2011)
Answer:
(a) Saprophytes. They are organisms that feed on dead or decaying organic matter by first secreting digestive enzymes and then absorbing the digested materials.
(b) Kingdom. Fungi.
(c) Cell Wall of Fungi. It is made up of aminosugar polymer called chitin or fungus cellulose.

Question 28.
(a) Identify the class of the following organism having following features,

1. Slimy skin and three chambered heart.
2. Covering of feathers and four chambered heart.

(b) List two important characteristics of phylum Nematoda.
(CCE 2011, 2013)
Answer:
(a)

1. Amphibian (e.g. Frog)
2. Bird (e.g. Pigeon).

(b) Nematoda.

1. Cylindrical body with bilateral symmetry
2. Triploblastic nature with pseudocoelom, digestive system with mouth and anus.

Question 29.
Give any two reasons why mosses are found in moist and humid places. (CCE 2011)
Answer:

1. Mosses are prone to get dried up because of the absence of cuticle over their surface. Water can be absorbed by the whole surface.
2. Sperms require a thin layer of water on the soil to reach the opened archegonia.

Question 30.
Write the names of parts A, B, C and D. (CCE 2011)

Answer:
A – Mouth.
B – Pectoral fin.
C – Dorsal fin.
D – Brood pouch.

Question 31.
What are gymnosperms ? Give two characteristics. (CCE 2011)
Answer:
Gymnosperms are phanerogams which possess exposed (naked) seeds and where the sporophylls are aggregated to form cones.

1. Sporophylls are aggregated to form separate male and female cones.
2. Seeds do not occur inside fruits but develop exposed over the surface of megasporophylls.

Question 32.
(a) State two characterisics of nematodes.
(b) Identify the phylum with the help of following feactures :

1. Spiny-skinned, radial symmetrical and have tube feet,
2. Triploblastic, worm-like having segmented body (CCE 2011)

Answer:
(a)

1. Cylindrical body with bilateral symmetry
2. Triploblastic nature with pseudocoelom, digestive system with mouth and anus.

(b)

1. Echinodermata
2. Annelida.

Question 33.
Who proposed the five kingdom classification ? What is the basis of this classification ? (CCE 2011)
Answer:
Whittaker (1969). Four criteria have been used for grouping of organisms into five kingdoms—

1. Procaryotic and eukaryotic nature
2. Unicellular and multicellular nature
3. Nutrition

Question 34.
Label X and Y in the given diagram. (CCE 2011)

Answer:
X — Stinging cell,
Y — Foot.

Question 35.
Write the major features of fungi (CCE 2011, 2012)
Answer:

1. The body called mycelium is made of achlorophyllous threads.
2. Cell wall contains chitin.
3. Nutrition is heterotrophic and absorptive,
4. Reserve food is glycogen and oil.

Question 36.
Enlist four main features of organisms placed in protista.
(CCE 2011)
Answer:

1. Unicellular or colonial, mostly aquatic, constituting plankton.
2. Eukaryotic organisation with nucleus and membrane bound cell organelles.
3. Locomotion present in many with the help of cilia, j flagella and pseudopodia.
4. Both asexual and sexual reproduction present. Sexual reproduction without an embryo stage.

Question 37.
Give four main features of phylum coelenterata.
(CCE 2011)
Answer:

1. Diploblastic animals with tissue level organisation.
2. Body has a single opening for both feeding and elimination.
3. Tentacles with cnidoblasts or nematoblasts.
4. Nerve cells present but nerve plexus absent.

Question 38.
Give one example of each of
(a) Reptile which has four chambered heart
(b) Egg laying mammal
(c) Parasitic platyhelminthes
(d) Division among plants which has the simplest organisms. (CCE 2011)
Answer:
(a) Crocodile
(b) Platypus
(c) Liver-fluke
(d) Uhthrix (thallophyta-algae).

Question 39.
Identify the phylum for the following characteristics given :
(a) Organisms with jointed appendages
(b) Organisms are generally flat worms
(c) Body is segmented
(d) Skin of organisms is full of spines. (CCE 2011)
Answer:
(a) Arthropoda
(b) Platyhelminthes
(c) Annelida
(d) Echinodermata.

Question 40.
Write any two characteristics of class mammalia.Name one egg laying mammal. (CCE 2011, 2012)
Answer:

1. Presence of mammary glands in females
2. Presence of body hair.

Egg Laying Mammal. Platypus, Echidna.

Question 41.
An animal is dorsoventrally flattened, has three embryonic germ layers and is acoelomate.
To which phylum does it belong ? What are they commonly called ? Give one example. (CCE 2012)
Answer:
Phylum. Platyhelminthes. Common Name Flatworms. Example. Planaria.

Question 42.
Write the name used for the following :
(a) Plants which bear naked seeds
(b) Animals which have pseudocoelom
(c) Animals which maintain a certain body temperature over a wide range of temperature in the environment.
(CCE 2012, 2015)
Answer:
(a) Gymnosperms
(b) Pseudocoelomates-Nemathelminthes
(c) Homoiotherms or warm blooded.

Question 43.
What is parasite ? Give two examples. (CCE 2012)
Answer:
Parasite is an organism which obtains its food from a living organism of another species called host. Examples. Fasciola (Liver Fluke), Ascaris (Common Roundworm).

Question 44.
(a) State the number of chambers in the heart of

1. Fishes
2. Frogs,

(b) Define

1. Triploblastic and
2. Bilateral Symmetry. (CCE 2012)

Answer:
(a)

1. 2 chambers
2. 3 chambers,

(b)

1. Triploblastic: Animals having three germinal layers—ectoderm, mesoderm and endoderm, viz., platyhelminthes to chordates.
2. Bilateral Symmetry: It is a symmetry in which organs are paired with each one of the pair lying on right and left sides of the body, e.g., chordates, arthropods.

Question 45.

1. Cat, Platypus and Man are all mammals. Yet one of the most unique feature of mammals when considered helps to divide them’ into two groups. What is that feature ?
2. Mention two other characteristic features which are common to all the three animals. (CCE 2012)

Answer:

1. Vivipary: Platypus is egg laying mammal while the other two give birth to young ones,
   1. Presence of hair over the body
   2. Occurrence of mammary glands in females.

Question 46.
Fungi have cell wall but still they cannot be classified under kingdom plantae. Give two reasons. (CCE 2012)
Answer:
Cell wall of fungi contains chitin while in plantae it has cellulose. Further, the reserve carbohydrate food is glycogen in fungi and starch in plantae. Fungi are heterotrophic while most plants are autotrophic.

Question 47.
List two reasons why whales are not grouped with fishes ?
(CCE 2012)
Answer:
Whales are mammals which have

1. Four chambered heart, pulmonary respiration and a diaphragm while fishes have two chambered heart, gill respiration and no diaphragm.
2. Whales are warm blooded with mammary glands in females. Fishes are cold blooded. Mammary glands do not occur in them.

Question 48.
Jelly fish and Star Fish are not true fishes. To which group do they belong ? Give one characteristic features of each to say they belong to the respective groups. (CCE 2012)
Answer:
Jelly Fish: Coelenterata—diploblastic with cnidoblasts. Star Fish. Echinodermata—Spiny skinned with tube feet.

Question 49.
Write four characters of monerans. (CCE 2012)
Answer:

1. Prokaryotic Nature. The genetic material is a single double stranded DNA coiled in the cytoplasm to form nucleoid. A nuclear mambrane is absent.
2. Cell Organelles. Membrane covered cell organelles are absent.
3. Flagella. If present, they are single stranded.
4. Cell Wall. It is made of murein or peptidoglycan.

Question 50.
Give three features of butterfly to justify its classification in phylum arthropoda. Mention one more animal of the same phylum.
Answer:

1. Chitinous exoskeleton,
2. Jointed appendages
3. Open circulatory System.
   Other Example. Prawn.

Question 51.
Some fungal species live in permanent mutually dependent relationship with blue-green algae. Name the relationship. Mention where these forms are grown and what they are called ? (CCE 2012)
Answer:
Symbiosis or mutualism. The dual organisms grow on rocks and tree trunks. They are called lichens.

Question 52.
Write one point of difference between bony fish and cartilaginous fish with one example of each. (CCE 2012)
Answer:
A bony fish has a bony endoskeleton with terminal mouth ‘‘find gill slits covered by operculum, e.g., Labeo. A cartilaginous fish has cartilaginous endoskeleton with ventral mouth and uncovered gill slits, e.g., Scoliodon.

Question 53.
Classify the following fishes as cartilaginous or bony,

1. Sting Ray
2. Scoliodon (Dog Fish)
3. Labeo rohita (Rohu)
4. Caulophrynejordani (Angler Fish). (CCE2012)

Answer:

1. String Ray. Cartilaginous,
2. Scoliodon. Cartilaginous.
3. Labeo rohita. Bony,
4. Caulophryne jordani. Bony. Cell wall of fungi is made of chitin.

Question 54.

1. What is chemical nature of chitin ?
2. What is the mode of nutrition in fungi ? (CCE 2012, 2013)

Answer:

1. Chitin is polysaccharide made of N-acetyl glucosamine monomers,
2. Absorptive heterotrophic.

Question 55.
Identify the class of animals having following characteristic
(a) Warm blooded having four chambered heart and modified fore limbs for flight,
(b) Organisms having mucous glands in the skin, lack scales, respire either through gills or lungs. (CCE 2012)
Answer:
(a) Aves
(b) Amphibia.

Question 56.
Select the odd one with respect to classification. Also give reason for your choice,
(a) Mango, Gram, Rice, Apple.
(b) Prawn, Scorpion, Octopus, Butterfly. (CCE 2012)
Answer:
(a) Rice: Rice is monocot while others are dicots,
(b) Octopus: Octopus belongs to mollusca while all others are arthrophods.

Question 57.
How do amphibians respire and reproduce ? (CCE 2012)
Answer:
Respiration: Amphibians respire through lungs, skin and in many cases gills.
Reproduction: Sexes are separate. Fertilization is external.

Question 58.
Name the phylum to which the following belong.
(a) Silver Fish
(b) Sea Horse,
(c) Star Fish
(d) Jelly Fish. (CCE 2012)
Answer:
(a) Silver Fish. Arthropoda.
(b) Sea Horse. Chordata.
(c) Star Fish. Echinodermata.
(d) Jelly Fish. Coelenterata.

Question 59.
Name the four categories used in hierarchical classification of organism. (CCE 2012)
Answer:
Kingdom, Division/Phylum, Class, Order.

Question 60.
Write three distinguishing features of phylum echinodermata. Give one example. (CCE 2012)
Answer:
Features

1. Skin is spiny,
2. A water vascular system connected with tube feet is present for helping in locomotion and respiration.
3. Symmetry is radial in adults and bilateral in larva. Example. Asterias (Star Fish).

Question 61.
The scientific name for tiger is Pantbera tigris. What does Panthera and tigris represent in binomial nomenclature. Name the scientist who introduced this system of scientific naming of organisms. (CCE 2012)
Answer:

1. Panthera: Genus or generic name, tigris. Species or specific epithet,
2. Carolus Linnaeus.

Question 62.
Identify the group :
(a) Animals without tissues, body bearing pores.
(b) Plant body differentiated into roots, stems and leaves but do not produce seeds,
(c) Body dorsoventrally flattened without coelom,
(d) Segmented worms with the body cavity with extensive organ differentiation.
(CCE 2012)
Answer:
(a) Porifera
(b) Pteridophyta
(c) Platyhelminthes
(d) Annelida.

Question 63.
State the type of body cavity found in platyhelminthes. Write whether they are parasitic or free living. (CCE 2012)
Answer:
Parenchymatous body cavity is present but coelom is absent. Both free living (e.g., Planaria) and parasitic (e.g., Fasciola) forms occur in platyhelminthes.

Question 64.
Echinoderms have a system that they use for moving around. Name the system. What is their skeleton made of ? (CCE 2012)
Answer:

1. Water vascular or ambulacral system.
2. Calcareous plates.

Question 65.
List any two similarities and two differences between Amoeba ‘ and Paramoecium. (CCE 2012)
Answer:
Similarities :

1. Unicellular nature
2. Eukaryotic nature.
3. Presence of contractile vacuoles.

Differences :

1. Amoeba possesses pseudopodia while Paramoecium has cilia.
2. Amoeba has a single nucleus. Paramoecium has two nuclei.

Question 66.
(a) What is scientific name of humans ?
(b) Find the odd one out of Riccia, Funaria, Fern, Marchanda. (CCE 2012)
Answer:
(a) Homo sapiens
(b) Fern: It is a pteridophyte while others are bryophytes.

Question 67.
Given below are two groups of organisms belonging to kingdom Animalia.
Write the name of phylum to which they belong.
(a) Octopus, Pita, Unio
(b) Centipede, Prawn, Scorpion.
(CCE 2013)
Answer:
(a) Mollusca
(b) Arthropoda.

Question 68.
Write two differences between pteridophyte and phanerogam. (CCE 2013)
Answer:

Question 69.
Name the phyla to which the following animals belong :
(a) Star Fish
(b) Leech. (CCE 2013)
Answer:
(a) Star Fish-Echinodermata
(b) Leech-Annelida.

Question 70.
Identify the organisms :
(a) A unicellular organism that uses flagella for moving around
(b) An organism that uses pseudopodia for moving around. (CCE 2013)
Answer:
(a) Flagella-Euglena
(b) Pisedopodia-Amoeba.

Question 71.
We start classification of plants on the basis of differentiation of plant body,

1. Which division lacks a well differentiated body design ?
2. Where are such plants predominantly found ? (CCE 2014)

Answer:

1. Thallophyta – algae,
2. Occurrence. Aquatic (both fresh and marine).

Question 72.
Give two features of Cockroach due to which it is classified as arthropod. (CCE 2014)
Answer:

1. Chitinous exoskeleton,
2. Jointed appendages
3. Open circulatory System.
   Other Example: Prawn.

Question 73.
Identify ‘X’ and ‘Y’ in the diagram of a part of earthworm. What function is performed by ‘X’. (CCE 2014)

Answer:
X- Prostomium.
Y-Peristomium.
Function of X: Sensory.

Question 74.
After observing an Earthworm, Samir decided to place it in phylum annelida. Which two features did he observe that helped him do so ? (CCE 2014)
Answer:

1. Long, segmented (metameric segmentation) body
2. Presence of rings of microscopic unjointed setae.

Question 75.
Give one function of gills in fishes. To which phylum do the fishes belong ? (CCE 2014)
Answer:
Gills: They are sites of respiration or exchange of gases between blood and water. Phylum. Chordata.

Question 76.
Mention two features adapted by birds which help them fly. (CCE 2014)
Answer:

1. Fore limbs modified into wings,
2. Stream-lined body, pneumatic bones.

Question 77.
Name the adaptation of fish which help them in
(a) Floating in water,
(b) Breathing. (CCE 2014)
Answer:
(a) Floating: Presence of air sac.
(b) Breathing: Occurrence of gills.

Question 78.
Name the habitat of earthworm and how is it useful to the animal. (CCE 2014)
Answer:
Earthworm lives in moist soil from which it can obtain food as decaying organic matter, keep the skin moist for respira¬tion and easily dig narrow burrows

Question 79.
(a) Why is the body of bony fishes stream-lined ?
(b) List two habitats of bony fishes. (CCE 2014)
Answer:
(a) Stream-Lined Body. For meeting little resistance during swimming.
(b) Habitats. Fresh and marine waters.

Question 80.
State any two specific features of earthworm. (CCE 2014)
Answer:

1. Segmented cylindrical body,
2. Occurrence of clitellum.

Question 81.
The body of an organism is stream-lined and has feathers on its body. Identify the organism and write one specific feature of it. (CCE 2014)
Answer:
Bird. Presence of wings and a toothless beak.

Question 82.
Why is it difficult to classify bacteria ? Give two reasons.
(CCE 2017)
Answer:

1. Bacteria are microscopic,
2. There are limited differences in structure and functions.

Question 83.
What is binomial nomenclature ? Explain it with the help of an example. (CCE 2017)
Answer:
Binomial nomenclature is scientific system of providing distinct and proper two word name to each and every organism. For example, the scientific name of Mango is Mangifera indica where Mangifera represents the genus while indica is the specific epithet.

Short Answer Questions (3 marks)

Question 1.

1. Draw a neat diagram of Hydra,
2. Label mesogloea and gastrovascular cavity,
3. Name the group of animals it belongs to.
4. Name one species of this group that lives in colonies. (CCE 2011, 2012)

Answer:

1. 
2. Label the two parts.
3. Phylum coelenterata.
4. Corals.

Question 2.
Identify the plant bodies which are named as cryptogamae1. State and explain two characteristics which are exhibited by each category of these plant bodies. (CCE 2011)
Answer:
Cryptogamae, the subkingdom of seedless plants, consists of three groups-thallophyta, bryophyta and pteridophyta.

1. Thallophyta: Simple, ill-differentiated plant body, e.g., algae like Ulothrix
   1. Unicellular and nonjacketed reproductive organs
   2. Embryo stage absent.
2. Bryophyta: Simple thallus-like or differentiated into stem and leaf-like structures, e.g., Riccia, Marchantia, Funaria (moss),
   1. Simplest but amphibious land plants which are fixed by means of rhizoids.
   2. Plant body is gametophyte. Sporophyte lives on it as a parasite.
3. Pteridophyta: Differentiated plant body consisting of true roots, stems and leaves, e.g., ferns,
   1. Dominant plant body is sporophyte. Gametophyte is small but independent.
   2. Vascular tissues present but seeds are absent.

Question 3.
List any three groups of plants, which are referred to as vascular plants. Out of these which group is further classified on the basis of number of cotyledons. State its two characteristics. (CCE 2011, 2012)
Answer:
Vascular plants are those plants which possess vascular tissues, xylem and phloem, for conduction of water and nutrients respectively. There are three groups of vascular plants or tracheophytes-pteridophytes, gymnosperms and angiosperms.
Angiosperms or flowering plants are classified on the basis of cotyledons present in their seeds, monocotyledoneae (single cotyledon) and dicotyledoneae (two cotyledons). Characteristics

1. Sporophylls are organised into flowers.
2. Seeds develop inside fruits.

Question 4.
(a) Draw a well labelled diagram of Euglena.
(b) Name the kingdom to which it belongs. (CCE 2011)
Answer:
(a)

(b) Protista.

Question 5.
Pick up the odd one out and justify your choice by giving reasons :
(a) Moss, Fern, Pinus, Spirogyra.
(b) Sea Cucumber, Octopus, Feather Star, Star Fish. (CCE 2011)
Answer:
(a) Pinus: The other three belong to cryptogamae while Pinus is a member of phanerogamae.
(b) Octopus: The other three belong to echinodermata while Octopus is a member of mollusca.

Question 6.
Write any three differences between Amphibia and Mammalia. (CCE 2011)
Answer:

Question 7.
(a) Write down four characteristic features of the members of class Aves.
(b) To which group do the following belong :
(t) Evergreen trees that bear naked seeds.
(it) Plants which have tap root system and two cotyledons in their seeds. (CCE 2011)
Answer:
(a) Aves is a class of warm-blooded vertebrates having fore-limbs modified into wings, body covered with feathers and jaws modified into horny toothless beak.
General Characters

1. Birds are the flying animals, having exoskeleton of feathers. Skin is dry except for a preen gland for dressing of feathers.
2. Body Temperature. Birds are warm blooded
3. Body Divisions. Body is divided into head, neck, trunk and tail.
4. Fore limbs are modified intowings while hind limbs have four clawed digits which are adapted for walking, running, perching or digging.
5. 5. Bones. They are very light because of air spaces (pneumatic bones).
6. Jaws are prolonged to form horny beak. Teeth are absent.
7. Bird’s Milk. Oesophagus is modified to store and soften the food. It is source of bird’s milk which is used for feeding the young birds.
8. Respiratory System. It possesses well-developed lungs which have air sacs attached to them for double respiration.

(b)

1. Gymnospermae.
2. Dicotyledoneae.

Question 8.
Identify the diagrams. Write the phylum do they belong to. Write down the characteristic features of each phylum.
(CCE 2011)
Answer:
(a) Wuchereria (Filarial worm). Phylum. Nematoda (nemathelminthes).

1. Cylindrical body with bilateral symmetry.
2. Triploblastic with pseudocoelom,
3. With both mouth and anus, having primitive system level of organisation.

(b) Sponges. Phylum. Porifera.

1. Sedentary adults with hard skeleton of spicules and fibres,
2. Diploblasdc with cellular level of organisation,
3. Canal system with ostia and osculum, flagellated choanocytes,

Question 9.
Differentiate between annelida and nematoda.
Answer:

Question 10.
(a) In which two ways amphibians are different from fishes,
(b) Identify the phylum of organisms having the following characteristics :

1. Pore bearing animals and radial symmetry,
2. Body spiny with radial symmetry,

(c) Why gymnosperms do not require water for fertilization ? (CCE 2011)
Answer:
(a)

1. Amphibians have limbs while fishes possess fins,
2. Amphibians have lungs while the same are absent in fishes.

(b)

1. Porifera
2. Echinodermata.

(c) In gymnosperms fertilization occurs through siphonogamy or pollen tube. Therefore, an external source of water is not required for carrying male gametes.

Question 11.
(a) Name the phylum to which each of the following animals belongs to – Silver Fish, Star Fish, Tapeworm, Leech.
(b) List two features of vertebrates. (CCE 2011 )
Answer:
(a)

1. Silver Fish – Arthropoda
2. Star Fish – Echinodermata.
3. Tapeworm- Platyhelminthes.
4. Leech – Annelida.

(b) Features of Vertebrates.

1. Notochord replaced by cranium and vertebral column,
2. Dorsal nerve cord transformed into brain and spinal cord.
3. Presence of paired gill pouches replaced by lungs in land animals.
4. A chambered ventral heart is present.

Question 12.
How do Aves differ from Mammals ? (three points). (CCE 2011, 2012, 2013)
Answer:

Aves	Mammalia
1. Wings. Forelimbs are modified into wings.	Wings are absent except in bats.
2. Feathers and Scales. The body is covered with feathers and scales.	Feathers and scales are absent.
3. Skin Glands. Skin is dry. Only a single preen gland is present.	Skin bears a number of sweat and oil glands.
4. Mammary Glands. They are absent.	Female possesses mammary glands for feeding the young
5. Diaphragm. A diaphragm is absent.	A partition called diaphragm is present between abdomen and thorax.
6. Beak. A toothless beak is present.	Jaws do not form a beak. Teeth are present.
7. Bones. They are hollow or pneumatic.	Bones do not possess air cavities.
8. Larynx/Syrinx. Larynx is non-functional. Instead syrinx is present.	Larynx is functional. Syrinx is absent.
External air sacs do not occur over lungs.
	9. Air Sacs. Lungs possess external air sacs.
10. Yolk. Eggs possess a lot of yolk (macrolecithal).	Eggs have little yolk (alecithal).
11. Reproduction. Birds are oviparous.	Mammals are viviparous with the exception of a few species.

Question 13.
To which group do the following organisms belong and give one reason for each
(a) Cyanobacteria
(b) Euglena
(c) Ulothrix ? (CCE 2011)
Answer:
(a) Cyanobacteria – Monera. Prokaryotic nature.
(b) Euglena – Protista. Unicellular eukaryote.
(c) Ulothrix – Plantae. Thallophyta-Algae. Little

Question 14.
differentiated autotrophic body with unicellular, non- jacketed sex organs.

1. What are vertebrates ?
2. Name four subgroups of vertebrates. (CCE 2011, 2012)

Answer:

1. Vertebrates. They are chordates in which notochord has been replaced by endoskeleton of vertebral column [ and cranium while dorsal nerve cord has been transformed into brain and spinal cord.
2. Pisces, Amphibians, Reptiles, Aves, Mammals.

Question 15.
On the basis of the following features, identify the group and give one example of each :

1. Presence of notochord at some stage of life,
2. Unicellular microscopic and eukaryotic.
3. Seeds are enclosed in fruits. (CCE 2011)

Answer:

1. Notochord At Some Stage. Protochordata, e.g., Herdmania.
2. Unicellular, Microscopic, Eukaryotic. Protista, e.g., Euglena, Amoeba.
3. Seeds Enclosed in Fruits. Angiospermae, e.g, Mango, Tomato.

Question 16.
Write one difference for each of the following pairs

1. Thallophyta and Bryophyta
2. Nematoda and Annelida
3. Amphibia and Pisces.
   (CCE 2011, 2012)

Answer:

1. Thallophyta and Bryophyta. In thallophyta the reproductive organs are unicellular, non-jacketed with no embryo stage. In bryophyta the sex organs are multicellular, jacketed with an embryo stage.
2. Nematoda and Annelida
   

Pisces	Amphibians
1. Scales. The body is covered by scales.	1. Scales are absent.
2. Mucous Glands. The skin does not possess mucous glands.	2. The skin has mucous glands that keep the skin moist and slippery.
3. Fins. Pisces possess fins for locomotion and steering	3. Fins may occur in larval stage. The adult does not possess fins. Limbs occur instead.
4. Heart. It is two chambered.	4. Heart is 3-chambered.
3. Lungs. Pisces do not have lungs.	5. Lungs are present.
Examples. Scoliodon, Labeo.	Examples. Frog, Toad.

Question 17.
(a) List any two main characteristics of chordates.
(b) In which class would you place an organism which has

1. Four chambered heart and lays eggs,
2. Skeletons made of both bones and cartilage and are cold blooded.
   (CCE 2011)

Answer:
(a) Chordate Features:

1. Occurrence of notochord that is transformed into cranium and vertebral column in higher chordates.
2. Presence of dorsal hollow nerve cord above the notochord which in higher chordates is transformed into brain and spinal cord.

(b)

1. Aves.
2. Pisces.

Question 18.
Name the phylum to which this organism belongs. Write any two characteristic features of the phylum. (CCE 2011, 2012)

Answer:
Mollusca (animal Octopus).

1. Soft bodied animals with a shell,
2. Unsegmented, triploblastic body with haemocoel. Both shell and haemocoel absent in Octopus.

Question 19.
Classify the following organisms based on the absence/ presence of true coelom, i.e., acoelomate, pseudocoelomate and coelomate :
(a) Scorpion
(b) Sea Anemone
(c) Ascaris
(d) Earthworm
(e) Wuchereria
(f) Nereis. (CCE 2011)
Answer:
(a) Scorpion – Coelomate (also haemocoelomate).
(b) Sea Anemone-Acoelomate.
(c) Attïzro-Pseudocoelomate.
(d) Earthworm- Coelomate.
(e) Wuchereria – Pseudocoelomate.
(f) Nereis-Coelomate.

Question20.
What is the most striking features of the following phyla :

1. Arthropoda
2. Amphibia
3. Porifera.
   (CCE 2011, 2012)

Answer:

1. Arthropoda: Chidnous exoskeleton and jointed appendages.
2. Amphibia: Living in both water and on land with smooth skin having mucous glands and three chambered heart.
3. Porifera: Diploblastic, acoelomate, sedentary animals with porous body and canal system.

Question 21.
Name the largest group of animals. Write the salient features of this group. Give two examples. (CCE 2012, 2013)
Answer:
Largest Group. Arthropoda.
Salient Features

1. Presence of jointed appendages.
2. Occurrence of chitinous exoskeleton,
3. Presence of haemocoel and open circulatory system.
   Examples. Cockroach, Housefly, Mosquito.

Question 22.
Classify the following organisms on the presence of coelom— Spongilla, Planaria, Scorpion, Birds, Ascaris, Nerreis.
(CCE 2012)
Answer:
Spongilla—acoelomate. Planaria-acoelomate.
Scorpion— coelomate (haemocoelomate).
Birds—coelomate. Ascaris- pseudocoelomate.
Nereis—coelomate.

Question 23.
State the appropriate term for the following :

1. Plants which bear seeds with two cotyledons.
2. Animals which do not have coelom.
3. Edible fungi. (CCE 2012)

Answer:

1. Dicots,
2. Acoelomate
3. Mushrooms.

Question 24.
State the type of cells monerans have. State their structure and the type of nutrition they have (CCE 2012)
Answer:
Monerans have prokaryotic cells.
Structure: Monerans are basically unicellular. The cells possess peptidoglycan (= murein) cell wall, no membrane bound organelles, genetic material coiled to form nucleoid without any membranous covering.
Nutrition: Varied, both autotrophic and heterotrophic.

Question 25.
Define

1. Lichens
2. Cryptogams
3. Phanerogams. (CCE 2012, 2013)

Answer:

1. Lichens: They are dual organisms which have been formed by a permanent symbiotic association between an alga and a fungus, e.g. Graphis.
2. Cryptogams: They are seedless lower plants where reproductive organs are inconspicuous requiring an external water for fertilization.
3. Phanerogams: They are seed bearing higher plants which possess conspicuous reproductive organs like cones and flowers, e.g., Pinus, Wheat.

Question 26.
List three distinguishing features between annelid animals and arthropods. (CCE 2012)
Answer:
1. Exoskeleton. Annelids do not have a chitinous exoskeleton which is present in arthropods.
2. Circulatory System. Annelids have a closed circulatory system while arthrpods have open circulatory system.
3. Appendages. Appendages are unjointed in annelids and jointed in arthropods.

Question 27.
(a) On what basis does the embryo of cryptogams differ from that of phanerogams ?
(b) Describe the feature that divides the angiosperms in two groups
(c) State the two subgroups of angiosperms. (CCE 2012)
Answer:
(a) Embryo of cryptogams is naked while that of phanerogams is covered being present inside the seed.
(b) Number of cotyledons in the seed.
(c) Dicots and monocots.

Question 28.
(a) What is the function of notochord ?
(b) List out any four features that all chordates possess.
(CCE 2012)
Answer:
(a) Function of Notochord. It provides attachment to muscles. Phylogenetically it has given rise to jointed axial skeleton of cranium and vertebral column.
(b) Presence of

1. Notochord which in higher forms is transformed into cranium and vertebral column,
2. Dorsal Hollow Nerve Cord. In higher chordates, it is transformed into brain and spinal cord.
3. Pharyngeal Gill Slits. Present at some stage of life cycle,
4. Post-anal tail.

Question 29.
Draw a neat diagram of Spirogyra and label the following parts
(a) Outermost layer of cell
(b) Organelle that performs the function of photosynthesis,
(c) Jelly-like substance in the cell where all organelles are suspended.
(d) Darkly coloured and dot-like structrue generally present in the centre of the cell. (CCE 2012)
Answer:

(a) Cell wall (outermost layer of cell)
(b) Chloroplast (organelle that performs the function of photosyntheis)
(c) Cytoplasm (jelly-like substance in the cell).
(d) Nucleus (darkly stained dot-like structrue).

Question 30.
Give reasons for the following :
(a) Echidna and Platypus lay eggs but are considered mammals
(b) Crocodile has four chambered heart but still is a reptile.
(c) Birds have pneumatic bones. (CCE 2012)
Answer:
(a) Platypus and Echidna possess body hair and mammary glands like other mammals.
(b) Crocodiles are piokilothermic, lay cleidoic eggs, with body having cornified skin covered with scales and bony plates.
(c) Pneumatic bones are light and strong required for birds in their flight.

Question 31.
Name the phylum to which the following organisms belong :
(a) Organisms which have peculiar water driven tube feet system that they use for moving around.
(b) Organisms which have a foot that is used for moving around and have an open circulatory system.
(c) The organisms have holes or pores all over their body.
They lead to a canal system that helps in circulating water throughout the body. (CCE 2012)
Answer:
(a) Echinodermata
(b) Mollusca
(c) Porifera.

Question 32.
Identify and name the following :
(a) Organisms that use dead and decaying organic material as food.
(b) Cell walls of fungi are made of this type of sugar
(c) Kingdom to which Amoeba belongs
(d) An example of moneran
(e) An animal with a pseudocoelom.
(f) A group which has an open circulatory system.
(CCE 2012)
Answer:
(a) Saprophyte, e.g., Rbizopus.
(b) N-acetyl glucosamine (forms chitin).
(c) Protista (unicellular eukaryotes)
(d) Escherichia coli, a bacterium
(e) Pseudocoelomate, e.g., Ascaris.
(f) Arthropoda.

Question 33.
Classify the following and write one characteristic of each :
(a) Lichen
(b) Sponges
(c) Flatworm. (CCE 2012)
Answer:
(a) Lichen: Dual organism made of an alga and a fungus showing mutualism,
(b) Sponges: Porifera. Having inhalent pores or ostia and an exhalent pore or osculum connected by a canal system.
(c) Flatworm: Platyhelminthes. Triploblastic, acoelomate.

Question 34.
“Tapeworm is triploblastic”, what does it mean ? How is Hydra different from Tapeworm in this aspect ? Name the phylum to which Hydra and Tapeworm belong.
(CCE 2012)
Answer:
Tapeworm is triploblastic because it has three germinal layers (ectoderm, mesoderm and endoderm). Hydra is diploblastic as it has two germinal layers (ectoderm and endoderm). Hydra—coelenterata. Tapeworm-
Platyhelminthes.

Question 35.
(a) Write two distinct features by which vertebrates are differentiated from invertebrates
(b) What are protochordates ? Give two examples.
(CCE 2012)
Answer:
(a)

(b) Protochordates are non-vertebrate chordates with a single layered epidermis, hollow dorsal but undifferentiated nerve cord as well as solid notochord in some stage of life cycle, e.g., Amphioxus.

Question 36.
Give other name to the category of plants that are called phanerogams. How are they further classified on the basis of their seeds ? Give example of each category. (CCE 2012)
Answer:
Seed plants or spermatophyta. Two categories

1. Gymnosperms-naked seeds, e.g., Pinus.
2. Angiosperms (Flowering Plants, seeds inside fruits).

Further of two types :

1. Monocots—single cotyledon in seeds, e.g., Maize.
2. Dicots—two cotyledons in seeds, e.g., Pea.

Question 37.
Write the names of the kingdom for the following organisms
(a) Single celled, eukaryotic and photosynethetic
(b) Multicellular, eukaryotic and photosynthetic
(c) Single-celled, prokaryotic and heterotrophic. (CCE2012)
Answer:
(a) Protista
(b) Plantae
(c) Monera.

Question 38.
(a) Name the kingdom to which Protozoa belong.
(b) Write one important characteristic of that kingdom.
(c) Name the appendages present in
(z) Euglena
{it) Paramoecium. (CCE 2012, 2013)
Answer:
(a) Protista
(b) Eukaryotic unicellular organisms.
(c) (t) Euglena-Ragellum
{iî} Paramoecium-cilia.

Question 39.
To which class do Salamander and Sparrow belong ?
Write any two differences between these classes.
(CCE 2012)
Answer:
Salamanader: Class Amphibia.
Sparrow: Class Aves.

Question 40.
(a) How are food and oxygen circulated in the body of organisms belonging to phylum porifera ?
(b) Why do fish have stream-lined body ?
(c) State the reason for birds having stream-lined body.
(CCE 2012)
Answer:
(a) By canal system which has many ostia or inhalent pores and one exhalent pore or ostium. Water circulates due to activity of flagellated collar cells or choanocytes.
(b) Fish have stream-lined body to meet minimum resistance while swimming in water
(c) Stream lined body provides least resistance to birds while flying.

Question 41.
Write one difference between
(a) Monera and Protista
(b) Platyhelminthes and Nematode. (CCE 2012)
Answer:
(a) Monera have prokaryotic nature while protista have eukaryotic nature.
(b) Platyhelminthes are acoelomate while nematodes are pseudocoelomate.

Question 42.
‘Snails are soft bodied shelled animal’. Identify the phylum to which they belong. Write any two distinguishing features of the phylum. (CCE 2012)
Answer:
Mollusca:

1. Unsegmented body with open circulatory system.
2. A muscular foot for locomotion.

Question 43.
What are cotyledons ? Name and discuss important features of two classes of angiosperms based on number of cotyledons. (CCE 2012)
Answer:
Cotyledons are seed leaves present over embryo axis below the plumule. On the basis of their number, angiosperms have been divided into two classes, monocots and dicots. Monocots. There is a single cotyledon. Monocots have parallel venation, fibrous root system and trimerous flowers.
Dicots: There are two cotyledons. Dicots have reticulate venation, tap root system and pentamerous or tetramerous flowers.

Question 44.
Write two examples of organisms belonging to.

1. Nematoda
2. Platyhelminthes
3. Arthropoda
   (CCE 2012)

Answer:

1. Nematoda: Ascaris, Wuchereria.
2. Platyhelminthes Planaria (Dugesia), Liver Fluke (Fasciola).
3. Arthropoda. Prawn (Palaeomon), centipede (Scolopendra).

Question 45.
Given below is a flow chart for classification of plants, Identify ‘a’, ‘b’, ‘c’, ‘d, ‘e’ and ‘f’ as an appropriate characteristic or plant group. (CCE 2012)

Answer:
(a) Thallophyta
(b) Bryophyta
(c) Pteridophyta
(d) Spermatophyta
(e) Bear naked seeds
(f) Angisperms.

Question 46.
Write four main features of pteridophyta and give any two examples. (CCE 2012)
Answer:

1. Sporophyte: Dominant sporophyte differentiated into stem, leaves and roots.
2. Gametophyte: Small but independent.
3. Vascular Tissues: Present.
4. Seeds: Naked embryo, seeds absent.
   Examples. Selaginella, Dryopteris (Fern).

Question 47.
Is the given figure of a dicot or monocot ? Differentiate between dicots and monocots on the basis of venation and number of cotyledons in the seed. (CCE2012)

Answer:
Dicot

1. In dicots the leaves have reticulate venation. Venation is parallel in monocots.
2. The seeds of dicots have two cotyledons. A single cotyledon is present in the seeds of monocots.

Question 48.
Draw and label any four parts of a bony fish.
(CCE 2012)
Answer:

Question 49.
Write one point of difference between the following :
(a) Annelids and arthropods
(b) Thallophytes and ; Pteridophytes
(c) Poriferans and coelenterates. (CCE 2013)
Answer:
(a) Annelids have unjointed appendages while arthropods possess jointed appendages.
(b) Thallophytes have simple undifferentiated and nonvascular plant body while it is differentiated and vascular in pteridophytes.
(c) Periferans have a number of inhalent pores and a single exhalent pore while coelenterates have a single opening.

Question 50.
Write one point of difference each between the j following :
(a) Amphibians and reptiles
(b) Aves and mammals
(c) Gymnosperms and angiosperms.(CCE 2013)
Answer:
(a) Skin is smooth, moist and non-cornified in amphibians while it is dry, scaly and cornified in reptiles.
(b) The body is covered by feathers and scales in aves. Hair occur in mammals.
(c) Gymnosperms possess naked seeds while angiosperms have seeds enclosed in fruits.

Question 51.
Write two examples of each

1. Egg laying mammals
2. Organisms with open circulatory system.
3. Prokaryotic organisms. (CCE 2013)

Answer:

1. Egg Laying Mammals. Platypus, Echidna.
2. Organisms with Open Circulatory System. Arthropoda, Mollusca.
3. Prokaryotic Organisms. Rhizobium, Escherichia.

Question 52.
State reasons for the following :
(a) Bryophytes are called amphibians of the plant kingdom
(b) Gymnosperms are called so.
(c) Birds have wings and feathers. (CCE 2013)
Answer:
(a) Bryophytes are called amphibians of plant kingdom as they live in moist, damp and shady places. A layer of water is required on the soil surface for

1. Sexual reproduction.
2. Protection from transpiration and hence desiccation
3. Supply of water to all parts in the absence of vascular tissues.

(b) Gymnosperms are so called as they possess naked seeds (gymnos-naked, sperma—seed).
(c) Birds have wings for flight and feathers for insulation.

Question 53.
Write one characteristic feature of each of the following groups of organisms :

1. Cryptogams
2. Arthropods
3. Mammals. (CCE 2013)

Answer:

1. Cryptogams: Absence of seed so that embryo, if present, is always naked.
2. Arthropoda: Presence of jointed appendages and legs.
3. Mammals: Occurrence of mammary glands in females to nourish new borns.

Question 54.
“Lichens” show symbiotic life form between two organisms.

1. Name the two organisms showing this relationship
2. Write the kingdom to which each one belongs
3. In such relationship, organisms are parasitic or mutually benefitted from each other or mutually dependent on one another. Explain. (CCE 2013)

Answer:

1. Lichen: Lichen is formed by an obligate association between a fungus and an alga.
2. Fungus-kingdom Fungi. Blue-green alga-kingdom Monera.
3. Mutually dependent and mutually benefitted. In lichen, the alga manufactures food for itself as well as fungus. The fungus provides protection to alga, helps in fixation and absorption of water as well as minerals.

Question 55.
State reason for the following :
(a) Fungi are called saprophytes
(b) Platyhelminthes are called so. (CCE 2013)
Answer:
(a) Fungi are heterotrophs with absorptive type of nutrition. The free living fungi feed on organic remains. They secrete digestive enzymes into external medium. The organic matter solubilises. It is absorbed by fungi. Hence, fungi are called saprophytes (sapros-tottcn, phyton-phstx).
(b) Platyhelminthes (platy-flat, helminthes-worms) are called flat worms as they are dorsoventrally flattened.

Question 56.
Identify the organisms and write one characteristic feature of the phylum to which they belong. (CCE 2013)

Answer:
A- Sycon: Porifera. Presence of many inhalent pores (ostia) and one exhalent pore (osculum).
B- Earthworm: Annelida. Body is metamerically segmented.
C- Star Fish: Echinodermata. Radial symmetry with spiny exoskeleton.

Question 57.
(a) Give scientific name of human beings.
(b) Write two characteristic features of Aves and Mammals.
(CCE 2013)
Answer:
(a) Homo sapiens.
(b) Aves: Body covered with feathers, fore limbs modified into wings and jaws modified into horny toothless beak, e.g., Pigeon.
Mammalia: Hair covered body with integumentary glands, mammary glands in females, e.g., Tiger.

Question 58.
(a) Most mammals give birth to young ones. How do they nourish their young ?
(b) Name two egg laying mammals. (CCE 2014)
Answer:
(a) Through mammary glands by the females,
(b) Egg Laying Mammals. Platypus, Echidna.

Question 59.
Mr. Sharmas family had gone to visit a garden. Many beau¬tiful roses were there. Mr. Sharmas five year old son Himanshu wanted to pluck few roses. He was told not to do so by his elder sister Kanika who was in class IX.

1. Rose belongs to which division of plant kingdom?
2. State the number of cotyledons and type of root in rose plant.
3. How can you contribute in the preservation of flora and fauna around you ? (CCE 2014)

Answer:

1. Spermatophyta
2. Cotyledons. 2. Root: Tap root.
3. Preservation of flora and fauna,
   1. By not enroaching upon their habitat.
   2. By not damaging them through over exploitation or de-struction.

Question 60.
Write two examples each of the following :
(a) Animals which do not locomote.
(b) Flightless birds
(c) Molluscs without shell. (CCE 2014)
Answer:
(a) Sponges, corals,
(b) Emu, Ostrich, Kiwi
(c) Octopus, Banana Slug.

Question 61.
Write four conventions which are followed while writing the scientific names of organisms. Write the scientific name of tiger. (CCE 2014)
Answer:
Conventions.

1. It consists of two words, first generic (like noun) and second specific (species).
2. Generic name has first letter capital while specific word begins with small letter.
3. Both are derived from latin language or are latinised.
4. They are printed in italics or are underlined separately in hand-written form.

Tiger: Panthera tigris.

Question 62.
Carolus Linnaeus gave the two kingdom classification. Later ; it was changed by Ernst Haeckel (1894) and in 1969 ; Whittaker gave the five kingdom classification. Do you think that studying about the work done by earlier scientists or j their obsolete theories is useful for students of this genera- i tion ? Give three reasons. (CCE 2014)
Answer:
Science is a continuous search of truth. Search is based on the j knowledge previously gained and the appliances available, i As the appliances improve and the knowledge becomes wider and deeper, new truths become known. This changes the | previous concepts or theories.

1. It is always rewarding to learn about the past obsolete j theories in the light of then known knowledge. This shall prompt the students to discover loop holes in the present knowledge and theories.
2. As the gaps of present day knowledge become apparent, j a student will like to find yet hidden truths.
3. Exceptions in the theories bring about their perusral by the students – the truth of yesterday has become fiction of today and truth of today shall become fiction of tomorrow.

Question 63.
Name the phylum to which the following organisms belong :
(a) Earthworm
(b) Planaria
(c) Sycon
(d) Starfish
(e) Housefly
(f) Octopus.
Answer:
(a) Earthworm-Annelida.
(b) Planaria-Platyhelminthes
(c) Sycon-Porifera.
(d) Starfish-Echinodermata.
(e) House- fly-Arthropoda.
(f) Octopus-Mollusca.

Question 64.

1. Assign a group to an organism ‘X’ which has notochord in some larval forms,
2. What would be the place of occur- rence of‘X’.
3. What would be symmetry of‘X’ ? (CCE 2014)

Answer:

1. ‘X’ — group Protochordata, subphylum Urochordata.
2. Sea.
3. Bilateral.

Question 65.
To study biodiversity, a group of students are taken to a zoo and another to a safari in the woods. Which is the better way S of learning and why ?
What more can you gain from such experiences ?
(CCE 2014)
Answer:
Safari in the woods is a better way of learning biodiversity j than a visit to Zoo.

1. Woods are pieces of natural biodiversity of both plants and animals. Zoo contain only captured or endangered ani¬mals fed and cared by humans.
2. Delicate balance of nature can be known only through a visit to the woods.

Question 66.
Learning. Nature should not be disturbed beyond its inbuilt regeneration capacity. Otherwise many organisms will become endangered and disappear for ever.
Will advanced organisms by the same as complex organisms ? If so why ? (CCE 2014, 2015)
Answer:
Yes. Advancement is based on development of specializations. Specialisation occurs where there is more elaboration and hence more complexity. However, there is likelihood of specialisation to lead to overspecialisation which becomes a hindrance to competitive nature of existence in the biosphere. Dinosaurs, giant crocodiles and mammoth have died down due to this reason. Therefore, advancement is possible only if specialisation leads to greater elaboration and efficiency.

Question 67.
Mention the problem which is associated with using local names of organisms. How was this resolved ? Name the scien-tist who had introduced the above solution.
(CCE 2015)
Answer:
Problem: All organisms do not have local names. Some or-ganisms have multiple local names while a local name is also used for two or more organisms. The problem was resolved through the development of binomial nomenclature of organisms. It was introduced by Carolus Linnaeus (1751).

Question 68.
Most mammals give birth to young ones,
(a) How do they nourish their young ones ?
(b) Name two egg laying mamamals. (CCE 2015)
Answer:
(a) Young ones are nourished inside the womb through pla-centa and by milk from mammary glands after birth.
(b) Duck-billed Platypus, Echidna.

Question 69.
Classify the following organisms on the basis of absence or presence of true coelom, i.e., coelomate, acoelomate and pseudocoelomate : Ascaris, Herdmania, Earthworm, Planaria, Fishes, Humans. (CCE 2015)
Answer:
Acoelomate. Planaria.
Pseudocoelomate. Ascaris.
Coelomate. Herdmania, Earthworm, Fishes, Humans.

Question 70.
Give three differences between monocotyledonous and di-cotyledonous plants. (CCE 2015)
Answer:

Dicotyledoneae	Monocotyledoneae
1.      Cotyledons. In the seeds, the embryo bears two cotyledons. 2.       Venation. The leaves show reticulate venation. 3.       Vascular Bundles. Vascular bundles of the stem are open and arranged in a ring. 4.       Root System. The plants have tap root system. 5. Secondary Growth. Secondary growth occurs. 6. Flowers. Flowers are pentamerous (have five of each floral part) or tetramerous.	In the seeds, the embryo bears one cotyledon.The leaves show parallel venation.Vascular bundles of the stem are closed and scattered in the ground tissue.The plants have fibrous root system.Secondary growth does not occur.Flowers are trimerous (have three of each floral part).

Question 71.
Name three plants under the group Thallophyta. Mention three characteristics of this group. (CCE 2015)
Answer:
Spirogyra, Ulothrix, Chara, Ulva.
Characteristics :

1. Simple body design called thallus.
2. Reproductive organs are unicellular and non-jacketed.
3. An embryo stage is absent.

Question 72.
Give two examples of organisms belonging to the following phyla :
(a) Arthropoda
(b) Mollusca
(c) Protochordata.
(CCE 2015)
Answer:
(a) Arthropoda. Cockroach, Mosquito, Prawn.
(b) Mollusca. Pila, Pearl oyster, Octopus.
(c) Protochordata, Balanoglossus, Herdmania, Ampbioxus.

Question 73.
List any three characteristics of the phylum to which Hydra belongs. (CCE 2015)
Answer:
Hydra belongs to phylum Coelenterata (= Cnidaria).
Characteristics.

1. Diploblastic animals with tissue level organisation.
2. Body has a single opening for both feeding and elimination.
3. Tentacles with cnidoblasts or nematoblasts.
4. Nerve cells present but nerve plexus absent.

Question 74.
(a) What is the scientific name of human ?
(b) To which class of vertebrates does it belong ?
(c) Mention any two character-istics features of this group. ( CCE 2015, 2016)
Answer:
(a) Homo sapiens
(b) Mammalia
(c) Characteristics.

1. Seven cervical vertebrae, a diaphragm dividing trunk and hair on the skin,
2. Vivipary and nourishing the young one by milk from mammary galnds.

Question 75.
What is classification ? Why do we need to classify organisms ? Mention any two major characteristics used for classifying organisms. (CCE 2015)
Answer:
Classification. Classification is the arrangement of organisms into groups and sub-groups on the basis of their similarities and dissimilarities and placing them in a hierarchy that brings out their relationships.
Need for Classification:

1. Identification is not possible without any system of classification.
2. Classification helps in bringing out similarities and dissimilarities amongst organisms.
3. Relationships are built up with the help of classification. They indicate the evolutionary pathways.
4. Organisms of other localities and fossils can be studied only with the help of a system of classification.
5. It is not possible to study every organism. Study of one or two organisms gives sufficient idea about other members of the group.
6. Other branches of biology depend upon proper identification of the organism which is possible only through a system of classification.

Major Characteristics:

1. Prokaryotic and eukaryotic nature.
2. Unicellularity and multicelliuarity.
3. Nutrition.

Question 76.
State reason for the following :
(a) Tapeworm does not have a digestive tract,
(b) Frogs use both skin and lungs for breathing,
(c) Birds have pneumatic / hollow bones.
(CCE 2015)
Answer:
(a) Tapeworm resides in the area of digestive tract where digested food is available.
(b) Frog lives both over moist land as well as inside water. Lungs are useful over land as well as after coming to the water surface. Moist skin is useful in respiration inside water and soil.
(c) Hollow or pneumatic bones are not only stronger than the solid bones but also make the body light weight for flight.

Question 77.
How do cnidarians (coelenterata) differ from porifera ?
(CCE 2015)
Answer:

Poriferans	Coelenterates
1. Organisation. It is of cellular level.	It is of tissue level.
2. Pores. A number of inhalent pores or ostia and a single exhalent pore or osculum are present.	There is a single opening.
3. Digestion. It is intracellular.	It is both intracellular and intercellular.
4. Muscle and Nerve Cells. They are absent.	Primitive muscle and nerve cells appear for the first time in coelenterates.
5. Appendages. They are absent.	Appendages are represented by tentacles.
6. Special Cells. The special cells are choanocytes or collar cells.	Special cells are cnidoblasts.

Question 78.

1. Draw the relevance of scientific naming of an organism.
2. Who introduced this system of nomenclature ?
3. Rana tigrina is the scientific name of common frog.
   What do these two terms imply ? (CCE 2015)

Answer:

1. Advantage,
   1. It is universal, being the same in all languages and conntries.
   2. It is distinct and sepcific with no two organisms having the same name.
2. Carolus Linnaeus.
3. In Rana tigrina, the word Rana signifies genus or ge¬neric name while tigrina is a specific epithet or species.

Question 79.
Differentiate between gymnosperms and angiosperms.
(CCE 2016)
Answer:

Gymnosperms	Angiosperms
1. Sporophylls. They are aggregated to form cones.	Sporophylls are aggregated to form flowers.
2. Seeds. The seeds are naked.	The seeds are enclosed by fruit wall.
3. Microspores and Megaspores. The micro-spores and megaspores are produced by male and female cones.	They are produced in the same or two different types of flowers.
4. Vascular Tissues. Xylem lacks vessels and phloem lacks companion cells.	Xylem contains vessels and phloem contains companion cells.
5. Ovules. The ovules are not contained in the ovary.	The ovules are enclosed in the ovary.
6. Endosperm. It is haploid.	It is triploid.

Question 80.
State three bases for classification of organisms into five king-doms. (CCE 2016)
Answer:
Four criteria have been used for grouping of organisms into five kingdoms—

1. Procaryotic and eukaryotic nature
2. Unicellular and multicellular nature
3. Nutrition

Question 81.
Name the scientist who proposed two kingdom classification of living organisms. Name those kingdoms. Write major drawbacks of the proposed classification. ( CCE 2016)
Answer:

1. Carolus Linnaeus,
2. Plant kingdom and Animal kingdom.

Drawbacks:

1. Prokaryotes. Both prokaryotes and eukaryotes are placed in the same kingdom.
2. Fungi are included amongst plants when they are structurally different from them,
3. Organisms like Euglena are included in both the kingdoms,
4. Viruses do not belong to either of the kingdom.

Question 82.
(a) Give any two important characteristics of kingdom Fungi.
(b) What is symbiotic relationship between blue-green algae and fungi called ? ( CCE 2016)
Answer:
(a) Protochordates are non-vertebrate chordates with a single layered epidermis, hollow dorsal but undifferentiated nerve cord as well as solid notochord in some stage of life cycle, e.g., Amphioxus.
(b) Lichen.

Question 83.
Classify the following organisms into their respective kingdoms as per Whittaker’s five kingdom classification : Amoeba, Euglena, Birds, Herbs, Cats, Lactobacillus. (CCE 2016)
Answer:
(a) Amoeba—Protista,
(b) Euglena—Protista,
(c) Birds— Chordata (class Aves).
(d) Herbs—Plantae.
(e) Cats — Chordata (class Mammalia),
(f) Lactobacillus—Monera.

Question 84.
State the advanced features present in and seen for the first time (according to evolution) in the following groups :

1. Pteridophyta
2. Gymnosperms
3. Angiosperms.
   (CCE 2017)

Answer:

1. Pteridophyta: Vascular tissues,
2. Gymnosperms: Seeds.
3. Angiosperms: Fruits.

Question 85.
Write the names of the following :

1. Plants which bear naked seeds
2. Animals which have pseudocoelom (any two)
3. Animals which maintain a constant body temperature. (CCE 2017)

Answer:

1. Gymnosperms
2. Nematoda, e.g., Ascaris, Wuchereria.
3. Homoeotherms.

Question 86.
Draw a neat labelled diagram of Paramecium and mention the group to which it belongs. (CCE 2017)
Answer:

Group Protista.

Question 87.
Write the difference between amphibians and Pisces.
(CCE 2017)
Answer:

Pisces	Amphibians
1. Scales. The body is covered by scales.	1. Scales are absent.
2. Mucous Glands. The skin does not possess mucous glands.	2. The skin has mucous glands that keep the skin moist and slippery.
3. Fins. Pisces possess fins for locomotion and steering	3. Fins may occur in larval stage. The adult does not possess fins. Limbs occur instead.
4. Heart. It is two chambered.	4. Heart is 3-chambered.
3. Lungs. Pisces do not have lungs.	5. Lungs are present.
Examples. Scoliodon, Labeo.	Examples. Frog, Toad.

Question 88.
State any three differences between cryptogamae and phanerogamae. (CCE 2017)
Answer:

Cryptogamae	Phanerogamae
1.             It contains seedless plants. 2.              It has both vascular and non-vascular plants. 3.              An external water is required for fertilization.	It contains seed plants. It possesses only vascular plants. An external water is not required

Long Answer Questions (5 Marks)

Question 1.
Draw a flow chart to show different divisions of kingdom plantae and answer the following :

1. Which division has the simplest plants ?
2. To which division Pinus and Cycas belong ?
3. What is the other name given to flowering plants. Classify them on the basis of number of cotyledons present in the seed. (CCE 2012)

Answer:

1. Simplest Plants: Thallophyta (Algae).
2. Pinus and Cycas: Gymnospermae of spermatophyta.
3. Angiosperms: Two groups, dicots (with two cotyledons in seeds) and monocots (with one cotyledon in seeds).

Question 2.

1. What is the scientific name of human ?
2. To which class of vertebrates does it belong ?
3. Write five characteristic features of this group. Also mention the exceptions, if any. (CCE 2012)

Answer:

1. Homo sapiens
2. Class mammalia.
3. Characteristics of Mammalia
   1. Presence of mammary glands in females.
   2. Occurrence of hair over the body.
   3. Cervical vertebrae are seven in number.
   4. A muscular diaphragm occurs between abdomen and thorax.
   5. Mammals are viviparous i.e., adult females give birth to young ones.

Exceptions:
Duck-billed Platypus and Echidna are egg laying mammals. Kangaroos and their relatives give birth to young ones in very early stage of development. They are nourished in mother’s marsupium,

Question 3.
(a) Name the group of plants which have unicellular undifferentiated body.
(b) Why are echinoderms named so ?
(c) Name plants not having well differentiated body design.
(d) Name the plants which are perennial, evergreen, woody and bear naked seeds.
Answer:
(a) Diatoms, dinoflagellates.
(b) The animals possess an exoskeleton of spines over the body.
(c) Bryophytes, thallophytes
(d) Gymnosperms.

Question 4.
(a) List two distinguishing features between poriferan and coelenterate animals.
(b) Give reason to justify the following statements

1. Platypus and Echidna lay eggs but are considered mammals.
2. Crocodiles have four chambered heart but are still reptiles.
3. Fore limbs of birds are modified. (CCE 2012)

Answer:
(a) Poriferans and Coelenterates

1. Pores: Poriferans have a canal system with a number of inhalent pores or ostia and a single exhalent pore or osculum. Coelenterates have a single opening.
2. Special Cells: Poriferans possess choanocytes or collar cells. Coelenterates have enidoblasts or stinging cells.

(b)

1. Platypus and Echidna possess body hair and mammary glands like other mammals.
2. Crocodiles are piokilothermic, lay cleidoic eggs, with body having cornified skin covered with scales and bony plates.
3. In birds the fore limbs are modified to form wings for flight.

Question 5.
(a) What is coelom ? State its significance.
(b) Pick out the organisms that have pseudocoelom from the following : Earthworm, Pinworm, Tapeworm and Roundworm
(c) What is peculiar about the coelom of arthropods ? What is such a condition called ? Explain.
(d) To which phylum of animalia do the following belong : Octopus, Pila, Chiton and Unio. Comment on their coelom. (CCE 2012)
Answer:
(a) Coelom. It is mesoderm lined fluid-filled space that occurs between alimentary canal and body wall. Significance. Coelom suspends and gives shock proof . environment to various body organs.
(b) Pseudocoelom. Pinworm, Roundworm.
(c) Coelom of Arthropods. True coelom is reduced. Sinuses or spaces in between the organs enlarge and fuse to form blood filled cavity called haemocoel. ‘
(d) Mollusca. They posses haemocoel.

Question 6.
(a) On the basis of characteristics given below, name the phyla :

1. Soft bodied animal with muscular foot, mantle and calcareous shell.
2. Animals which have double layers of cells, single opening and tentacles.
3. Body simple, multicellular, vase-like with pores, opening at one end.
4. Largest group of animals, bilaterally symmetrical, segmented, coelomic cavity is blood filled.

(b) “Star Fish cannot be placed under the phylum of pisces.” Explain. (CCE 2012)
Answer:
(a)

1. Mollusca
2. Coelenterata
3. Porifera
4. Arthropoda.

(b) Star Fish is an echinoderm with spiny exoskeleton, water vascular system and tube feet. It does not have any fish-like characters (fins, gills, lateral line organs).

Question 7.
(a) Write four characteristic features of protochordates.
(b) State reasons for the following :

1. Tapeworms do not have digestive tract.
2. Frogs have both skin and lungs for breathing.
3. Whale is a mammal, not a fish. (CCE 2012)

Answer:
(a) Characteristic Features of Protochordates.

1. Single layered epidermis,
2. Occurrence of notochord at least in some stage.
3. There is a dorsal hollow nerve cord,
4. Gill slits are present,
5. A post-anal tail is found.

(b)

1. Tapeworm lives in that part of human intestine which contains digested absorbable food.
2. Frog has a smooth moist skin richly supplied with blood vessels for cutaneous respiration. Being amphibian it also possesses lungs for breathing over land.
3. Whale has pulmonary respiration, four-chambered heart, mammary glands and other traits of mammals. It appears fish like because it lives in water and has a body structure suitable for swimming.

Question 8.
Classify vertebrates in five classes giving two characteristics and an example for each. (CCE 2012)
Answer:
The five classes of vertebrates are pisces, amphibia, reptilia, aves and mammalia.

1. Pisces: Stream-lined scale covered body with 2-chambered heart, gills and fins, e.g. Labeo.
2. Amphibia: Smooth scale-less body surface with mucous glands, 3-chambered heart and two pairs of limbs, e.g., Frog.
3. Reptilia: Dry scale covered skin, incompletely four chambered heart, e.g., Wall Lizard.
4. Aves: Body covered with feathers, fore limbs modified into wings and jaws modified into horny toothless beak, e.g., Pigeon.
5. Mammalia: Hair covered body with integumentary glands, mammary glands in females, e.g., Tiger.

Question 9.
Classify kingdom Plantae into five groups giving one characteristic feature and two examples of each group.
(CCE 2012, 2015)
Answer:
Plantae is divisible into five groups of thallophyta, bryophyta, pteridophyta, gymnosperms and angiosperms.

1. Thallophyta: Simple undifferentiated plant body with unicellular reproductive organs lacking an embryo stage, e.g. Spirogyra, Chara.
2. Bryophyta: Simple, amphibious with gametophytic plant body and parasitic sporophyte, e.g., Marchantia, Moss.
3. Pteridophyta: Seedless, differentiated, vascular sporophytic plant body with small independent gametophyte, e.g. Lycopodium, Fern.
4. Gymnosperms: Vascular plants with exposed or naked seeds, e.g., Pinus, Cycas.
5. Angiosperms: Flowering plants with fruits enclosing seeds, e.g. Maize, Rose.

Question 10.
Cockroach, spider and prawn are placed under phylum arthropoda. State the reason for this. Write three other distinct features of this phylum. Give another example of an aquatic arthropod and terrestrial arthropod. (CCE 2012)
Answer:
Cockroach, spider and prawn are included in phylum arthropoda because they are segmented triploblastic bilaterally symmetrical animals having jointed appendages.
Other features.

1. Chitnous exoskeleton,
2. Body divided into head, thorax and abdomen with head and thorax fused in some groups.
3. Coelom is reduced. Haemocoel with open circulatory system present.

Question 11.
Aquatic Arthropod. Cancer (Crab). Terrestrial arthropod, Silver Fish.
(a) What is the basis of major division of kingdom plantae ?
(b) What was the modification introduced by Woese in kingdom Monera ? (CCE 2012)
Answer:
(a) Presence or absence of seeds or distinct reproductive structures dividing plantae into phanerogamae (covered embryo) and cryptogamae (naked embryo or seeds absent),
(b) Woese (1977, 1994) has divided kingdom monera and created two independent kingdom of Eubacteria and Archaea (formerly archaebacteria) on the basis of cell wall, cell membrane and RNA structure.

Question 12.
The following is a list of invertebrates. Classify them into different phyla giving one characteristic morphological feature to justify your classification : (CCE 2012)
(a) Star Fish
(b) Nereis
(c) Housefly
(d) Sycon
(e) Planaria.
Answer:
(a) Star Fish: Echinodermata. Spiny skinned with tube j feet,
(b) Nereis: Annelida. Metameric segmentation, true j coelom with closed vascular system,
(c) Housefly, Arthropoda: Chitinous exoskeleton with jointed appendages,
(d) Sycon: Porifera. Sedentary diploblastic animals with ostia, osculum and canal system,
(e) Planaria: Platyhelminthes. Triploblastic, acoelomate.

Question 13.
What are the five kingdoms of Whittaker ? Give the most important characteristic feature of each kingdom.
(CCE 2012)
Answer:

1. Monera: Prokaryotic organisms.
2. Protista: Unicellular eukaryotic organisms.
3. Fungi: Nonchlorophyllous, spore producing heterotrophs j with cell wall having chitin and glycogen as reserve food,
4. Plantae: Photosynthetic organisms having plastids and cellulose cell wall.
5. Animalia: Wall-less heterotrophic organisms with holozoic nutrition.

Question 14.
Name the five classes of vertebrates. Compare any two on the basis of their

1. Habitat
2. Covering of skin
3. Respiratory organs
4. Chambers of heart
5. Reproduction. (CCE 2012)

Answer:
Pisces, amphibia, reptilia, aves and mammalia.

Question 15.
(i) To which division of plantae do algae belong ? Write one characteristic of the division. Give two examples.
(ii) Name the group

(a) Which includes unicellular eukaryotic organisms.
(b) In which mode of nutrition is saprophytic
(c) In which seeds are not enclosed in fruit.

(iii) Write scientific names of

(a) Peacock
(b) Neem
(c) Potato.

(iv) Name the division whose members are called amphibians of plant kingdom,
(v) Write one difference between thallophytes and bryophytes with one example of each. (CCE 2012)
Answer:
(i) Algae belong to division thallophyta. Thallophyta is characterised by single celled non-jacketed reproductive structures without an embryo stage, e.g., Ulothrix, Chara.
(ii)

(a) Protista
(b) Fungi
(c) Gymnosperms.

(iii)

(a) Peacock. Pavo cristatus
(b) Neem. Azadirachta indica
(c) Potato. Sotanum tuberosum

(iv) Bryophyta
(v) Reproductive organs are nonjacketed and unicellular in thallophyta (e.g., Ulothrix). They are jacketed and multi-cellular in bryophyta, e.g., Marchantia.

Question 16.
(a) Differentiate between fungi and plantae
(b) Mention the basis of classification among plants to different levels. (CCE 2012, 2015)
Answer:
(a) Differences


(b)

1. Presence or absence of conspicuous reproductive organs— phanerogamae and cryptogamae.
2. In cryptogamae, undifFerentiated plant body-thallophyta.
3. In cryptogamae, plant body differentiated without vascular tissues-bryophyta while with vascular tissues-pteridophyta
4. In phanerogamae, gymnosperms if seeds are naked and angiosperms if seeds are enclosed inside fruits.

Question 17.
(a) State two uses of classifying plants and animals into different categories,
(b) List two characteristic features of fungi. Some fungal species live in permanent mutually dependent relationship with cyanobacteria. What is this relationship called ? Where are they found ? (CCE 2013)
Answer:
(a)

1. Classifying plants and animals into categories gives us an idea of whole range of diversity found in them
2. It help in studying inter-relationships and evolution of various groups.

(b) Characteristics of Fungi.

1. The body called mycelium is made of achlorophyllous threads.
2. Cell wall contains chitin.
3. Nutrition is heterotrophic and absorptive,
4. Reserve food is glycogen and oil.

Fungal Relationship With Some Blue-Green Algae or Cyanobacteria.
Symbiosis or mutualism. The dual organisms grow on rocks and tree trunks. They are called lichens.
Occurrence. Rocks, bark of trees, ice.

Question 18.
(a) State four characteristic features of mammals.
(b) Identify the group to which the following belong :

1. Plants with body differentiation into stem and leaf-like structures and hidden reproductive organs,
2. Plants with tap root system and two cotyledons in the seed,
3. Plants that do not have well differentiated body designs.
   (CCE 2013)

Answer:
(a) Mammals are viviparous i.e., adult females give birth to young ones.
(b)

1. Bryophytes
2. Dicotyledons
3. Thallophytes.

Question 19.
(a) State two characteristic features of phylum arthropoda
(b) Identify the organisms on the basis of the following features :

1. Egg laying mammal
2. A reptile with four chambered heart
3. A nematode causing elephantiasis. (CCE 2013)

Answer:
(a)

1. Presence of jointed appendages.
2. Occurrence of chitinous exoskeleton,

(b)

1. Echidna
2. Crocodile
3. Wuchereria.

Question 20.
(a) How do poriferan animals differ from coelenterate animals ?
(b) Identify the kingdom on the basis of following features :

1. Multicellular eukaryotes without cell wall
2. Unicellular eukaryotes
3. Multicellular eukaryotic autotrophs. (CCE 2013)

Answer:
(a)

Poriferans	Coelenterates
1. Organisation. It is of cellular level.	It is of tissue level.
2. Pores. A number of inhalent pores or ostia and a single exhalent pore or osculum are present.	There is a single opening.
3. Digestion. It is intracellular.	It is both intracellular and intercellular.
4. Muscle and Nerve Cells. They are absent.	Primitive muscle and nerve cells appear for the first time in coelenterates.
5. Appendages. They are absent.	Appendages are represented by tentacles.
6. Special Cells. The special cells are choanocytes or collar cells.	Special cells are cnidoblasts.

(b)

1. Animalia
2. Protista
3. Plantae.

A person enters a museum and observes animal specimens. He looks at one marked ‘Salamander’ and calls it a lizard.

Question 21.
How will you explain to him that salamanders and lizards belong to different classes by listing out at least four features and give one example each. (CCE 2013)
Answer:
Salamander belongs to amphibia and lizard to reptilia.

Amphibia	Reptilia
1. Skin. It is glandular smooth and moist.	Skin is non-glandular, dry and keratinised.
2. Scales. They are absent.	Scales are present over the body.
3. Claws. Digits do not possess claws.	Digits end in claws.
4. Heart. It is three chambered.	Heart is incompletely four chambered.
5. Fertilization. It is external.	Fertilization is internal.
6. Membranes. Extra-embryonic membranes are absent.	Extra-embryonic membranes are present.
7. Eggs. They have a soft covering.	They have a hard covering or shell.
Examples. Frog, Toad.	Examples. Lizards, Snakes, Tortoise.

Question 22.
Create a flow chart to show the classification of four eukaryotic kingdom ? (CCE 2014)
Answer:

Question 23.
Give the scientific and common name of an organism that possesses the following features :
(a) Are found both on land and water,
(b) Lay eggs on land.
(c) Skeleton made of cartilage,
(d) Hair on their body.
(e) Cold blooded. (CCE 2014)
Answer:
(a) Amphibians. Frog – Rana tigrina
(b) Aquatic Reptiles. Crocodile – Crocodylus.
(c) Chondrichthyes – Dog Fish – Scoliodon.
(d) Mammalia. Monkey – Macaca.
(e) Poikieothermous. Garden Lizard – Calntes.

Question 24.
Identify the phylum of animalia in which the animals have
(a) Apseudocoelons
(b) A water driven tube system.
(c) Jointed legs,
(d) Pores in the body leading to a canal system,
(e) Notochord at some stage of their life.
(CCE 2014, 2015)
Answer:
(a) Nemathelminthes
(b) Echinodermata
(c) Arthropoda
(d) Porifera
(e) Chordata (Protochordata).

Question 25.
Prove that Labeo rohita is a chordate. (CCE 2014)
Answer:
Labeo rohita is a chordate because it possesses all the chordate characters.
Diagnostic Characteristics:

1. Notochord (Gk. noton—back, chorde—cord). It is a long rod-like structure that develops between dorsal nervous system and gut. Notochord functions as a support structure that provides points for attachment to muscles. In higher chordates, notochord is transformed into cranium and vertebral column.
2. Dorsal Hollow Nerve Cord. It occurs above the notochord. In higher chordates it gets transformed into brain and spinal cord.
3. Pharyngeal Gill Slits (Gill Pouches). They are paired respiratory structures which remain functional throughout life in fishes and some amphibians. In others they occur only in embryo.
4. Post-anal Tail. It occurs in most chordates for balancing, protection of genital and anal regions.

Question 26.
Assign appropriate class/phylum/division to the following :
(a) Salamonder
(b) Flying lizard
(c) Ostrich
(d) Bat
(e) Herdmania
(f) Wuchereria
(g) Ulva
(h) Marchantia
(i) Marsilea
(j) Ipomoea. (CCE 2014)
Answer:
(a) Salamander. Chordata-Amphibia.
(b) Flying lizard. Chordata-Reptilia.
(c) Ostrich. Chordata-Aves
(d) Bat. Chordata—Mammalia,
(e) Herdmania. Chordata- Protochordata- Urochordata.
(f) Wuchereria. Nemathelm- inthes-Nematoda.
(g) Ulva. Thallop.hyta-Algae.
(h) Marchantia. Bryophyta
(i) Marsilea. Pteridophyta.
(j) Ipomoea. Spermatophyta – Angiospermae – Dicotyledoneae.

Question 27.
State one difference between each of the following :
(a) Thallophyta and Bryophyta
(b) Bryophyta and pteridophyta
(c) Pteridophyta and gymnosperms
(d) Gym¬nosperms and angiosperms
(e) Monocotyledonous and di¬cotyledonous plants. (CCE 2015)
Answer:
(a) Thallophyta and Bryophyta. In thallophyta the reproductive organs are unicellular, non-jacketed with no embryo stage. In bryophyta the sex organs are multicellular, jacketed with an embryo stage.
(b) Bryophyta and Pteridophyta. In bryophyta the plant body is non-vascular, gametophytic with parasitic sporophyte. In pteridophyta the plant body is vascular and sporophytic while gametophyte is small and independent.
(c) Pteridophyta and Gymnosperms. Pteridophyta has seedless vascular plants while gymnosperms have naked seeded vascular plants.
(d) Gymnosperms and Angiosperms: Thallophyta and Bryophyta In thallophyta the reproductive organs are unicellular, non-jacketed with no embryo stage. In bryophyta the sex organs are multicellular, jacketed with an embryo stage.
(e) Monocotyledonous and Dicotyledonous Plants. Mono- cotyledonous plants have parallel venation, fibrous roots and single cotyledon in seeds. Dicotyledonous plants have reticulate venation, tap roots and two cotyledons in seeds.

Question 28.
Explain the meaning of the terms and give an example in each of the following :
(a) Symbiotic relationship
(b) Cotyle¬dons
(c) Cryptogam
(d) Saprophytic
(e) Prokaryotic.
(CCE 2015)
Answer:
(a) Symbiotic Relationship. It is a mutually beneficial obligatory relationship between two organisms, e.g. Lichen.
(b) Cotyledons. They are seed leaves present over the embryo axis below the plumule in seeds. A single cotyledon occurs in the seeds of monocots (e.g., Maize) while two cotyledons occur in the seeds of dicots, (e.g., Pea).
(c) Cryptogam. It is a seedless plant with incospicuous reproductive organs and requiring external water for fertilization. e.g. : Ferns, Moss.
(d) Saprophytic. It is an organism that feeds on organic re-mains by the process of external diagestion, e.g., Rhizopus.
(e) Prokaryotic. It is a primitive organism that lacks membrane covered organelles and an organized nucleus, e.g., Escherichia coli.

Question 29.
Associate the following features with appropriate organisms and their kingdom (in ii and iv), division (in i) and phylum (in iii and v) :

1. Presence of pyrenoids.
2. Presence of heterocysts
3. Presence of genital papillae and anus
4. Presence of chloroplast and flagella
5. Presence of palp and parapodia. (CCE 2015)

Answer:

1. Presence of Pyrenoids. Spirogyra—Thallophyta (division).
2. Presence of Heterocysts. Nostoc— Monera (kingdom).
3. Presence of Genital Papillae and Anus. Earthworm— Annelida (phylum)
4. Presence of Chloroplast and Flagella. Euglena—Protista (Kingdom)
5. Presence of Palps and Parapodia. Nereis—Annelida (Phylum).

Question 30.
Study the figure and answer the following :

(a) Label A and B.
(b) Identify the organism and its kingdom.
(c) Name two organisms (other the one shown here) belonging to same kingdom.
Answer:
(a) A – Akinete.
B – Heterocyst.
(b) Anabaena – Monera.
(c) Nostoc, Clostridium, Escherichia.

Question 31.
Differentiate between the following :
(a) Amphibia and Mammalia
(b) Arthropoda and Echinodermata
(c) Platyhelminthes and Nematoda.
(CCE 2015)
Answer:
(a) Amphibia and Mammalia:

(b) Difference between Arthropoda and Echinodermata :

(c) Platyhelminthus and Nematoda :

Platyhelminthes	Nematheliminthes
1.      Form. They are flatworms. 2.      Coelom. Platyhelminthes are acoelomate. 3.      Digestive Tract. It is incomplete. 4.      Sexuality. Animals are hermaphrodite.	They are cylindrical in form and are called roundworms. Nemathelminthes are pseudocoelomate. It is complete. Animals are unisexual.

Question 32.
(a) Identify the picture and mention the phylum and class of kingdom animalia to which it belongs. (CCE 2015)

(b) Label a, b, c, d, e, and f.
Answer:
(a) Torpedo (Electric Ray),
Phylum- Chordata,
Class- Chondrichthyes.
(b) a – Spiracle,
b – Eye,
c – Pelvic fin,
d— Dorsal fin,
e—Tail,
f— Caudal fin.

Question 33.
Give a comparative account of 5 classes of phylum vertebrata based on :
(a) Organ of breathing
(b) Chambers in heart.
(CCE 2015)
Answer:

1. Pisces. Gills for breathing.
2. Chambered heart.
3. Amphibia. Gills, lungs and skin for breathing, 3-chambered heart.
4. Reptilia. Lungs for breathing, incompletely 4-chambered heart.
5. Aves. Lungs with air sacs for double respiration, four- chambered heart.
6. Mammalia. Lungs for breathing, four-chambered heart.

Question 34.
Schematically illustrate the classification of phanerogams. Give two examples of plants with vascular tissues which do not produce seeds. (CCE 2015)
Answer:

Examples of Seedless Vascular Plants. Selaginella, Fern.

Question 35.
Give a comparative account of the following :
(a) Ulothrix and Funaria
(b) Marchantia and Marsilca
(c) Fern and Pinus,
(d) Cycas and Rose,
(e) Wheat and Gram. ( CCE 2015)
Answer:
(a) Ulothrix and Funaria. Ulothrix is a filamentous green alga with simple structure of thallophytes. Funaria is a leafy moss plant with differentiated but non-vascular stmcture of bryophytes.
(b) Marchantia is a non-vascular little differentiated bryophyte while Marsilea is a vascular plant of pteridophyta which is differentiated into stem, leaves and roots.
(c) Fern is a seedless vascular plant belonging to pteridophyta while Pinus is a naked seeded vascular plant belonging to gymnosperms.
(d) Cycas is a naked seeded plant belonging to gymnosperms while Rose is covered seeded or fruit bearing plant belonging to angiosperms.
(e) Wheat is a monocot while Gram is a dicot.

Question 36.
Draw a diagram of Euglena and label the following parts : Flagellum, Photoreceptor, Eye Spot, Chloroplast, Nucleus, Contractile Vacuole. ( CCE 2016)
Answer:

Question 37.
(a) State three distinguishing features between the animals belonging to Aves group and those in the Mammalia group.
(b) List four conventions followed while writing the scientific names ofliving organisms. (CCE 2016)
Answer:
(a) Aves and Mammalia.

Aves	Mammalia
1. Wings. Forelimbs are modified into wings.	Wings are absent except in bats.
2. Feathers and Scales. The body is covered with feathers and scales.	Feathers and scales are absent.
3. Skin Glands. Skin is dry. Only a single preen gland is present.	Skin bears a number of sweat and oil glands.
4. Mammary Glands. They are absent.	Female possesses mammary glands for feeding the young
5. Diaphragm. A diaphragm is absent.	A partition called diaphragm is present between abdomen and thorax.
6. Beak. A toothless beak is present.	Jaws do not form a beak. Teeth are present.
7. Bones. They are hollow or pneumatic.	Bones do not possess air cavities.
8. Larynx/Syrinx. Larynx is non-functional. Instead syrinx is present.	Larynx is functional. Syrinx is absent.
External air sacs do not occur over lungs.
	9. Air Sacs. Lungs possess external air sacs.
10. Yolk. Eggs possess a lot of yolk (macrolecithal).	Eggs have little yolk (alecithal).
11. Reproduction. Birds are oviparous.	Mammals are viviparous with the exception of a few species.

(b) Binomial nomenclature is a scientific system of providing distinct and proper two word name to each and every organism.
Conventions:

1. It consists of two words, first generic (like noun) and second specific (species).
2. Generic name has first letter capital while specific word begins with small letter.
3. Both are derived from latin language or are latinised.
4. They are printed in italics or are underlined separately in hand-written form.

Question 38.
Identify the phylum/division

1. They have kidney like organs for excretion
2. They reproduce by spores and have specialised tissue for conduction of water and other substances,
3. Their body is dorsiventrally flattened.
   (CCE 2016)

Answer:

1. Mollusca
2. Pteridophyta
3. Platyhelminthes.

Question 39.
A plant specimen was found with rhizoids instead of differentiated roots,
(a) Identify the group to which it belongs,
(b) Write any two characteristics of this group
(c) Draw the diagram of a plant belonging to this group.
(CCE 2016)
Answer:
(a) Bryophyta
(b) Aves, Reptilia
(c)

Question 40.
Identify the phylum of kingdom animalia in which the animal has
(a) A pscudocoelom
(b) A water driven tube system
(c) Jointed legs
(d) Pores in the body leading to a canal system
(d) Notochord at some stages of their life. ( CCE 2017)
Answer:
(a) Pseudocoelom—Nematoda
(b) A water driven tube system—Echinodermata
(c) Jointed legs—Arthropoda
(d) Pores in the body leading to a canal system—Porifera
(e) Notochord at some stages of their life—Protochordata.

Question 41.
(a) Which division of plants is called the amphibians of plant kingdom ?
(b) What are characteristics of above division ? (any three)
(c) Give two examples of this division of plant kingdom. (CCE 2017)
Answer:
(a) Bryophyta
(b)

1. Very simple nonvascular amphibious land plants
2. Gametophytic plant body fixed by means of rhizoids
3. Sporophyte parasitic over the gametophyte

(c) Marchantia, Funaria.

Question 42.
(a) What is the largest phylum of animal kingdom.
( b) You are given Leech, Nereis, Scolopendra, Prawn and Scorpion. All of them have segmented body organisation. Will you classify them in are group. ( CCE 2017)
Answer:
(a) Largest Phylum. Arthropoda.
(b) Nereis and Leech belong to annelids while the other three belong to arthropoda. Annelids have unjointed appendages. Arthropods have jointed appendages. They also possess chitinous exoskeleton and open circulatory system. Annelids do not possess chitinous exoskeleton. They have closed circulatory system.

Question 43.
Complete the flow chart using appropriate features of groups : (CCE 2017)

Answer:
a—Tissue level of organisation,
b—Porifera.
c—Pseudocoelom,
d—Coelenterata.
e—Platyhelminthes.
f—Mesodermal cells develop from a single cell during growth of the embryo
g—Arthropoda.
h—Notochord present,
i—Echinodermata.
j—Protochoardata.

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