Diversity in Living Organisms Class 9 Notes

On this page, you will find Diversity in Living Organisms Class 9 Notes Science Chapter 7 Pdf free download. CBSE NCERT Class 9 Science Notes Chapter 7 Diversity in Living Organisms will seemingly help them to revise the important concepts in less time.

CBSE Class 9 Science Chapter 7 Notes Diversity in Living Organisms

Diversity in Living Organisms Class 9 Notes Understanding the Lesson

1. What is classification?
Grouping the organisms on the basis of their similarities and differences is called classification.

2. Need for classification

  • To provide information regarding diversity of plants and animals on the Earth.
  • Understand the interrelationship between different groups of plants and animals.
  • To find similarities or dissimilarities in their characteristic features.
  • To identify the organism.
  • To indicate evolutionary trends.

3. Characteristics or criteria of classification

  • Complexity of structure: Prokaryotes or Eukaryotes
  • Body organisation: Unicellular or Multicellular
  • Mode of obtaining Nutrition: Autotrophic or Heterotrophic
  • Evolutionary relationship
  • Presence or absence of cell wall

4. Kingdom
It is the highest category of classification. Each kingdom has some similar fundamental characteristics in all organisms grouped under that kingdom. The five-kingdom classification was given by R.H. Whittaker.

Characteristics Monera Protista Fungi Plantae Animalia
Complexity of structure Prokaryotes Eukaryotes Eukaryotes Eukaryotes Eukaryotes
Body organisation Unicellular Unicellular Multicellular (at some stage of life) Multicellular Multicellular
Mode of nutrition Autotrophic or Heterotrophic Autotrophic or Heterotrophic Heterotrophic
Autotrophic Heterotrophic


Characteristics Monera Protista Fungi Plantae Animalia
Cell wall Present or absent Present or absent Present (made up of chitin) Present (made up of cellulose) Absent
Appendages Cilia or flagella for movement Cilia, flagella or pseudopodia for movement Do not move Do not move


e.g., Bacteria e.g., Amoeba e.g., Mushroom e.g., Rose e.g., Monkey

Differentiate between:

S. No. Thallophyta Bryophyta Pteridophyta
1. Plant body thallus like, not differentiated into root, stem or leaf. Plant body does not have true root, stem or leaf but shows root­like and leaf-like structures. Plants have true root stem or leaf.
2. Vascular system absent. True vascular system is absent. True vascular system is present.
3. Predominantly aquatic. They live on land and in water. They are known as the Amphibians of the plant kingdom. They are terrestrial, i.e., they live on land.
4. No embryo formation after fertilization.
e.g., Algae
Embryo formed after fertilisation.
e.g., Mosses, liverworts .
Embryo formed after fertilisation.
e.g., Ferns


S. No. Cryptogamae Phanerogamae
1. Reproductive organs are hidden. Reproductive organs are visible.
2. Fertilisation results in the formation of a naked embryo called spores. Fertilisation results in the formation of seeds which consists of embryo and cotyledons.
3. Water is required for fertilisation. Water is not required for fertilisation always except for aquatic phanerogams.
e.g., Thallophyta, Bryophyta, Pteridophyta e.g., Gymnospermae and Angiospermae


S. No. Gymnospermae Angiospermae
1. Plants bear naked seeds. Seeds are present inside fruits.
2. Xylem is without vessels and phloem is without companion cells. Well developed vascular tissue present.
3. Plants are perennial, woody and evergreen. Plants are annual, biennial, perennial, woody or green.
e.g., Pinus, Cycas e.g., Neem, Rose, Mango


S. No. Monocotyledonous Plants Dicotyledonous Plants
1. Single cotyledon in seeds. Two cotyledons in seeds.
2. Fibrous roots. Tap roots.
3. Parallel venation. Reticulate venation.
e.g., Lily, Rice, Wheat e.g., Hibiscus, Pea, Gram

5. Characteristic features of different Phyla of Kingdom Animalia Porifera

  • Porifera means organisms with holes.
  • Non-motile animals attached to solid support
  • Holes or pores all over body
  • Have canal system that helps in circulating water throughout the body to bring in food and oxygen.
  • Body covered with hard outside layer or skeleton
  • Minimal differentiation of body and division into tissues
  • Commonly called sponges found in marine habitats
  • Acoelomate (without body cavity)
    Examples: Euplectella, Sycon, Spongilla

6. Coelenterata

  • Animals living in water
  • More body design differentiation
  • Diploblastic body
  • Some species live in colonies (corals) while others have a solitary life span (Hydra)
    Examples: Jelly fish, Sea Anemone, Hydra

7. Platyhelminthes

  • Body is complexly designed
  • Bilaterally symmetrical body
  • Triploblastic body
  • Acoelomate
  • Body flattened dorsi-ventrally, so called flatworms
  • Free living or parasitic
    Examples: Planarian (free living) liver flukes, tapeworms (Parasitic)

8. Nematodes

  • Bilaterally symmetrical
  • Triploblastic body
  • Cylindrical body
  • Tissues present but no real organs
  • Presence of pseudo coelom, a sort of body cavity
  • Familiar as parasitic worms causing diseases, present in intestines
    Examples: Ascaris, Wucheraria

9. Annelida

  • Bilaterally symmetrical
  • Triploblastic
  • Coelomate (having a body cavity or coelon)
  • Extensive organ differentiation
  • Segmented body (Metamerism)
  • Found in fresh water, marine and on land
    Examples: Earthworms, Leech, Nereis

10. Arthropoda

  • Largest group of animals
  • Bilaterally symmetrical
  • Segmented body
  • Open circulatory system
  • Coelomate
  • Arthropoda means jointed legs
    Examples: Prawns, Butterflies, Housefly, Cockroach

11. Mollusca

  • Bilaterally symmetrical
  • Coelomic cavity is reduced
  • Little segmentation
  • Open circulatory system
  • Kidney like organ for excretion
  • There is a foot like structure for moving around
    Examples: Snails, mussels, Chiton, Octopus, Unio, Pila

12. Echinodermata

  • They are spiny skinned organisms
  • Echinos’ means hedgehog and ‘Derma’ means skin.
  • Exclusively free living marine animals
  • Triploblastic
  • Acoelomate
  • Peculiar water driven tube system
  • Hard calcium carbonate structures as skeleton
    Examples: Star fish, sea urchin, feather star, sea cucumber

13. Protochordate

  • Bilaterally symmetrical
  • Triploblastic
  • Coelomate
  • Notochord present during larval stage
  • Provides place for muscles to attach for easy movement
  • Marine animals
    Examples: Balanoglossus, Herdmania, Amphioxu

14. Vertebrata

  • Have a true vertebral column and internal skeleton
  • Bilaterally symmetrical
  • Triploblastic
  • Coelomate and segmented
  • Complex differentiation of body tissues and organs

15. All chordates possess the following features:

  • Have a notochord
  • Have a dorsal nerve cord
  • Are triploblastic
  • Have paired gill pouches in some stage of their life cycle
  • Are coelomate

16. Vertebrates are grouped into 5 classes

  • Exclusively aquatic animals
  • Skin covered with scales or plates
  • Obtain oxygen dissolved in water
  • Streamlined body and muscular tail for movement in water
  • Cold-blooded
  • Two-chambered heart
  • Lays eggs in water

17. Are of two types:

  • Cartilaginous fish (skeleton made entirely of cartilage), e.g., Shark
  • Bony fish (skeleton made of both cartilages and bones), e.g., Rohu, Tima

18. Amphibia

  • Lack scales
  • Have mucus glands in skin
  • Cold-blooded
  • Three-chambered heart
  • Respiration through gills, lungs or skin
  • Lay eggs in water
  • Live both on land and in water
    Examples: Frogs, toads, salamander, etc.

19. Reptilia

  • Have scales
  • Three-chambered heart but crocodiles have four chambered heart
  • Cold-blooded
  • Breathe through lungs
  • Lay eggs with tough coverings so they do not lay eggs in water
    Examples: Snakes, turtles, lizards, crocodiles, chameleon

20. Aves

  • Outside covering of feathers
  • Four-chambered heart
  • Warm-blooded
  • Breathe through lungs
  • Lay eggs
  • Two forelimbs modified into wings for flight
    Examples: All birds like crow, pigeon, peacock, etc.

21. Mammalia

  • Skin has hairs, oil and sweat glands
  • Four-chambered heart
  • Warm-blooded.
  • Most of them give birth to young ones
  • Few like Platypus and Echidna lay eggs
  • Some like kangaroos give birth to poorly developed young ones
  • Mammary glands present for production of milk to nourish their young ones
    Examples: Cat, human, rat, bat, whale, etc.

21. Nomenclature: System of assigning names or terms to the organisms is called as nomenclature. The names given to the organism can be

  • Common name or
  • Scientific name.

Common names cannot be used in the same way by the scientist world over and can often result in confusion. To avoid this, a system of scientific names has been proposed.

Binomial System of Nomenclature: The binomial system of nomenclature assigns two names to the organism in order to identify it first is the generic name (genus) and the second is the specific epithet (species). This system of nomenclature was given by Carolus Linnaeus.

22. Convention for writing the scientific names:

  • The name of the genus begins with a capital letter.
  • The name of the species begins with a small letter.
  • When printed, the scientific name is given in italics.
  • When written by hand, the genus name and the species name have to be underlined separately.

23. Scientific names of some organisms:

  • Tiger – Panthera tigris
  • Peacock – Pauo cristatus
  • Mango – Mangifera indica
  • Lotus – Nelumbo nucifera
  • Neem – Azadiraehta indica
  • Potato – Solanum tuberosum
  • Ant – Hymenopetrous formicidae
  • Frog – Rana tigrina
  • Rose – Rosa indica
  • Pea – Pisum sativum

Class 9 Science Chapter 7 Notes Important Terms

Prokaryotes: Organisms which do not have a clearly demarcated nucleus and other organelles.

Eukaryotes: Organisms having membrane bound cell organelles and a well-defined nucleus.

Unicellular: Organisms having only one cell in their body.

Multicellular: Organisms having many cells in their body.

Autotrophs: Organisms synthesising their own food by photosynthesis.

Heterotrophs: Organisms which depend on other organisms for their food.

Bilateral symmetry: The body organisation in which the left and right halves have same body design.

Radial symmetry: Arrangement of similar parts around a central body axis as in a wheel.

Diploblastic: Animals having a body made up of two layers of cells i.e., ectoderm and endoderm.