Thursday , March 28 2024
Diversity in Living Organisms

9th Class (CBSE) Science: Diversity in Living Organisms

Question: What are the differences between animals belonging to the Aves group and those in the mammalia group?

Answer:

Aves:

  1. Body is covered with feathers.
  2. Beak is present, teeth absent.
  3. Forelimbs modified for flying.
  4. Hollow bones for flying.
  5. Streamlined body.

Mammalia:

  1. Body is covered with hairs.
  2. Teeth present, beak absent.
  3. Forelimbs modified for various activities.
  4. No hollow bones.
  5. Body is not streamlined, except in whales.

Question: What are the advantages of classifying organisms?

Answer: Advantages of classification:

  1. Better categorisation of living beings based on common characters.
  2. Easier study for scientific research.
  3. Better understanding of human’s relation and dependency on other organisms.

Helps in cross breeding and genetic engineering for commercial purposes.

Question: How would you choose between two characteristics to be used for developing a hierarchy in classification?

Answer:Gross Character will “form-the basis of start of the hierarchy and fine character -will -form “the basis of further steps of single the hierarchy.
Example:

  1. Presence of vertebral column in human beings can be taken under vertebrata.
  2. Presence of four limbs makes them members of Tetrapoda.
  3. Presence of mammary glands keeps them under mammalia.

Question: Explain the basis for grouping organisms into five kingdoms.

Answer: Basis Of Classification:

  1. Number of cells
  2. Layer of cells
  3. Presence or absence of cell wall
  4. Mode of nutrition
  5. Level Of organisation

Question: What are the major divisions in the Plantae? What is the basis for these divisions?

Answer: Major Divisions of Kingdom plantea:

Division:

  1. Thallophyta or Algae
  2. Bryophyta
  3. Pteridophyta
  4. Gymnosperm
  5. Angiosperm

Basis of Classification:

  1. Thallus like body
  2. Body is divided into leaf and stem
  3. Body is divided into root, stem and leaf
  4. Seed bearing, naked seeds
  5. Seed bearings covered seeds

Question: How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?

Answer:In plants body basic structure is a major criteria based on which Thallophytes are different from Bryophytes. Apart from this absence or presence of seeds is another important criteria. Gymnosperms and angiosperms are further segregated based on if seeds are covered or not. It is clear that it is the morphological character which makes the basis for classification of plants.

In animals classification is based on more minute structural variations. So in place of morphology, cytology forms the basis. Animals are classified based on layers of cells, presence or absence of coelom. Further higher the hierarchy animals are classified based on presence or absence of smaller features, like presence or absence of four legs.

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