Class Nine Science Chapter 7 NCERT Solutions
Chapter 7: Diversity in Living Organisms
Intext Questions (Page No. 94)
- How do poriferan animals differ from coelenterate animals?
2. How do annelid animals differ from arthropods?
3. What are the differences between amphibian and reptiles?
4. What are the differences between animals belonging to the aves group and those in the mammalian group?
1. What are the advantages of classifying organisms?
Ans. Advantages of classifying organisms :
(i) Classification makes the study of the wide variety of organism existing in the living world convenient, easy and time – saving.
(ii) Classification presents before us a picture of all life forms at a glance.
(iii) Classification tells us about the inter-relationships between different groups of organisms, and in return provides us with information about their evolution.
(iv) It allows easy means of communication of information to other people.
(v) Classification is an information storage system and the biologists need it for the specific organism they work with.
(vi) Classification serves as a base for all other disciplines of biology.
(vii) Various fields of applied biology such as agriculture, environmental biology and public health depend on the correct identification and classification of disease-causing organisms and insect pests.
2. How would you choose between two characteristics to be used for developing a hierarchy in classification?
Ans. The characteristics which are taken into account for developing a hierarchy in classification are:
(i) Whether cell has membrane-bound organelles or not. Because such cells would have different biochemical pathways having an effect on every aspect of cell design.
(ii) Whether the cells occur singly or are they grouped together. This makes a very basic distinction in the body designs of organisms.
(iii) Whether organisms produce their own food (plants) or acquired it (animals).
Thus, we can build up a whole hierarchy of mutually related characteristics to be used for classification.
3. Explain the basis for grouping organisms into five kingdoms.
Ans. The basis for grouping organisms into five kingdoms depends on their :
(i) Cell shape and structure
(ii) Body organisation
(iii) Mode of nutrition
4. What are the major divisions in the Plantae? What is the basis for these divisions?
Ans. Major divisions of kingdom Plantae are :
(i) Thallophyta (ii) Bryophyta
(iii) Pteridophyta (iv) Gymnosperms
Basis of division
(i) Presence of distinct organelles. The primitive nucleus or well-developed membrane-bound nucleus.
(ii) Unicellular or multicellular
(iii) Differentiation of tissue-like vascular tissue to carry food, water etc.
(iv) Presence or absence of seeds
(v) Seeds is enclosed in fruit or not.
5. How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?
Ans. The criteria for deciding divisions in plants are different from the criteria for deciding the subgroups among animals because the basic designs of their body are different. The body designing of the two groups is based on the need to make their own food in case of plants and to acquire it from an external source in case of animals. The other characteristics such as presence or absence of skeleton, etc are used to make sub-group among animals.
6. Explain how animals in Vertebrata are classified into further sub-groups.Ans. The following characteristics are considered while classifying Vertebrata into further sub-groups or classes.