शनिवार, 29 जुलाई 2017


(Page No. 80)
1. Why do we classify organisms?

Ans. A large number of organisms exist on this earth. We cannot study such enormous biodiversity one by one i.e. studying variety of life forms individually is an impossible task.

Hence, we make groups or categories of organisms depending upon their similarities and dissimilarities with other organisms. This allows an  easier and systematic study of the life forms.

2. Give three examples of the range of variations that you see in life forms around you.

Ans. i) Life forms vary in their size – Some organisms are too small and cannot be seen with naked eyes like microorganisms while others are too big like the biggest animal which is the blue whale.

ii) Number and type of cells – Some organisms have a prokaryotic cell like bacteria and that single cell performs all the required functions while others have eukaryotic cells organized into tissue, organ and even organ systems like human beings.

iii) Mode of nutrition – Some organisms are autotrophic i.e. capable of making their own food eg plants while other organisms are heterotrophic i.e. they are dependent on other organisms for their food supply.

(Page No. 82)

1. Which do you think is a more basic characteristic for classifying organisms?

(a)the place where they live.

(b) the kind of cells they are made of. Why?

Ans. The classification of organisms based on the place where they live is not quite convincing because other living in the same habitat they hardly share any other feature for example whales, corals, starfishes, octopus, fishes, sharks etc all are aquatic i.e. they live in water their appearance and all other features are very different.

Therefore classification of organisms based on the kind of cells they are made of is more widely accepted. For such catergorisation organisms belonging to prokaryotic group will have a particular cell structure and functional pattern which will be different from the eukaryotic group.

2. What is the primary characteristic on which the first division of organisms is made?

Ans. The primary characteristic on which the first division of organisms is made is the form and functions of that organism.

3. On what bases are plants and animals put into different categories?

Ans. On the basis of their mode of nutrition plants and animals are put into different categories.

(Page No. 83)

1. Which organisms are called primitive and how are they different from the so-called advanced organisms?

Ans. Such organisms that possess quite simple structure and body design also haven’t changed much from their ancient sort of details even after long period of evolution on earth are called as the primitive organisms like bacteria who are still single celled and prokaryotic while advanced organisms have complex body design like trees and humans.

2. Will advanced organisms be the same as complex organisms? Why?

Ans. Yes we can say that the advanced organisms are the same as complex organisms because advancement has occurred due to the process of evolution where a group of simple organisms have changed themselves into the complex forms of life for better survival.

(Page No. 85)

1. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

Ans. The criterion used for classification of organisms as belonging to kingdom Monera or Protista is their cell structure.

Both Monerans as well as Protists are unicellular or single celled organisms but among monerans the cell is prokaryotic i.e. do not contain well defined nucleus while in protists the cell is eukaryotic i.e. have a well-defined nucleus.

2. In which kingdom will you place an organism which is single celled, eukaryotic and   photosynthetic?

Ans. Kingdom Protista.

3.In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?

Ans. Smallest number of organisms with a maximum of characteristics in common will be Species while grouping with largest number of organisms with common characteristics will be the Kingdom.

(Page No. 88)

1. Which division among plants has the simplest organisms?

Ans. Division thallophyta.

2. How are pteridophytes different from the phanerogams?

Ans. Pteridophytes do not produce seeds but develop naked embryos while phanerogams are seed producing plants like gymnosperms and angiosperms.

3. How do gymnosperms and angiosperms differ from each other?


(Page No. 94)

1. How do poriferan animals differ from coelenterate animals?


2. How do annelid animals differ from arthropods?


3. What are the differences between amphibians and reptiles?


4. What are the differences between animals belonging to the Aves group and those in the mammalian group?


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