NCERT Class 9 Science Solutions: Chapter 7 – Diversity In Living Organisms Part 1

Download PDF of This Page (Size: 290K)

Question 1:

Q. Why do we Classify organisms?

Image of Classify Organism for Diversity In Living Organisms

Image of Classify Organism for Diversity

Image of Classify Organism for Diversity In Living Organisms

A. There are a wide range of life forms (about 10 million -13 million species) around us. These life forms have existed and evolved on the Earth over millions of years ago. The huge range of these life forms makes it very difficult to study them one by one. Therefore, we look for similarities among them and classify them into different classes to study these different classes as a whole. Thus, classification makes our study easier.

Question 2:

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

A.

Examples of range of variations observed in daily life are:

(i) Variety of living organisms in terms of size ranges from microscopic bacteria to tall trees of 100 metres.

(ii) The colour, shape, and size of snakes are completely different from those of lizards.

(iii) The life span of different organisms is also quite varied. For example, a crow lives for only 15 years, whereas a parrot lives for about 140 years.

Question 1:

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

(a) The place where they live.

(b) The kind of cell they are made of. Why?

A. The kind of cells that living organisms are made up of is a more basic characteristic for classifying organisms, than on the basis of their habitat. This is because on the basis of the kind of cells, we can classify all living organisms into eukaryotes and prokaryotes. On the other hand, a habitat or the place where an organism lives is a very broad characteristic to be used as the basis for classifying organisms. For example, animals that live on land include earthworms, mosquitoes, butterfly, rats, elephants, tigers etc. these animals do not resemble each other except for the fact that they share a common habitat. Therefore, the nature or kind of a cell is considered to be a fundamental characteristic for the classification of living organisms.

Question 2:

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

A. The primary characteristic on which the first division of organisms is made is the nature of the cell. It is considered to be the fundamental characteristic for classifying all living organisms. Nature of the cell includes the presence or absence of membrane-bound organelles. Therefore, on the basis of this fundamental characteristic, we can classify all living organisms into two broad categories of eukaryotes and prokaryotes. Then, further classification is made on the basis of cellularity or modes of nutrition.

Question 3:

Q. On What basis are plants and animals put into different categories?

Image of Plants and Animals Put into Different Categories for Diversity In Living Organisms

Plants and Animals Put into Different Categories

Image of Plants and Animals Put into Different Categories for Diversity In Living Organisms

A. Plants and animals differ in many features such as the absence of chloroplasts, presence of cell wall, etc. But locomotion is considered as the characteristic feature that separates animals from plants. This is because the absence of locomotion in plants gave rise to many structural changes such as the presence of a cell wall (for protection), the presence of chloroplasts (for photosynthesis) etc. Hence, locomotion is considered to be the basic characteristic as further differences arose because of this characteristic feature.

Question 1:

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

A. A primitive organism or lower organism is the one which has a simple body structure and ancient body design or features that have not changed much over a period of time. An advanced organism or higher organism has a complex body structure and organization. For example, an Amoeba is more primitive as compared to a starfish Amoeba has a simple body structure and primitive features as compared to a starfish. Hence, an Amoeba is considered more primitive than a starfish.