Class Nine NCERT Solutions Science Chapter 7
Chapter 7: Diversity in Living Organisms
Intext Questions (Page No. 80)
1. Why do we classify organisms?
Ans. There are more than a million kinds of living things exhibiting an infinite variety of form, structure and living places. It is practically not possible to examine and study every organism separately at the individual level. It is, therefore, advisable to study the diversity of organism by classifying them in proper order.
2. Give three examples of the range of variations that you see in life forms around you.
Ans. The range of variation in life forms is vast. Most common of these are the size (living fern ranges
from microscopic bacteria to giant blue whale), colour (living beings range from colourless or even transparent worms to brightly coloured birds and flowers), and life span (like insects which live for only a few days while pine trees live for thousands of years).
Intext Questions (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. (b) The kind of cells they are made of :
In a place, very different types of organisms may live. They may not have similarities except common habitat. Thus, habitat cannot be basic characteristic for the classification of organism into groups.
2. What is the primary characteristic on which the first division of organisms is made?
Ans. The primary characteristic used for making the first division of organisms is: “Whether the organisms are prokaryotic or eukaryotic.”
3. On what bases are plants and animals put into different categories?
Ans. Plants and animals are put into different categories on the basis of whether they can produce their own food or not. Being able to produce one’s own food versus having to get food from outside would make very different body designs necessary. In this way, plants and animals have been categorised into different groups.
Intext Questions (Page No. 83)
1. Which organisms are called primitive and how are they different from the so-called advanced organisms?
Ans. The organisms which have not changed much and bear ancient body designs are known as primitive organisms. On the other hand, advanced organisms have acquired specific body design relatively recently. Primitive organisms bear simple body design due to primitive structure and advanced organisms bear complex structure.
2. Will advanced organisms be the same as complex organisms? Why?
Ans. Yes. The complex organisms are comparatively more advanced as compared to simple organisms. It is because the complexity of organisms has increased over evolutionary time.
Intext Questions (Page No. 85)
1. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?
Ans. Monerans are unicellular and prokaryotic. The nucleus is not well organised and membrane-bound organelles are not present. Protists are unicellular and eukaryotic. They bear the well-defined nucleus and membrane-bound organelles.
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. In the hierarchy of classification, species will have the smallest number of organisms with a maximum of characteristics in common and kingdom will have the largest number of organisms.
Intext Questions (Page No. 88)
1. Which division among plants has the simplest organisms?
Ans. The organisms belonging to division Thallophyta has the simplest plants.
2. How are pteridophytes different from the phanerogams?
Ans. The plants belonging to pteridophytes do not produce seeds whereas those belonging to phanerogams produce seeds.
3. How do gymnosperms and angiosperms differ from each other?
Ans.
| Gymnosperms | Angiosperms |
| 1. Naked seeded plants i.e. seeds are not enclosed within the fruits. | 1. Closed seeded plants, i.e. seeds are enclosed inside the fruit formed. |
| 2. Fruits are absent. | 2. Fruits are present. |
| 3. Occupy an intermediate position between the pteridophytes and the angiosperms. | 3. The dominant group of land plants and the most common flowering plants. |