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NCERT Solution for Class 9 Science Chapter 7: Diversity in Living Organisms

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Chapter 7 is also a part of Biology and it is called Diversity in Living Organisms. You can see many living organisms around you, and you must have noticed the huge diversity in plants and animals (or living organisms). So in this chapter, you will get to know about the classification of organisms. This chapter explains to you about the hierarchy in the plant and animal kingdom. How they are different from each other and their ways of life are explained through this chapter.

NCERT Solution for Class 9 Science Chapter 7 includes all Intext exercises 1, 2, 3, 4, 5, 6, and an NCERT exercise for you. The end exercise includes solutions to all 6 questions. All these questions are memory-based questions to test your cognizance.

Ncert solutions

NCERT Solution for Class 9 Science Chapter 7: Diversity in Living Organisms Ex 7.1

Exercise 7

Why do we classify organisms?

There are several varieties of living organisms on Earth. It is not easy to study all of them one by one. For this, we place them in different groups based on similarities and differences. This make their study systematic, easy and quick. This, it is recommended to study the diversity of organism
by classifying them in orderly manner.

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

The examples of range of variations in different life forms are:
(i) Variations in size: The bacteria are so small in size that they cannot be seen without a microscope. On the other hand, blue whale and redwood trees of california are giant living creatures.
(ii) Variations in life span: The insects like fruit flies live for few hours, while some trees like pine live for several years.
(iii) Variations in body colours: Some living organisms are colourless, e.g. Worms, whereas birds, insects, flowers are colourful.

Exercise 7.1

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?

The more basic characteristic for classifying organisms is the kind of cells they are made of. This is because the cell and its components are responsible for the specialized functions that help organisms to survive and multiply The habitat is misleading for classing organisms because many different kinds of organisms may live in same habitat, e.g., corals, whales, octopuses, starfishes and
sharks live in the sea.

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

The primary characteristic on which first division of organisms is based is whether the cells occurs individually (unicellular) or they are group together and function as an individual group (multicellular).

On what basis are the plants and animals 9.“ into different categories?

Plants and animals are put into different .categories on the basis of their mode of nutrition and their body designs. Plants are autotrophic and their cells have a cell wall, whereas animals are hot. erotrophic and their cells lack a cell wall.

Exercise 7.2

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

The organisms, which have ancient body designs that have not changed much overtime, are called primitive or lower organisms. These are simple life forms. On the other hand, the organisms that have acquired their particular body designs relatively in recent times, are called advanced organisms or higher organisms. These are more complex life forms.

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

The advanced organisms will be the same as complex organisms. This is because advancement in body design and characteristics cannot be taken up without increasing the complexity in body structure.

Exercise 7.3.5

What is the criterion for classification of organisms as belonging to kingdom Monera and Protista?

The criteria for the classification of organisms as belonging to kingdom-Monera and Protista are the presence or the absence of a well-defined nucleus. Monera has no nuclear membrane (i.e. they are prokaryotes) while Protista show well defined nucleus (ie they are eukaryotes).

In which kingdom will you place an organ/ ism, which is single-celled,
eukaryotic and photosynthetic?

Kingdom-Protista have members who are single’ celled, eukaryotic and most of them are photo; synthetic. Therefore, the organism given in. the question can be placed In this kingdom.

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

In the hierarchy of classification, the species is the grouping which has the smallest number of organisms with a maximum of characteristics in common. The grouping which have the largest number of organisms is the kingdom.

Exercise 7.4.5

Which division among plants has the simplest organisms?

The division-Thallophyta of plant kingdom has the simplest organisms. The organisms of this kingdom do not have well-differentiated body design.

How are pteridophytes different from the phanerogams ?

Pteridophytes are seedless plants. Gametophytes in pteridophytes are small but independent. Reproductive organs are inconspicuous and external water is required for fertilisation. On the other hand, phanerogams are seed bearing plants whose gametophytes are nutritionally dependent upon the sporophyte. Reproductive organs are quite conspicuous and the process of fertilisation does not require an external water.

How do gymnosperms and angiosperms differ from each other?

Solution: Refer pdf.

Exercise 7.5.10

How do poriferan animals differ from coelenterate animals?

Solution: Refer pdf.

Question 2.
How do annelid differ from arthropods ?

Solution:  Refer pdf.

What are the difference between amphibians and reptiles ?

Solution:  Refer pdf.

What are the difference between animals belonging to the Aves and those in the Mammals group?

Solution:  Refer pdf.

Exercise Chapter 7

What are the advantages of classifying organisms?

Classification is the arrangement of organisms into groups and subgroups on the basis of their similarities and dissimilarities and placing them in hierarchy that brings out their relationships.
Following are the advantages of classifying organisms:
1. Classification gives us a system for identification of known and unknown organisms.lt gives an idea of whole range of diversity found in organisms. By classifying organisms we place them in groups that reflect their most significant their most significant features and relationships.
2. Organisms can be named, remembered and easily studied. Fossils as well as organisms of other regions can be studied if there is a system of classification.
3. It is not possible to study every organism. Study of a few organisms of a group can give a fair idea about the general identifying features of the group.
4. Other biological sciences like biogeography, ecology, pathology, forestry depend on the system of classification for study of organisms.

How would you choose between two characteristics to be used for developing 2 hierarchy in classification?

Characteristics which create fundamental differences amongst life forms are used for raising kingdoms, divisions and other large groups. They are generally present in large number of organisms. On the other hand the character of lesser importance which is present in smaller number
of individuals is used for raising lower category. For example, complexity of the cell stricture will  be considered first wherein organisms would be classified into eukaryotes and prokaryotes. The complexity of body structure will now be taken into account and organisms can be classified as unicellular or multicellular. All unicellular organisms with eukaryotic cell structure has now been
placed in kingdom protista.

Explain the basis for grouping organisms into five kingdoms?

The basis for grouping organisms into five kingdoms are complexity of cell structure, complexity of body structure, mode of nutrition, reproduction, ecological role and phylogenetic relationship.

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

The major divisions in Kingdom Plantae are:
i. Thallophyta
ii. Bryophyta
iii. Pteridophyta
iv. Gymnosperms
v. Angiosperms
Divison Basis of classification
Thallophyta Like body
Bryophyta The body is divided into leaf and stem
Pteridophyta The body is separated into root, stem and leaf
Gymnosperms Seed-bearing, naked seeds
Angiosperms Seed bearings covered seeds

Question 5.
How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?

Criteria for deciding divisions in plants:
1. Differentiation of plant body.
2. Presence or absence of special tissues for transport of water and other substances within it.
3. Ability to bear seeds.
4. Whether seeds are naked or enclosed within the fruit.
Criteria for deciding subgroups among animals:
(i) Body plan.
(ii) Number of germinal layers in the body.
(iii) Presence of coelom.
(iv) Symmetry.
(v) Cold-blooded or warm-blooded.
(vi) Egg lying or give birth to young ones.
(Vii) Presence or absence of vertebral column 0r notochord.

Explain how animals in Vertebrata are classified into further sub-groups.

Animals of Vertebrata are further classified into sub-groups on the basis of following features:
1. Nature of heart (two, three or four chambered).
2. Presence of exoskeleton either in the form of scales, feathers or hair.
3. Ability to regulate their body temperature or n01 (cold-blooded or warm-blooded).
4. Reproduction (Egg laying or give birth to young ones).
5. Presence of mammary glands.
6. Nature of egg (hard shelled, soft shelled or with out shell).
7. Mode of respiration (By skin, lungs or gills).

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