Diversity in Living Organisms(NCERT Solutions, Class 9)

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(1) Why do we classify organisms?

Ans-  Classification of organism makes study of organisms essay because organisms are classified according to their different characteristics. Therefore, we do classification of organisms.

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

Ans- Three examples of the range of variations that we see in life – forms around us are-given below –

(i) Some pine trees live for thousands of years while insects like mosquitoes die within a few days.

(ii) Life also ranges from colourless or even transparent worms to brightly coloured birds and flowers.

(iii) Microscopic bacteria have size of few micrometer while blue whale is the largest fish.

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(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 kind of cells they are made of’ is a more basic characteristic for classifying organisms. Because organisms is divided according to number of cells they have, ie, unicellular or multicellular. Both have their specific characteristics.

Classification can be done on the basis of the place where they live. But, classification will not be proper. For example lion tiger, monkey, earthworm etc. all live on land but they are differ in every aspect. Therefore we can not include them in same category.

(2) What is the primary characteristic on which the broad division of organisms is made?

Ans– Cell is the primary characteristic on which the broad division of organisms.

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

Ans- The plants and animals put into different categories on the bases of their body design. The plants can make their own food with the photosynthesis process but animals have to eat other animals or plants as a food. Therefore they have different body design.

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(1) Which organisms are called primitive and how are they different from the so – called advanced organisms?

Ans- Some organisms have ancient body design and considered as primitive group. Eg :- Amoeba etc.

Primitive group animals are different from advanced group animals because advanced group organisms have relatively recent body design in comparison of primitive group organisms.

(2) Will advanced organisms be the same as complex organisms? Why?

Ans- Yes, advanced organisms are complex organisms. They have relatively recent body design in comparison of primitive group of organisms.

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

Ans- The criterion for classification of organisms as belonging to kingdom Monera or Protista is presence or absence of well – defined nucleus. Monera are unicellular prokaryotes and do not have well defined nucleus. Protista are unicellular eukaryotes and have well defined nucleus.

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

Ans- The organism which is single-celled, eukaryotic and photosynthetic will be place in Protista kingdom.

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

Ans- In the hierarchy of classification, kingdom will have the largest number of organisms and species will have the smallest number of organisms.

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(1) Which division among plants has the simplest organisms?

Ans- Thallophyta among plants has the simplest organisms. They can not be differentiated among roots, leaves and stems. Eg:- algae.

(2) How are pteridophytes different from the phanerogams?

Ans- Differences between pteridophytes and phanerogams

SN Pteridophytes Phanerogams
1. The reproductive organs are not visible and are called cryptogams’. The plants with well – differentiated reproductive parts.
2. They do not produce seeds. Seeds consist of the embryo along with stored food, which assists for the initial growth of the embryo during germination.
3. Eg:-Marsilea, ferns and horse – tails Eg:- Pines and deodar

(3) How do gymnosperms and angiosperms differ from each other?

Ans- Differences between gymnosperms and angiosperms

SN Gymnosperms Angiosperms
1. They have naked seeds. They have covered seeds.
2. The plants are perennial, evergreen and woody. These are also called flowering plants.
3. Eg:- Pines and deodar Eg:- Roses, sunflowers etc.

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(1) How do poriferan animals differ from coelenterate animals?

Ans- Differences between poriferan animals and coelenterate animals

SN Poriferan Animals Coelenterate Animals
1. These are non – motile animal attach to some solid support.

 

These are mobile animals.
2. The organisms of this group have holes or pores and canals or channels all over body. These organisms have cavity in their bodies.
3. Skeleton or hard outside layer covered these organisms. The body is made of two layers of cells.

The one layer makes up cells on the outside of the body and the other makes the inner lining of the body.

 

4. The body of these organisms shows very minimal differentiation and division into tissues. They show more body design differentiation.
5. They are found in marine habitat. These animals live in water.
 6. Eg:- Sponges Eg:- Jellyfish and sea anemones.

(2) How do annelid animals differ from arthropods?

Ans- Differences between annelid animals and arthropods

SN Arthropods Annelid
1. The coelomic cavity is blood filled. They have a true body cavity that allows true organs to be packaged in the body structure.
2. These animals have jointed legs.

 

The differentiation occurs in segments lines up one after other from head to tail.
3. Eg:- Prawns, butterflies, houseflies, spiders, scorpions and crabs. Eg:- Earthworms and leeches.

(3) What are the differences between amphibians and reptiles?

Ans- Differences between amphibians and reptiles

SN Amphibians Reptiles
1. Amphibians lack of scales. They have scales.
2. They have a three chambered heart. Most of these animals have three chambered heart. But crocodiles have four heart chambers.
3. These animals respirate through either gills or lungs. These animals respirate through lungs.
4. Eg:- Frogs, toads and salamanders etc. Eg:- Snakes, turtles, lizards and crocodiles etc.

(4) What are the differences between animals belonging to the aves group and those in the mammalia group?

Ans- Differences between aves group and mammalia group

SN Aves Group Mammalia Group
1. They lay eggs. These animals produced live young ones. But few of them like platypus and the echidna lay eggs.
2. These animals have outside covering of feathers and two forelimbs are modified for flight. Their skin has hairs.
3. They do not have mammary glands. They have mammary glands for the production of milk to nourish their young.
4. These animals do not have sweat and oil glands. These animals have sweat and oil glands.
5. Eg:- Ostrich, Pigeon, crow and sparrow etc. Eg:- Human. Kangaroo etc.

Exercises

(1) What are the advantages of classifying organisms?

Ans- The advantage of classifying organisms are given below –

(i)It helps in exploring the diversity of life forms.

(ii) It also helps in understanding evolution of life.

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

Ans- The two characteristics below are used for developing a hierarchy in classification –

(i) The type of cell, ie, whether the organisms is prokaryotic or eukaryotic cells.

(ii) The mode of preparing food, ie, whether they are autotroph or heterotroph.

(3) Explain the basis for grouping organisms into five kingdoms.

Ans- Robert Whittaker proposed five kingdoms on the basis of cell structure, mode and source of nutrition and body organisation. Woese modified this classification by dividing the Monera into Archaebacteria (or Archaea) and Eubacteria (or Bacteria) is also in use.

(i) On the basis of membrane bound organnels, organisms are divided into Prokayotes and Eukaryotes.

(ii) On the basis of cellularity, organisms are divides ad unicellular or multicellular.

(iii) Multicellular is further divided to with cell wall and with out cell wall.

(iv) On the basis of food preparation, the organisms are divided in to autotrophs or heterotrophs.

(4) What are the major divisions in the planate? What is the basis for this division?

Ans-

SN Division of Planate Basis for Division
1. Thallophyta Plant body does not has well – differentiated distinct parts.

 

2. Bryophyta Without specialized vascular tissue.
3. Pteridophyta Do not produce seeds.
4. Phanerogams Produce seeds.

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

Ans-

SN Criteria Plants Animals
1. Food Autotrophs Heterotrophs
2. Cell – wall With cell – wall Without cell – wall
3. Mobility Not mobile Mobile

(6)Explain how animals in vertebrata are classified in to further subgroups.

Ans – Vertebrata are classified into subgroup as follows –

SN Sub group of Vertebrata Basis of Sub group
1. Cyclostomata These are jawless vertebrates. They have an elongated eel – like body. They have circular mouth and slimy and scale less skin. They are ectoparasites or borers of other vertebrates. Eg:- Petromyzon (Lamprey) and Myxine (Hagfish)

 

2. Pisces These are fish. They are aquatic animals. Their skin is covered with scales or plates. They have gills to take oxygen dissolved in water. Their body is streamlined. They have a muscular tail for movement. They are cold – blooded. Their heart has two chambers. They lay eggs. Some fishes with skeletons made entirely of cartilage (Shark). Some fishes with a skeleton made of both bone and cartilage (Tuna or rohu).Other examples of this group are Mandarin fish, Lion fish, Electric ray , Flying fish etc.

 

3. Amphibia These animals respirate through either gills or lungs.

They lay eggs. These animals are found both in water and on land. Amphibians lack of scales. They have mucus glands in the skin. They have a three chambered heart. Eg:- Frogs, toads and salamanders etc.

 

4. Reptilia These animals have scales. They breathe through lungs. These animals are cold – blooded. Most of these animals have three chambered heart. But crocodiles have four heart chambers.  They lay eggs with tough covering. They do not lay their eggs in water. Eg:- Snakes, turtles, lizards and crocodiles etc.

 

5. Aves These are warm – blooded animals. They have four chambered heart. They lay eggs. These animals have outside covering of feathers and two forelimbs are modified for flight. They breathe through lungs. All birds fall in this category. Eg:- Ostrich, Pigeon, crow and sparrow etc.

 

6. Mammalia Mammals are warm – blood animals. They have four – chambered heart. They have mammary glands for the production of milk to nourish their young. Their skin has hairs. These animals have sweat and oil glands. These animals produced live young ones. But few of them like platypus and the echidna lay eggs. Eg:- Human, kangaroos, cat etc.

 

Helping Topics

Diversity in living organisms

Practice sheet, class 9

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