NCERT Class 11 Biology Chapter 4 Animal Kingdom

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NCERT Class 11 Biology Chapter 4 Animal Kingdom

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Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. CBSE Class 11 Biology Solutions are part of All Subject Solutions. Here we have given NCERT Class 11 Biology Chapter 4 Animal Kingdom Notes, NCERT Class 11 Biology Textbook for All Chapters, You can practice these here.

Animal Kingdom

Chapter: 4



Q.1. What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?

Ans. If common fundamental characteristics are not considered for the classification of living organisms, then organisms with different body symmetry, level of organanisation, arrangement of cells and nature of coelom will be placed in same group.

Q.2. If you are given a specimen, what are the steps that you would follow to classify it?


1. Levels of Organization.

2. Body Plans.

3. Symmetry.

4. Diploblastic and Triploblastic Organisation.

5. Segmentation.

6. Coelom.

7. Notochord.

8. Blood Vascular System.

9. Development.

Q.3. How useful is the study of the nature of body cavity and coelom in the classification of animals?

Ans. Coelom:

(a) Acoelomates-

(i) The animals which do not have coelom are called acoelomates.

(ii) e.g. sponges, cnidarians ctenophores and flat worms.

(b) Pseudocoelomates-

(i) The mesoderm is present as scattered pouches in between the ectoderm and endoderm to form a body cavity called pseudocoelom.

(ii) e.g. round worms

(c) Eucoelomates-

(i) The animals which possess true coelom are called eucoelomates or coelomates.

(ii) The true coelom is a body cavity which arises as a cavity in embryonic mesoderm.

(d) True Coelom are of two types:

1. Schizocoelom-

(i) It develops as a split in the mesoderm sheet.

(ii) It is found in annelids, arthropods, molluscs.

2. Enterocoelom-

(i) The mesoderm arises from the wall of the embryonic gut or enteron as hollow outgrowths.

(ii) It occurs in echinoderms and chordates.

Q.4. Distinguish between intracellular and extracellular digestion?

Ans. Intracellular digestion:

1. The digestion of food occurs within the cell.

2. Digestive enzymes are secreted by surrounding cytoplasm in the food vacuole.

3. Digestive products diffuse into the cytoplasm.

4. It occurs in unicellular organisms.

Extracellular digestion:

1. The digestion occurs in the cavity of alimentary canal.

2. Digestive enzynes are secreted by special cells into the cavity of alimentary canal.

3. Digestive products diffuse across the intestinal wall into different body parts.

4. It occurs in multicellular organisms.

Q.5. What is the difference between direct and indirect development?

Ans. Direct development:

(i) Young ones resemble the adults in all respects.

(ii) There is no intermediate stage.

(ii) E.g. Hydra, Earthworm, Human beings

Indirect development:

(i) Young ones do not resemble the adults.

(ii) The young ones pass through one or more intermediate stages before becoming adults.

(iii) E.g. Silk moth, House fly, Frog.

Q.6. What are the peculiar features that you find in parasitic platyhelminthes? 

Ans. Platyhelminthes:

The body is dorso — ventrally flattened and is without true segments.

(i) They are bilaterally symmetrical.

(ii) They are triploblastic animals with Organ level of organization.

(iii) Rod shaped bodies; the rhabdites are present in body wall of Platyhelminthes. They are protective and used in food capture.

(iv) Parasitic forms have hooks and suckers.

(v) Taenia (Tapeworm) and Fasciola (liver fluke) are examples of parasitic platyhelminthes.

Q.7. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?

Ans. The reasons are as follows:

(i) The body is segmented externally.

(ii) The body of arthropods is covered by chitinous exoskeleton.

(iii) The body consists of head, thorax and abdomen.

(iv) Body has jointed appendages.

Q.8. Water vascular system is the characteristic of which group of the following:

(a) Porifera.

(b) Ctenophora.

(c) Echinodermata.

(d) Chordata.

Ans. Echinodermata.

Q.9. “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.

Ans. The characteristic features of the phylum, Chordata is the presence of a notochord. In Vertebrata, the notochord present in embryos gets replaced by a cartilaginous or bony vertebral column in adults. Thus, it can be said that all vertebrates are chordates but all chordates are not vertebrates.

Q.10. How important is the presence of air bladder in Pisces?

Ans. Bony fishes have a sac like outgrowth the swim bladder or air bladder which is air filled organ used to maintain balance and to swim up and down.

Q.11. What are the modifications that are observed in birds that help them fly?

Ans. Modifications in birds that help them fly are as follows:

(i) The characteristic features of Aves (birds) are the presence of feathers.

(ii) The forelimbs are modified into wings. The hind limbs are modified for walking, swimming or clasping tree branches and have epidermal scales.

(iii) Endoskeleton is fully ossified (bony) and the long bones are hollow with air cavities (pneumatic).

(iv) Respiration is by lungs. Air Sacs Connected to lungs supplement respiration.

Q.12. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?

Ans. The numbers of eggs produced by an oviparous mother will be more than the young ones produced by a viviparous mother.

Oviparous animals lay large numbers of eggs as eggs are laid outside the mother’s body which exposes them to tough environmental conditions and predators. Viviparous organisms have the development of embryo in safe conditions inside the body of the mother. They are less exposed to environmental conditions and predators. Therefore, there are more chances of their survival and hence, less number of young ones is produced compared to the number of eggs.

Q.13. Segmentation in the body is first observed in which of the following:

(a) Platyhelminthes.

(b) Aschelminthes.

(c) Annelida.

(d) Arthropoda.

Ans. (c) Annelida.

Q.14. Match the following:

Column IColumn II
(a) Operculum(i) Ctenophora
(b) Parapodia(ii) Mollusca
(c) Scales(iii) Porifera
(d) Comb plates(iv) Reptilia
(e) Radula(v) Annelida
(f) Hairs(vi) Chondrichthyes Cyclostomata
(g) Choanocytes(vii) Mammalia
(h) Gill slits(viii) Osteichthyes


Column IColumn II
(a) Operculum(viii) Osteichthyes
(b) Parapodia(v) Annelida
(c) Scales(iv) Reptilia
(d) Comb plates(i) Ctenophora
(e) Radula(ii) Mollusca
(f) Hairs(vii) Mammalia
(g) Choanocytes(iii) Porifera
(h) Gill slits(vi) Cyclostomata and Chondrichthyes

Q.15. Prepare a list of some animals that are found parasitic on human beings.

Ans. (i) Taenia Solium [Platyhelminthes]

(ii) Fasciola hepatica [Platyhelminthes]

(iii) Ascaris lumbricoides [Aschelminthes]

(iv) Wuchereria Bancrofti [Aschelminthes]

(v) Ancyclostoma [Aschelminthes]

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