Animal Kingdom Class 11 Science Biology NCERT Solutions

Animal Kingdom Class 11 Science Biology NCERT Solutions: Animal Kingdom is the chapter 4 from class 11 Science Biology. Here you'll get Animal Kingdom class 11 Science/Animal Kingdom class 11 Science Biology NCERT Solutions. 

Animal Kingdom Class 11 Biology chapter 4 Main Points / Summary

The basic fundamental features such as level of organisation, symmetry, cell organisation, coelom, segmentation, notochord, etc., have enabled us to broadly classify the animal kingdom. Besides the fundamental features, there are many other distinctive characters which are specific for each phyla or class.

Porifera includes multicellular animals which exhibit cellular level of organisation and have characteristic flagellated choanocytes. The coelenterates have tentacles and bear cnidoblasts. They are mostly aquatic, sessile or free-floating.

The ctenophores are marine animals with comb plates. The platyhelminths have flat body and exhibit bilateral symmetry. The parasitic forms show distinct suckers and hooks. Aschelminthes are pseudocoelomates and include parasitic as well as non-parasitic round worms.

Annelids are metamerically segmented animals with a true coelom. The arthropods are the most abundant group of animals characterised by the presence of jointed appendages. The molluscs have a soft body surrounded by an external calcareous shell. The body is covered with external skeleton made of chitin. The echinoderms possess a spiny skin. Their most distinctive feature is the presence of water vascular system. The hemichordates are a small group of worm-like marine animals. They have a cylindrical body with proboscis, collar and trunk.

Phylum Chordata includes animals which possess a notochord either throughout or during early embryonic life. Other common features observed in the chordates are the dorsal, hollow nerve cord and paired pharyngeal gill slits.

Animal Kingdom Class 11 Biology chapter 4 Notes

Some of the vertebrates do not possess jaws (Agnatha) whereas most of them possess jaws (Gnathostomata). Agnatha is represented by the class, Cyclostomata. They are the most primitive chordates and are ectoparasites on fishes. Gnathostomata has two super classes, Pisces and Tetrapoda. Classes Chondrichthyes and Osteichthyes bear fins for locomotion and are grouped under Pisces. 

The Chondrichthyes are fishes with cartilaginous endoskeleton and are marine. Classes, Amphibia, Reptilia, Aves and Mammalia have two pairs of limbs and are thus grouped under Tetrapoda. The amphibians have adapted to live both on land and water. 

Reptiles are characterised by the presence of dry and cornified skin. Limbs are absent in snakes. Fishes, amphibians and reptiles are poikilothermous (cold-blooded). Aves are warm-blooded animals with feathers on their bodies and forelimbs modified into wings for flying. Hind limbs are adapted for walking, swimming, perching or clasping. The unique features of mammals are the presence of mammary glands and hairs on the skin. They commonly exhibit viviparity.

NCERT Solutions for Class 11 Biology Chapter 4 Animal Kingdom

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

Ans: There are millions of living organisms with a vast variety of shapes, sizes, and forms. They occur in a variety of habitats. It is difficult to identify and describe them at random, so they are classified into various categories. Animals are classified on the basis of common features such as cell arrangement, body symmetry, nature of coelom, digestive tract, circulation or reproductive system. Without these common features it is very difficult to treat each organism individually, it is impossible to add new species detected every day without common features. To study diversity in animals, classification must be based on common basic features

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

Ans: Classification of specimen deals according to a systematic plan on the basis of their similarities, differences and relationship.

We will take the following steps

(i) Level or grade of organisation: There are different types of cell which are organised into functional units of progressively increasing complexity. Such as acellular, cellular, tissue, organ and organ system.

(ii) Pattern in organ system: There are different organ system in which specific group of organs work together to do a specific function. Such as digestive organs in digestive system. Respiratory organs in respiratory system, etc. in animal body.

(iii) Symmetry: In animals, 4-types of symmetry are seen. These are spherical, radial, bilateral, Asymmetrical species are classified according to symmetry.

(iv) Diploblastic and triploblastic organisation: According to number of germ layers which differentiate at the time of gastrulation in developing embryo. Species are classified as diploblastic i.e. two germ layer and Triploblastic i.e. three germ layers.

(v) Body cavity or coelom: According to types of coelom, species are classified into acoelom, pseudocoelom and eucoelom animals.

(vi) Segmentation: Species are classified according to segmentation. It is of three types i.e. pseudometamerism or false segmentation, internal and external segmentation.

(vii) Notochord: On the basis of notochord, animals or species are divided into chordates and non-chordates.

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

Ans: Coelom is the gap between gut and body wall. Coelom is the characteristic feature of complex or higher animals while lower animals like Platyhelminthes are acoelomate. The absence of coelom indicates that the animal is yet to develop a functional division of labour to carry out various activities. So the coelom characterises complexity of the animals and represents organic evolution.

There are three types of coelom

(i) Acoelom: It means absence of body cavity which is due to the failure of mesoderm to cavitate during embryogency, so there is no coelom, no peritonium. e.g. porifera, colenterata, etc.

(ii) Pseudocoelom: It means presence of coelom that develops from the blastocoel but not lined by mesoderm, e.g. nematodes, etc.

(iii) Eucoelom: It means hue coelom, which is lined by mesoderm resulting in tube within -tube design. e.g. higher invertebrates, chordates, etc.

NCERT Solutions of Class 11 Biology Chapter 4 Animal Kingdom

4. Distinguish between intracellular and extracellular digestion ?

Ans:

Intracellular digestion

(i) It occurs in lower organisms.

(ii) It occurs within cells.

(iii) It is less efficient with no regional differentiation.

(iv) Enzymes associated are very few.

Extracellular digestion 

(i) It occurs in multicellular organisms.

(ii) It occurs within cavity of the ailmentry canal, outside the cell.

(iii) Highly efficient with regional differentiation.

(iv) Large number of digestive glands and enzymes are required.

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

Ans:

Direct development

(i) An embryo develops into a young one without any intermediate larval stage.

(ii) Occurs in fish, reptile birds and mammals.

(iii) Young ones resemble the adult.

Indirect development

(i) An embryo develops into a young one with some intermediate larval stages.

(ii) Occurs in in vertebrate amphibians.

(iii) Young ones do not resemble the adult.

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

Ans: The peculiar features of parasitic platyhelminthes are

(i) The thick tegument (outer covering) resistant to the host’s digestive enzymes and anti-toxins.

(ii)Adhesive organs like suckers in flukes and the hooks and suckers in tapeworms for a firm grip on or in the host’s body.

(iii)Loss of locomotory organs.

(iv)Digestive organs are absent in tapeworms because digested and semidigested food of the host is directly absorbed’ through the body surface.

(v) Reproductive system is best developed in parasitic flatworms.

(vi)Parasitic flatworms, such as liver fluke and tapeworms perform anaerobic respiration.

(vii)They possess a considerable osmotic adaptability, as they can successfully live in different media.

Animal Kingdom class 11 NCERT Solutions

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 for arthropods being the largest group of animals are as follows

(i) They have jointed legs that allow them to motile, and perform many other functions due to these jointed appendages.

(ii) Presence of tough cuticle for protection of the body. It also helps in tolerating diverse terrestrial conditions.

(iii) Presence of jointed appendages for performing diverse functions.

(iv) A hardened skeleton made of chitin protects their body.

(v) Presence of striated muscles for quick movements.

(vi) Tracheal respiration for direct supply of oxygen as in insects

(vii)  Well developed nervous system and sense organs.

(viii) Presence of pheromones for communication.

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

   (a) Porifera (b) Ctenophora (c) Echinodermata (d) Chordata

Ans: Echinodermata.

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

Ans: Phylum chordata includes animals characterised by the presence of notochord. This phylum includes sub-phyla urochordata, cephalochordata and vertebrata. In vertebrates, the notochord is replaced by vertebral column, in urochordates and cephalochordates vertebral column is absent. Thus, all vertebrates are chordates but all chordates are not vertebrates as they can be urochordates and cephalochordates also.

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

Ans: The air bladder is found to be present in the members of class Osteichthyes while it is absent in Chondrichthyes. The main function of air bladder is to regulate buoyancy and help the fishes to float in the water. It also prevents them from sinking in the water. Since Chondrichthyes do not have air bladder they have to swim continuously to avoid sinking.

Animal Kingdom class 11/ HS 1st Year Science Biology chapter 4

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

Ans: Modifications in birds to help them fly are as follows:

(i) The bones of birds are pneumatic. These contain air cavities making the bones light. This feature helps the birds in flying.

(ii) The body of birds is streamlined offering least resistance while flying.

(iii) Flight muscles are well developed

(iv) Forelimbs of birds are modified into wings to allow flying. Hind limbs are used for walking, perching etc.

(v) Absence of urinary bladder causes net body weight loss and facilitates them to fly.

(vi) Additional air sacs are present to supplement respiration.

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

Ans: No, the number of eggs or young ones produced by an oviparous and viviparous mother respectively cannot be equal. Oviparous mother lays large number of eggs, as the eggs are laid outside the body, so they are not protected from predators and harsh environmental conditions, and therefore destroyed. However in viviparous mother, eggs are not laid outside, but the embryos develop inside the mother and thus are protected from the outside harsh environment, thus, the number of eggs produced are less. Therefore, the number of eggs or young ones produced by an oviparous and viviparous mother respectively cannot be equal.

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

  (a) Platyhelminthes (b) Aschelminthes (c) Annelida (d) Arthropoda

Ans: Annelida

14. Match the following:

     (a) Operculum                   (i) Ctenophora

     (b) Parapodia                    (ii) Mollusca

     (c) Scales                          (iii) Porifera

     (d) Comb plates                (iv) Reptilia

     (e) Radula                          (v) Annelida

     (f ) Hairs                            (vi) Cyclostomata and Chondrichthyes

     (g) Choanocytes              (vii) Mammalia

     (h) Gill slits                       (viii) Osteichthyes

Ans:

     (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

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

Ans: Some animals that are found parasitic in humans are as follows:

(i) Taenia ( Tapeworm)

(ii) Ascaris (roundworm)

(iii) Ancylostoma (hookworm)

(iv) Enterobius (pinworm)

(v) Wuchereria (filarial worm)