NCERT Solutions For Class 11 | Biology | Chapter 4 | Animal Kingdom

NCERT Class 11 Chapter 4 – Animal Kingdom talks about the different types of classifications. While some of the fundamental features of the Animals are common (includes body symmetry, cell organization, nature of coelom, and different digestion, circulatory and reproductive systems), the basis of the classification may be different. This chapter talks in detail about the type of classification and basis of the same.

Our solutions are carefully crafted to help you with the conceptual understanding required for understanding the Animal Kingdom.

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

Answer – Animals are classified on the basis of characteristics like presence of coelom, nature of body symmetry, level of organization, open or closed digestive tract, circulatory or respiratory system. Without these bases, it is very difficult to classify animals.

Therefore, it is very important to take common fundamentals into account.

Difficulties faced are –

  • (i) Studying the relationships between animals would prove to be difficult.
  • (ii) Developing a new species of animal would be strenuous without proper classification.

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

Answer – Steps to classify a specimen are –

  • (i) State the level of organization present, i.e. cellular or tissue level of organization.
  • (ii) Classify the symmetry of the specimen, i.e. radial or bilateral symmetry.
  • (iii) State the triploblastic or diploblastic organization of specimens.
  • (iv) State the presence or absence of a body cavity.
  • (v) Type of coelom present and its development.
  • (vi) Classify the segmentation, i.e. absent or present.
  • (vii) Distinguish the presence or absence of notochord.

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

Answer –

  • The presence or absence of body cavity between the gut wall and body wall is very important for the classification of animals and to study its complexity at an organ level of body organization.
  • A coelom is the body cavity lined by mesoderm and the animals with the presence of coelom are called coelomates. Example- annelids, arthropods, chordates, molluscs, echinoderms, and hemichordates
  • Animals in which the body cavity is lined by scattered pouches of mesoderm in between the endoderm and ectoderm are called pseudocoelomates. Example- aschelminthes
  • Animals without body cavity or coelom are called acoelomates. Example- platyhelminthes.

4. Distinguish between intracellular and extracellular digestion?

Answer –

The digestion occurs inside the cell.The digestion occurs in the digestive tract of the body.
Usually occurs in lower organisms.Occurs in higher organisms.
Very few enzymes are associated.Number of digestive glands and enzymes are used. 
Less efficientHighly efficient.

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

Answer –

In this type of development, the embryo develops into a mature adult without any larval stage.In this type of development, many sexually immature larval stages are present in the life cycle.
No metamorphosis occurs.Metamorphosis occurs.
Usually found in reptiles, fishes, birds and mammals.Usually found in vertebrates and amphibians
Example- earthwormExample- butterfly, frog

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

Answer – Major features of parasitic platyhelminthes are –

  • They are mostly endoparasites, i.e. found inside the body, and free-living parasites.
  • They are hermaphrodites, i.e. sexes are distinguished.
  • Parasitic forms are characterized by the presence of hookers and suckers.
  • Body is covered with cuticles to protect them.
  • They are bilaterally symmetrical, triploblastic, and acoelomate animals.
  • They have an organ level of organization.
  • Special cells like flame cells help in excretion and osmoregulation.
  • Internal fertilization and indirect development are found.
  • Example- Taenia, Fasciola.

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

Answer – The reasons due to which arthropods make the largest group of animal kingdom –

  • The presence of jointed legs for locomotion and many other functions.
  • Hard exoskeleton of chitin reduces water loss and protects the body.
  • They have the ability and adaptability to live in diverse habitats and harsh climates.
  • Well developed sensory organs and nervous systems.
  • As compared to other phyla, they are more developed.

8. Water vascular system is the characteristics of which group of the following;

  • (a) Porifera
  • (b) Ctenophora
  • (C) Echinodermata
  • (d) Chordata

Answer – The correct answer is (c) Echinodermata

Water vascular system is the characteristic of Echinoderms. The perforated panel called madreporite, allows water to percolate throughout the systems.

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

Answer – The characteristic features of phylum Chordata is the presence of notochord and pharyngeal gill slits. The subphylum Vertebrata has notochord in the embryonic stage but it is replaced by the cartilaginous or bony vertebral column in the adult. Therefore it is said that “All vertebrates are chordates but all chordates are not vertebrates”.

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

Answer – In order to regulate buoyancy which prevents the fishes from sinking, it is important for the air bladder to be present. In class Chondrichthyes, due to its absence the fishes have to swim constantly in order to not sink.

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

Answer – Modifications found in the birds that help them fly –

  • The presence of feathers.
  • Presence of hind limbs scales and forelimbs modified into feathers.
  • Their long bony skeleton and bones are hollow or pneumatic.
  • Absence of urinary bladder makes their body weight lesser and helps them fly.
  • The streamlined body facilitates less resistance as they fly.

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

Answer – No, the number of eggs or young ones produced by an oviparous and viviparous mother are no equal. As oviparous animals involve external fertilization, in order to sustain the progeny as there is a risk of getting hunted by predators, there is a requirement of more eggs. Whereas in viviparous animals, the egg is present inside the female’s body where fertilization takes place which makes successful incubation of young animals lesser.

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

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

Answer – The correct option is (c) Annelida.

14. Match the following:

OperculumI. Ctenophora 
ParapodiaII. Mollusca
ScalesIII. Porifera
Comb platesIV. Reptilia
RadulaV. Annelida
HairsVI. Cyclostomata and Chondrichthyes
Choanocytes VII. Mammalia
Gill slitsVIII. Osteichthyes

Answer –

(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.

Answer –

  • Ancylostoma (Hookworm)
  • Taenia (Tapeworm)
  • Ascaris (Roundworm)
  • Enterobius (Pinworm)
  • Wuchereria (Filarial worm)

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