NCERT Solutions for Class 11 Biology Chapter 4 Animal Kingdom

NCERT
SOLUTIONS
CLASS - 11th

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Class : 11th
Subject : Biology
Chapter : 4
Chapter Name : Animal Kingdom

Q1 What are the dif culties that you would face in classi cation of animals, if common fundamental
features are not taken into account?

Answer. For the classi cation of living organisms, common fundamental characteristics are considered. If
we consider speci c characteristics, then each organism will be placed in a separate group and the entire
objective of classi cation would not be achieved. Classi cation of animals is also important in comparing
different organisms and judging their individual evolutionary signi cance. If only a single characteristic is
considered, then this objective would not be achieved.

Q2 If you are given a specimen, what are the steps that you would follow to classify it?

Answer. There is a certain common fundamental feature that helps in classi cation of living organisms.
The features that can be used in classi cation are as follows.

On the basis of above features, we can easily classify a specimen into its respective category.

Q3 How useful is the study of the nature of body cavity and coelom in the classi cation of animals?

Answer. Coelom is a uid lled space between the body wall and digestive tract. The presence or absence
of body cavity or coelom plays a very important role in the classi cation of animals. Animals that possess
a uid lled cavity between body wall and digestive tract are known as coelomates. Annelids, mollusks,
arthropods, echinoderms, and chordates are examples of coelomates. On the other hand, the animals in
which the body cavity is not lined by mesoderm are known as pseudocoelomates. In such animals,
mesoderm is scattered in between ectoderm and endoderm. Aschelminthes is an example of
pseudocoelomates. In certain animals, the body cavity is absent. They are known as acoelomates. An
example of acoelomates is platyhelminthes.

Q4 Distinguish between intracellular and extracellular digestion?
Answer. Intracellular and Extracellular digestion

Q5 What is the difference between direct and indirect development?

Answer. Direct and Indirect development

Q6 What are the peculiar features that you nd in parasitic platyhelminthes?

Answer. Taenia (Tapeworm) and Fasciola (liver uke) are examples of parasitic platyhelminthes. Peculiar
features in parasitic platyhelminthes are as follows.
1. They have dorsoventrally attened body and bear hooks and suckers to get attached inside the body of
the host.
2. Their body is covered with thick tegument, which protects them from the action of digestive juices of
the host.
3. The tegument also helps in absorbing nutrients from the host's body.

Q7 What are the reasons that you can think of for the arthropods to constitute the largest group of the
animal kingdom?

Answer. The phylum, Arthropoda, consists of more than two-thirds of the animal species on earth. The
reasons for the success of arthropods are as follows.
i. Jointed legs that allow more mobility on land.
ii. Hard exoskeleton made of chitin that protects the body.
iii. The hard exoskeleton also reduces water loss from the body of arthropods making them more adapted
to terrestrial conditions.

Q8 Water vascular system is the characteristic of which group of the following:
(a) Porifera
(b) Ctenophora
(c) Echinodermata
(d) Chordata

Answer. Water vascular system is a characteristic feature of the phylum, Echinodermata. It consists of an
array of radiating channels, tube feet, and madreporite. The water vascular system helps in locomotion,
food capturing, and respiration.

Q9 “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement?

Answer. The characteristic features of the phylum, Chordata, include the presence of a notochord and
paired pharyngeal gill slits. In subphylum 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.

Q10 How important is the presence of air bladder in Pisces?

Answer. Gas bladder or air bladder is a gas lled sac present in shes. It helps in maintaining buoyancy.
Thus, it helps shes to ascend or descend and stay in the water current.

Q11 What are the modi cations that are observed in birds that help them y?

Answer. Birds have undergone many structural adaptations to suit their aerial life. Some of these
adaptations are as follows.
(i) Streamlined body for rapid and smooth movement
(ii) Covering of feathers for insulation
(iii) Forelimbs modi ed into wings and hind limbs used for walking, perching, and swimming
(iv) Presence of pneumatic bones to reduce weight
(v) Presence of additional air sacs to supplement respiration

Q12 Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal?
Why?

Answer. The numbers of eggs produced by an oviparous mother will be more than the young ones
produced by a viviparous mother. This is because in oviparous animals, the development of young ones
takes place outside the mother's body. Their eggs are more prone to environmental conditions and

predators. Therefore, to overcome the loss, more eggs are produced by mothers so that even under harsh
environmental conditions, some eggs might be able to survive and produce young ones. On the other
hand, in viviparous organisms, the development of young ones takes place 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.

Q13 Segmentation in the body is rst observed in which of the following:
(a) Platyhelminthes (b) Aschelminthes (c) Annelida (d) Arthropoda

Answer. The body segmentation rst appeared in the phylum, Annelida (annulus meaning little ring).

Q14 Match the following:

Answer.

Q15 Prepare a list of some animals that are found parasitic on human beings.

Answer.