NCERT Solutions for Class 11th Biology
Chapter 4 ANIMAL KINGDOM DOWNLOAD OUR APP
Question 1: What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?
Answer For the classification of living organisms, common fundamental characteristics are considered. If we consider specific characteristics, then each organism will be placed in a separate group and the entire objective of classification would not be achieved. Classification of animals is also important in comparing different organisms and judging their individual evolutionary significance. If only a single characteristic is considered, then this objective would not be achieved. DOWNLOAD OUR APP 2.If you are given a specimen, what are the steps that you would follow to classify it? soln. Various steps considered to classify a specimen are: (i)Mode of nutrition – It can be autotrophic, holozoic, saprophytic or parasitic. (ii)Complexity of body structure – Whether the specimen is unicellular or multicellular. (iii)Presence or absence of membrane bound organelles. (iv)Body symmetry, i.e., the plane by which organism can be divided into two equal halves. (v)Presence or absence of coelom, it can be acoelomates, pseudocoelomates, eucoelo- mates. (vi)Phylogenetic relationship. Question 3: How useful is the study of the nature of body cavity and coelom in the classification of animals? Answer Coelom is a fluid filled space between the body wall and digestive tract. The presence or absence of body cavity or coelom plays a very important role in the classification of animals. Animals that possess a fluid filled cavity between body wall and digestive tract are known as coelomates. Annelids, mollusks, arthropods, echinodermates, 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. 4.Distinguish between intracellular and extra-cellular digestion. soln. Differences between intracellular and extracellular digestion are:   5.What is the difference between direct and indirect development? soln. Differences between direct development and indirect development are :  Question 6: What are the peculiar features that you find in parasitic platyhelminthes? Answer Taenia (Tapeworm) and Fasciola (liver fluke) are examples of parasitic platyhelminthes. Peculiar features in parasitic platyhelminthes are as follows. 1. They have dorsiventrally flattened 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. DOWNLOAD OUR APP Question 7: 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. 8.Water vascular system is the characteristic of which group among the following ? (a) Porifera (b) Ctenophora (c) Echinodermata (d) Chordata soln. (c) Echinodermata 9.”All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement. soln. Chordates are the animals that possess notochord (a stiff, supporting rod like structure present on the dorsal side) at some stage of their lives. Phylum Chordata is divided into three Subphyla: Urochordata or tunicata, Cephalochordata and Vertebrata. Subphyla Urochordata and Cephalochordata are often referred to as protochordates and are exclusively marine. In urochordata, notochord is present only in tail of larva and disappears in adults, while in cephalochordata, it extends from head to tail region and persists throughout the life.The members of Subphylum Vertebrata a possess notochord during the embryonic period and is replaced by a cartilaginous or bony vertebral column in the adult. Thus all vertebrates are chordates but all chordates are not vertebrates. Question 10: How important is the presence of air bladder in Pisces? Answer Gas bladder or air bladder is a gas filled sac present in fishes. It helps in maintaining buoyancy. Thus, it helps fishes to ascend or descend and stay in the water current. Question 11: What are the modifications that are observed in birds that help them fly? 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 modified 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
12. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?
soln. 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 soln. (c) 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) Hair (vi)Cyclostomata and Chondrichthyes (g) Choanocytes (vii)Mammalia (h) Gill slits (viii Osteichthyes soln.(a) – (viii), (b) – (v), (c) – (iv), (d) – (i), (e) – (ii), (f) – (vii), (g) – (iii), (h) – (vi).
15. Prepare a list of some animals that are found parasitic on human beings.
soln.List of some animals that are found parasitic on human beings :  DOWNLOAD OUR APP LIKE US ON FACEBOOK |
Comments
Post a Comment