NCERT Exemplar Class 11 Biology Solutions Structural Organisation in Animals

Multiple Choke Questions
1.Which one of the following types of cell is involved in making of the inner walls of large blood vessels?
(a) Cuboidal epithelium
(b) Columnar epithelium
(c) Squamous epithelium
(d) Stratified epithelium
S0ln.(c): Simple squamous epithelium lines the inner walls of blood vessels. It is  composed of large flat cells which rest on a thin basement membrane.

2.To which one of the.following categories does adipose tissue belong?
(a) Epithelial
(b) Connective
(c) Muscular
(d) Neural
Soln.: Adipose tissue is a fat-storing loose connective tissue found subcutaneously, around the heart, kidney, eyeballs, mesenteries,etc. It is also found in blubber of whales and humps of camels. Subcutaneous fat prevents loss of heat from the body.

3.Which of the following is not a connective tissue?
(a) Bone (b) Cartilage
(c) Blood (d) Muscles
Soln.(d) : Muscular tissue consists of muscle fibres, it is not a connective tissue. Bone and cartilage are specialised connective tissue and blood is fluid connective tissue.

4.The ditellum is a distinct part in the body of earthworm, it is found in
(a) Segments 13-14-15
(b) Segments 14-15-16
(c) Segements 12-13-14
(d) Segments 15-16-17
Soln.(b) The ditellum, a prominent circular band of glandular nature, is found from the 14t]l to 16th segments. The ditellum secretes mucus and albumen. Its secretion helps in the formation of cocoon, which is used for fertilisation of the eggs.

5.Setae help in locomotion in earthworm but are not uniformly present in all the segments. Select among the following that represents setae.
(a) 1segment
(b) Last segment
(c) Clitellar segment
(d) 20th – 22nd segment
Soln.(d): In each body segment of earthworm, except the first, last and ditellum (segments 14-16), there are rows of setae, embedded in the epidermal pits in the middle of each segment. Setae helps in locomotion.

6.Which one of the following statements is true for cockroach?
(a) The number of ovarioles in each ovary are ten.
(b) The larval stage is called caterpillar.
(c) Anal styles are absent in females.
(d) They are ureotelic.
Soln.(c): Anal styles are paired, thin, unjointed outgrowths, projecting backwardly from the sides of 9th sternum of the male cockroach only. They are absent in females.  Each ovary contains eight ovarioles. The juvenile stage of cockroach is called nymph. Cockroach is uricotelic.

7.Match the following and choose the correct option.
A.Adipose tissue                                      (i) Nose
B.Stratified epithelium                        (ii) Blood
C.Hyaline cartilage                               (iii) Skin
D.Fluid connective tissue (iv) Fat storage
(a) A-(i), B-(ii), C-(iii), D-(iv)
(b) A-(iv), B-(iii), C-(i), D-(ii)
(c) A-(iii), B-(i), C-(iv), D-(ii)
(d) A-(ii), B-(i), C-(iv), D-(iii)

8.Match the following and choose the correct answer.
A. Hermaphrodite                            (i)  Produces blood cells  and haemoglobin
B. Direct development                    (ii) Testis and ovary in  the same animal
C. Chemoreceptor                            (iii) Larval form absent
D. Blood gland in earthworm       (iv) Sense of chemical  substances
(a) A-(ii), B-(iii), C-(iv), D-(i)
(b) A-(iii), B-(ii), C-(iv), D-(i)
(c) A-(i), B-(iii), C-(ii), D-(iv)
(d) A-(ii), B-(iv), C-(iii), D-(i)
Soln. (a)

9.Match the following with reference to cockroach and choose the correct option.
A. Phallomere          (i)  Chain of developing  ova
B. Gonopore              (ii) Bundles of sperm
C. Spermatophore (iii) Opening of the  ejaculatory duct
D. Ovarioles              (iv) The external  genitalia
(a) A-(iii), B-(iv), C-(ii), D-(i)
(b) A-(iv), B-(iii), C-(ii), D-(i)
(c) A-(iv), B-(ii), C-(iii), D-(i)
(d) A-(ii), B-(iv), C-(iii), D-(i)

10 .Match the following and choose the correct answer.
A. Touch                              (i) Nasal epithelium
B. Smell                               (ii) Foramen magnum
C. Cranial nerves             (iii) Sensory papillae
D. Medulla oblongata     (iv) Peripheral  nervous system
(a) A-(iii), B-(i), C-(ii), D-(iv)
(b) A-(ii), B-(i), C-(iv), D-(iii)
(c) A-(iii), B-(iv), C-(ii), D-(i)
(d) A-{iii), B-(i), C-(iv), D-(ii)

Short Answer Type Questions
1.State the number of segments in earthworm which are covered by a prominent dark band or clitellum.
Soln. 3 clitellar segments : 14,15 and 16

2.Where are sderites present in cockroach?
Soln. In each segment of cockroach body, i.e., head, thorax and abdomen, exoskeleton has hardened plates called sclerites, that are joined to each other by thin and flexible arthrodial membrane.

3.How many times do nymphs moult to reach the adult form of cockroach?
Soln. Nymphs moult 13 times to reach the adult form.

4.Identify the sex of a frog in which sound producing vocal sacs are present.
Soln. Male frog

5.Name the process by which a tadpole develops into an adult frog.
Soln. Metamorphosis

6.What is the scientific term given to earthworm’s body segments?
Soln. Metameres

7.A muscle fibre tapers at both ends and does not show striations. Name the muscle fibre.
Soln. Smooth muscle fibre

8.Name the different cell junctions found in tissues.
Soln. Tight junctions, adhering junctions and gap junctions.

9.Give two identifying features of an adult male frog.
Soln. Male frogs can be distinguished by the presence of sound producing vocal sacs and  copulatory pad on the first digit of forelimb, which are absent in female frogs.

10. Which mouth part of cockroach is comparable to our tongue?
Soln. Hypopharynx

11 .The digestive system of frog is made of the following parts. Arrange them in an order beginning from mouth.
Soln.Mouth, oesophagus, buccal cavity, stomach, intestine, cloaca, rectum, cloacal aperture. Maflft Mouth — » buccal cavity —> oesophagus —> stomach —> intestine — »rectum —> cloaca —> cloacal aperture.

12.What is the difference between cutaneous and pulmonary respiration?
Soln. Cutaneous respiration is exchange of gases through skin, it occurs in water, while pulmonary respiration involves lungs and occurs on land.

13.Special venous connection between liver and intestine and between kidney and intestine is found in frog, what are they called?
Soln. Hepatic portal system and renal portal system respectively.

Short Answer Type Questions
1.Give the location of hepatic caecae in a cockroach. What is their function?
Soln.Hepatic caecae are arise from the anterior end of midgut. They are present at junction of midgut and gizzard and are 6-8 in number. They are lined by the glandular cells which secrete digestive secretion containing amylolytic, proteolytic and lipolytic types of enzymes, which help in the digestion of carbohydrates, proteins and fats.

2.Frogs are beneficial for mankind, justify the statement.
Soln.Frogs are beneficial for mankind as they help in maintaining ecosystem, because they are involved in food chain. Frogs eat up insects which are harmful for crops and thus help in protecting the crop damage and saves expenditure on insecticides. In some parts of India and other countries, muscles of the legs of frog are used as food. Moreover, they are also used as an experimental material for teaching and research.

3.The body of sponges does not possess tissue level of organisation though it is made of thousands of cells. Comment.
Soln. Sponges show cellular level of body organisation, i.e., body consists of large number of cells but cells are loosely arranged and are not organised to form specific tissues specialised for particular function.

4.Structural organisation in animals attains different levels as cell – organ – organ system. What is missing in this chain? Mention the significance of such an organisation.
Soln. Tissue level of organisation is missing in this chain. Cell -tissue-organ-organ system. Such an organisation split up the work in a way that exhibits division of labour and contribute to the survival of the body as a whole.

5.Stratified epithelial cells have limited role in secretion. Justify their role in our skin.
Soln. Stratified epithelium (compound epithelium) has limited role in secretion and absorption because it is made up of multiple layers of cells. Stratified epithelium provides protection against chemical and mechanical stresses. E.g., keratinised stratified epithelium forms epidermis of skin of land vertebrates, it is impermeable to water and forms protective covering against abrasions.

6.How does a gap junction facilitate intercellular communication?
Soln. Gap junctions are meant for chemical exchange between adjacent cells. They facilitate the cells to communicate with each other by connecting the cytoplasm of neighbouring cells for rapid transfer of ions, small molecules and sometimes big molecules.

7.Why are blood, bone and cartilage called connective tissue?
Soln.Connective tissue connects different tissues or organs and provides support to various structures of animal body. Blood, bone and cartilage are specialised connective tissue. Blood is a fluid connective tissue and transports various materials from one part of the body to the other and thereby forming link between different body parts. Bone and cartilage forms endoskeleton of vertebrates and they support the body, protect various organs and help in locomotion.

8.Why are neurons called excitable cells? Mention special features of the membrane of the neuron?
Soln. Neurons are called excitable cellsbecause they have the ability to initiate nerve impulse in response to stimuli and transmits impulses in form of electrical and chemical signals. Neuronal membrane serve as barrier between cytoplasm of neuron and surrounding external medium. It helps to establish electrical potential as ion channels of membrane are selectively permeable to different ions. It also helps in impulse conduction and is sensitive to neurotransmitter and modulator.

9.Why earthworm is called the friend of farmer?
Soln. Earthworm is called the friend of farmer because it helps in making the soil loose and porous by burrowing, which in turn causes aeration and absorption of water by soil and thus, helps in respiration and penetration of the developing plant roots. Earthworms are also used in vermicomposting as worm castings are used as manure and increases soil fertility. Nitrogenous wastes of earthworms are used as plant food and they help in creating optimum conditions for plant growth by reducing acidity and alkalinity of soil.

10.How do you distinguish between dorsal andventral surface of the body of earthworm.
Soln. The dorsal surface of the body of earthworm is marked by a dark mid dorsal line (dorsal blood vessel) along the longitudinal axis of the body and dorsal pores on the mid dorsal line. The ventral surface is distinguished by the presence of genital pores, genital papillae.

11.Correct the wrong statements among the
(a) In earthworm, a single male genital pore is present.
(b) Setae help in locomotion of earthworm.
(c) Muscular layer in the body wall of earth-worm is made up of only circular muscles.
(d) Typhlosole is the part of intestine of earthworm.
Soln. (a) In earthworm, a pair of male genital pores are present in segment 18.
(c) Muscular layer in the body wall of earthworm is made up of outer layer of circular muscles and inner layer of longitudinal muscles.

12.Why nephridia in earthworm that are basically similar in structure is classified into three types? Mention the names of each.
Soln. In earthworm nephridia perform the function of excretion and osmoregulation. Though nephridia are basically similar in structure, yet they are classified into three types according to their location:
(i) Septal nephridia: They are present from
fifteenth segment to last, there are 80 to 100 septal nephridia in each segment. The septal nephridia discharge their excretory matter into the lumen of the alimentary canal/enteron, thus, they are called enteronephric nephridia. ••••
Pharyngeal nephridia: They occur in three pair of bunches in the 4th, 5th, and 6th segments. The ducts of the nephridia of the sixth segment open into the buccal cavity while the ducts from the nephridial bunches of the fourth and fifth segments open into the pharynx. These ducts carry excretory matter into the gut. Thus, are also known as enteronephric nephridia,
Integumentary nephridia are found scattered in the body wall (integument)
in each segment except the first two segments. In each segment they number from 200 to 250 except in the fourteenth, fifteenth and sixteenth segments (clitellar region) where their number is about ten times more than that in the other segments. Thus, clitellar segments are often called as the “forest of nephridia”. These nephridia discharge their contents directly to the outside hence they are called ectonephric (= exonephric) nephridia.

13. Common name of some animats are given in Column A, write their scientific name in Column B.
Column A Column B
(a) Tiger________
(b) Peacock________
(c) Housefly________
Soln.(a) Tiger – Panthera tigris
(b) Peacock – Pavo cristatus
(c) Housefly – Musca domestica

14. Complete the following statement:
(a) In cockroach grinding of food particle is
performed by ___________________
(b) Malpighian tubules help in removal of___________________
(c) Hind gut of cockroach is differentiated into___________________
(d) In cockroach blood vessels open into___________________
spaces called
Soln. (a) gizzard.
(b) metabolic wastes like potassium and sodium urate, water and carbon dioxide from blood.
(c) ileum, colon, rectum and anus.
(d) haemocoel.

15. Mention special features of eye in cockroach.
Soln.Cockroach has a pair of compound eyes situated on the dorsal surface of the head. Each eye consists of about 2000 hexagonal ommatidia, with the help of which a cockroach can receive several images of an object. This kind of vision is known as mosaic vision. Each ommatidium sees only small part of object, therefore, image formed by an eye as a whole consists of several pieces which are put together to make up whole picture received by the eye.

16. Frog is a poikilotherm, exhibits camouflage and undergoes aestivation and hibernation, how are all these beneficial to it?
Soln. Frog is a poikilotherm (cold blooded), i.e., it cannot maintain constant body temperature and it varies with change in environmental temperature. Being cold blooded, frog cannot withstand very cold weather and extreme high temperature and thus burries itself deep in mud during winters and summers, known as hibernation (winter-sleep) and aestivation (summer sleep) respectively. These periods are of little activities and energy required is obtained from fat bodies, or stored glycogen in liver, which have been stored earlier. Camouflage is the ability to change body colour with change in its surroundings and climatic conditions. It helps the animal to escape from predators or to attack its prey.

17.Write the functions in brief in Column B, appropriate to the structures given in Column A.
Column A Column B
(a) Nictitating membrane (i)________
(b) Tympanum                     (ii)________
(c) Copulatory pad            (iii)________
Column A                                            Column B
(a) Nictitating membrane                i.Protect the eyeswhile the frog is  in water
(b) Tympanum                                 ii.Receives sound  signals
(c) Copulatory pad                         iii. Helps the male in  grasping the female  during amplexus.

18. Write the appropriate type of tissues in Column B according to the functions mentioned in Column A.
Column A Column B
(a) Secretion and                             i.________
(b) Protective covering                 ii.________
(c) Linking and                               iii.________
supporting framework
Column A                                                        Column B
(a) Secretion and  absorption                      i. Simple epithelium
(b) Protective  covering                                ii. Compound (Stratified) epithelium
(c)Linking and  supporting framework.   iii. Connective tissue

19. Using appropriate examples, differentiatebetween false and true body segmentation.
Soln. Segmentation is differentiation of body into distinct segments. In true segmentation or metameric segmentation, body is divided both externally and internally into number of segments (metameres). E.g., Earthworm. In false segmentation or pseudometamerism, body is divided only externally but not internally. In this type of body segmentation, segments are not of embryonic origin. E.g., Tapeworms.

20.What is special about tissue present in the heart?
Soln.Heart contain cardiac muscle tissue. Cardiac muscle fibres are cylindrical, branched, uninucleated (nucleus present near the centre). Fibres have transverse light and dark bands, alternating with each other. Cardiac muscle fibres also have intercalated discs between two adjacent fibres, to transmit wave of contraction from one cardiac fibre to another. Heart muscle is involuntary and never get fatigued.

Long Answer Type Questions
1.Classify and describe epithelial tissue on the basis of structural modifications of cells.
Soln.Refer answer 11, NCERT section.

2.Write down the common features of the connective tissue. On the basis of structure and function, differentiate between bones and cartilages.
Soln. Common features of connective tissue are :
(i) Connective tissue is the most abundant and widely distributed tissue of the body. It connects tissues organs and also provides support to various body parts.
(ii) Connective tissue is developed from the embryonic mesoderm.
(iii) Three components are majority present in the connective tissue: matrix, cells and fibres.
(iv) The extracellular matrix has nearly amorphous ground substance made of glycoproteins with associated muco-polysaccharides. This ground substance may be liquid, gel or solid.
(v) The tissue has good amount of regenerative ability.
Differences between bone and cartilage are:

3.Comment upon the gametic exchange in earthworm during mating.
Soln. Earthworm is hermaphrodite i.e., both testes and ovaries are present in the same individual. But self-fertilisation does not occur as the testes and ovaries do not mature at the same time. Thus, cross-fertilisation takes place. Two worms attach themselves with their ventral surfaces and become opposed to each other in opposite direction. During copulation male genital papilla of one earthworm is inserted into the spermathecal pore of the other earthworm to transfer the sperms and prostatic fluid. After copulation two earthworms separate. Now the glandular cells of the clitellum secrete a fluid that forms a girdle around the clitellum. The girdle is filled with mature ova released through female genital pore. The worm wriggles backwards. When the girdle passes over the spermathecal pores it receives the sperms stored in the spermathecae and albuminous secretion of the epidermal gland cells of skin. Ultimately, the worm wriggles out completely and the girdle is, therefore, left free in moist soil. Now this structure is called cocoon. Fertilisation and development occur inside the cocoon and on an average four baby worms are produced in one cocoon.

4.Explain the digestive system of cockroach with the help of a labelled sketch.
Soln.The cockroach has well developed digestive system consisting of alimentary canal and associated digestive glands. Alimentary canal is divided into three regions: foregut, midgut and hindgut. Foregut consists of mouth, pharynx, oesophagus, crop and gizzard. Mouth, a narrow opening opens into a short tube-like structure called pharynx which further leads into tubular passage called oesophagus. Oesophagus opens into a pear-shaped structure called crop which is used for storing the food. The crop leads into gizzard which has an outer of layer strong circular muscles and inner cuticle forming six teeth which help in grinding the food particles. Foregut is followed by midgut where digestion and absorption of food takes place. At junction of midgut and gizzard six to eight finger-like structures called hepatic caecae are present and 100-150 yellow fine thread-like structures called Malpighian tubules are present at junction of midgut and 5. hindgut.
The hindgut is differentiated into ileum, colon, rectum and anus.
Digestive glands include the following:
(i) There are paired salivary glands, one on each side of oesophagus and crop. They secrete saliva which contains enzymes amylase, chitinase and cellulase.
(ii) Hepatic caecae lined by glandular cells secrete digestive secretions containing amylolytic, lipolytic and proteolytic enzymes.
(iii) Midgut lining-glandular epithelial cells lining midgut secrete digestive secretion containing proteoloytic, amylolytic and lipolytic enzymes.

5.Draw a neat and well labelled diagram of male reproductive system of a frog.