NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals

NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals

These Solutions are part of NCERT Solutions for Class 11 Biology. Here we have given NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals.

Question 1.
Answer in one word or one line.
(i) Give the common name of Periplaneta americana.
(ii) How many spermathecae are found in earthworms?
(iii) What is the position of ovaries in cockroach?
(iv) How many segments are present in the abdomen of the cockroach?
(v) Where do you find malpighian tubules?
Solution:
(i) Cockroach
(ii) Four pairs of spermathecae are found in the 6“ to 9th segments (one pair in each segment).
(iii) Cockroach includes a pair of ovaries, that lies laterally in the 2nd to 6th abdominal segments of the abdomen.
(iv) Ten
(v) At the junction of midgut and hindgut. 100-150 yellow coloured thin filamentous ring is present in earthworm, which is called malpighian tubules.

Question 2.
Answer the following :
(i) What is the function of nephridia?
(ii) How many types of nephridia are found in earthworms based on their location?
Solution:
(i) Nephridia is the excretory organ of the earthworm or pheretima.
(ii) There are three types of nephridia –
(i) Septal nephridia – Present on both the sides of intersegmental septa of segment 15 to the last that open into the intestine.
(ii) Integumentary nephridia – Attached to the lining of the body wall of segment 3 to the last that opens on the body surface.
(iii) Pharyngeal nephridia – Present as three paired tufts in the 4th, 5th, and 6th segments.
These three different types of nephridia are almost similar in structure.

Question 3.
Draw a labelled diagram of the reproductive organs of an earthworm.
Solution:
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1

Question 4.
Draw a labelled diagram of the alimentary canal of a cockroach
Solution:
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 2

Question 5.
Distinguish between the followings :
(a) Prostomium and peristomium
(b) Septal nephridium and pharyngeal nephridium
Solution:
(a) The main difference between prostomium and peristomium are :
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 3
(b) The main difference between septal nephridium and pharyngeal nephridium are:
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 4
Question 6.
What are the cellular components of blood?
Solution:
Red blood cells and white blood cells are the cellular components of blood.

Question 7.
What are the following and where do you find them in an animal body.
1. Chondrocytes
2. Axons
3. Ciliated epithelium
Solution:
1. Chondriocytes: The intercellular material of cartilage is solid and pliable and resists compression. Cells of this tissue (Chondriocytes) are enclosed in small cavities within the matrix secreted by them. Most of the cartilages in vertebrate embryos are replaced by bones in adults. Cartilage is present in the tip of the nose, outer ear joints, between adjacent bones of the. vertebral column, limbs, and hands in adults.

2. Axons: It is found in the nervous system neuron. It is a long fiber, the distal end of which is branched. The main function of axons is the transmission of impulses by means of neurotransmitters.

3. Ciliated epithelium: If the columnar or cuboidal cells bear cilia on their free surface they are called the ciliated epithelium. They are found in the lining of the stomach and intestine and help in secretion and absorption, their function is to move particles or mucus in a specific direction over the epithelium. They are mainly present in the inner surface of hollow organs like bronchioles and fallopian tubes.

Question 8.
Describe various types of epithelial tissues with the help of labelled diagrams.
Solution:
Epithelial tissues
Epithelial tissues provide covering to the inner and outer lining of various organs. The cells of epithelial tissues are compactly packed with a little intercellular matrix.
There are two types of epithelial tissues:
(i) Simple epithelium
(ii) Compound epithelium
(i) Simple epithelium :
Composed of a single layer of cells and functions as a lining for body cavities ducts and tubes. It is further divided into three types on the basis of structure modifications-
(a) Squamous epithelium – It is made of a single layer of flattened cells with irregular boundaries.
It is found as a lining for body cavities, ducts, and tubes such as in the walls of blood vessels and air sacs of lungs.
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 5
Functions – It helps in forming a diffusion boundary.
(b) Cuboidal epithelium – It is made of a single, layer of cube-like cells. It is commonly found in the ducts of glands and tubular parts of nephrons in kidneys. Specialized cuboidal cells are capable of producing gametes found in gonads called the germinal epithelium.
Functions- It helps in secretion and absorption and also in moving particles or mucus in a specific direction over the epithelium.
(c) Columnar epithelium – It is composed of a single layer of tall and slender cells. Nuclei are located at the base.
Its free surface may have microvilli.
It is found inlining of the stomach and intestine.
Functions – It helps in secretion and absorption.
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 6

Question 9.
Distinguish between
(a) Simple epithelium and compound epithelium
(b) Cardiac muscle and striated muscle
(c) Dense regular and dense irregular connective tissues
(d) Adipose and blood tissue
(e) Simple gland and compound gland
Solution:
(a) The main difference between simple epithelium and compound epithelium are as following.
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 7
The main difference between Cardiac muscles and striated muscle are as following.
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 8
The main difference between dense regular connective tissues and dense irregular connective tissues are as following.
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 9
The main difference between adipose tissue and blood tissue are as following.
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 10
The main difference between simple gland and compound gland are as following
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 11

Question 10.
Mark the odd one in each series:
(a) Areolar tissue; blood; neuron; tendon
(b) RBC; WBC; platelets; cartilage
(c) Exocrine: endocrine; salivary gland;ligament
(d) Maxilla; mandible; labrum; antennae
(e) Protonema; mesothorax; metathorax; coxa
Solution:
(a) Neuron
(b) Cartilage
(c) Ligament
(d) Antennae
(e) Protonema

Question 11.
Match the terms in column I with those in column II:
Column I Column II
(a) Compound epithelium – (i) Alimentary canal
(b) Compound eye – (ii) Cockroach
(c) Septal nephridia – ( iii) Skin
(d) Open circulatorysystem – (iv) Mosaic vision
(e) Typhlosole – (v) Earthworm
(f) Osteocytes – (vi) Phallomere
(g) Genitalia – (vii) Bone
Solution:
(a) Compound epithelium ( iii) Skin
(b) Compound eye – (iv) Mosaic vision
(c) Septal nephridia – (v) Earthworm
(d) Open circulatory system – (ii) Cockroach
(e) Typhlosole – (i) Alimentarycanal
(f) Osteocytes – (vii) Bone
(g) Genitalia – (vi) Phallomere

Question 12.
Mention briefly the circulatory system of earthworms.
Solution:
Pheretima exhibits a closed type of blood vascular system, consisting of blood vessels capillaries, and heart. Due to the closed circulatory system, blood is confined to the heart and blood vessels. Contractions keep blood circulating in one direction. Smaller blood vessels supply the gut, nerve cord, and body wall. Blood glands are present on the 4th, 5th, and 6th segments. They produce blood cells and hemoglobin which is dissolved in blood plasma. Blood cells are phagocytic in nature. Earthworms lack specialized breathing devices. Respiratory exchange occurs through moist body surfaces into their bloodstream.

Question 13.
Draw a neat diagram of the digestive system of the frog.
Solution:
The digestive system of frog:
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 12

Question 14.
Mention the function of the following:
(a) Ureters in frog
(b) Malpighian tubules
(c) Body wall in earthworm
Solution:
Functions:
(1) Ureters in frog:

  • They carry the urine from the kidneys to the cloaca.
  • In males, it also conducts the sperm as it is the urinogenital duct.
  • In females, the ureters and oviduct open- separately in the cloaca.

(2) Malpighian tubules:

  1. They are the excretory organs of a cockroach.
  2. They collect the nitrogenous wastes from the haeomolymph and send them into the intestine.
  3. Each tubule is lined by glandular and ciliated cells. They absorb nitrogenous waste products and convert them into uric acid which is excreted out through the hindgut.

(3) Body wall of earthworm:
The body wall of the earthworm is covered externally by a thin non-cellular cuticle

VERY SHORT ANSWER QUESTIONS

Question 1.
Name the protein found in white fibres.
Solution:
Collagen.

Question 2.
State the function of setae.
Solution:
It helps in locomotion by gripping the earth.

Question 3.
What is the functional unit of the cockroach eye?
Solution:
Ommatidium.

Question 4.
Name the unit of neural or nervous system.
Solution:
Neurons.

Question 5.
What is worm casting ?
Solution:
It is the insoluble and undigested food that is given out along with soil through anus.

Question 6.
Which cell covers the exposed surfaces of the body (skin) and internal passage ways (digestive tract and glands) ?
Solution:
Squamous epithelium

Question 7.
Name the type of epithelium that lines the inner surface of stomach.
Solution:
Columnar epithelium

Question 8.
Name the type of epithelium that lines the buccal cavity.
Solution:
Stratified squamous epithelium.

Question 9.
N ame of type of tissue that is the most abundant in animal body.
Solution:
Connective tissue.

Question 10.
What is the other name given to the gizzard of cockroach?
Solution:
Proventriculus.

Question 11.
Name the larva of a frog.
Solution:
Tadpole.

Question 12.
What is the scientific name of Indian (bull) frog?
Solution:
Rana tigrina.

SHORT ANSWER QUESTIONS

Question 1.
What are the neuroglia cells?
Solution:
Cells which holds the neuron together are known as neuroglia cells.

Question 2.
What is vermicompositing?
Solution:
The process of increasing soil fertility by earthworms is known as vermicomposting.

Question 3.
What are exocrine glands? Name any two secretions of them.
Solution:
Exocrine glands : Those glands which have ducts to pour their secretion(s) into the respective site of action, are called exocrine.
(i) Salivary glands secrete saliva into the buccal cavity.
(ii) Liver secretes bile into the duodenum.

Question 4.
Write four functions of bones.
Solution:
Functions of bones:
(i) They provide place for attachment of muscles and help in movement and locomotion.
(ii) Bone marrow is the site of manufacture of blood cells.
(iii) Bones provide protection to the internal organs.
(iv) The long bones of the limbs serve the weight-bearing function.
(v) They act as the depot of calcium and phosphorus.

Question 5.
Describe the three types of cell junctions present in the epithelium and other tissues.
Solution:
Cell junctions
(i) Tight junctions – They check leaking of substances across a tissue.
(ii) Adhering junctions – They help in cementing the neighbouring cells together.
(iii) Gap junctions – They facilitate the cells to communicate with each other by cytoplasmic connections, for rapid transfer of ions, small molecules, etc.

Question 6.
How is the gizzard in the alimentary canal of a cockroach suitable for grinding the food?
Solution:
Gizzard of cockroach has following characteristics:
(i) The gizzard has an outer layer of thick circular muscles.
(ii) The inner thick layer of cuticle forms six plate like teeth.
(iii) The movement with the help of muscles and the teeth-like structures help in grinding the food.

Question 7.
What is a typhlosole in an earthworm? Where is it found? What is its function?
Solution:
Typhlosole: It is an internal median fold of the dorsal wall of the intestine. It is found in the intestine between 26th and 35th segments of the body.
It increases the effective area of absorption.

LONG ANSWER QUESTIONS

Question 1.
Describe the female reproductive organs of frog.
Solution:
The female reproductive organs include a pair of ovaries. The ovaries are situated near kidneys and there is no functional connection with kidneys. A pair of oviduct arising from the ovaries opens into the cloaca separately. A mature female can lay 2500 to 3000 ova at a time.
Fertilisation is external and takes place in water. Development involves a larval stage called tadpole. Tadpole undergoes metamorphosis to form the adult.

NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 13

Question 2.
Describe with examples, various types of connective tissues.
Solution:
Connective tissues are most abundant and widely distributed in the body of complex animals. They are named connective tissues because of their special function of linking and supporting other tissues/C ••gans of the body. Connective tissues are classified into three types:
(i) Loose connective tissue,
(ii) Dense connective tissue and
(iii) Specialised connective tissue.
(i) Loose connective tissue:

  • It has cells and fibres loosely arranged in a semi-fluid ground substance, for example, areolar tissue present beneath the skin.
  • Often it serves as a support framework for epithelium. It contains fibroblasts (cells that produce and secrete fibres), macrophages and mast cells.
  • Adipose tissue is another type of loose connective tissue located mainly beneath the skin. The cells of this tissue are specialised to store fats.

(ii) Dense connective tissue :

  • Fibres and fibroblasts are compactly packed in the dense connective tissues.
  • Orientation of fibres show a regular or irregular pattern and are called dense regular and dense irregular tissues.
  • In the dense regular connective tissues, the collagen fibres are present in rows between many parallel bundles of fibres.
  • Tendons, which attach skeletal muscles to bones and ligaments which attach one bone to another are examples of this tissue.
  • Dense irregular connective tissue has fibroblasts and many fibres (mostly collagen) that are oriented differently. This tissue is present in the skin.

(iii) Specialised connective tissue :

  • Cartilage, bones and blood are various types of specialised connective tissues.
  • The intercellular material of cartilage is solid and pliable and resists compression.
  • Cells of this tissue (chondrocytes) are enclosed in small cavities within the matrix secreted by them.
  • Cartilage is present in the tip of nose, outer ear joints, between adjacent bones of the vertebral column, limbs and hands in adults.

Bones : It has a hard and non-pliable ground substance rich in calcium salts and collagen fibres which give bone its strength. It is the main tissue that provides structural frame to the body.
Blood : It is a fluid connective tissue containing plasma, red blood cells (RBC), white bloo4 cells (WBC) and platelets. It is the main circulating fluid that helps in the transport of various substances.

Question 3.
Describe the alimentary canal of earthworm.
Solution:
The alimentary canal is a straight tube and mns between first to last segment of the boay. It has following parts.
Mouth : A terminal mouth opens into the buccal cavity (1-3 segments) which leads into muscular pharynx.
oesophagus: A small narrow tube, oesophagus (5-7 segments), continues into a muscular gizzard (8-9 segments). It helps in grinding the soil particles and decaying leaves, etc.
Stomach : The stomach extends from 9-14 segments. The food of the earthworm is decaying leaves and organic matter mixed with soil. Calciferous glands, present in the stomach, neutralise the humic acid present in humus.
• Intestine starts from the 15th segment onwards and continues till the last segment. A pair of short and conical intestinal caecae project from the intestine on the 26th segment.
Typhosole : The characteristic feature of the intestine between 26-35 segments is the presence of internal median fold of dorsal wall called typhlosole. This increases the effective area of absorption in the intestine.
Anus : The alimentary canal opens to the exterior by a small rounded aperture called anus. The ingested organic rich soil passes through the digestive tract where digestive enzymes breakdown complex food into smaller absorbable units. These simpler molecules are absorbed through intestinal membranes and are utilised.

Question 4.
Draw a labelled diagram of external features of cockroach.
Solution:
NCERT Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 14

We hope the NCERT Solutions for Class 11 Biology at Work Chapter 7 Structural Organization in Animals, help you. If you have any query regarding NCERT Solutions for Class 11 Biology at Work Chapter 7 Structural Organization in Animals, drop a comment below and we will get back to you at the earliest.

NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals

NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals

These Solutions are part of NCERT Exemplar Solutions for Class 11 Biology. Here we have given NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals.

VERY SHORT ANSWER QUESTIONS

Question 1.
State the number of segments in earthworm which are covered by a prominent dark band or clitellum.
Solution:
Segments 14-16 bare covered by a prominent dark band of glandular tissue called clitellum in a mature earthworm. It secretes mucus and albumen that help in formation of cocoon.
NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1.1

Question 2.
Where are sclerites present in cockroach?
Solution:
In all the body segments of cockroach sclerites are present. They are of two types dorsal sclerites often known as tergites, and ventral sclerites which are referred to as sternites.

Question 3.
How many times do nymphs moult to reach the adult form of cockroach?
Solution:
The nymph grows by moulting about 13 times to reach. In cockroach’, the development is indirect and paurometabous adult form has three stages, i.e., egg, nymph and adult. The nymph resembles adult except/or undeveloped wings and genitalia.

Question 4.
Identify the sex of a frog in which sound producing vocal sacs are present.
Solution:
Sex of frogs can be distinguished on the basis of presence of sound producing vocal sacs. These organs are present in males which make them crock lauder than females, so as to attract females for mating.

Question 5.
A muscle fibre tapers at both ends and does not show striations. Name the muscle fibre.
Solution:
Muscle fibres that taper at both the ends (fusiform) and do not show striations are smooth muscle fibres. They are also called involuntary muscles.

Question 6.
Name the different cell junctions found in tissues.
Solution:
The different cell junctions found in tissue include:
(i) Tight junctions are regions where plasma membrane of adjacent epithelial cells are held close together. They check the movement of material between then.
(ii) Gap junctions are meant for chemical exchange between adjacent cells.
(iii) Adhering junctions function to keep neighbouring cells together.

Question 7.
Give two identifying features of an adult male frog.
Solution:
The two identifying features of an adult male frog include
(a) Nuptial Pad is a copulatory pad present on the first digit of the forelimb of male frog and helps in closing female during amphelexus.
(b) Vocal Sacs are loose skin folds on throat of male frogs for producing louder croak to attract females for mating purposes.

Question 8.
Which mouth part of cockroach is comparable to our tongue?
Solution:
In cockroach, hypopharynx acts as a tongue and lies within cavity enclosed by the mouth parts.

Question 9.
The digestive system of frog is made of the following parts. Arrange them in an order beginning from mouth. Mouth, oesophagus, buccal cavity, stomach, intestine, cloaca, rectum, cloacal aperture.
Solution:
The correct arrangement of the part of digestive system in frog is
Mouth —> Buccal cavity —> Oesophagus —> Stomach —>Intestine —> Rectum —> Cloaca —> Cloacal aperture.

Question 10.
What is the difference between cutaneous and pulmonary respiration?
Solution:
In frog respiration takes place via the skin as well lungs.
Pulmonary respiration and occurs outside the water through lungs. Cutaneous respiration takes place in water as well as land, occurs through highly vascularised moist skin.

Question 11.
Special venous connection between liver and intestine and between kidney and intestine is found in frog, what are the called?
Solution:
In frog, venous connection between liver and intestine is called hepatic portal system and venus connection between the kidney and the lower parts of the frog is called renal portal system.

SHORT ANSWER QUESTIONS

Question 1.
Stratified epithelial cells have limited role in secretion. Justify their role in our skin.
The edible part of the peach or pear pome fruit for the fleshy thalamus.
Solution:

  1. Stratified epithelium consists of epithelial cells in which the innermost layer is made up of columnar or cuboidal cells.
  2. It is a type of compound epithelium and a waterproof protein called keratin is present few outer layers.
  3. These layers of dead cells is called homy layer which is shed at intervals due to frictions and thus has a limited role in secretions and absorption.
  4. The main function of stratified epithelium is to provide protection to the body against mechanical and chemical stresses.

Question 2.
How does a gap junctions facilitate intercellular communication ?
Solution:
Intercellular communication is facilitated by gap Junction allowing small signaling molecules to pass from cell to cell.
These are fine hydrophilic channels, between two adjacent animal cells that are formed with the help of two protein cylinders called connexus.
Each connexus consists of six proteins subunits that surround a hydrophilic channel. Opening or closing of channel is controlled by pH and Ca2+ ion concentration.

Question 3.
Why are blood, bone and cartilage called connective tissue?
Solution:

  1. Connective tissue pt’ovides the structural framework and support to different organs forming tissue.
  2. Blood is a fluid or vascular connective tissue, which connects various organs and transports substances from one place to another.
  3. Bone is a solid, rigid and strong skeletal connective tissue, which supports the body and helps in locomotion.
  4. Cartilage is also a skeletal connective tissue, not as rigid bone but piable and resists compression.
  5. It plays role in support and protection and present in tip of nose, outer ear joints etc.

Question 4.
How do you distinguish between dorsal and ventral surface of the body of earthworm?
Solution:
The body of an earthworm can be distinguished into dorsal and ventral sides due to the presence of certain peculiar feature in it which include the following.
(i) The dorsal surface is darker than ventral surface because it is marked by a dark median mid dorsal line along the longitudinal axis of body. This is due to dorsal blood vessel, seen through integument.
(ii) Genital openings (pores), are present in the ventral surface of both male and female.
(iii) On vental surface genital papilla is located and helps in copulation.
NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1.2

Question 5.
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 ……
Solution:
(a) Gizzard is a muscular and greatly folded structure which marks the end of foregut in cockroach and bears six plates with teeth for crushing and grinding the food.
(b) Malpighian tubules are excretory in ‘ function as they help in the removal of
nitrogenous wastes in arthropods.
(c) Ileum, colon and rectum and rectum opens and through anus.
(d) Haemocoel is the body cavity of cockroach divided into sinuses and contains visceral organs of cockroach floating in haemolymph.

Question 6.
Mention special features of eye in cockroach. Discuss compound eye in arthropods and mention its structural features.
Solution:

  1. In cockroach the eyes are large sessile, paired bean-shaped and present on either side of head.
  2. The are compound in nature. Each compound eye consists of a large number of visual elements called ommatidia.
  3. Each ommatidium is composed of a diopteric region and reticular (receptor) region. It is capable of producing a separate image of a small part of object seen.
  4. Thus, the image of the object viewed consists of several pieces and is known as mosaic image.
  5. Fine nerve fibres arise from the inner end of each ommatidium all of which combine to form one optic nerve connected to the brain.
    NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1.3

Question 7.
Frog is a poikilotherm, exhibits camouflage and undergoes aestivation and hibernation, how are all these benficial to it?
Solution:

  1. A trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection and evolution and help organism in its survival is an adapture triat.
  2. Frog is a poikilotherm or a (cold blooded animal). It regulates its body temperature according to its environment.
  3. It undergoes winter sleep (hibernation) for withstanding very cold temperatures and sujnmer sleep in hot temperatures (aestivation).
  4. During this period, it lives in a dormant stage with very minimal vital body activities.
  5. Frog is capable of changing its body colour as well, though gradually, with the change in its surrounding and climatic conditions.
  6. This capability in frog is called as camouflage which lets it escape from the predators, an essential survival parameter for living.

Question 8.
Write the functions in brief in Column II, appropriate to the structures given in column I.
NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1.4
Solution:
(a) Nictitating Membrane in frog protects the eye from water and any damage by covering the eye ball of frog.
(b) Tympanum is present on each side of the frog head and is involved in the hearing process.
(c) Copulatory Pad present in the limbs of the male frog and helps in copulation by holding the female during its sexual activity.

Question 9.
Using appropriate examples, differentiate between false and true body segmentation.
Solution:

  1. The serial repetition of similar body parts along the length of an animal is segmentation. The body of animals can be truely segmented or pseudo/false segmented.
  2. True segmentation is found in annelids, arthropods and some chordates. In these organisms there is a linear repetition of body parts and each repeated unit is called somite (metamere).
  3. In earthworms, the successive somites are externally and intemaly. ‘
  4. Pseudosegmentation is seen when body is divided into number of false segments which are independent of each other.
  5. Each segment is able to perform all the vital function of body. Growth occurs by the addition of new segments from the anterior end, e.g., tapeworm.

Question 10.
What is special about tissue present in the heart?
Solution:
Special tissue present in heart is called cardiac muscle, which has the following features
(i) Cardiac muscle fibres are supplied with both central and autonomic nervous system and are not under the control of will of animal.
(ii) These muscles show rhythmicity and are immune to fatigue.
(iii) They have a rich supply of blood.
(iv) They are myogenicas. They possess the property of contraction even if completely isolated from the body.
NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1.5

LONG ANSWER QUESTIONS

Question 1.
Comment upon the gametic exchange in earthworm during mating. Discuss the physiology in reproduction of earthworm.
Solution:
In earthworm mating is a unique process. Earthworm is a hermaphrodite. In which breeding takes place during rainy season and copulation begins soon after maturation of the sperms.
The gametic exchange and the physiology of reproduction during mating can described in the following manner.
(i) Earthworms are protandrous animal (i.e., maturation of sperm takes place much earlier then that of ova).
(ii) Mating process in earthworm occurs through process of cross-fertilisation.
(iii) The mating process involves exchange of gametic materials between the two worms.
(iv) Two individuals from adjacent burrows emerge half but and lie in contact with each other, and exchange packets of sperms called spermatophores opposite gonadal opening.
NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1.6
(v) The skin encircling male pore, elevates a little during the process to form a temporary papilla that fits like a penis into the opposite spermathecal pore to keep it open.
(vi) The copulating worm after filling of spermatheca moves a bit to adjust another pair of spermathecae to face the other male pores. This is accomplished in about an hour’s copulation.
(vii) The sperms mostly remain in their diverticula within the spermathecae and the ampulla is associated with the secretion of nutritive substances for the sperms.
(viii) The sperm and egg are passed into cocoon, secreted by clitellar gland.
(ix) Fertilisation is therefore external.

Question 2.
Explain the digestive system of cockroach with the help of labelled sketch.
Solution:
The alimentary canal of cockroach is divided
into three regions foregut, midgut and hindgut.
(i) Mouthy cavity, pharynx, oesophagus, crop and gizzard are included in foregut.
(ii) Mouth cavity is a small space, surrounded by mouth parts. Food is crushed and acted upon by the salivary secretion in mouth.
(iii) The mouth opens into a short tubular pharynx, leading towards the narrow tubular passage called oesophagus and then into a sac-like structure called crop which acts as a storage organ.
NCERT Exemplar Solutions for Class 11 Biology Chapter 7 Structural Organization in Animals 1.7
(iv) The crop is followed further by gizzard ‘ (proventriculus). Gizzard is composed of thick circular muscles and thick inner cuticle forming six highly chitinous plates called as teeth. It associated with the grinding and crushing of food particles. A thick cuticle lines the entire foregut.
(v) About one-third middle part of alimentry canal comprises of midgut or mesentron. The internal lining of midgut is an endodermal epithelium of columnal cells raised into several small villi like folds.
(vi) Anterior most part of midgut surrounding the stomadaeal valve is called cardia. Finger like blind processes called as enteric or hepatic caeca are present at the junction of foregut and midgut.
(vii) A ring of yellow filamentous structures is formed between the midgut and hindgut that aid in the removal of excretory products from haemolymph.
(viii) The remaining one-third posterior part of alimentary canal is Hindgut. It is relatively thicker than the midgut lined by cuticle and ectodermal epithelium.
(ix) Hindgut is diffrentiated into three parts anterior Ileum, middle colon and posterior rectum. Ileum is short and relatively narrower and its cuticie bears minute spines. Colon is the longest, relatively thicker and a coiled part of hindgut. Rectum is a small and oval chamber that opens out through anus.

We hope the NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 7 Structural Organization in Animals, help you. If you have any query regarding NCERT Exemplar Solutions for Class 11 Biology at Work Chapter 7 Structural Organization in Animals, drop a comment below and we will get back to you at the earliest.