Structural Organisation in Animals Question Answers: NCERT Class 11 Biology

The band of glandular skin completely surrounds the 14^th – 16^th Segment which is known as clitellum.

Clitellum is thick glandular and non- segmented section of body wall near the head in earthworms. It secretes a viscid sac that helps in egg’s storage.

Hypopharynx is the mouth part of the cockroach which is comparable to human tongue. Hypopharynx is a median tongue like structure having two pointed lobes called superlingua. The mouth parts of cockroach are chewing type because they are used for the mastication of food.

Mouth, buccal cavity, oesophagus, stomach, intestine, rectum, cloaca, cloacal aperture; is the order beginning from the mouth. 

Cutaneous respiration is the respiration which occurs through the skin. Example: Amphibians.

Pulmonary respiration is the respiration which occurs through the alveoli of the lungs. Example: Human beings.

 The special venous connection between the liver and intestine is known as Hepatic Portal system and between kidney and intestine is known as the Renal Portal system found in the frog.

1. Gizzard
2. Nitrogenous excretory product
3. Ileum, colon and rectum
4. Haemocoel

Features of eye in a cockroach are:

1. Compound eyes are pair of large, black, kidney shaped organs.
2. Ommatidium is the visual unit of eye which is represented by a facet in cockroach.
3. Cockroaches have compound eyes that contain numerous visual units.
4. Their eyes are the organ of sight and have higher sensitivity.

Frog is a Poikilotherm as it exhibits camouflage and undergoes aestivation and hibernation. These are beneficial for it as it sleeps and uses the stored energy in the body and emerges after the harsh environmental temperature has passes camouflage helps in its protection and catching prey.

1. Nictitating membrane: (i) it is the third eyelid of frog’s eye. It protects the frog’s eye from water and land environment.
2. Tympanum: (ii) It is a part of ear in frogs that helps in transmission of soundwaves to the inner parts.
3. Copulation pad: (iii) It is present in male frogs forelimbs which help them in holding the female tightly during mating.

1. (i) Simple columnar epithelium
2. (ii) Stratified epithelium
3. (iii) Connective tissue

Sclerites are the hardened plates by which entire body is covered, present in exoskeleton of cockroach. They are formed by chitin which is a polysaccharide of acetylglucosamine molecules.

The involuntary tissue present in the hearth is known as cardiac tissue which have same characteristics like smooth muscles.

Nymph moult to reach the adult form of cockroach about 13 times.

Sound producing vocal sacs are present in the male frogs only. They are present on the throat and are distensible or swells up like balloons. They serve to increase the pitch of a sound. 

Metamorphosis is the process by which a tadpole develops into an adult frog. The fertilized undergoes holoblastic cleavage (complete cleavage) and produces a small larvae called tadpole.

Metamerism is the scientific term given to earthworm’s body segment. The external segmentation of the body by annuli largely corresponds to the internal division by the septa. This type of segmentation is known as metameric segmentation or Metamerism.

Smooth muscle fibre can taper at both the ends and does not show striations.

Adhering junction, gap junction, desmosomes and tight junction.

Two identifying features of an adult male frog are:

1. Presence of vocal sacs.
2. Sound producing vocal sacs are present in the male frogs only. They are present on the throat and are distensible or swells up like balloons. They serve to increase the pitch of a sound. 
3. Presence of copulation pad.

(i) The common name of Periplaneta americana is the American cockroach.

(ii) Four pairs of spermathecae are present between sixth and the ninth segments. They help in receiving and storing the spermatozoa during copulation.

(iii) In a cockroach, the pair of ovaries is located between 12th and 13th abdominal segments.

(iv) In both sexes, the abdomen of a cockroach consists of ten segments.

(v) Malphigian tubules are excretory organs of cockroaches. They form a part of the alimentary canal.

(a) Areolar tissue, blood, and tendons are examples of connective tissues. Neuron is an example of neural tissue.

(b) RBCs, WBCs, and platelets are the three most important components of blood (fluid connective tissue) while Cartilage is skeletal connective tissue.

(c) Exocrine, endocrine, and salivary glands are examples of simple glandular epithelium. Ligament is a connective tissue.

(d) Maxilla, mandible, and labrum are mouthparts of a cockroach; white antennae are present in the head constituent of region of cockroaches.

(e) Prothorax, Mesothorax and metathorax are parts of thorax of cockroach and present in the legs of a cockroach.

Earthworm (Pheretima) have closed blood vascular systems, which consists of the heart, blood vessels, and capillaries. The heart pumps blood for circulating it in one direction. Blood is supplied by smaller blood cells to the gut, nerve cord and the body wall. Blood glands are present in the 4th, 5th, and 6th segments, which produce blood cells and haemoglobin dissolved in blood plasma. Blood cells in earthworms are phagocytic in nature.

(a) Ureters in frogs: A ureter acts as a urinogenital duct, which carries sperms along with urine in male frogs.

(b) Malphigian tubules: Malphigian tubules are excretory organs in cockroaches.

(c) Body wall in earthworms: In earthworms, the body wall consists of muscle layers. It helps in movement and burrowing.

(i) Nephridia are segmentally arranged excretory organs present in earthworms.

(ii) On the basis of their location, three types of nephridia are found in earthworms. They are:

(a) Septal nephridia: These are present on both sides of the inter-segmental septa behind the 15th segment and they open into the intestine.

(b) Integumentary nephridia: These lie attached to the body wall from the third segment to the last segment, which opens on the body surface.

(c) Pharyngeal nephridia: These are present as three paired tufts in fourth, fifth, and sixth segments.

 (a)

(b)

Components of blood include erythrocytes (RBCs), leucocytes (WBCs), and thrombocytes (platelets). These components form 45% of blood. They are suspended in the remaining fluid portion, called plasma.

Mammalian erythrocytes are biconcave, coloured cells devoid of a nucleus. They help in transporting respiratory gases.

Leucocytes or white blood cells are nucleated cells. They can be divided into two types, granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes). They help fight against various disease-causing agents entering the body.

Thrombocytes are cell fragments produced from megarkaryocytes of the bone. They play a major role during blood coagulation.

Chondriocytes:

They are cells of cartilages, and are present in small cavities within the matrix secreted by them.

Axons:

They are long, slender projections of neurons that help in carrying nerve impulses away from the neuron body. Axons aggregate in bundles which make up the nerves.

Ciliated epithelium:

It consists of simple columnar or cuboidal epithelium with cilia on their free surfaces. It is present on the inner surface of the oviducts and bronchioles. Where it helps in the movement of eggs or mucus in specific directions.

Epithelial tissue lines the surface of a body and forms a protective covering. Epithelium cells are packed tightly together with little intercellular matrix.

Epithelial tissue in the body is of two types.

(a) Simple epithelium: It consists of a single layer of cells where cells are in direct contact with the basement membrane. It is further sub-divided into the following types:

(i) Simple squamous epithelium: It consists of a single layer of flat cells with irregular boundaries. It is found in the walls of the blood vessels and in the lining of alveoli.

(ii) Simple cuboidal epithelium: It consists of a single layer of cube-like cells. It is present in regions where secretion and absorption of substances takes place such as the proximal convoluted tubule region of the nephron.

(iii) Simple columnar epithelium: It consists of a single layer of tall, slender cells with their nuclei present at the base of the cells. They may bear micro-villi on the free surfaces. Columnar epithelium forms the lining of the stomach and intestines, and is involved in the function of secretion and absorption.

(iv) Ciliated epithelium: It consists of columnar or cuboidal cells with cilia on their free surfaces. They are present in bronchioles and oviducts from where they direct mucus and eggs in specific directions.

(v) Glandular epithelium:It consists of columnar or cuboidal cells involved in the secretion of substances. Glands are of two types, unicellular glands (goblet cells of the alimentary canal) and multicellular glands (salivary glands). They can be classified as exocrine (ductless glands) and endocrine glands (duct glands) by the method through which they release enzymes.

(b)

Compound epithelium: It consists of many layers of cells. It is involved mainly in the function of providing protection and has a limited role in secretion and absorption.

Dry surface of the skin or moist inner lining of the buccal cavity, pharynx, pancreatic ducts, and the inner lining of ducts of salivary glands are some of the examples of compound epithelium

(a)

(b)

(c)

(d)

(e)