NCERT Solutions for Class 11th: Ch 7 Structural Organisation in Animals Biology

NCERT Solutions for Class 11th: Ch 7 Structural Organisation in Animals Biology

Page No: 121

Exercises

1. Answer in one word or one line:

(i) Give the common name of Periplanata americana.
► American cockroach.

(ii) How many spermathecae are found in earthworm?
► Four pairs

(iii) What is the position of ovaries in cockroach?
► Between 12th and 13th abdominal segments

(iv) How many segments are present in the abdomen of cockroach?
► Ten segments

(v) Where do you find Malpighian tubules?
► Malpighian tubules are the main excretory organs of the cockroach.

Page No: 122

2. Answer the following:
(i) What is the function of nephridia?
(ii) How many types of nephridia are found in earthworm based on their location?

Answer

(i) Nephridia regulate the volume and composition of the body fluids.

(ii) There are three types of nephridia found in earthworm:
• Septal nephridia: present on both the sides of intersegmental septa of segment 15 to the last that open into intestine
• Integumentary nephridia: attached to lining of the body wall of segment 3 to the last that open on the body surface
• Pharyngeal nephridia: present as three paired tufts in the 4th , 5th and 6th segments.

3. Draw a labelled diagram of the reproductive organs of an earthworm.

Answer
Reproductive system of earthworm

4. Draw a labelled diagram of alimentary canal of a cockroach.

Answer
Alimentary Canal of Cockroach

5. Distinguish between the following
(a) Prostomium and peristomium
(b) Septal nephridium and pharyngeal nephridium

Answer

(a)
Prostomium
Peristomium
Prostomium is a small fleshy lobe, which overhangs the mouth of an earthworm. It helps the organism push into the soil and is sensory in function. The first body segment in the earthworm is called the peristomium. It surrounds the mouth opening.

(b)
Septal nephridium
Pharyngeal nephridium
They are present on both sides of inter-segmental septa behind the 15th segment. They open into the intestines. They are present as three paired tufts in the fourth, fifth, and sixth segments.

6. What are the cellular components of blood?

Answer

The cellular components of blood are red blood cells (RBC), white blood cells (WBC) and platelets.

7. What are the following and where do you find them in animal body
(a) Chondriocytes
(b) Axons
(c) Ciliated epithelium

Answer

(a) Chondriocytes are cells of cartilages and are present in small cavities within the matrix secreted by them.

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

(c) Ciliated epithelium are columnar or cuboidal cells bear cilia on their free surface. They are mainly present in the inner surface of hollow organs like bronchioles and fallopian tubes.

8. Describe various types of epithelial tissues with the help of labelled diagrams.

Answer

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.
→ 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:
• 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.
• 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.
• 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 andabsorption.
• 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.
• 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.

Simple Epithelium

→ 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. Examples of compound epithelium include the 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.
Compound Epithelium
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

Answer

(a)
Simple epithelium
Compound epithelium
• It is composed of only one layer of cells.

• It is mainly involved in the function of absorption and secretion.

• It is present in the lining of the stomach, intestine.
It is composed of many layers of cells.


• It is mainly involved in the function of protection and has a limited role in absorption and secretion.

• It is present in the lining of the pharynx and buccal cavity.

(b)
Cardiac muscles
Striated muscles
• They are involuntary in function.

• They are multi-nucleate and branched.

• They are found only in the heart.
• They are voluntary in function.

• They are multi-nucleate and unbranched.

• They are found only in triceps, biceps, and limbs.

(c)
Dense regular connective tissues
Dense irregular connective tissues
• In dense regular connective tissues, collagen fibres are present in rows between parallel boundless fibres.

• They are present in tendons and ligaments.
• In dense irregular connective tissues, fibres are arranged irregularly.

• They are present in the skin.

(d)
Adipose tissue
Blood tissue
• It is composed of collagen fibres, elastin fibres, fibroblasts, macrophages, and adipociytes.

• It helps in the synthesis, storage, and metabolism of fats.

• It is present beneath the skin.
• It is composed of RBCs, WBCs, platelets, and plasma.

• It helps in the transportation of food, wastes, gases, and hormones.

• It is present in the blood vessels.

(e)
Simple glands
Compound glands
• They contain isolated glandular cells.

• They are unicellular.

• Examples include goblet cells of the alimentary canal.
• They contain a cluster of secretory cells.

• They are multicellular.

• Examples include salivary glands.

10. Mark the odd one in each series:

(a) Areolar tissue; blood; neuron; tendon
► Neuron, because it is an example of neural tissue while all other are connective tissue.

(b) RBC; WBC; platelets; cartilage
► Cartilage, as all others are components of blood.

(c) Exocrine; endocrine; salivary gland; ligament
► Neuron, because it is an example of neural tissue while all other are connective tissue.

(d) Maxilla; mandible; labrum; antennae
► Neuron, because it is an example of connective tissue while all other are examples of simple glandular epithelium.

(e) Protonema; mesothorax; metathorax; coxa
► Antennae, as it is not a masticating part of cockroach

11. Match the terms in column I with those in Column II:

Column I
Column II
(a) Compound epithelium
(b) Compound eye
(c) Septal nephridia
(d) Open circulatory system
(e) Typhlosole
(f) Osteocytes
(g) Genitalia
(i) Alimentry canal
(ii) Cockroach
(iii) Skin
(iv) Mosaic vision
(v) Earthworm
(vi) Phallomere
(vii) Bone

Answer

Column I
Column II
(a) Compound epithelium
(b) Compound eye
(c) Septal nephridia
(d) Open circulatory system
(e) Typhlosole
(f) Osteocytes
(g) Genitalia
(iii) Skin
(iv) Mosaic vision
(v) Earthworm
(ii) Cockroach
(i) Alimentary canal
(vii) Bone
(vi) Phallomere

12. Mention briefly about the circulatory system of earthworm

Answer

Earthworm exhibits a closed type of blood vascular system. It consists of blood vessels, capillaries and heart. Due to a 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 haemoglobin which is dissolved in blood plasma. Blood cells are phagocytic in nature.

13. Draw a neat diagram of digestive system of frog.

Answer

Digestive system of frog

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

Answer

(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.

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