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

NCERT
SOLUTIONS
CLASS - 11TH

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Class : 11th
Subject : Biology
Chapter : 7
Chapter Name : Structural Organisation In Animal

Q1 Answer in one word or one line.
(i) Give the common name of Periplaneta americana.
(ii) How many spermatheca are found in earthworm?
(iii) What is the position of ovaries in the cockroach?
(iv) How many segments are present in the abdomen of cockroach?
(v) Where do you nd malpighian tubules?

Answer. (i) The common name of Periplaneta americana is the American cockroach.
(ii) Four pairs of spermathecae are present in earthworms. They are located 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) Malpighian tubules are main excretory organs of cockroaches. They form a part of the
alimentary canal.

Page : 121 , Block Name : Exercise

Q2 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 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 intersegmental septa behind the 15th
segment. They open into the intestines.
(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, fth. and sixth
segments.

Q3 Draw a labelled diagram of the reproductive organs of an earthworm.

Answer.

Q4 Draw a labelled diagram of alimentary canal of a cockroach.

Answer.

Q5 Distinguish between the following
(a) Prostomium and peristomium
(b) Septal nephridia and pharyngeal nephridium

Answer.
(a)

(b)

Q6 What are the cellular components of blood?

Answer. Components of blood include erythrocytes (RBCs), leucocytes (WBCs), and thrombocytes
(platelets). These components form 45% of blood. They are suspended in the remaining uid
portion, called plasma Mammalian erythrocytes are biconcave, coloured cells devoid of a nucleus.
They help in transporting respiratory gases.
Leukocytes 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 ght against various disease-causing germs entering the body.
Thrombocytes are cell fragments produced from megakaryocytes of the bone. They play a major
role during blood coagulation.

Q7 What are the following and where do you nd them in animal body
(a) Chondrocytes

(b) Axons
(c) Ciliated epithelium

Answer. Chondrocytes: 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 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. It helps in the
movement of eggs or mucus in speci c directions.

Q8 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.
(a) Simple epithelium: It consists of a single layer of cells where cells are in direct contact with the
basement membrane. It is further subdivided into the following types:
(i) Simple squamous epithelium: It consists of a single layer of at 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 microvilli 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 speci c
directions.
(v) Glandular epithelium: lt 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 classi ed 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. 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.

Q9 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 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

Q10 Mark the odd one in each series:
(a) Areolar tissue; blood; neuron; tendon
(b) RBc; WBc; platelets; canilage
(c) Exocrine; endocrine; salivary gland; ligament
(d) Maxilla; mandible; labrum; athorax; coxa

Answer. (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. Cartilage is
therefore, the odd one out.
(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. Antennae, on the other hand,
are present in the head region of
(e) Protonema forms the developmental stage in the life cycle of a moss. Mesothorax, metathorax,
and coxa are parts or segments present in the legs of a cockroach.

Q11 Match the terms in column I with those in column II:

Answer.

Q12 Mention brie y about the circulatory system of earthworm.

Answer. Earthworms (Pheretima) have closed blood vascular systems. which consists of the heart,
blood vessels, and capillaries, The heart pumps blood to 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.

Q13 Draw a neat diagram of digestive system of frog.

Answer.

Q14 Mention the function of the following
(a) Ureters in trog
(b) Malpighian tubules
(c) Body wan in earthworm

Answer. (a) Ureters in frogs: A ureter acts as a urinogenital duct, which carries sperms along with
urine in male frogs.
(b) Malpighian tubules: Malpighian tubules are excretory organs in earthworms.
(c) Body wan in earthworms: In earthworms, the body wall consists of muscle layers. It helps in
movement and burrowing.