NCERT Solutions Class 11 Biology Chapter 7

Q.1 Answer in one word or one line.

(i) Give the common name of Periplanata Americana.

(ii) How many spermathecae are found in earthworm?

(iii) What is the position of ovaries in cockroach?

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

(v) Where do you find Malpighian tubules?

Ans-

(i) Cockroach

(ii) Eight spermathecae are found in earthworm.

(iii) The two large ovaries are found lying laterally in the 2^nd-6^th abdominal segment.

(iv) 10 segments are present in the abdomen of both male and female cockroaches.

(v) Malpighian tubules are found at the junction of midgut and hindgut of a cockroach.

Q.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?

Ans-

(i) Nephridia (sing.: nephridium) are the excretory organs of earthworm. They regulate the volume and composition of body fluids and excrete out the wastes of the body through a pore to the surface in the body.

(ii) Based on the location, three types of nephridia are found in earthworm:

a) Septal nephridia: They are present on both the sides of intersegmental septa of segment 15 to the last. They open into the intestine.

b) Integumentary nephridia: They are very minute and are hardly visible to the naked eye. They are attached to the lining of the body wall from segment 3 to the last. They open separately on the body surface.

c) Pharyngeal nephridia: They are present as three paired structures at the sides of the oesophagus in 4th, 5th and 6th segment.

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

Ans-

The diagram showing the reproductive organs of an earthworm is depicted below:

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

Ans-

The diagram showing the alimentary canal of a cockroach is depicted below:

Q.5 Distinguish between the followings

(a) Prostomium and peristomium

(b) Septal nephridium and pharyngeal nephridium

Ans-

(a)

(b)

Q.6 What are the cellular components of blood?

Ans-

Blood is a fluid connective tissue. It contains red blood cells (RBCs), white blood cells (WBCs) and platelets (together constituting ~45% of volume) suspended in plasma (~55% of volume).

Red Blood Cells (erythrocytes): They are biconcave, large microscopic cells without nuclei. They carry oxygen from the lungs to the body’s tissue and take carbon dioxide back to the lungs to be exhaled out from the body.

White Blood Cells (leukocytes)- They exist in variable numbers and types (granulocytes and agranulocytes) but constitute only about 1% of blood’s volume. Leukocytes are not limited to blood. Most are produced in bone marrow from the same kind of stem cells that produce red blood cells.

Platelets (thrombocytes)- They are small, colourless cell fragments without nuclei in the blood. Their main function is to interact with clotting proteins to stop or prevent bleeding.

Q.7 What are the following and where do you find them in animal body.

(a) Chondrocytes

(b) Axons

(c) Ciliated epithelium

Ans-

(a) Chondrocytes are cells of healthy cartilage tissue. They are found in the small cavities within the matrix secreted by them. Examples of cartilage tissue are the tip of the nose, outer ear joints, etc.

(b) The long slender projections of the nerve cells of nervous tissues are called axons. They help in sending messages by conducting electrical impulses away from the neuron’s cell body. They are present in the neural tissues like brain, spinal cord, nerves etc.

(c) When the columnar or cuboidal cells of epithelia bear cilia on their free surface, they are called the ciliated epithelium. They help in the movement of particles or mucus in a particular direction over the epithelium. They are present in the inner surface of hollow organs like bronchioles and fallopian tubes.

Q.8 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

Ans-

(a)

(b)

(c)

(d)

(e)

Q.9 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

Ans-

(a) Neuron

(b) Cartilage

(c) Ligament

(d) Antennae

(e) Protonema

Q.10 Match the terms in column I with those in column II:

Ans-

Q.11 Mention briefly about the circulatory system of earthworm.

Ans-

Characteristic features of the circulatory system of earthworm:

• It consists of blood vessels, capillaries and heart.
• It carries food, waste and respiratory gases along with coelomic fluid.
• The blood vascular system is closed in nature and blood remains confined to heart and blood vessels.
• The contractions of heart pump blood in one direction.
• Smaller blood vessels supply the gut, nerve cord and the body wall.
• Blood cells and haemoglobin are produced in blood glands present in 4^th, 5^th and 6^th segment and then dissolved in the blood plasma. Blood cells are phagocytic in nature.

Q.12 Draw a neat diagram of digestive system of frog.

Ans-

The diagram showing the digestive system of a frog is depicted below:

Q.13 Mention the function of the following:

(a) Ureters in frog

(b) Malpighian tubules

(c) Body wall in earthworm

Ans-

(a) The two ureters emerging from the kidneys of male frog act as a urinogenital duct that carry both urine and sperms. In female frogs, ureter carries only urine and excretes it out through cloaca.

(b) Malpighian tubules present at the junction of midgut and hindgut is involved in the removal of excretory products from the haemolymph of cockroaches.

(c) The body wall in earthworm performs the following functions:

• Helps retain water
• Helps in motion
• Helps in respiration (diffusion of gases)
• Helps in the contraction of the earthworm
• Secretes mucus which helps in locomotion and burrowing
• Also performs a sensory function

Q.14 Describe various types of epithelial tissues with the help of labelled diagrams.

Ans-

Epithelial tissue is the tissue provides lining to a body part and has a free surface either facing body fluid or the outside environment. There are two major types of epithelial tissues:

1. Simple epithelium: It is composed of a single layer of cells and functions as a lining for body cavities, ducts and tubes. On the basis of structural modification, the simple epithelium is further divided into three types

• Squamous epithelium: Single thin layer of flattened cells with irregular boundaries mostly involved in the diffusion process. E.g. cells of walls of blood vessels, air sacs of lungs.
• Cuboidal epithelium: Single layer of cube-like cells. They are mostly found in ducts of glands and nephrons and are mainly involved in secretion and absorption.
• Columnar epithelium: Single layer of tall and slender cells with microvilli on the free surface. They are found in the lining of stomach and intestine and are involved in secretion and absorption.
  

Sometimes, cuboidal or columnar epithelium bear cilia (known as ciliated epithelium) and move particles in a specific direction or get specialized for secretion (known as glandular epithelium).

2. Compound epithelium: It consists of two or more cell layers and has protective function e.g. our skin. They mainly provide protection against chemical and mechanical stresses. They form a dry protective layer of the skin, the moist surface of the buccal cavity, pharynx, inner lining of ducts of salivary glands and of pancreatic ducts.