Biology Class 11 NCERT Solutions: Chapter 7 Structural Organisation in Animals Part 1

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Q: 1. Answer in one word or one line.

(i) Give the common name of Periplaneta Americana.

(ii) How many spermathecae 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 find malpighian tubules?


(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.

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?


(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.

Image of the three types of Nephridia

Image of the Three Types of Nephridia

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They are:

(A) Septal Nephridia: These are present on both sides of the inter-segmental 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, fifth, and sixth segments

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


Reproductive System of Earthworm

Reproductive System of Earthworm

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


Alimentary canal of cockroach

Alimentary Canal of Cockroach

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Q: 5. Distinguish between the following

(A) Prostomium and peristomium

(B) Septal nephridium and pharyngeal nephridium



Prostomium vs. 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.

Prostomium and peristomium in image

Prostomium and Peristomium in Image

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Septal vs pharyngeal nephridium

Septal Nephridium

Pharyngeal Nephridium

They are present on both sides of inter-segmental septa the 15th segment. They open into the intestines.

They are present as three paired tufts in the fourth, fifth, and sixth segments.

Q: 6. What are the cellular components of blood?


Components of blood include erythrocytes (RBCs), leucocytes (WBCs), and thrombocytes (platelets). These components form 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, eosinophil’s, and basophils) and agranulocytes (lymphocytes and monocytes). They help fight 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.

Composition of blood

Composition of Blood

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