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

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) American cockroach

(ii) 4 pairs of spermathecae are found in earthworm.

(iii) The position of ovaries in cockroach is under the 4th to 6th abdominal terga.

(iv) 10 segments

(v) Malpighian tubules are present at the junction of mid gut and hind gut of the alimentary canal of cockroach.

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 are segmentally arranged
excretory organs present in earthworms.
They perform the function of excretion and osmoregulation in earthworms.

(ii) Based on location, three types of nephridia are found in earthworm. 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 the fourth, fifth, and sixth segments.

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

Ans. Diagram of reproductive organs of an earthworm:

Structural Organisation inANS3

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

Ans. Diagram of alimentary canal of a cockroach:

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5. Distinguish between the followings:

(a) Prostomium and peristomium

(b) Septal nephridium and pharyngeal nephridium

Ans. (a) Prostomium and peristomium:

Prostomium Peristomium
  1. A small flap overhanging the mouth is called prostomium or upper lip.
The first segment of the body of earthworm is called peristomium.
  1. It is sensory in function.
It is not sensory.

(b) Septal nephridium and pharyngeal nephridium:

Septal Nephridium Pharyngeal Nephridium
  1. These are present on either side of the intersegment septa from 15th segment to the last.
These are present as three paired tufts in the 4th, 5th and 6th segments.
  1. These open into the intestine.
These open into the pharynx.

6. What are the cellular components of blood?

Ans. The blood consists of fluid, called plasma, in which various blood cells are suspended. The three major categories of cellular components of blood are:

(a) Erythrocytes (red blood cells)

(b) Leukocytes (white blood cells)

(c) Thrombocytes (platelets)

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

(a) Chondriocytes

(b) Axons

(c) Ciliated epithelium

Ans. (a) Chondriocytes are the cells of cartilage. They are located in intervertebral discs in the form of cartilage. They produce and maintain cartilage matrix.

(b) Axons are long, slender, thread like projections of neurons. The neuron consists of a cell body, dendrites and an axon. The axon extends from the cell body of neuron.

(c) Ciliated epithelium a type of epithelium tissue that consists of columnar epithelial cells lined with cilia. Ciliated epithelium lines the trachea, bronchi of the lungs, parts of the nasal cavities, the uterus and oviduct of the female, and the vas deferens and epididymis of the male.

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

Ans. Epithelial tissues form an outermost, protective layer of the body. These tissues have closely packed cells, so there is very little intercellular matrix between them.

The epithelial tissue can be grouped into following types based on the structure and organisation of the components of the cell:

(a) Squamous epithelium

(b) Cuboidal epithelium

(c) Columnar epithelium

(d) Ciliated epithelium

(e) Glandular epithelium

(a) Squamous epithelium: The tissue which is composed of a single layer of thin, flat, irregular, plate like cells is called squamous epithelium. The squamous epithelium lines the blood vessels, lymph vessels in Bowmanโ€™s capsule and uriniferous tubules, alveoli of lungs, buccal cavity, pharynx and oesophagus, etc.

(b) Cuboidal epithelium: It may be simple and stratified. It is composed of single layer of cubical cells. The simple cuboidal epithelium lines the uriniferous tubules, germinal layers of sex organs, thyroid gland, small salivary glands and pancreatic ducts.

(c) Columnar epithelium: It is formed by a single layer of tall, slender cells with their nuclei present at the base of the cells. Columnar epithelium forms the lining of the stomach and intestines.

(d) 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.

(e) Glandular epithelium: These are 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).

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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

Ans. (a) Difference between simple epithelium and compound epithelium:

Simple epithelium Compound epithelium
1. It is composed of only one layer of cells. It is composed of many layers of cells.
2. It is involved in absorption and secretion related functions. It is mainly involved in the function of protection.
3. It is present in the lining of the stomach, intestine. It is present in the lining of the pharynx and buccal cavity.

(b) Differences between cardiac and striated muscles:

Cardiac muscles Striated muscles
1. They are involuntary in function. They are voluntary in function.
2. They are multi-nucleated and branched. They are multi-nucleated and unbranched.
3. They are found only in the heart. They are found in triceps, biceps, and limbs.

(c) Differences between regular connective tissues and dense irregular connective tissues:

Dense regular connective tissue Dense irregular connective tissue
1. It is orientation of fibres is regular. It is orientation of fibres is irregular.
2. It is present in tendons and ligaments, etc. They are present in the skin.
3. It is fibres are arranged transversally. It is fibres are arranged differentially.

(d) Differences between adipose tissue and blood tissue:

Adipose tissue Blood tissue
1. It is a type of loose connective tissue. It is a type of fluid connective tissue.
2. It is composed of collagen fibres, elastin fibres, fibroblasts and adipocytes. It consists of plasma and blood cells.
3. It helps in the synthesis, storage, and metabolism of fats. It helps in the transportation of food, wastes, gases, and hormones.
4. It is present beneath the skin. It is present in the blood vessels

(e) Differences between simple glands and compound glands:

Simple glands Compound glands
1. They contain isolated glandular cells. They contain a cluster of secretory cells.
2. They are unicellular. They are multicellular.
For example, goblet cells of the alimentary canal. For example, salivary glands.

10. 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 while Areolar tissue, blood and tendons are connective tissues.

(b) Cartilage while RBC, WBC and platelets are blood cells.

(c) Ligament while the others are examples of simple glandular epithelium.

(d) Antennae (present in head of cockroach) while Maxilla, mandible and labrum are mouthparts of cockroach.

(e) Protonema (development stage in life cycle of moss) while the others are segments present in the legs of cockroach.

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

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

Ans. The correct match is as follows:

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

12. Mention briefly about the circulatory system of earthworm.

Ans. Earthworms (Pheretima sps.) possess a closed circulatory system in which blood always flows in the vessels and never comes in direct contact with tissues. The system consists of several tubes or vessels, blood glands and blood. The arrangement of different vessels is very complicated and that in the first thirteen segments differs from that of the rest body segments.

The blood of Pheretima is red coloured due to the presence of a respiratory pigment haemoglobin in it. The haemoglobin is not contained in the corpuscles like the vertebrates but it is found dissolved in the plasma. The plasma also contains many corpuscles which are colourless and nucleated.

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

Ans. Digestive system of frog:

Structural Organisation in Animals

14. Mention the function of the following:

(a) Ureters in frog

(b) Malpighian tubules

(c) Body wall in earthworm

Ans. (a) Ureters in frog acts as urogenital duct which carries urine and sperm in the male frog.

(b) Malpighian tubules are excretory organs in cockroaches.

(c) Body wall in earthworm helps in movement and burrowing.