Basic Science Solutions for Class 7 Science Chapter 4 Fibres From Animals are provided here with simple step-by-step explanations. These solutions for Fibres From Animals are extremely popular among Class 7 students for Science Fibres From Animals Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Basic Science Book of Class 7 Science Chapter 4 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Basic Science Solutions. All Basic Science Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

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Question A.1:

Answer:

Silk and wool are animal fibres that are suitable for making fabrics.

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Question A.2:

Silk and wool are animal fibres that are suitable for making fabrics.

Answer:

A larva refers to a phase of an animal's life cycle that occurs before metamorphosis.
Example: A silkworm emerging from the egg laid by the female silk moth is in its larval stage.

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Question A.3:

A larva refers to a phase of an animal's life cycle that occurs before metamorphosis.
Example: A silkworm emerging from the egg laid by the female silk moth is in its larval stage.

Answer:

A cocoon is a soft covering of silk threads that is spun by an insect to protect itself.

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Question A.4:

A cocoon is a soft covering of silk threads that is spun by an insect to protect itself.

Answer:

Throwing of silk (or silk throwing) is the process of preparing thrown silk by twisting the raw silk.

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Question A.5:

Throwing of silk (or silk throwing) is the process of preparing thrown silk by twisting the raw silk.

Answer:

Sheep shearing is the process of cutting off the fleece from the body of sheep to obtain wool. In India, sheep are shorn twice a year.

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Question A.6:

Sheep shearing is the process of cutting off the fleece from the body of sheep to obtain wool. In India, sheep are shorn twice a year.

Answer:

The spring is the best mating season for the sheep.

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Question A.7:

Answer:

Washed wool is obtained from sheep that are washed thoroughly to remove dirt from their wool.
Clipped wool is the wool obtained from live sheep.
Pulled wool is the wool obtained from dead sheep.

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Question B.1:

Washed wool is obtained from sheep that are washed thoroughly to remove dirt from their wool.
Clipped wool is the wool obtained from live sheep.
Pulled wool is the wool obtained from dead sheep.

Answer:

Moulting is the process of growth and maturation of a larva such as silkworm. During moulting, a silkworm sleeps four times. While in its feeding and sleeping periods, its skin cracks. When the larva awakes, it leaves the old skin and forms a new skin.

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Question B.2:

Moulting is the process of growth and maturation of a larva such as silkworm. During moulting, a silkworm sleeps four times. While in its feeding and sleeping periods, its skin cracks. When the larva awakes, it leaves the old skin and forms a new skin.

Answer:

Cross-breeding of sheep is necessary in India to improve the quality and quantity of wool. The native sheep are cross-bred with the exotic breeds to yield better wool.
Three exotic breeds used for cross-breeding in India are Merino, Rambouillet, and Dorset.

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Question B.3:

Cross-breeding of sheep is necessary in India to improve the quality and quantity of wool. The native sheep are cross-bred with the exotic breeds to yield better wool.
Three exotic breeds used for cross-breeding in India are Merino, Rambouillet, and Dorset.

Answer:

Cross-breeding of sheep is necessary in India to improve the quality and quantity of wool. The native sheep are cross-bred with the exotic breeds to yield better wool.
Three exotic breeds used for cross-breeding in India are Merino, Rambouillet and Dorset.

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Question C:

Cross-breeding of sheep is necessary in India to improve the quality and quantity of wool. The native sheep are cross-bred with the exotic breeds to yield better wool.
Three exotic breeds used for cross-breeding in India are Merino, Rambouillet and Dorset.

Answer:

Following are the chemical properties of wool:

(i) It is affected by heat and changes its colour at 100°C, but does not catch fire easily. It turns yellowish if left in hot and humid condition for a long time.
(ii) It gets dissolved in acids and bases.
(iii) Its fibres can be bleached without any loss of strength.

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Question D:

Following are the chemical properties of wool:

(i) It is affected by heat and changes its colour at 100°C, but does not catch fire easily. It turns yellowish if left in hot and humid condition for a long time.
(ii) It gets dissolved in acids and bases.
(iii) Its fibres can be bleached without any loss of strength.

Answer:

1. The process of obtaining silk from the silk moth is called sericulture.
2. The sleeping period of a silkworm is 24 hours.
3. The quality and quantity of wool depend upon the breed of the sheep.
4. The thinner the fibre, the better is the wool.
5. Wool has high tensile strength.
6. Wool dissolves in acids and alkalis.

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Question E:

1. The process of obtaining silk from the silk moth is called sericulture.
2. The sleeping period of a silkworm is 24 hours.
3. The quality and quantity of wool depend upon the breed of the sheep.
4. The thinner the fibre, the better is the wool.
5. Wool has high tensile strength.
6. Wool dissolves in acids and alkalis.

Answer:

 

A B
(a) Mulberry (iii) The best feed for silkworms
(b) Organize (iv) The lengthwise thread in silk weaving
(c) Tram (v) The crosswise thread in silk weaving
(d) Combing (i) To remove burrs from fleece
(e) Weighting (ii) To soak silk in solutions of salts



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