Living Science Solutions for Class 7 Science Chapter 4 Animal Fibres are provided here with simple step-by-step explanations. These solutions for Animal Fibres are extremely popular among Class 7 students for Science Animal Fibres Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Living 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 Living Science Solutions. All Living Science Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

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Question 1:

What are natural fibres?

Answer:

Fibres which are obtained from nature are called natural fibres.They can be obtained from plants(vegetable fibre) like cotton, jute, etc., or from animals(animal fibre) like silk and wool.

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Question 2:

List five animals from which wool is obtained.

Answer:

Five animals from which wool is obtained are sheep, goat, rabbit, camel and yak.

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Question 3:

Name three vegetable fibres.

Answer:

Name of three vegetable fibres are cotton, jute and flax.

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Question 1:

Which of these is not an animal fibre?

(a) wool
(b) silk
(c) jute
(d) angora

Answer:

(c) Jute
Jute is a vegetable fibre.

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Question 2:

Which of these is a synthetic fibre?

(a) alpaca
(b) mohair
(c) rayon
(d) vicuna

Answer:

(c) rayon
Rayon is a synthetic fibre as it is manufactured from naturally occurring polymers.

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Question 3:

Fibres based on cellulose as their structural material are

(a) flax
(b) cashmere
(c) silk
(d) wool

Answer:

(a) flax
Flax is a vegetable fibre, and all vegetable fibres have cellulose as their structural material.

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Question 4:

A rare and expensive fibre called cashmere is obtained from

(a) camel
(b) rabbit
(c) goat
(d) sheep

Answer:

(c) goat
Cashmere is obtained from the underbelly of a cashmere goat.

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Question 5:

Which of these is not a fibre?

(a) cotton
(b) nylon
(c) leather
(d) wool

Answer:

(c) leather
Leather is not a fibre. It is just the animal skin treated with chemicals.

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Question 1:

Name the source from which the following are obtained:

(a) silk
(b) wool
(c) angora

Answer:

(a) Silk is obtained from a silkworm.
(b) Wool is obtained from a sheep.
(c) Angora is obtained from an Angora rabbit.

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Question 2:

Which complex compounds are animal fibres made up of?

Answer:

Proteins are the complex compounds that make up animal fibres.

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Question 3:

Which material forms the base of vegetable fibres?

Answer:

Cellulose forms the base of all vegetable fibres.

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Question 4:

The removal of wool from a sheep is called _______

Answer:

The removal of wool from a sheep is called shearing.

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Question 5:

___________ is the management and breeding of silkworms for the production of silk.

Answer:

Sericulture is the management and breeding of silkworms for the production of silk.

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Question 6:

Wool traps more air than cotton. True of false?

Answer:

True.
Wool can trap more air because of the air spaces present in its fibres.



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Question 4:

What property of silk makes it so attractive?

Answer:

The lustrous appearance of silk makes it attractive.

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Question 5:

What is the basis to decide the quality of wool obtained from sheep?

Answer:

The thickness of fibre, its length, colour, strength and shine are the basis of deciding the quality of wool obtained from a sheep.

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Question 6:

What are two types of fibres obtained from the fleece of a sheep? Which one is used to make wool?

Answer:

The two types of fibres obtained from the fleece of a sheep are beard hair, which are coarse and fine, and soft under hair, which grow near the skin. The under hair are used to make wool.

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Question 1:

We wear clothes suited to the weather. Explain the statement.

Answer:

We wear clothes suited to the weather.

  • Loose and light-coloured cotton clothes are worn in the summers. Light-coloured clothes reflect the heat and keep our body cool. In cotton-made clothes, air circulates freely thereby allowing the body heat to escape easily.
  • Dark-coloured and thick woollen clothes are worn in the winters to prevent the body heat from escaping. Thus, woollen clothes help in keeping our body warm.
  • Generally, we wear cotton clothes in the rainy season. Raincoats are used to keep body dry.

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Question 2:

Differentiate between animal and vegetable fibres. Give two examples of each.

Answer:

 Animal Fibres  Vegetable Fibres
They are derived from animals. They are derived from plants.
They are made up of proteins. They have the base of cellulose.
For example, wool and silk For example, jute and cotton

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Question 3:

How does wool fibre help in keeping our body warm?

Answer:

Woollen clothes comprise slots or spaces between their fibres that can easily trap the air inside. This trapped air being the bad conductor of heat does not allow the body heat to escape. Thus, it helps in keeping the body warm.

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Question 4:

Draw a diagram to show the life cycle of a silk moth.

Answer:



              The above diagram depicts the life cycle of a silk moth.

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Question 5:

Mention the steps in silk production.

Answer:

Steps involved in silk production are as follows:

  • The first step is to collect the cocoons and kill the insect inside them. For this, the cocoons are either boiled, steamed or treated in an oven.
  • The next step is reeling or filature. It is a delicate process of extracting silk fibres from the treated cocoons. In the next step, these fibres are then spun into threads.
  • These silk threads are then used to weave silk clothes.

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Question 6:

What adverse effects are observed on health of workers in the silk industry?

Answer:

Those working in the silk industry are prone to respiratory diseases, scabies or other skin infections.
The vapour produced during the steaming, cooking and reeling of cocoons, if inhaled, can cause asthma, respiratory problems or bronchial ailments. During reeling, the workers need to boil the cocoons in warm water. Because of the regular dipping of hands into the warm or boiling water, their skin develops blisters, and later starts peeling-off.

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Question 1:

Why is sheep shearing not done during the cold season?

Answer:

Sheep shearing is avoided in the winters so as to allow the sheep to keep itself warm with its thick coat of hair. This wooly coat protects the sheep from the harsh winter conditions. In summers, sheep need to keep their body cool and no more need the thick coat of wool. Thus, shearing is done in the summers and not in the winters. 

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Question 2:

Does shearing hurt the sheep?

Answer:

No, shearing does not hurt the sheep. Shearing is the process of shaving the thick coat of wool from the sheep's skin. Since, hair is a dead tissue, its shaving does not hurt the sheep.

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Question 3:

Animal activists oppose the present process of getting silk from the cocoon. Why do you think they are against it?

Answer:

The present process of extracting silk from the cocoons involves boiling and killing of cocoons. For obtaining 1 kg of silk, 5500 silkworms are killed. Animal activists are against this process, as it involves the killing of silkworms on a large scale.

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Question 4:

Which of these fabrics traps air the most−silk, wool or cotton? What is the effect of this on the porperty of the fabric made from this fibre?

Answer:

Wool fabric can trap most of the air. This property of the fabric helps it to prevent heat from escaping. Because air is a bad conductor of heat, the body heat cannot escape. Thus, the fabric helps in keeping our body warm and protecting us from the harsh cold.



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