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Class VII - science: Fibre To Fabric
One Word Answer Questions:
Q) Cleaning of hairs of sheep to remove dirt is called?
    
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Q) Angora goats are found in which region?
    
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Q) Silk fibres are obtained from which animal?
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Q) Which is the most common silk moth?
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Q) What is the larva of silk moth called?
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Q) What do we require to protect our body against the weather, sunlight, cold and heat?
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Q) The fibres obtained from plants and animals are called?
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Q) Silk fibre is drawn from which animal?
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Q) Name an animal which produce wool?
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Short Answer Questions:
Q) What is selective breeding? Why is it important?
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Q) What is Sericulture? Explain briefly?
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Q) Explain processing of silk?
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Q) Is the process of shearing harmful to the animal? Give reasons?
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Q) Explain about natural fibres with examples?
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Q) What are Synthetic fibres?
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Q) What is Weaving?
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Q) Explain briefly the spinning of cotton yarn?
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Q) Explain about synthetic properties?
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Long Answer Questions:
Q) Explain about the wool producing animals found in different regions?
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Q) What are the steps involved in the processing of fibres to wool?
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Q) Explain about the life history of silk moth?
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Q) Explain briefly about the rearing of silkworm?
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Fiber To Fabric And Silk

INTRODUCTION

Cloth is one of our basic needs. It protects us from heat, cold, rain, dust, insects, etc. Clothes also make one civilized and smart. Clothes are made of cloth. Cloth is also known as fabric. Fabric is made of fiber.Fibers are two types Natural and Manmade.

Natural fibers:

Natural fibers are obtained from plants and animals; such as jute, cotton, wool, silk, etc. Natural fibers can be classified into two types:

  • Plant fiber
  • Animal fiber

Plant Fiber:

Fiber obtained from plants is called plant fiber.
Example: Cotton, jute, flex, etc.

Animal Fiber:

Fiber obtained from animals is called animal fiber.
Example: Wool and silk.

Manmade fibers:

Fibers that are synthesized in laboratory are called manmade fiber, such as terylene, terry-cotton, acrylic, etc.

WOOL

There are many animals that bear a thick coat of hair on their body. Such animals generally live in cold climates. Thick coat of hair over the body of such animals traps lot of air and keep them warm as air is a bad conductor of heat. It prevents the warmth of the body from escaping and also prevents the coldness of the surroundings from entering. Thus, thick layer of hair over their body protects them from harsh cold. Example: Sheep, Goat, Camel, Yak, etc.
Fleece and Wool bearing animals:
Sheep, goat, Camel, Yak, etc. bear two types of hairs are coarse hair and fine-soft under hair. Fine soft hair is found close to the skin in such animals. The fine soft under hair is called fleece. Fiber for wool is obtained from the fleece (hair) of such animals and hence such animals are called wool bearing animals.

Many breeds of sheep are found in India. Sheep gives milk and meat; in addition to wool, but are reared mainly to obtain wool in different parts of the world. Angora wool is obtained from Angora Goats. Angora Goats are found in hilly regions, such as Jammu and Kashmir.

fiber to fabric and silk
Angora Goat

Pashmina wool is obtained from Pashmina Goats.

fiber to fabric and silk
Pashmina Goat

Yak wool is obtained common in Tibet and Ladakh

fibre to fabric and silk
Wild Tibetan Yak

Alpaca and Llama are other animals that give wool.

fibre to fabric and silk
Llama
fibre to fabric and silk
Alpaca

Selective breeding and rearing of sheep: Some breeds of sheep bear only a coat of fine hair. Such animals are reared by selective breeding.

“Selective breeding is the process to obtain animals or plants having special characteristics“.

In India, sheep are reared generally in the sates of Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Arunachal Pradesh and Sikkim, or the plains of Haryana, Punjab, Rajasthan and Gujarat.

Food of sheep: Sheep are herbivores and feed generally on grass and leaves. Apart from grass and leaves they also feed on corn and oil cakes. Oil cakes are materials left after obtaining of oil from oil seeds.

Process to obtain wool from sheep

Steps given below are followed to obtain wool from sheep or other wool bearing animals:

Step1:
Shearing: The fleece (hair) of sheep is shaved off along with a thin layer of skin. In olden days this was done using pair of metal blades. But now-a-days machine is used to cut off the fleece. This is similar to shaving of beards or hair. This process is called shearing. Shearing is done generally in summer so that sheep could get new hair by winter to get protection against cold.

fibre to fabric and silk
Step2:

Scouring: Fleece, after shearing, is washed properly to remove dirt and grease. The washing of fleece; after shearing; is called scouring.

fibre to fabric and silk
Step3:

Sorting: After scouring, fleece is sorted according to texture. This process is called sorting.

fibre to fabric and silk
Step4:

After sorting, fluffy fibers; called burr; are picked out from hair. The fibres are scoured again and dried. Thus, wool is ready to be drawn into fibres.

fibre to fabric and silk
Step5:
Dying:

After sorting and picking out of burrs, these are dyed in desired colors.

fibre to fabric and silk
Step6:
Spinning: The fibers are then straightened, combed and rolled into yarns.
fibre to fabric

Wool yarn is used in knitting sweaters and woolen cloths, i.e. fabric

fibre to fabric
SILK

Silk is another important animal fiber. Silk worm spins silk. Silkworm is reared to obtain silk.

History of Silk:

Silk was discovered in China; around 3500 BC. Silk became a prized possession because of its fine quality and luster. Originally, it was used by emperors only. It was through trade that silk spread to other parts of the world over a period of time. Silk was a staple item of trade during ancient times. Due to this, the ancient trade routes which linked China to other parts of the world are called Silk Route. As per historians, silk was produces in India also. Proof of use of silk in during the Indus Valley Civilization has also been found.

Types of Silk:

Different types of silk worm produce different types of silk in terms of luster and texture.
Example: Tassar silk, mooga silk, kosa silk, etc. are produced by different types of silk moth. Mulberry silk is the most common silk moth. Rearing of silkworm: Rearing of silkworm is known as SERICULTURE. Silkworms are reared on mulberry leaves as they feed on mulberry leaves.

Life cycle of silk moth:
  1. Female silk moth
  2. Lays eggs
  3. After about 14 days eggs are hatched into larva Grown into Pupa
  4. Weave a net and enclosed itself
  5. Produce liquid protein from its salivary glands moving its head in the shape of 8 forming cocoon
  6. Live in the cocoon for some time
  7. After coming out of cocoon grows into silk moth.
fibre to fabric and silk
Silk moth to silk:

After they are laid by the silk moth; eggs are stored over a clean cloth or paper strips. When larvae are hatched from eggs, they are kept in clean bamboo trays with fresh leaves of mulberry. Larvae feed on mulberry leaves for about 20 to 25 days. After that, larvae move into tiny chambers of bamboo in which they start spinning cocoon. They do it by secreting liquid protein from their salivary glands. Finally they enclose themselves in cocoon. Cocoons get hardened because of exposure to air. The silk fibre from the cocoon of mulberry silk moth is soft, lustrous and elastic and can be dyed in different colours.


Obtaining of silk from cocoon:

For obtaining silk, moths are reared and their cocoons are collected to get silk threads.

Rearing Silkworms:

A female silk moth lays hundreds of eggs at a time which are stored carefully on strips of cloth or paper and sold to silkworm farmers. The farmers keep eggs under hygienic and suitable conditions of temperature and humidity. The eggs are warmed to a suitable temperature for the larvae to hatch from the eggs. This is done when mulberry trees bear a fresh crop of the leaves. The larvae, which is also called caterpillar eat day and night and increase enormously in size. After some days, the larvae stops eating and moves to a tiny chamber of bamboo in which it is kept, to spin cocoons. The caterpillar or silkworm spins the cocoon inside which develops the silk moth.

fibre to fabric and silk
Silk processing:

A pile of cocoon is used for obtaining silk fibres. First of all, cocoons are boiled and then silk fiber is separated out; using machines. Machine unwinds the silk thread from cocoons. The process by which silk fiber is obtained is called REELING THE SILK. Silk thread so obtained is woven into different types of cloths, i.e. fiber.

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