NCERT Solutions for Class 7 Science, CBSE Class 7, NCERT Solutions for Class 7 Science,, CTETpaperII, CTET2020, CTETTGT

Chapter 3

Fibre to Fabric

Fibres can be defined as the smallest unit of textile product and spun on yarn and finally, the fabric is made.

NCERT Solutions for Class 7 Science, CBSE Class 7, NCERT Solutions for Class 7 Science,, CTETpaperII, CTET2020, CTETTGT

Yarn: - It is a long length of interlocked fibres that can be used for making of fabrics. In this chapter, we will study about animals fibres obtained from sheep and silkworm. So wool is obtained from the sheep or wool yielding animal's hairs called Fleece.

Coarse Beard and Fine Soft Under Hairs, NCERT Solutions for Class 7 Science, CBSE Class 7, NCERT Solutions for Class 7 Science,, CTETpaperII, CTET2020, CTETTGT
Coarse Beard and Fine Soft Under Hairs

Wool yielding animals, NCERT Solutions for Class 7 Science, CBSE Class 7, NCERT Solutions for Class 7 Science,, CTETpaperII, CTET2020, CTETTGT
Wool Yeilding Animals

From fibres to wool
      Sheep are reared to collect wool; hair is cut and processed into wool.

Following are steps:
Rearing and breeding of Sheep
Hilly region of Jammu & Kashmir, Uttaranchal, Himachal Pradesh, Arunachal Pradesh, Sikkim, plains of Haryana, Rajasthan, Punjab and Gujarat, we can see shepherds taking their herds of sheep for grazing.
Rearers also feed sheep oil cakes, jow, jowar, corn, the mixture of pulses, etc. In winters they are kept inside and fed on grain, dry fodder and leaves.

Sheep breed, sheep rearing, Breed of sheep in india, NCERT class 7 science chapter 3 fibre to fabric
Breeds of Sheep and Their Rearing in Particular Area

Processing fibres into wool
Step 1:-
  • Fleece with the thin layer of skin is removed from its body and the process is called Shearing. The shearing machines is the same as a trimmer.
  • This process is done in summer so that they can survive.
  • Hairs provide woollen fibres à Woollen fibres then processed to obtain woollen yarn.
  • Sheep is safe as hairs grow again same as our hairs.

Step 2:-
Sheared skin is washed in tanks to remove grease, dirt and dust. The process is called Scouring.

Step 3:-
Sorting is done after scouring, hairy skins are sent to the factory where the hair of different textures are sorted.

Step 4:-
Burrs are fluffy fibres which are sorted and scoured again and dried, and now wool is ready to make fibres.

Step 5:-
Fibres can be dyed into various colours because natural sheep or goats hairs are black, brown or white.

Step 6:-
Fibres are straightened and rolled into yarn, the longer fibres are used for sweaters and smaller one for woollen cloths. 

There is an occupational hazard related to sorting called as sorter's disease because wool is sometimes house for the bacteria Bacillus anthracis and this is the causative agent of Anthrax disease.

Shearing, Scouring, making of yarn, cotton processing, NCERT 7th class solution, fibre to fabric
Cotton Processing
Silk fibres are also animal fibres, the process of rearing silkworms and obtaining silk is called as Sericulture.

Life history of the silk moth
Female silk moth lays eggs and from which caterpillars or silkworms hatched. Caterpillar grows and ready to enter the next stage called Pupa.
Pupa secretes fibre which gets harden on the exposure of air and the covering called Cocoon
Silk is as strong as steel of the same diameter. Pupa continues to grow inside the cocoon.
Silkmoth, sericulture, Fibre to fabric, NCERT 7th class, silkworm life cycle
Life Cycle of Silkmoth

There are so many varieties of silk moth depends on the source from which type of silk moth they obtained the silk may be smooth, shiny, coarse, etc. There are few strains of silk moth Tassar silk, Mooga silk, Kosa Silk, etc.
Commonly used silk is obtained from Mulberry Silk Moth, the silk of this moth is very soft, lustrous and elastic and these are dyed in many colours.  Sericulture in India is very old occupation.

Rearing silkworms:-
1. Female silk moth lays eggs in hundreds and kept on paper or cloth and sold to silkworm farmers.
2. They keep eggs in suitable condition like proper hygiene, temperature, etc. and then eggs are warmed to optimal temperature and caterpillar come out and they eat leaves day and night and get bigger in size.
3. Caterpillar kept in the bamboo tray for 25-30 days then they stop eating and move into the hole and start making a cocoon.

Processing of Silk:-
Cocoons are boiled or kept under the sun so silk fibers separate out and this process is called reeling the silk done by special machines that unwind fibers and then spun into silk threads. 

Silk Route:-
The silk industry was a secret in China for so many years but after travellers start travelling they introduced silk in a different country and the route they travelled is still called “Silk route”.

Silk Route

Silk Story:
Exactly it is not unknown when the silk was discovered but according to a story of a Chinese empress, Si-lung-Chi asked the reason behind the damaged leaves of mulberry in her garden to emperor Huang-ti. She came to know that some white worms were eating the leaves and once day a cocoon dropped into the cup of hot tea and tangled the soft and delicate threads. That’s how the silk the industry started and initially, the silk was a big secret kept in China but after the invasion of travellers to china the silk industry spread to other countries via ‘silk route’.

Silkstory, silk route, fibre to fabric
Silk Story and How The Silk was discovered

For detail video visit below link: https//

1. You must be familiar with the following nursery rhymes:
(i) ‘Baa baa black sheep, have you any wool.’
(ii) ‘Mary had a little lamb, whose fleece was white as snow.’
Answer the following:
(a) Which parts of the black sheep have wool?
Answer: The hairy part of black sheep has wool.

(b) What is meant by the white fleece of the lamb?
Answer: The white colour of their fur is referred to as the white fleece of the sheep

2. The silkworm is (a) a caterpillar, (b) a larva. Choose the correct option.
(i) a (ii) b (iii) both a and b (iv) neither a nor b.
Answer: (iii) both a and b

3. Which of the following does not yield wool?
(i) Yak (ii) Camel (iii) Goat (iv) Woolly dog
Answer: Woolly Dog

4. What is meant by the following terms?
(i) Rearing (ii) Shearing (iii) Sericulture
(i) Rearing: Keeping animals like sheep, goats, cow, etc. for the commercial use is called rearing.

(ii) Shearing: Trimming or removal of hairs of sheep by trimmers is called as shearing.

(iii)  Sericulture: Rearing the silkworms for the collection of silk is called sericulture.

5. Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.
Shearing, Scouring, sorting, Picking out furs, Dying, Yarn making

6. Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk.
NCERT Class 7 Science chapter 3 Fibre to Fabric, NCERT Solutions for Class 7 Science, Chapter 3 - Fibre to Fabric,NCERT Solutions for Class 7 Science,

7. Out of the following, which are the two terms related to silk production? Sericulture, floriculture, moriculture, apiculture and silviculture.
Hints: (i) Silk production involves the cultivation of mulberry leaves and rearing silkworms. (ii) The scientific name of mulberry is Morus alba.
Answer: Sericulture and Moriculture.

8. Match the words of Column I with those given in Column II:
Column I
Column II
Cleaning sheared skin
Mulberry leaves
Food of silkworm
Wool yielding animal
Yields silk fibres

Keywords: Cocoon, Fleece, Reeling, Silkmoth, Silkworm, Sorting, Scouring, Sericulture, Shearing, CTET Paper-II, CTET TGT, KVS, CTET 2020, NCERT, NCERT Science Chapter 7, Fibres to Fabric.

Pic Sources: Pixabay, Recreational work done by Anil Kashyap

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