NCERT Solutions for Class 7 Science Chapter 3 - Fiber To Fabric (Not in the Updated Syllabus)

1. You must be familiar with the following nursery rhymes:

1. ‘Baa baa black ship, have you any wool’. 

2. ‘Mary had a little lamb, whose fleece was white as snow’.

Answers the following:

1. Which parts of the black sheep have wool?

2. What is meant by the white fleece of the lamb?

Ans:

1. Wool is mostly found on the sheep's abdomen and back.

2. White fleece refers to the white hair used to make wool from lambs.

2. The silkworm is

1. a caterpillar,

2. a larva. 

Choose the correct option. (i) a  (ii) b  (iii) both a and b  (iv) neither a nor b.

Ans: (iii) both a and b 

Explanation - The female silk moth lays eggs, of which larvae known as caterpillars or

silkworms hatch.

3. Which of the following does not yield wool? 

(i) Yak   (ii) Camel   (iii) Goat   (iv) Wooly dog 

Ans: (iv) Wooly dog.

4. What is meant by the following terms?

(i) Rearing  (ii) Shearing   (iii) Sericulture

Ans:

1. Rearing: Rearing refers to the process of raising and caring for sheep.

2. Shearing: Shearing is the process of removing the sheep's fleece as well as a thin layer of skin from its body in order to acquire wool. Shearing is the term for this procedure.

3. Sericulture: is the cultivation of silkworms for the purpose of producing silk.

5. Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.

Shearing, ---------------, sorting, ----------------, ---------------. 

Ans: Shearing, Scouring, sorting, reeling, dying.

6. Make the sketch of two stages in the life history of the silk moth which are directly

related to the production of silk.

Ans: The two stages of the silk moth's life cycle that are directly connected to silk

manufacturing are:

• Stage 1 -  The caterpillar weaves a cocoon of silk threads around itself, gradually covering itself. 

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• Stage 2 - The caterpillar then transforms into a pupa. Development of the pupa into moth continues inside the cocoon

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7. Out of the following, which are the two related to the production of silk.

Sericulture, Floriculture, Moriculture, Apiculture and Silviculture.

Ans: Sericulture and Moriculture.

8. Match the words of Column I with those given in Column II.

Ans: 1. (e) 2. (c) 3. (b) 4. (a)

9. Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank space with letters that complete the words. 

Down 

1. Thorough washing 

2. Animal fibre 

3. Long thread like

Across

1. Keep warm. 

2. Its leaves are eaten by silkworms. 

3. Hatches from eggs of both structures.

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Ans: 

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NCERT Grade 7 Science, Chapter 3, Fibre to Fabric starts with the fundamentals of two animal fibres: silk and wool. This chapter is divided into two sections where the first discusses in detail fibre wool. The process of obtaining wool starts with a few sources of wool and the concept of selective breeding. Further, we will talk about varieties of wool such as sheep wool, yak wool, angora wool, etc.

So, the entire process of converting this fibre into a fabric is described in the following stages:

From fibre to wool - rearing and breeding of sheep

First - The processing of fibre into wool, which further includes the following steps:

• Shearing 

• Scouring 

• Sorting 

• Dyeing 

• Rolling 

Likewise, the second section of the chapter, Fibre to fabric, explains the second fibre - silk where the term sericulture is defined. With the help of a suitable diagram, different stages of the lifecycle of a silk moth are also discussed.

Besides this, the understanding of how a caterpillar grows into a cocoon which is further converted into silk is extensively covered. Different varieties of silk-like are:

• Mulberry silk, 

• Moga silk, 

• Tussar silk, and 

• Kosa silk

Short information about the discovery of silk is also provided in the chapter, Fibre to Fabric of Class 7 Science. 

NCERT Solutions for Class 7 Science Chapter 3 Fibre to Fabric PDF Download

Fibre to Fabric Class 7 NCERT is an important chapter to build the concepts regarding the subject in the brains of the students. Students can have easy access to the PDF version of Ch 3 Science Class 7. NCERT Solutions Class 7 Science Chapter 3 Fibre to Fabric covers all those topics that guarantee every student of success in terms of high marks in their examination.

NCERT Solutions for Class 7 Science Chapter 3 Fibre to Fabric, prepared by subject experts, are designed to assist students in their studies. Therefore, Vedantu provides all its study materials in an easily downloadable format, free of cost! With detailed explanations in NCERT Solutions, along with extra conceptual information related to different topics covered in the chapter, our NCERT Solutions for Class 7 Science Chapter 3 Fiber To Fabric serve as the ultimate preparation resource for students. So, access them for free and ensure your better performance.

Class 7 Science Chapter 3 – Fibre to Fabric Summary Notes

3.1 Wool

Sheep are the primary source of wool. Different breeds of sheep produce different qualities of wool. Apart from sheep, Yak (in Ladakh and Tibet), Angora goat (source of angora wool in Jammu and Kashmir), Alpaca and Llama (in South America) are also the sources of wool. Goat hair from the Kashmiri goat’s underfur can also be used to produce wool and is mainly woven into rich-quality Pashmina shawls. Camel Fur can also be used to produce wool.

Although there are so many sources of wool, sheep are reared mainly to support the wool industry. The sheep fur is cut, collected and processed to produce wool. The entire process starts with the breeding and rearing of sheep. You will see these herds of sheep along with their shepherds if you travel to the hilly regions of Uttaranchal, Himachal Pradesh, Jammu and Kashmir, Sikkim and Arunachal Pradesh.

You will also see them in the plains of Punjab, Haryana, Gujarat and Rajasthan. Although sheep mainly feed on leaves and grasses, the shepherds also feed them with mixtures of corn, pulses, oil cakes, jowar and minerals. Shepherds mainly prefer to keep the herds indoor during winter and feed them with grains, dry leaves and fodder.

The wool that we use for weaving shawls or knitting sweaters is actually the finished product obtained from processing the fleece collected from the sheep. The process of conversion of fleece into wool is a long process involving several steps.

Step 1: Shearing: The fleece and a thin layer of the skin are peeled off the sheep’s body by the process called shearing. Shearing is done with the help of machines that are similar to the ones used by the barbers. Generally, shearers prefer hot weather so that the sheep can survive without protective fur. These hairs in the fur have woolen fibres which are then processed to form the woolen yarn.

Do not think that the sheep get hurt during shearing. The process is similar to a normal haircut. Moreover, the top layer of the skin is dead. The sheep regrow the top skin layer as well as the hair, just like our body hair.

Step 2: Scouring: After the skin and hair are sheared, the shearers wash them thoroughly in tanks to remove dust, dirt and grease. This washing process is called scouring. Although done manually in previous times, machines are used nowadays to do this job.

Step 3: Sorting: After scouring, the sorting of different textures of hairs is done. The hairs are sent to a factory, where they are sorted according to their texture.

Step 4: Picking Burrs: The hairs might contain fluffy and small fibres called burrs. You might find small pieces of them on your woolen clothes. These burrs are picked and the fibres are then scoured and dried. The wool is now ready to be converted to fibres.

Step 5: Dyeing: In general, the natural colours of the fleece of goats and sheep are white, brown or black. However, the fibres thus obtained are dyed in various colours.

Step 6: Rolling into Yarns: After dyeing, the fibres are combed, straightened and rolled in the shape of a yarn. Sweaters are made from the long fibres while other woolen clothes are made from the shorter fibres.

Different breeds of sheep are reared for different qualities of wool. For example, 

• Lohi breed from Punjab and Rajasthan is reared for good quality wool. 

• Marwari breed from Gujarat is reared for coarse quality wool. 

• Rampur Bushair breed from Himachal Pradesh and Uttar Pradesh is reared for brown fleece. 

• Carpet wool is obtained from the Nali breed from Haryana, Punjab, and Rajasthan.

• Bakharwal is bred in Jammu and Kashmir for woolen shawls. 

• Patanwadi breed in Gujarat is reared for the manufacture of hosiery. 

In general, the breed of sheep that produce good quality wool is selectively bred. Once the sheep develops a thick hair growth, the fur is shaved off and processed for making wool.

Although the wool industry is considered to be a stable source of income for many, the workers face serious occupational hazards as well. The sorter experiences the risk of getting infected with the Anthrax bacterium, which is responsible for sorter’s disease. This disease is a fatal disease affecting the blood of the sorter.

3.2 Silk

Another type of animal fibre that is used to make clothes is silk fibre. Silkworm is the architect of the silk fibre. Sericulture is the process of rearing silkworms to generate silk.

The life history of a silk moth is an interesting story. It begins when the female moth lays eggs. The eggs hatch and the larvae (also known as silkworms or caterpillars) come out. The caterpillars grow in size and it enters the next stage called the pupa. In the pupa stage, the worm first weaves a net-like structure to support itself. Then it makes its head swing from side to side, resembling the figure eight (8).

During such movements, the caterpillar produces a secretion which on contact with air, hardens and forms the silk fibre. The caterpillar covers itself totally in this silk fibre and forms the pupa. Cocoon is the scientific term to describe this silk covering. It is the place where the worm develops from the pupa stage to the moth stage. The cocoon of the silkworm is used to make the silk yarn.

Several varieties of silk moths produce different qualities and varieties of silk yarn. Mulberry silk moth is the most common type, and the fibre obtained from it is lustrous, soft, elastic, and can be dyed with different colours. Other types of silk including muga silk, tussar silk and kosa silk, are also present. Sericulture is a very old and common occupation in India, producing silk on a commercial basis.

There are several steps to the process of producing silk. They are:

Rearing Silkworms: In general, a mother silk moth lays about a hundred eggs at once. These eggs are carefully stored on paper or cloth strips and sold to the silkworm farmers. The farmers maintain suitable temperature, humidity and hygienic conditions for the eggs to hatch. The larvae eat on fresh mulberry leaves all throughout the day and increase in size. 

The farmers keep the larvae with the mulberry leaves on clean, tiny chamber-containing bamboo trays. The larvae stop eating and enter the tiny chambers to spin the cocoon after 25-30 days. The farmers sometimes provide small twigs or racks to those chambers. Inside the cocoon, the pupa develops into the silk moth.

Silk Processing: The farmers use a pile of cocoons to make the silk fibres. The cocoons are first exposed to sun, steam or boiled. During this heating process, the fibres separate from each other. This process of obtaining the silk threads from the cocoon is known as the reeling of silk. Special machines perform the reeling process. The fibres are then spun into threads, and silk cloth is made from it by the weavers.

Despite the plethora of uses of silk, its discovery is not completely known. According to a Chinese legend, emperor Huang-ti asked his empress Si-Lung-Chi about the cause of damaged mulberry leaves in the garden. The empress noticed small white worms eating the leaves and also spinning cocoons around them. One such cocoon accidentally dropped in her tea and dismantled into delicate threads. 

Although silk was discovered in China, it was kept secret from the rest of the world for several centuries. Years later, travelers and traders traded silk with businessmen in other countries. The route taken by these travelers is called the silk route.

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NCERT Solutions Class 7 Science Chapters

• Chapter 1 - Nutrition in Plants

• Chapter 2 - Nutrition in Animals

• Chapter 4 - Heat

• Chapter 5 - Acids

• Chapter 6 - Physical and Chemical Changes

• Chapter 7 - Weather

• Chapter 8 - Winds

• Chapter 9 - Soil

• Chapter 10 - Respiration in Organisms

• Chapter 11 - Transportation in Animals and Plants

• Chapter 12 - Reproduction in Plants

• Chapter 13 - Motion and Time

• Chapter 14 - Electric Current and Its Effects

• Chapter 15 - Light

• Chapter 16 - Water: A Precious Resource

• Chapter 17 - Forests: Our Lifeline

• Chapter 18 - Wastewater Story