Class 7 Science Chapter 3 Fibres to Fabric

Class 7 Science Chapter 3 Fibres to Fabric Oxford Book Solutions

1. Objective type questions

A. Fill in the blanks with the correct words.

  1. A fabric is woven using………….(yarns/fibres).
  2. During different parameters………(scouring/grading), wool is sorted on the basis of different parameters
  3. The silkworm eggs hatch only once a year in…….. (winter/spring).
  4. The filaments secreted by silkworm are made of a protein) that hardens to form silk. ……(vitamin/
  5. …………(Filaments/Fibres) from many cocoons are twisted together to make a strong thread which is wound on a reel.

Ans:

  1. A fabric is woven using yarns.
  2. During different parameters grading, wool is sorted on the basis of different parameters.
  3. The silkworm eggs hatch only once a year in spring.
  4. The filaments secreted by silkworm are made of a protein that hardens to form silk.
  5. Filaments from many cocoons are twisted together to make a strong thread which is wound on a reel.

B. Write T for the True and F for the False statements. Correct the false statements.

  1. All varieties of sheep give us wool that have the same fineness, shine and length.
  2. The sliver is a machine that combs loose wool fibres into a sheet.
  3. Silk fibres are produced by the silkworm, and are soft and lustrous.
  4. The moth stage of the silkworm gives out silk filaments.
  5. Continuous exposure to noise made by spinning and winding machines in sericulture leads to diseases like anthrax or sorter’s disease.

Ans:

  1. False – All varieties of sheep do not give the same fineness, shine, and length of wool.
    Reason: Different breeds produce different qualities of wool.
  2. False – The sliver is not a machine. It’s the long, loose bundle of wool fibres combed together.
    Reason: Machines like carding machines help in making slivers.
  3. True – Silk fibres are indeed soft, shiny (lustrous), and made by silkworms.
  4. False – It is the larva or caterpillar stage of the silkworm that gives out silk filaments, not the moth.
    Reason: The adult moth does not produce silk.
  5. False – Diseases like anthrax or sorter’s disease are caused by bacteria in contaminated wool, not from the noise of machines.
    Reason: Continuous exposure to noise may cause hearing issues, but not anthrax.

C. Choose the correct option.

1. Which of these is not a breed of sheep reared in India?

  1. Lohi and Nali
  2. Marwari and Patanwadi
  3. Angora and Merino
  4. All

2. Which of these do sheep eat?

  1. Mixture of grass and leaves
  2. Mixture of corn, jowar and pulses
  3. Mixture of grass, corn and milk
  4. Both a and b

3. Which of these are goats that give us wool?

  1. Alpaca and Llama
  2. Cashmere and Angora
  3. Ankara
  4. All of these

4. Which of these is the first step in wool production?

  1. Scouring
  2. Shearing
  3. Sorting
  4. Dyeing

5. Which of these are different varieties of silk?

  1. Tassar and Sericulture
  2. Kosa and Angora
  3. Tassar, Moonga and Kosa
  4. All of these

6. Which hair of sheep is used to make wool?

  1. Under hair
  2. Beard hair
  3. Body hair
  4. Angora, Cashmere and Mohair

7. Which breed of sheep provides wool to make carpets?

  • a. Marwari
  • b. It’s slow

8. What distinguishes mohair from other wool?

  1. Chemical composition
  2. Durability
  3. Warmth
  4. Smoother surface

9. Which of these refers to rearing silkworms to produce silk?

a. Shearing

b. Scouring

c. combing

d. sericulture

10. Which of these processes suggests that sericulture is not an eco-friendly activity?

a. Putting cocoons in hot water

b. Passing the filaments through an eyelet

c. Twisting filaments to make a strong threads

d. Dyeing and weaving threads to form a fabric

Ans:

1. (c) Angora and Merino – These are not Indian breeds of sheep.

2. (d) Both a and b – Sheep eat both grass and leaves, and corn, jowar, pulses.

3. (b) Cashmere and Angora – These are goats that give wool.

4. (b) Shearing – This is the first step in wool production.

5. (c) Tassar, Moonga and Kosa – These are all varieties of silk.

6. (a) Under hair – This is the soft and fine hair used for making wool.

7. (a) Marwari – This breed gives wool used in carpets.

8. (d) Smoother surface – Mohair is known for its smoothness and sheen.

9. (d) Sericulture – This is the process of rearing silkworms for silk.

10. (a) Putting cocoons in hot water – This step kills the pupae, hence not eco-friendly

II. Very short answer type questions | Class 7 Science Chapter 3 Fibres to Fabric

Give one word for the following.

1. A breed of sheep that gives the finest wool

2. Fibre obtained from Angora goat

3. The process of removing fleece from the sheep

4. The stage in the life cycle of silkworms, after hatching of eggs

5. The process by which filaments are taken out from the cocoons of silkworm

Ans:

Merino

Mohair

Shearing

Larva or caterpillar

Reeling

III. Short answer type questions | Class 7 Science Chapter 3 Fibres to Fabric

What are the two types of fibres on a sheep’s coat?

Ans: . Ans:

Two types of fibres on a sheep’s coat

The coarse outer hair and the soft under hair.

The under hair is used to make wool.

What are the various features that make wool different from each other?

Ans: Features that make wool different

Wool varies based on fineness, shine, length, texture, and strength.

3. Define the following:

a. Scouring

b. Spinning

c. Sericulture

Ans: a. Scouring – The process of washing the wool to remove dirt, grease, and sweat.
b. Spinning – The process of twisting wool fibres to make yarn.
c. Sericulture – The practice of rearing silkworms to produce silk.

4. What is sorter’s disease? Why were people working in wool industry prone to it?

Ans: It is an infection caused by anthrax bacteria, found in contaminated wool.

Workers in the wool industry were prone to it due to handling infected wool

IV. Long answer type questions | Class 7 Science Chapter 3 Fibres to Fabric

1.Explain the various processes involved in the production of wool.

Ans: Ans:

The production of wool involves several steps, from getting the wool from sheep to making it ready for use in clothing:

Shearing: The fleece (hair) of the sheep is cut off using clippers. This is usually done once a year and doesn’t hurt the sheep.

Scouring: The sheared wool is full of dirt, sweat, and grease. So, it’s thoroughly washed with soap and water to clean it.

Grading and Sorting: The wool is then sorted based on its quality, length, and texture. This helps in using the right wool for the right product.

Carding: The cleaned and sorted wool is passed through machines that untangle and comb the fibres to make them smooth and aligned.

Spinning: The wool fibres are then twisted to form yarn or thread, which can be used for weaving or knitting.

Dyeing and Finishing: The yarn is dyed in different colours and finally woven into fabric or made into woollen products.

2. Explain the various stages in the life cycle of a silkworm moth.

Ans: The life cycle of a silkworm moth has four main stages:

Egg: The female moth lays hundreds of tiny eggs on mulberry leaves.

Larva (Caterpillar or Silkworm): The eggs hatch into larvae, which are hungry caterpillars. They feed on mulberry leaves and grow fast.

Pupa (Inside Cocoon): Once fully grown, the silkworm spins a cocoon around itself using a sticky liquid that hardens into silk. Inside the cocoon, the caterpillar turns into a pupa.

Adult Moth: After a few days, the pupa turns into an adult moth, which comes out of the cocoon, and the cycle starts again.

In silk production, the cocoons are collected before the moth comes out, to keep the silk thread long and unbroken.

3. Explain the processes involved in sericulture.

Ans: Sericulture is the process of rearing silkworms to produce silk. It includes the following steps:

Raising silkworms: Silkworms are raised in clean shelters and are fed mulberry leaves regularly.

Harvesting cocoons: When the caterpillars are ready, they spin cocoons using silk threads. These cocoons are collected carefully.

Boiling the cocoons: The cocoons are boiled in hot water to kill the pupae and loosen the silk threads.

Reeling the silk: The long silk filaments are then unwound or reeled from the cocoons.

Twisting and weaving: These threads are twisted together to make stronger yarn and then dyed and woven into silk fabric

4. What are the various health hazards involved in sericulture?

Ans: People working in sericulture often face several health risks:

Heat exposure: Boiling cocoons in hot water for long hours can lead to heat-related problems.

Chemical exposure: The use of dyes and chemicals during silk processing can cause skin allergies or respiratory issues.

Infections: Workers handling raw wool or silk may be at risk of infections like sorter’s disease, which is caused by bacteria present in animal fibres.

Poor working conditions: In some places, lack of proper ventilation, protective equipment, and cleanliness can make the situation worse.

Proper safety gear, cleanliness, and awareness can help reduce these health hazards

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