The clothes we wear are made from different types of fibres, but have you ever wondered where these fibres come from? Class 7 Science Chapter 3 Fibres to Fabric-Oxford Book Solutions, takes us on an interesting journey from raw materials like sheep’s wool and silkworm cocoons to the soft, warm, and colourful fabrics we use every day.
In this chapter, students learn about:
- The types of animal fibres such as wool and silk
- The sources of these fibres, like sheep, goats, and silkworms
- The processes involved in converting fibres into fabric — including shearing, scouring, spinning, weaving, and dyeing
- The life cycle of silkworms and how sericulture is carried out
- Health hazards and precautions related to working in wool and silk industries
Class 7 Science Chapter 3 Fibres to Fabric Solutions (Oxford Book )
1. Objective type questions
A. Fill in the blanks with the correct words.
- A fabric is woven using………….(yarns/fibres).
- During different parameters………(scouring/grading), wool is sorted on the basis of different parameters
- The silkworm eggs hatch only once a year in…….. (winter/spring).
- The filaments secreted by silkworm are made of a protein) that hardens to form silk. ……(vitamin/
- …………(Filaments/Fibres) from many cocoons are twisted together to make a strong thread which is wound on a reel.
Ans:
- A fabric is woven using yarns.
- During different parameters grading, wool is sorted on the basis of different parameters.
- The silkworm eggs hatch only once a year in spring.
- The filaments secreted by silkworm are made of a protein that hardens to form silk.
- 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.
- All varieties of sheep give us wool that have the same fineness, shine and length.
- The sliver is a machine that combs loose wool fibres into a sheet.
- Silk fibres are produced by the silkworm, and are soft and lustrous.
- The moth stage of the silkworm gives out silk filaments.
- Continuous exposure to noise made by spinning and winding machines in sericulture leads to diseases like anthrax or sorter’s disease.
Ans:
- False – All varieties of sheep do not give the same fineness, shine, and length of wool.
Reason: Different breeds produce different qualities of wool. - 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. - True – Silk fibres are indeed soft, shiny (lustrous), and made by silkworms.
- 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. - 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?
a. Lohi and Nali
b. Marwari and Patanwadi
c. Angora and Merino
d. All
Answer: (c) Angora and Merino
Reason: Angora and Merino are foreign breeds — Angora is from Turkey and Merino is a fine wool breed from Spain/Australia. The others are native Indian breeds.
2. Which of these do sheep eat?
a. Mixture of grass and leaves
b. Mixture of corn, jowar and pulses
c. Mixture of grass, corn and milk
d. Both a and b
Answer: (d) Both a and b
Reason: Sheep are herbivores and are fed both green fodder (grass and leaves) and grains like corn, jowar, and pulses for better wool growth.
3. Which of these are goats that give us wool?
a. Alpaca and Llama
b. Cashmere and Angora
c. Ankara
d. All of these
Answer: (b) Cashmere and Angora
Reason: Cashmere and Angora goats are known for producing soft, high-quality wool. Alpacas and llamas are related animals, but not goats.
4. Which of these is the first step in wool production?
a. Scouring
b. Shearing
c. Sorting
d. Dyeing
Answer: (b) Shearing
Reason: Wool production begins with shearing, which is the process of cutting off the fleece from the sheep.
5. Which of these are different varieties of silk?
a. Tassar and Sericulture
b. Kosa and Angora
c. Tassar, Moonga and Kosa
d. All of these
Answer: (c) Tassar, Moonga and Kosa
Reason: These are all natural varieties of silk produced by different species of silkworms. Sericulture is the process, not a silk variety. Angora is wool, not silk.
6. Which hair of sheep is used to make wool?
a. Under hair
b. Beard hair
c. Body hair
d. Angora, Cashmere and Mohair
Answer: (a) Under hair
Reason: The soft, fine under hair close to the skin is used to make wool, while the coarse outer hair is usually not used.
7. Which breed of sheep provides wool to make carpets?
a. Marwari
b. It’s slow
Answer: (a) Marwari
Reason: Marwari sheep produce coarse wool, which is commonly used in making carpets and blankets.
8. What distinguishes mohair from other wool?
a. Chemical composition
b. Durability
c. Warmth
d. Smoother surface
Answer: (d) Smoother surface
Reason: Mohair, obtained from the Angora goat, is known for its shiny, smooth texture and is less itchy compared to regular wool.
9. Which of these refers to rearing silkworms to produce silk?
a. Shearing
b. Scouring
c. Combing
d. Sericulture
Answer: (d) Sericulture
Reason: Sericulture is the process of breeding and managing silkworms for the production of silk.
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 strong threads
d. Dyeing and weaving threads to form a fabric
Answer: (a) Putting cocoons in hot water
Reason: This process kills the pupae inside the cocoon, making it ethically controversial and less eco-friendly.
II. Very short answer type questions | Class 7 Science Chapter 3 Fibres to Fabric
Give One Word for the Following
- A breed of sheep that gives the finest wool
Ans: Merino - Fibre obtained from Angora goat
Ans: Mohair - The process of removing fleece from the sheep
Ans: Shearing - The stage in the life cycle of silkworms, after hatching of eggs
Ans: Larva or Caterpillar - The process by which filaments are taken out from the cocoons of silkworm
Ans: Reeling
III. Short Answer Type Questions
1. What are the two types of fibres on a sheep’s coat?
Ans:
A sheep’s coat has two types of fibres:
- Coarse outer hair
- Soft under hair – This is used to make wool.
2. What are the various features that make wool different from each other?
Ans:
Wool varies based on the following features:
- Fineness
- Shine
- Length
- Texture
- Strength
3. Define the following:
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 the wool industry prone to it?
Ans:
Sorter’s disease is an infection caused by anthrax bacteria found in contaminated wool.
Workers in the wool industry were prone to it because they handled infected wool without proper protection.
IV. Long Answer Type Questions
1. Explain the various processes involved in the production of wool.
Ans:
The production of wool involves a series of processes that transform raw fleece from a sheep into usable yarn or fabric.
The Wool Production Process
The main steps in the production of wool are:
- Shearing: The fleece is removed from the sheep’s body, typically once a year in the spring. This is done with clippers and does not harm the sheep.
- Scouring: The sheared fleece, known as “grease wool,” contains dirt, grease, and other impurities. It is washed thoroughly in large tanks with a detergent solution to remove these contaminants.
- Sorting and Grading: After cleaning, the wool is sorted by quality, length, and texture. The best quality wool, usually from the shoulders and sides, is used for fine clothing, while coarser wool from other parts is used for items like carpets.
- Dyeing: The cleaned and sorted wool can be dyed at this stage to achieve a specific color.
- Carding: The wool fibers are passed through a series of rollers with fine wire teeth to untangle and straighten them. This process creates a continuous, untwisted rope of fibers called a “sliver.”
- Spinning: The sliver is stretched and twisted into a continuous strand of yarn. The amount of twist determines the yarn’s strength and texture.
- Weaving or Knitting: The spun yarn is then woven on a loom or knitted to create fabric. This fabric can be used for a wide range of products, from clothing to home furnishings.
2. Explain the various stages in the life cycle of a silkworm moth.
Ans:
The life cycle of a silkworm moth, Bombyx mori, is a process of complete metamorphosis, which includes four distinct stages.
The Four Stages of the Silkworm Life Cycle
- Egg: The life cycle begins when a female silk moth lays tiny eggs, typically on a mulberry leaf. A single female can lay up to 400 eggs at a time. The eggs are dormant during the winter and hatch in the spring as the weather warms.
- Larva (Caterpillar): Once the eggs hatch, a small, hairy caterpillar, or silkworm, emerges. This is the feeding stage. The silkworm is a voracious eater, consuming large amounts of mulberry leaves to grow rapidly. During this stage, which can last for several weeks, the silkworm sheds its skin four times as it grows, a process called molting.
- Pupa: After the larval stage, the silkworm stops eating and begins to spin a protective silk casing around itself. This casing is called a cocoon. Inside the cocoon, the silkworm transforms into a pupa. This is a resting stage where the larval organs break down and adult structures, such as wings and antennae, begin to form.
- Adult Moth: After about two to three weeks, the pupa undergoes its final transformation and emerges from the cocoon as an adult silk moth. The moth is creamy-white and has a very short lifespan, typically only a few days. Its sole purpose is to reproduce. The female moth lays eggs, and the cycle begins anew.
3. Explain the processes involved in sericulture.
Ans:
Sericulture includes the following steps:
· Rearing of Silkworms: Silkworm eggs are hatched in a controlled environment. The newly hatched silkworms are placed on trays and fed fresh mulberry leaves. They are kept in a clean, temperature-controlled space to ensure healthy growth.
· Cocoon Formation: After several weeks of feeding, the silkworms stop eating and begin to spin their silk cocoons. They secrete a liquid protein that hardens into a single, continuous thread.
· Reeling the Silk: The cocoons are harvested and subjected to a stifling process (heating with hot water or steam) to kill the pupa inside, preventing the moth from breaking the silk thread. The cocoons are then soaked to loosen the gum (sericin), and the silk filaments are carefully unwound and reeled together to form a single, strong thread.
· Processing and Weaving: The raw silk thread is spun and twisted into yarn. This yarn can be dyed and then woven or knitted into a variety of fabrics for making clothes and other products.
4. What are the various health hazards involved in sericulture?
Ans:
Breathing Problems
Workers often breathe in tiny bits of dust and fiber from the silk cocoons. This can cause problems like coughing, sneezing, and even breathing difficulties, similar to having a bad allergy. The dust from the moths can also be a cause.
Skin Issues
One of the biggest problems is for the hands. To get the silk thread, workers put their hands into hot water to loosen the cocoons. This can cause their hands to become red, sore, and sometimes even get blisters. This is also known as “Reeler’s Disease.”
Body Pain
Because the work is done for many hours a day, workers can get tired and develop pain. Standing or sitting in one position for a long time can lead to a sore back and joint pain in the knees and shoulders. Also, constantly focusing on the tiny threads can cause eye strain.
Preventive Measures: Use of protective equipment, maintaining hygiene, and ensuring proper working conditions can reduce these hazards.
Class 7 Science – Chapter 3: Fibre to Fabric ( NCERT BOOK)
Textbook Exercise Answers
1. You must be familiar with the nursery rhymes:
(i) “Baa Baa Black Sheep, have you any wool?”
(ii) “Mary had a little lamb, whose fleece was white as snow.”
(a) Which parts of the black sheep have wool?
Answer: The wool is obtained from the skin of the sheep, especially from the under-hair close to the skin.
(b) What is meant by the ‘white fleece’ of the lamb?
Answer: It refers to the white hairy coat (wool) of the lamb.
2. The silkworm is
(a) a caterpillar
(b) a larva
Choose the correct option:
Answer: (c) Both a and b
3. Which of the following does not yield wool?
Options: Yak, Camel, Goat, Woolly dog
Answer: Woolly dog
4. What is meant by the following terms?
(i) Rearing:
The process of raising and taking care of animals for obtaining useful products like wool and milk.
(ii) Shearing:
The process of removing the fleece of the sheep along with a thin layer of skin using shears or machines.
(iii) Sericulture:
The rearing of silkworms for the production of silk.
5. Given below is a sequence of steps in the processing of wool. Which are the missing steps?
Shearing → ______ → Sorting → ______ → ______ → ______
Answer:
Shearing → Scouring → Sorting → Removing burrs → Dyeing → Making yarn
6. Make sketches of two stages in the life history of the silk moth which are directly related to the production of silk.
Answer:
Draw and label the following:
- Silkworm (Larva stage) – which spins the cocoon
- Cocoon – from which silk fibre is obtained
7. Out of the following, which are the two terms related to silk production?
Sericulture, Floriculture, Moriculture, Apiculture, Silviculture
Answer:
Sericulture and Moriculture
- Sericulture – rearing of silkworms
- Moriculture – cultivation of mulberry leaves (food for silkworms)
8. Match the following:
| Column I | Column II |
|---|---|
| (1) Scouring | (e) Cleaning sheared skin |
| (2) Mulberry leaves | (c) Food of silkworm |
| (3) Yak | (b) Wool-yielding animal |
| (4) Cocoon | (a) Yields silk fibre |
9. Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Across:
- Keeps us warm in winter – Wool
- Its leaves are eaten by silkworms – Mulberry
- Hatches from the egg of a moth – Caterpillar
Down:
- Thorough washing – Scouring
- Animal fibre – Silk
- Animal fibre – Fibre
📘 Math & Science Solutions by Class
🔹 Class 10
🔹 Class 9
🔹 Class 8
🔹 Class 7
🔹 Class 6
🔹 Class 12
🔹 Class 11
- Class 11 Math Solutions
- Class 11 Physics Solutions
- Class 11 Chemistry Solutions
- Class 11 Biology Solutions
For the official Class 10 Mathematics Solutions, you can visit:
- NCERT Textbooks (for Class 10):