Fiber to Fabric – Class 7 Science Chapter 3 Notes (NCERT) | Detailed Explanation

Introduction

Class 7 Science Chapter 3 Notes: The clothes we wear daily are made up of different types of fabrics. But have you ever wondered where these fabrics come from? Class 7 Science Chapter 3, “Fibre to Fabric”, explains the journey of natural fibers like wool and silk, from their source to the final fabric we use. Understanding this process is important not just for exams but also for real-life awareness of how raw materials are converted into useful products.

In Class 7 Science Chapter 3 Notes, we will cover:

• What are natural fibers?
• How wool and silk are obtained.
• The process of making fabric from animal fibers.
• Key questions and exam-oriented notes.

What are Fibres?

Fibres are thin, thread-like strands used to make fabrics. They are broadly classified into:

1. Natural Fibres – Obtained from plants and animals (e.g., cotton, jute, wool, silk).
2. Synthetic Fibres – Man-made using chemicals (e.g., nylon, polyester, acrylic).

In this Class 7 Science Chapter 3 Notes, we focus on animal fibers: wool (from sheep, goat, yak, camel) and silk (from silkworm).

Wool – From Sheep to Sweater

Wool is an important natural fibre used in making warm clothes. It is mainly obtained from the hairy skin of animals such as sheep, goat, yak, and camel.

Sources of Wool

• Sheep wool → Commonly used for sweaters and blankets.
• Yak wool → Found in Tibet and Ladakh.
• Camel wool → Used for making shawls, rugs, and carpets.
• Angora wool → From Angora goats of Jammu & Kashmir.
• Alpaca & Llama wool → Found in South America.

Steps in Processing Wool

The process of obtaining wool from sheep involves several steps:

1. Shearing – The fleece (wool-bearing skin) of the sheep is shaved off.
2. Scouring – The wool is washed in tanks to remove dirt, grease, and sweat.
3. Sorting – The wool is sorted according to texture and quality.
4. Combing – The fibres are straightened and cleaned to remove small tangles.
5. Dyeing – Wool is dyed in different colors.
6. Spinning – Fibres are twisted into yarn.
7. Weaving/Knitting – Yarns are converted into fabric to make woolen clothes.

👉 Key Point for Exams: Wool is obtained from the hairy skin of animals, not from their body flesh.

Silk – The Queen of Fibers

Silk is another animal fibre obtained from the silkworm, which feeds on mulberry leaves. It is known for its shine, smoothness, and high value.

Life Cycle of the Silkworm

1. Eggs – Female silk moth lays eggs on mulberry leaves.
2. Larva or Caterpillar – The eggs hatch into larvae, also known as silkworms.
3. Cocoon – The caterpillar spins a cocoon around itself using a liquid protein (silk).
4. Pupa – The silkworm develops inside the cocoon.
5. Adult Silk Moth – A fully grown moth comes out of the cocoon.

Process of Obtaining Silk

1. Rearing of Silkworms – Farmers rear silkworms by feeding them mulberry leaves.
2. Spinning of Cocoon – The silkworm secretes silk fibre, forming a cocoon.
3. Harvesting – Cocoons are collected for processing.
4. Reeling of Silk – Silk fibres are carefully unwound from the cocoon.
5. Spinning into Yarn – The silk fibre is twisted into silk thread.
6. Weaving/Dyeing – The yarn is dyed and woven into beautiful silk fabrics.

👉 Key Point for Exams: The soft silk yarn is obtained from the cocoon of the silkworm.

Difference Between Wool and Silk

Health Hazards for Workers

• Wool Industry Risks – Workers may suffer from a bacterial disease called Anthrax, also known as “Sorter’s Disease”.
• Silk Industry Risks – Boiling of cocoons kills silkworms, which raises ethical issues.

Environmental and Ethical Concerns

• Wool and silk production involve animal rearing and may cause harm to animals.
• Synthetic alternatives like rayon and polyester are now used to reduce dependence on animal fibres.
• However, natural fibres are biodegradable and eco-friendly compared to synthetics.

Chapter Summary (For Quick Revision)

Here is the summary of Class 7 Science Chapter 3 Notes

• Fibres are of two types: Natural and Synthetic.
• Wool is obtained from hairy animals like sheep, goat, camel, and yak.
• Silk is obtained from silkworms that spin cocoons.
• Wool processing involves shearing, scouring, sorting, dyeing, and weaving.
• Silk production involves rearing silkworms, spinning cocoons, reeling silk, and weaving.
• Wool workers may suffer from anthrax (sorter’s disease).

Important Questions & Answers

Q1. Name two animals that provide wool.
A: Sheep and Yak.

Q2. What is the process of obtaining silk fibre from cocoon called?
A: Reeling of silk.

Q3. Which disease is common among wool industry workers?
A: Anthrax (Sorter’s Disease).

Q4. Which fibre is called the “Queen of Fibres”?
A: Silk.

Marks Weightage for Exams (Approximate)

👉 Total Expected Weightage: 12–15 Marks

Class 7 Science Chapter 3 Notes: Conclusion

The chapter Fibre to Fabric explains the fascinating journey of animal fibres from their natural sources to the fabric we use every day. Understanding wool and silk production not only helps in exams but also makes us aware of health, ethical, and environmental aspects of the textile industry. If you feel beneficial, please the link of Class 7 Science Chapter 3 Notes share among your friends.

Class 7 Science Chapter 3 Notes: FAQs

Q1. Why are woolen clothes warm?
A: Wool fibers trap air, which acts as an insulator and keeps us warm.

Q2. Which country is the largest producer of silk?
A: China is the largest producer of silk in the world.

Q3. Can we make silk without killing silkworms?
A: Yes, “Ahimsa Silk” or “Peace Silk” is made without killing silkworms.

Q4. Which type of wool is used in Kashmir shawls?
A: Pashmina wool.

📥 Download PDF Notes → Click Here to Download Class 7 Science Chapter 3 Notes PDF