Solutions to the NCERT textbook questions are a valuable resource for students for their exam preparations as most of the exam questions are based on textbook questions. Thus, to help students with their preparations, Extramarks offers NCERT Solutions for Class 7 Science Chapter 3. These solutions are prepared by subject matter experts who have years of experience in teaching. As the explanations of all the answers are comprehensive, the fundamentals of the chapter are understood by the students in a better way.
Hence, students will find these resources to be very helpful with their preparations, last-minute revisions, and for help with their assignments.
NCERT Solutions for Class 7 Science Chapter 3
Access NCERT Solutions for Class 7 Science Chapter 3 – Fibre to Fabric
NCERT Solutions for Class 7 Science Chapter 3 Fibre to Fabric
The NCERT Class 7 Science Chapter 3 focuses on several aspects of how fibres are transformed into fabric. It talks about the entire lifecycle of how fibre is converted to a piece of fabric. This includes all steps from extracting wool and silk fibres from sheep, goats, yak, and silkworms, to how these are converted to fabric by weavers.
Chapter 3 – Fibre to Fabric
3.1 Wool
Wool can be extracted from sheep, goats, yak and even camel. Animals of various breeds provide wool of varying quality. Some of the examples of famous wool-yielding animals across the world are; Yak (in Ladakh and Tibet), Angora goat (source of angora wool in Jammu and Kashmir), and Alpaca, and Llama (in South America). The underfur of Kashmiri goats is soft and hence, used for making high-quality Pashmina shawls.
Even though there are numerous sources of wool, sheep are generally raised to assist the wool industry. The sheep’s fur is clipped, gathered, and processed to make wool. The breeding and rearing of sheep is the beginning of the process. If you visit the hills in Uttaranchal, Himachal Pradesh, Jammu & Kashmir, Sikkim, and Arunachal Pradesh, you will come across herds of sheep with their shepherds. The wool we wear, shawls and knitted sweaters are the completed product of processing sheep’s fleece.
The entire process of converting wool to fabric can be divided into the following steps:
Step 1 Shearing: It is the first step in removing the fleece and a thin layer of skin from a sheep’s body. Shearing is carried out with the assistance of machines similar to those used by barbers. Shearers prefer hot weather because it allows the sheep to survive without its protective fur. Woollen fibres are found in the fur hair and are subsequently processed to make woollen yarn.
Step 2 Scouring: After shearing, the shearers vigorously wash the skin and hair in tanks to remove dust, filth, and oil. This process is known as Scouring. Although in the past this task was done manually, now it is completed by machines.
Step 3 Sorting: After scouring, the hair skin is sent to a factory, where hair of different sorts and textures are separated by texture.
Step 4 Picking Burrs: The hairs may contain burrs, which are puffy and tiny fibres, similar to ones found on our sweaters. The fibres of these burrs are scoured again and dried the wool is now ready to be spun into yarn.
Step 5 Dyeing: The natural colours of a goat’s or sheep’s fleece are white, brown, or black. However, the fibres can be dyed in a variety of colours.
Step 6 Yarn Rolling: After dyeing, the fibres are combed, straightened and rolled into yarn. Long fibres are used in wool for sweaters, while shorter fibres are spun and woven into woollen cloth.
3.2 Silk
Silk fibre is another form of animal fibre used to produce fibres. Silkworms are the creators of silk fibre. Sericulture is the practice of raising silkworms to produce silk.
The life cycle of a silk moth is fascinating to learn about. The process begins by the female moth laying her eggs. The larvae (also known as silkworms or caterpillars) hatch from the eggs.
As the caterpillar grows in size, it advances to the pupa stage.
The worm weaves a net-like structure to support itself during the pupa stage. Then it makes a figure eight with its head, swinging from side to side (8). During these movements, the caterpillar secretes a fluid that solidifies and becomes the silk thread when it comes into contact with air. The pupa is formed after the caterpillar is completely covered with silk fibre. The scientific term for this silk coating is a cocoon. It’s where the worm transitions from pupa to the moth stage. Silk yarn is made from the cocoon of the silkworm.
Exercise 3.2 total Solutions: 16 Questions (9 short questions and 7 long questions)
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Key Features of NCERT Solutions for Class 7 Science Chapter 3
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- NCERT Solutions by Extramarks are prepared by subject matter experts that have years of experience in their respective fields. They give special attention to providing accurate solutions that students can rely on.
- The solutions are drafted in simple and easy-to-understand language so that students have no trouble understanding them.
- These solutions can be used by students for their exam preparations, last-minute revisions, and for any help that they require with their assignments.
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