Exercises: Fibre to Fabric | Class 7 Oxford Science: Chapter Notes, Worksheets & Tests PDF Download

Fill in the blanks with the correct words.

A fabric is woven using yarns.

Yarns are long continuous strands of fibers that are woven together to create a fabric.

Q. 2. During ____ (scouring/grading), wool is sorted on the basis of different parameters.

During grading, wool is sorted on the basis of different parameters.
Grading is the process of sorting materials according to quality, size, or weight. In the case of wool, it is sorted based on factors like fiber length, fineness, and color.

Q.3. The silkworm eggs hatch only once a year in ____ (winter/spring).

The silkworm eggs hatch only once a year in spring.
Silkworm eggs are laid in late summer or early fall and hatch in the spring when the weather is warm enough for them to survive.

Q.4. The filaments secreted by silkworm are made of a ____ (vitamin/protein) that hardens to form silk.

The filaments secreted by silkworm are made of a protein that hardens to form silk.
Silk filaments are made up of a protein called fibroin, which hardens and forms the silk thread when it comes into contact with air.

Q.5. ____ (Filaments/Fibres) from many cocoons are twisted together to make a strong thread which is wound on a reel.

Filaments from many cocoons are twisted together to make a strong thread which is wound on a reel.

Silk filaments from multiple cocoons are unwound and twisted together to create a stronger thread that can be used to create silk fabric. This thread is then wound onto a reel for storage and transport.

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

False
All varieties of sheep give us wool but the fineness, shine, and length may vary. The breed, age, health, and living conditions of the sheep can all affect the quality of wool produced.

Q.2. The sliver is a machine that combs loose wool fibres into a sheet.

True
A sliver is a long, narrow bundle of wool fibers that have been combed and aligned in preparation for spinning into yarn.

Q.3. Silk fibres are produced by the silkworm, and are soft and lustrous.

True
Silk fibres are produced by the silk moth or silkworm and are known for their softness and lustrous shine.

Q.4. The moth stage of the silkworm gives out silk filaments.

False
The caterpillar or larval stage of the silkworm gives out silk filaments. During this stage, the silkworm spins a cocoon of silk around itself, which can be harvested to make silk fabric.

Q.5. Continuous exposure to noise made by spinning and winding machines in sericulture leads to diseases like anthrax or sorter's disease.

False
While continuous exposure to noise in sericulture can lead to hearing problems and other health issues, there is no specific link between noise exposure and anthrax or sorter's disease. Anthrax is a bacterial infection that can be contracted through exposure to infected animals or animal products, while sorter's disease is a lung condition caused by inhaling organic dust particles.

II. Very short answer type questions

Give one word for the following.

Q.1. A breed of sheep that gives the finest wool

Merino

Q.2. Fibre obtained from Angora goat

Mohair

Q.3. The process of removing fleece from the sheep 

Shearing

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

Larva

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

Reeling

III. Short answer type questions

The two types of fibres on a sheep's coat are - (i) Coarse, long, and wiry outer hair or kemp fibres, and (ii) Soft, fine, and curly inner wool fibres.

Q.2. What are the various features that make wool different from each other?

The various features that make wool different from each other are - (i) The breed of the sheep, (ii) The age of the sheep, (iii) The diet and living conditions of the sheep, (iv) The season when the wool was shorn, and (v) The method of processing and finishing the wool.

Q.3. Define the following: a. Scouring b. Filature c. Sericulture

The following are the definitions of the given terms:

(a) Scouring - The process of cleaning the wool of grease, dust, dirt, and other impurities is called scouring.

(b) Filature - The process of obtaining silk fibres by unwinding the silk threads from the cocoon is called filature.

(c) Sericulture - The process of rearing silkworms for the production of silk is called sericulture.

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

Sorter's disease was a lung disease caused by inhaling dust and fibres while sorting wool. People working in the wool industry were prone to it because they had to handle wool and breathe in its fibres and dust for long periods, often in poorly ventilated areas.

IV. Long answer type questions

The production of wool involves the following processes:

(a) Shearing: The process of removing the fleece of the sheep from its body is called shearing.

(b) Sorting: After shearing, the fleece is sorted based on the quality of the wool. The wool from different parts of the body is also separated.

(c) Scouring: The wool is washed with soap and hot water to remove dirt, grease, and other impurities.

(d) Carding: The wool fibers are separated and straightened using a carding machine.

(e) Spinning: The straightened wool fibers are twisted together to form yarns.

(f) Weaving/Knitting: The yarns are then weaved or knitted to make woolen clothes.

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

The stages in the life cycle of a silkworm moth are as follows:

(a) Egg: The life of a silkworm starts from an egg laid by a female moth.

(b) Larva: The egg hatches into a larva, which is the silkworm. The silkworm feeds on mulberry leaves and grows in size.

(c) Pupa: After about a month, the silkworm stops eating and starts spinning a cocoon around itself. This stage is called the pupa stage.

(d) Adult: After about two weeks, the adult moth emerges from the cocoon by breaking the silk threads. The adult moth does not eat and dies within a week of emerging.

Q.3. Explain the processes involved in sericulture.

Sericulture involves the following processes:

(a) Rearing of silkworms: The silkworms are reared on a diet of mulberry leaves.

(b) Harvesting of cocoons: The silkworm spins a cocoon around itself, which is harvested after about a month.

(c) Killing of pupae: The cocoons are boiled in hot water to kill the pupae inside.

(d) Reeling of silk: The silk fibers are collected from the cocoon by reeling the silk thread.

(e) Spinning of silk: The silk thread is twisted together to form silk yarn.

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

The various health hazards involved in sericulture are as follows:

(a) Exposure to pesticides: Pesticides are often used in mulberry plantations to protect the leaves from pests. The silkworms and the workers involved in sericulture are exposed to these pesticides, which can cause health problems.

(b) Allergic reactions: Some people may develop allergic reactions to the silk fibers, which can cause skin rashes and other problems.

(c) Injuries: Workers involved in sericulture may suffer injuries while handling the silk cocoons or using the equipment for reeling and spinning the silk.