DAV Class 7 Science Chapter 14 Fabric from Fibre Question Answer Notes
DAV Class 7 Science Chapter 14 Fabric from Fibre Question Answer Notes Solution by Expert Science Teacher. DAV Class 7 Science 14th Chapter Fabric from Fibre for Students of DAV Schools.
Lesson No 14
Fabric from Fibre
A.) Fill in the blanks.
Answer: (1) fleece (2) shearing (3) scouring (4) sorting (5) sericulture (6) Reeling (7) protein
B.) Write True or False for the following statements.
Answer: (1) True (2) False, it is a bad conductor of heat(3) False the process is called shearing,(4) False ,the process is called spinning (5) True (6) True (7) True
C.) Tick the correct option.
1.) The process, of removing fleece along with a very thin layer of dead skin of sheep, is called
Answer: shearing
2.) Which of the following animals does not yield wool?
Answer: buffaloe
3.) The caterpillars of silkworms feed on
Answer: mulberry leaves
4.) The egg of a silk moth hatches into a
Answer: caterpillar
5.) The process of taking out silk threads from the cocoon is called
Answer: reeling
D.) Answer the following questions in brief.
1.) Name three animals whose fleece is used for making woollen fibres.
Answer: sheep, goat and camel
2.) Name three common varieties of wool.
Answer: angora, pashmina & shahtoosh
4.) Define the term: ‘sericulture.
Sericulture is the practise of raising silkworms to produce silk. Raising silkworms—the larval phase of the silk moth—includes feeding them mulberry leaves as food. Once the silkworms’ development is finished, the cocoons are opened and the silk is removed. The current course of action is reeling. The silk is then woven into textile or other products. Sericulture is a well-known practise that originated in China and has now expanded to countries like India, Japan, and Europe.
5.) How is silk fibre obtained from cocoon?
Answer: The technique called “sericulture” is used to remove silk fibre from either a cocoon. This involves taking a cocoon’s thread and unravelling it before stringing it onto a spinning. A cocoon is made by a silkworm from a single element of silk fibre made of the protein fibroin. The cocoon is then submerged in hot water to soften the material that holds the fibres together. The cocoon is unwound, and the single strand is then woven onto a spool. Reeling is typically done by hand, though it can also be done with machinery. The thread is then spun into yarn, which can then be used for weaving or knitting.
6.) Name two countries in which silk is produced on a large scale.
Answer: China and India.
E.) Answer the following questions.
1.) How do woollen clothes keep us warm in winter?
Wool acts as an insulator, preventing our body heat from being lost while also storing it to help us stay warm in the winter. Wool can hold its weight in water before becoming damp, which helps to keep body heat from the inside and away from the chilly surroundings.
2.) Describe the purpose of ‘scouring’ in the production of wool?
Scouring removes dirt, grime, and any leftover traces of the organism’s natural oils from wool fibres. Because it ensures the fibres remain clean and uncontaminated, this process is necessary to generate wool so that it may be used to create high-quality garments. Additionally, scouring helps to improve the whiteness and suppleness of the wool.
3.) State the practical uses of the (a) long (b) short yarn threads, obtained during the making of wool.
Long yarn strands made from wool can be used for spinning, knitting, and other crafts. Short yarn threads created during the manufacture of wool can be used to make wool, fill cushions and mattresses, and add texture and colour to fabric crafts.
4.) Write a short note on ‘rearing of silkworms’.
Silkworms are the larva of the domesticated silk moth. When they are young, they only consume mulberry leaves. Silkworm farming is a substantial cottage industry in many countries because silkworms produce the precious silk fibre that is used to make clothing and other things. Raising silkworms requires providing them with a controlled environment, ample food, and protection from predators. The silkworms eventually change into moths, which spin cocoons that are later harvested to make silk thread.
5.) Describe the different stages in the life cycle of a silk moth.
The silk moth lays numerous small eggs, usually about the size of a pinhead, to start its life cycle.
After a few days, the fertilised eggs develop into larvae, or caterpillars (caterpillars). During this stage, the caterpillars eat mulberry leaves and develop swiftly. After roughly a month, the caterpillars wrap themselves in a silken cocoon to protect itself while they grow into adult moths.Pupa: The caterpillar develops into a moth larva (chrysalis) inside the cocoon, at which stage its body begins to deteriorate before reconstructing into the mature moth.
Adult: The moth exits from its cocoon three weeks later as an adult. When the female lays eggs, the cycle is restarted.
More Extra Questions for Preparation
Q.1.) Fill in the blanks.
1.) Sheep wool is most commonly available wool.
2.) Air is poor conductor of heat.
3.) The sheared fleece contains dirt and grease.
4.) The rearing of silkworms for obtaining silk is known as sericulture.
5.) Cocoons are covering of fine silk fibres around the caterpillar.
6.) Wool and silk are two main fibres.
7.) China ranks first in world for silk production.
Q.2.) Define the following.
1.) Sorting.
Answer – The process of separating hair of different textures from the fleece is called sorting.
2.) Spinning.
Answer – The raw and dyed fibres are then twisted together to make threads called yarn.
3.) Sericulture.
Answer – The rearing of silkworms, for obtaining silk, is known as sericulture.
4.) Reeling.
Answer – The cocoons are collected and exposed to steam. The silk fibres then separate out from cocoons. This process is called reeling.
Q.3.) Answer the following.
1.) Explain scouring.
Answer – a.) The sheared fleece contains dirt and grease.
b.) It is cleaned by washing with detergent in hot water in large tanks.
c.) Suitable machines are also used for this purpose. This process is called scouring.
2.) How do woollen clothes protect us from cold in winter? Explain.
Answer – Woollens clothes protect us from cold because wool traps air. Since air is a poor conductor of heat, it does not allow our body heat to escape. This keeps our body warm during winters.
3.) Explain rearing of silkworms.
Answer – Rearing of silkworms:
a.) Silk moth is a large, white insect.
b.) A female silk moth lays hundred of eggs which are stored at a suitable temperature.
c.) These eggs hatch to produce larvae which are called caterpillars or silkworms.
d.) These larvae are kept in clean boxes where they feed on fresh mulberry leaves for 25-30 days and grow in size.
e.) The caterpillar then secretes a liquid. This liquid hardens on coming in contact with air and changes into a fine thread which is made up of a protein.
f.) The caterpillar covers itself completely with these fine fibres. This covering is called as cocoon.
g.) The silkworm develops into a silk moth inside the cocoon.
h.) The cocoons are collected and exposed to steam.
4.) Explain why sorting is hazardous job?
Answer – Sorting is a hazardous job because the person involved may get infected by a bacterium called anthrax, which can cause a fatal disease called sorters disease.
5.) Write varieties of wool obtained.
Answer – Varieties of wool obtained like angora, pashmina, shahtoosh, etc.
6.) How silk is obtained?
Answer – Silk is obtained from silkworms which feed on the leaves of mulberry plant.
7.) What are longer and shorter threads used for?
Answer –
a.) The longer threads are usually knitted to make sweaters, mufflers, caps, gloves, socks, etc.
b.) The shorter threads are woven to make woollen fabrics which are used for jackets and shawls, king coats, trousers.