NCERT Solutions for Class 7th Science
Chapter 3. Fibre to Fabric
Additional Questions with Solutions
Ques: Name the animal fibres.
Ans: Wool and silk.
Ques: Where does wool obtain from?
Ans: Wool obtains from animals like sheep, goat, yak and some other animals.
Ques: Define term selective breeding.
Ans: The process of selecting parents for obtaining special characters in their offspring, such a soft under hair in the sheep, is ‘termed selective’.
Ques: What types of wool fibres are mostly found from sheep that form its fleece?
Ans: The sheep has two types of fibres.
(i) The coarse beard hair.
(ii) The fine soft.
Ques: Where does Pashmina shawls make?
Ans: Jammu and Kashmir.
Ques: By which animal is Angora wool obtain?
Ans: Angora goat of Jammu and Kashmir.
Ques: Name the animals those yield wool?
Ans: (i) Angora goat
Ques: What occupational hazard may be the workers in wool industry?
Ans: They may get infected by a bacterium, anthrax. Which causes a fatal blood disease called sorter’s disease.
Ques: Write the steps of obtaining wool.
Ans: There are six steps of obtaining wool.
1. Shearing: The fleece of the sheep along with a thin layer of skin is removed from its body. This process is called shearing. In this process the hairs are shaved off. The hair provide woolen fibres.
2. The sheared skin with hair thoroughly washed in tanks to remove grease, dust and dirt. This is called scouring.
3. The hairy skin is sent to a factory where hair of different textures are separated. This ia called sorting.
4. The small fluffy fibres, called burrs, are picked out from the hair. The fibres are scoured again and dried. This is the wool ready to be drawn into fibres.
5. The dyeing in various colours.
6. The fibres are straightened, combed and rolled into yarn.
Ques: What is sericulture?
Ans: The rearing of silkworms for obtaining silk ios called sericulture.
Ques: What is cocoon?
Ans: The caterpillar completely covers itself by silk fibers and turns into pupa. This covering is known as cocoon.
Ques: write the life history of the silk moth.
Ans: The female silk moth lays eggs, from which hatch larvae which are called caterpillars or silkworm. They grow into pupa. It first weaves a net to hold itself is known as cocoon. Then they swing and move during these movement they secrete fibre made of a protein which hardens on exposure to air and becomes silk fibre.
Ques: Make sketches of the life history of the silk moth.