Fibre to Fabric Question Answers: NCERT Class 7 Science

a) The skin of black sheep is fully covered by hair which is also known as wool.
b) Fleece is refered as the upper layer of the skin which is removed with the hairs of a lamb.

(iii) both a and b; Caterpillar and larva

We obtain silk from the silk moth or the caterpillar or the larva of the silkworm. The life cycle of the silkworm is: female silkmoth lays eggs which converts in the larva and then hatches into caterpillar, then cocoon formation (pupa stage) occurs and then mature form is obtained. 

(iv) Woolly dog
Among all of these only woolly dogs are unable to give wool. Wool is a fibre typically obtained from yak, camel, goat etc. which are then used in various purposes.

(i) Rearing: It is the process of taking care of useful animals is known as rearing of animals. These animals produce various useful products for human beings.

(ii) Shearing: The process of removing the fleece or the upper layer of the sheep along with a the hairy fibre is known as shearing. The person who removes the sheep’s hair is called a shearer. Typically each adult sheep is shorn once each year, this process is done generally in summers; this enable the animal's survival without their protective coat of hair.

(iii) Sericulture: The rearing of silkworms for obtaining silk is known as sericulture. Sericulture is the process of cultivating silkworms and extraction of silk from them. Sericulture involves rearing and breeding of sheep. The quality and texture of fibre depends on the breed of the animal.

In the rearing and breeding, process of shearing is done then the sheared skin with hair is washed in tanks to remove the dirt and dust. This process is known as scouring. After scouring, sorting is done. In this, the hairy skin is then sent to the factories where the different textures of hair are separated. Then the fibres can be dyes in various colours and send to the market. 

Scouring, Cleaning of burrs, Dyeing, making of yarn.

In the rearing and breeding, process of shearing is done then the sheared skin with hair is washed in tanks to remove the dirt and dust. This process is known as scouring. After scouring, sorting is done. In this, the hairy skin is then sent to the factories where the different textures of hair are separated. After sorting, the small fluffy fibres called burrs are picked out from the hair then the fibres are scoured again and dried. Then the fibres can be dyes in various colours and send to the market. Making of yarn, in this the fibres are straightened, combed and rolled into the yarn. then, the longer fibres are made into wool for the sweaters and the shorter fibres are spun and woven into woolen clothes. 

The two stages in the life history of the silk moth are: Caterpillar and Cocoon.

1. Caterpillar: Bombyx mori, the domestic silk moth which helps in making warm clothes, is an insect from the moth family Bombycidae. The silkworm is the larva or caterpillar of a silk moth which is developed by the eggs that lays by female silkmoth. Silkworm is reared at the commercial level for obtaining silk. Silkworm feeds on mulberry leaves.

2. Cocoon: When the caterpillar is ready to enter the next stage of its life history called pupa. firstly it weaves the net to hold itself. during this, the caterpillar secretes a fibre that is made up of proteins which hardens on the exposure of air and becomes silk fibre. Soon the caterpillar completely coveres itself by silk fibre by making it and turns into the pupa. This covering is known as cocoon. The further development of pupa into moth continues inside the cocoon.

The silf yarn (thread) is obtained from the cocoon of the silkmoth.

Sericulture, Moriculture

1. Sericulture: Sericulture is the process of rearing silk worms to obtain silk. The caterpillars of the domestic silk moth are the most commonly used silk warm species in sericulture. Sericulture, also called silk farming. It starts by raising silkworms. Silk fibres are combined into silk thread. The thread can then be turned into yarn or woven into silk cloth or the woolen clothes.

2. Moriculture: Moriculture may be defined as the process in which mulberry plants are cultivated for the feeding of silk moth.

Column I                              Column II
1. Scouring                      (e) Cleaning sheared skin
2. Mulberry leaves           (c) Food of silk worm
3. Yak                              (b) Wool yielding animal
4. Cocoon                        (a) Yields silk fibres

Scouring is the process in which the sheared skin with hair is thoroughly washes in tanks to remove greece, dirt and dust that is done by machines. The cultivation of Muberry plants for the feeding of silkmoth, are called Moriculture. We obtain wool from the Yak also. Yak wool is common in Tibbat and Ladakh. Cocoon is the hard protective covering which is made up of proteins around the pupa. Silk yarn is obtained from the cocoon of the silk moth. Most common silkmoth is the mulberry silk moth.