IV. Answer the following questions in two sentences.

1. Mention two characteristics of wool fibre.

Ans. 

1. Wool is elastic.

2. Wool absorbs good amount of moisture without getting damp.

2. List the steps involved in wool processing.

The steps in wool processing are: shearing, washing, drying, dyeing, rolling, roving, combing and weaving or knitting.  

3. Name two varieties of silkworms.

Ans. Eri and Muga are two wild varieties of silkworm.

4. How do the farmers come to know that a silkworm is ready to spin a cocoon?

When the caterpillars stop eating at the end of the growth stage, farmers know that they are ready to spin their cocoons. The caterpillars are then placed in rectangular frames where they form cocoons.  

5. Why does the farmer keep silk moth's eggs in warm and humid conditions?

Ans: Farmers who rear silkworm keep the eggs in a clean place under warm and humid conditions, so that the eggs hatch successfully.  

6. What are the health hazards of silk production?

Ans: a. Fumes produced during boiling of the cocoons lead to respiratory diseases.

b. At times, the workers, mostly women, get infected by a fatal blood related disease called anthrax.

c. The constant noise of machines and long working hours lead to headaches and back pain. Constant dipping of hands into boiling hot water leads to blisters and secondary infections.

V. Answer the following questions in about four to five sentences:

1. Explain how wool yarn is produced from the fleece of sheep.

Ans: The processing of wool involves the following steps.

• Shearing is the first step in the processing of wool. The fleece is peeled off in one piece. The sheep need to be protected from rain for a day before shearing.  

• The next step is washing the raw wool (fleece) to remove grease, vegetable matter and other impurities. This is done in a series of tubs filled with soap water.

• The raw wool is then squeezed and dried by passing it through a series of rollers and dryers.

• The wool is dyed using different colors.

•The fibres are then rolled over onto one another into fine strands called slivers.

• The fine strands are then gently twisted into rope-like strands through a process called roving.

• The strands are combed and prepared for spinning into wool yarn.

2. What are the characteristics of silk fibre?

Ans: Silk fibre is extremely elastic . it is the smoothest and finest of all fibres.

• It can be dyed easily and takes the highest lustre.

• Silk is the strongest natural fibre and can be stretched to almost twenty-five per cent of its original length.

3. How will you distinguish wool from cotton?

Ans:

Cotton fibres :

a. Obtained from plants.

b. When cotton burns, it leaves behind ash and gives out a characteristic odour of burning paper. 

Wool fibres.

a. Obtained from Animal.

b. Pure wool burns with a sooty flame and gives out an unpleasant odour of burning hair. The residue of the burnt wool is hard. 

4. How is silk extracted from cocoons?

Ans: The cocoons are closely observed. Before the moths emerge, cocoons are put in boiling water leaving them intact. 

The boiled cocoons are sorted by size, colour and texture and are soaked in warm water to separate the silk fibre.  

The fibre of a single cocoon is too fine to handle, so up to ten cocoons are wound together onto a reel by hand.  

The raw silk threads undergo a series of processes such as rolling, warping and twisting before being woven into a fabric on a loom. 

5. Explain the life cycle of the silk moth?

Ans: Egg: The female silk moth lays large number of eggs. In about two weeks time, the fertile, live eggs hatch into larva. 

Larva: After hatching, the tiny caterpillars feed vigorously and grow in size. They are fed with fresh mulberry leaves. During this period, the caterpillars shed their skin four times while they grow. 

Pupa: Once the caterpillars are about a month old, they stop eating and secrete silk fibres all around them. The fibre hardens on exposure to air and forms a cocoon. Each cocoon is made from a single silk fibre around 1 km long. 

Moth: The caterpillars develop in the cocoons and become moths. The moths come out of the cocoons and live for a few days. They are unable to fly.