Q3. Draw a wall labeled diagram / flowcharts to show the steps
involved in the process of getting wool from sheep and silk from silkworm
Answers
Answer:
You also learnt that wool and silk fibres are obtained from animals. Wool is obtained from the fleece (hair) of sheep or yak. Silk fibres come from cocoons of the silk moth. Do you know which part of the sheep’s body yields fibres? Are you aware how these fibres are converted into the woollen yarn that we buy from the market to knit sweaters? Do you have any idea how silk fibres are made into silk, which is woven into saris? In this Chapter we shall try to find answers to these questions.
Animal fibres — wool and silk
3.1 WOOL
Wool comes from sheep, goat, yak and some other animals. These wool-yielding animals bear hair on their body. Do you know why these animals have a thick coat of hair? Hair trap a lot of air. Air is a poor conductor of heat, as you would learn in Chapter 4. So, hair keeps these animals warm. Wool is derived from these hairy fibres.
Activity 3.1
Feel the hair on your body and arms and those on your head. Do you find any difference? Which one seems coarse and which one is soft?
Like us, the hairy skin of the sheep has two types of fibres that form its fleece: (i) the coarse beard hair, and (ii) the fine soft under-hair close to the skin. The fine hair provide the fibres for making wool. Some breeds of sheep possess only fine under-hair. Their parents are specially chosen to give birth to sheep which have only soft underhair. This process of selecting parents for obtaining special characters in their offspring, such as soft under hair in sheep, is termed ‘selective breeding’.
NCERT Class VII Science Chapter 3 Fibre to Fabric
Fig. 3.1 Sheep with thick growth of hair
Animals that yield wool
Several breeds of sheep are found in different parts of our country (Table 3.1). However, the fleece of sheep is not the only source of wool, though wool commonly available in the market is sheep wool (Fig. 3.1). Yak (Fig. 3.2) wool is common in Tibet and Ladakh. Angora wool is obtained from angora goats, (Fig. 3.3) found in hilly regions such as Jammu and Kashmir.