Fibre to Fabric Class 7 Science Notes - Chapter 3

Some fibres are obtained from plants and some from animals. Fibres obtained from animals are silk and wool. Let us understand what type of fibres are got from which animals along with the process of extraction.

  • Silk – These fibres are got from cocoons of a silk moth. How? It is obtained from a process called sericulture. When a female silkworm lays eggs and then, it hatches to form silkworms or caterpillars. They grow and are ready to enter the pupa stage, they weave a net to hold themselves which secretes fibre made of protein. This protein becomes hard when exposed to air. The pupa stage is said to be complete when the caterpillar completely covers itself in the silk fibres. This cover is called cocoon. The pupa is developed to moth inside the cocoon. Now let us understand about the rearing of a silkworm. As soon as the female silk moth lays eggs, they are carefully stored on paper or cloth and sold to silkworm farmers for the process from cocoon to silk. These eggs are kept at a suitable temperature in a hygienic condition for the larvae to hatch. Bamboo trays and mulberry leaves are used to store larvae. For 25 – 30 days caterpillars eat day and night. When they stop eating, they move to tiny chambers of bamboo and form cocoons. The last step is the reeling of silk.
  • Wool is obtained from wool yielding animals such as yak, goat, sheep, etc. The steps involved are sheering, scouring, sorting and rolling.

Few Important Questions

  1. Choose the correct answer from the following-What is silkworm?

    a) a larva (b) a caterpillar (c) none (d) both

  1. What is Shearing?
  2. Wool is obtained from which parts the black sheep?
  3. What is Sericulture?
  4. Does camel yield wool?
  5. What is Rearing?
  6. Explain the term white fleece of the lamb.
  7. Explain the stages of life history of the silk moth with relevant sketches.

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Practise This Question

Consider a right-angled triangle, if a = 3cm, b = 4 cm, find the value of hypotenuse c?