TEXT 9 for questions 47-50

    Silkworms live for only two or three days after laying eggs. About 36,000 to 50,000 eggs are laid, and these are carefully stored at the silkworm farm until they are ready to hatch. The eggs hatch into caterpillars, which feed on mulberry leaves. Soon, the caterpillars are ready to spin their cocoons. Not all caterpillars can spin silk cocoons. Only the caterpillars of a silkworm moth known as 'Bombyx mori' can do such spinning.

    This caterpillar has special glands which secrete liquid silk through its lower lip. The liquid produced later hardens to form fine strands. The caterpillar makes its cocoons using these strands. The threads on the outside of the cocoon are rough, while those inside are soft and smooth.

    Some fully-spun cocoons are heated. This kills the pupa inside. The cocoons are then put into hot water to loosen the fine threads. Finally, these threads are reeled off the cocoons. The length of unbroken thread produced by a single cocoon measures about one and half kilometers. Being twisted together several of these threads make single woven materials.

48. What is the purpose of the text?