Question

Commercial silk is obtained from _______
A. Cocoon or pupa
B. Caterpillar
C. Adult moth
D. Both egg and adult

Answer 1

Hint: The process of silk production is known as “Sericulture”. The best silk is obtained from Mulberry silkworms Bombyx mori which are reared in Captivity (sericulture). Silk is one of the strongest natural fibre but loses its strength when wet and has good moisture regain.
Complete answer:
Silk is obtained from cocoon(pupa, chrysalis) of Bombyx mori which is the mulberry silkworm. Caterpillar of these silkworms feeds on mulberry leaves, it’s salivary gland secretes liquid silk. The salivary gland (labial gland) is modified forming the silk gland of the larva. Silk is obtained from the cocoon. Ripe cocoons are treated with boiling water to kill the moth before hatching and so that the cocoon softens and dissolves gum that is holding the cocoon together. Boiling them ensures there is no damage to the continuity of each thread. Silk thread is formed of two proteins namely fibroin and sericin. Natural silk contains nitrogen. The shining appearance of silk is due to the triangular prism-like structure of the silk fibre, which allows silk cloth to refract incoming light at different angles which produces different colours. Mysore is the biggest centre for the production of raw silk in India. Central sericulture Institute is situated in Berhampore.
Hence, the correct answer is (A),i.e. cocoon or pupa.

Note: There are various applications of silk other than clothing such as:
-Furniture: Its attractive lustre and drape make it suitable for many furnishing applications.
-Industry: It has many industrial and commercial uses such as parachutes, bicycle tires, etc.
-Medicine: During silk manufacturing the outer coating sericin is removed which make it suitable as non absorbable surgical sutures.