Question

Silk is obtained from $.........$ of the silk moth.
A.Pupa
B.Larva
C.Cocoon
D.caterpillar

Answer 1

Hint: Silk is obtained by rearing the silkworms in the captivity. It is a natural animal fiber. It is one of the luxurious fabrics like cotton and wool. The process by which silk is obtained is known as sericulture.

Complete step by step answer:
-Silk is made up of protein fiber namely: fibroin and sericin.
-They are present in the ratio $70:30$.
-During silk formation the protein fibroin is covered up with the layer of sericin.
-Fibroin consists of layers of anti parallel long chain of amino acids whereas sericin has various types of amino acids with serine as maximum percentage.
-The coated layer of sericin on fibrion leads to intra and intermolecular hydrogen bonding between amino groups leading to high tensile strength and glue like structure of the silk fabric.
-The silk is obtained from Bombyx mori’s cocoon which is a type of silkworm.
-The process of extracting silk is as follows:
-During the larva stage, the silkworms begin to produce silk.
-This larva weaves a cocoon for three to four days in order to prevent itself from the development of pupa.
-Here, the silk is obtained from silkworms before it gets developed into adult silk moths.
-Further, the silk is extracted at the pupa stage.
-Later on these cocoons are submerged in the boiling water where the layer of cocoons starts to get soft.
-Now the next step includes the reeling process. In this process, the cocoons are exposed to extreme heat in order to separate cocoons from silk fibers.
-During this reeling process the fibers are twisted continuously to form silk yarn.
-This silk yarn is then rolled under the roller to make it uniform.
-After making it uniform the manufacturer dyes it in order to make colorful silk fabric.
-Final step is that the garment is produced from this silk yarn.
-There are various types of silk available namely: mulberry silk, eri silk, tasar silk, spider silk, muga silk, sea silk and coan silk.

So the correct answer is option C) cocoon.

Note: Apart from the silkworms, insects like raspy crickets and web spinners produce silk.
-The most popular silk is the mulberry silk.
-The raspy crickets produce silk in order to construct their nest and web spinners produce silk with their front legs to make a web.