Question

The maximum length of silk fiber, which surrounds the single cacoon is about
A. 180-200 feet
B. 800-1200 feet
C. 1000-1500 feet
D. 8000-12000 feet

Answer 1

Silk is a natural protein fiber and can be woven into textiles in certain ways. The protein fibre of silk consists primarily of fibroin and is produced to form cocoons by certain insect larvae. The shimmering appearance of silk is attributed to the silk fibre’s triangular prism-like shape, which enables silk fabric to refract incoming light at various angles, creating various colours.

Complete answer: A single incessant thread of unprocessed silk fiber from ${\text{300 to 600}}$ meters (${\text{1000 to 1500}}$ feet) can be drawn from a solitary cocoon. The fibers are very fine and shiny, about 10 micrometres in width.
By producing and covering itself with a long, continuous fibre, or filament, the silkworm caterpillar builds its cocoon. From the spinneret, a single exit tube in the head, liquid secretions from two large glands inside the insect emerge, hardening upon exposure to air and forming twin filaments composed of fibroin, a protein substance. Sericin, a gum material that cements the two filaments together, secretes a second pair of glands.
So, the correct answer is “Option c”.

Note:
With a smooth surface that does not readily retain dirt, the degumming process leaves silk lustrous and semitransparent. When exposed to weights of about $4$ grams ($0.5$ ounce) per denier, Silk has good strength, avoiding breakage. Wetting decreases power by approximately $15 - 25\%$. Before splitting, a silk filament may be extended about $\;20$ per cent beyond its original length, but when stretched more than about $2$ per cent, it does not immediately restore its original length.