Question

What is a constituent of natural silk?

• A. Phosphorus
• B. Nitrogen
• C. Potassium
• D. Magnesium

Answer 1

The correct option is B Nitrogen

Silk fibers are composed of fibroin. It is an insoluble protein. Sericin and fibroin are two main proteins present in the raw material of protein. It has a amino acid sequence of (Gly-Ser-Gly-Ala-Gly-Ala)n. It is secreted by caterpillar larva of silkworm but is obtained from the cocoon. All the constituent of silk, glycine, serine and alanine has nitrogen as integral component. The chemical formula of serine is C${}_3$H${}_7$NO${}_3$, glycine is NH₂‐CH₂‐COOH and alanine is C${}_3$H${}_7$NO${}_2$.

So, the correct answer is option B.