Question

When wool sweaters are washed in hot water, they shrink. In contrast, when silk clothes are washed, they do not shrink under the same conditions:
(A) The β-woolen polypeptide chains are converted to the native α-helical conformation.
(B) The structure of silk β-sheets is more stable than that of wool.
(C) The β-woolen polypeptide chains remain in their native conformation.
(D) The structure of silk β-sheets is less stable than that of the wool protein structure.
Choose the correct answer from the options given below:

• A. (A) only
• B. (A), (B) and (D) only
• C. (A), (B), (C) and (D)
• D. (B), (C) and (D) only

Hint:

Wool’s shrinkage is due to a shift from β-sheet to α-helix, while silk’s β-sheets remain stable.

Answer 1

The Correct Option is A

- (A) Correct: Wool proteins, when heated, shift from their native β-sheet structure to an α-helical conformation, causing the material to shrink.
- (B) Incorrect: While silk β-sheets are stable, this does not explain the behavior of wool.
- (C) Incorrect: Wool’s polypeptide chains do not remain in their β-sheet conformation upon heating.
- (D) Incorrect: Silk β-sheets are more stable than wool’s α-helix, but this does not directly address the question.