Question

High extensibility of wool fibre is due to:

• A. Presence of scales
• B. \( \alpha \)-helix structure of proteins
• C. Cross-linking
• D. \( \beta \)-sheet structure of proteins

Hint:

The extensibility of wool fibres is due to the flexible \( \alpha \)-helix structure in the proteins, which allows wool to stretch and return to its original shape.

Answer 1

The Correct Option is B

Wool fibres are primarily composed of proteins, specifically keratin. The structure of these proteins plays a key role in the properties of wool, including its extensibility. The high extensibility of wool fibres is largely due to the \( \alpha \)-helix structure of proteins. This helical structure allows the fibres to stretch and then return to their original shape. The \( \alpha \)-helix structure is flexible and provides wool with its elastic properties, making it naturally extensible. The helical configuration allows the wool to stretch when force is applied and return to its initial shape when the force is removed, giving wool its characteristic ability to "bounce back." - (A) Presence of scales: The presence of scales on the surface of wool fibres (which are characteristic of animal fibres) can affect the texture and feel of the wool, but it does not contribute directly to its extensibility. - (C) Cross-linking: Cross-linking refers to the formation of bonds between the polymer chains, which typically strengthens the material. However, this does not contribute to the high extensibility seen in wool fibres. - (D) \( \beta \)-sheet structure of proteins: The \( \beta \)-sheet structure is another form of protein folding, but it provides more rigidity to the material, reducing its extensibility. This structure is often associated with more rigid fibres, unlike the flexible \( \alpha \)-helix structure in wool that allows for high extensibility. Thus, the correct answer is (B), the \( \alpha \)-helix structure of proteins.