Which one of the following is resistant to enzyme action?
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Cork
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Wood fibre
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Pollen exine
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Leaf cuticle
C.
Pollen exine
The pollen wall consists of two layers the outer exine and inner intine. The exine chiefly made up of sporopollenin, which is derived by the oxidative polymerization of carotenoids. Sporopollenin is one of the most resistant biological materials known. The exine is thin in beginning but becomes very thick with maturity.
During secondary growth in the extrastelar region, cork cambium or phellogen cells divide periclinal, cutting off cells towards the outside and inside. The cells cutoff towards outside become suberised and dead and form cork. Cork is impervious to water due to suberin and provides protection to the underlying tissue.
