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Which one of the following is resistant to enzyme action?
A
Pollen exine
B
Leaf cuticle
C
Cork
D
Wood fibre
Detailed Solution
The wall of a pollen grain has two layers: the outer hard exine and the inner thin intine.
The exine is made up of sporopollenin, which is one of the most resistant organic materials known.
It can withstand high temperatures and strong acids and alkalis, and no enzyme that degrades sporopollenin is so far known.
That is why pollen grains are well preserved as fossils.
The intine is made of cellulose and pectin, which can be digested by enzymes.
Leaf cuticle (cutin), cork (suberin) and wood fibre (cellulose and lignin) are all decomposed by microbial enzymes in course of time.
So the structure resistant to enzyme action is the pollen exine.
The exine is made up of sporopollenin, which is one of the most resistant organic materials known.
It can withstand high temperatures and strong acids and alkalis, and no enzyme that degrades sporopollenin is so far known.
That is why pollen grains are well preserved as fossils.
The intine is made of cellulose and pectin, which can be digested by enzymes.
Leaf cuticle (cutin), cork (suberin) and wood fibre (cellulose and lignin) are all decomposed by microbial enzymes in course of time.
So the structure resistant to enzyme action is the pollen exine.