Question

Assertion: The pollen wall proteins are contributed by two generations in the life cycle of flowering plants.
Reason: The exine proteins are of sporophyte origin and intine proteins are of gametophyte origin.
A. Both assertion and reason are correct and the reason is the correct explanation for the assertion.
B. Both assertion and reason are correct but the reason is not the correct explanation for the assertion.
C. Assertion is correct but reason incorrect.
D. Both assertion and reason are incorrect.

Answer 1

Hint: Exine proteins are sporophytic in origin and are held in exine cavities and intine proteins held in angiosperm pollen grains are gametophytic in origin.

Complete answer:
The cellulosic intine proteins are stored mainly in the circular apertures of the pollen grain walls of Malvaceae.
The exine proteins in the sculptured layers of exine of the pollen grain walls of Malvaceae.
During the growth of the wall, the intine proteins are incorporated whereas the exine materials are obtained from tapetum which releases cisternae with a granular fibrillar content bounded by ribosomal membranes.
The exine cavities are injected with the fraction and a PAS reacting material through the microspores in the tectum.
The Pollenkitt is a tapetal fraction that is lipid in nature and commonly contains carotenoids.
Within 30 seconds of moistening the exine held proteins began to pass through the microspores.
The main apertural intine discharge is followed by 4-5 mins after moistening.
These points prove that the intine proteins are produced by male gametophytes and exine proteins are sporophytic in origin obtained from tapetum.

Hence the correct answer is an option(A).

Additional information :
The intine and exine proteins are mostly enzymes.
They are hydrolytic enzymes.
The intine protein comes through the germ pore and has the function of protecting the pollen grain as it is made of cellulose and pectin.
Exine also hard in nature is made of a highly decay-resistant chemical called “sporopollenin” and it also protects the pollen grains from harsh environmental conditions.

Note: Exine and intine proteins are contributed by two generations. Exine sporophytic in origin and intine is gametophytic in origin.
Both proteins contribute to the protection of pollen grains as they are hard in nature.