Question

Assertion: Endosperm is a nutritive tissue and it is triploid.
Reason: Endosperm is formed by the fusion of the secondary nucleus to the second male gamete. It is used by developing embryos.
A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B. Both Assertion and Reason are true and Reason is not the correct explanation of Assertion.
C. Assertion is true but the reason is false.
D. Both Assertion and Reason are false.

Answer 1

Hint: The triploid endosperm is formed by the fusion of the secondary nucleus and the male gamete in angiosperms. The whole process is also called double fertilization.

Complete answer: In flowering plants, the eight nucleate female gametophytes have an egg apparatus at the micropylar end. The egg apparatus has one egg cell and two flanking cells. The flanking cells serve as a site for entry of the pollen tube. They are known as synergids. Antipodals are three cells that are present at the chalazal end of embryo sac. The diploid secondary nucleus is formed by the migration of one nucleus from each pole in the middle. The pollen tube penetrates the stylar canal and then enters the ovule through the micropyle chalaza or integument. Further, the male gametes discharge in the embryo sac. The diploid embryo is formed by the fusion of one male gamete with the egg nucleus, i.e., also known as syngamy and the triploid primary endosperm nucleus is formed by the fusion of the other male gamete with diploid secondary nucleus/central cell. This formed triploid primary endosperm nucleus divides to form large nutritive endosperm.
Thus, the correct answer is option A.

Note: Endosperm serves as a source of food material to the growing embryo and also to the seedling. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein.