Question

In mesogamy, pollen tube enters the ovule through
A. Middle of integuments after piercing the tissues
B. Middle of integuments without piercing the tissues
C. Chalaza
D. Middle of micropyle

Answer 1

Hint: Pollen tube carries the pollen grains and enters the ovule through different pathways so that nucleus from pollen grains can fuse with the nucleus of egg cell present in the ovule.

Complete answer:
Mesogamy is mostly observed in the plants like cucurbits, pumpkin, gourds. Here the Pollen tubes insert into the ovule through the mid part of the ovule. Pollen tube is a hollow tube which arises through Pollen Grain when pollens are aggregated on the flower's stigma. Pollen tube pierces the style and delivers the male gamete inside the ovule. So pollen tubules behave as a passenger way to deliver sperm cells of the pollen grain. In order to continue the fertilization it’s a very important step for a pollen grain to get inside the ovule and fertilize the cell. The pollen grains visit through stigma by style and then reach the oval only after the filiform Apparatus gets a break.
Mesogamy is the type of entry of pollen tube through the integuments in the ovule. The pollen tube pierces the tissues of the integuments in the middle and then enters into the embryo sac through micropylar pore. Entry of pollen tube through micropylar end is known as porogamy whereas through chalazal end, it is known as chalazogamy.

The correct answer is (A) middle of integuments after piercing the tissues.

Note: The entry of the pollen tube is necessary for the pollen grains to reach the embryo sac in the ovule for the process of syngamy and triple fusion. It can be either through the micropyle or chalazal end.