Question

When pollen tube enters through micropyle, the process is called as
A.Porogamy
B.Chalazogamy
C.Mesogamy
D. Apogamy

Answer 1

Hint: In flowering plants, flowers are the site of sexual reproduction. The male reproductive organ produces pollen that travels to the female reproductive system and fuses with the egg cell.

Complete step by step answer:
In most flowering plants, only one of the megaspores is functional and it develops into the female gametophyte which is also known as the embryo sac. After complete maturation, the embryo sac has a characteristic distribution of the cells with one end called the micropylar end and the other end is called the chalazal end. At the micropylar end, three cells are grouped together (two synergids and an egg cell) forming the egg apparatus. At the chalazal end also, three cells are present which are known as antipodals.
The synergids also have a special thickened cellular structure at their micropylar tip called the filiform apparatus. The filiform apparatus has importance in guiding the pollen tube so that it could enter into the synergid. When the pollen tube enters through the micropyle into the embryo sac, the process is known as Porogamy. So, the correct option is (A) Porogamy.

Hence, option A is the correct answer.

Additional information:
Chalazogamy is also a process of fertilization but in this process, the pollen tube enters through the chalaza end instead of the micropylar end. Mesogamy is the process when the pollen tube enters through the funicle (stalk) or the integument. Apogamy is the process of development of the embryo without any kind of fertilization.

Note: Apart from the three antipodal cells, and the three cells of the egg apparatus, there is a large cell at the center of the embryo sac having two polar nuclei. Thus, this typical structure of an angiosperm embryo sac is known as 8-nucleate and 7-celled structure.