Question

What is double fertilization? Describe the process in brief.

Answer 1

Hint: The pollen is the male gamete which moves via air, water etc. to the ovary of the female gametophyte through the style and stigma. The ovary in the female plants has the egg cell which will fuse to give the embryo. It has various other cells which have an important role to play at a particular time.

Complete answer:
Fertilization is the fusion of male and female gametes in the female body to form the zygote which turns into an embryo. This male and female gametes here are the formed zygote is 2n.
In the double fertilization, the one pollen fuses with the egg cell while the other pollen fuses with the secondary nucleus. Double fertilization is the characteristic feature of the angiosperms.
It is important as it will involve the fusion of both the male gametes. This helps in avoiding polyembryony.
Due to two fertilizations, two products will be formed. One will be the zygote which will next form the new plant.
The other product is the triploid PEN (primary endosperm nucleus). This is triploid as the secondary nucleus is binucleate. So the resulting endosperm is triploid and is the nutritive tissue for a developing embryo.

Note: Double fertilization is important as it will give rise to endosperm. Endosperm work as the nutrient supplier to the growing embryo. Later on, it forms the edible part of the fruit in some fruits. It increases the viability of the seeds. Therefore using both the male gametes from the pollen, this process has its ultimate importance.