Question

What is double fertilization and tripple fusion ?

Answer 1

Double fertilization is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm). It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive structure of a flower. The pollen grain then takes in moisture and begins to germinate, forming a pollen tube that extends down toward the ovary through the style. The tip of the pollen tube then enters the ovary and penetrates through the micropyle opening in the ovule. The pollen tube proceeds to release the two sperm in the megagametophyte.



Definition of triple fusion. : the fusion involving two polar nuclei and a sperm nucleus that occurs in double fertilization in a seed plant and results in the formation of the endosperm.

Answer 2

Double fertilization involves two steps :-

1. Syngamy

2. Triple fusion

Syngamy ⇒ During the fertilization in flowering plants pollen tube releases two male gametes & it moves towards the egg cell and fuses with the nucleus to form diploid zygote.  

Triple fusion ⇒ The other male gametes move towards the two polar nuclei located in the central cell & fuses with it & produce triploid primary endosperm nucleus.  

This is called double fertilization.