Question

What is double fertilization . Explain with an example

Answer 1

in flowering plants the fertilization is called double fertilization bcoz fertilization occurs twice. on entering the ovary the pollen tube releases 2 male gametes .in the first reaction , one of the male gametes fuses with eggcell and forms the zygote . this reaction is a diploid reaction and is also called syngamy.

in the second reaction  the second male gamete fuses with the 2 polar nuclei and form the product called P.E.N - primary endosperm nucleus. this reaction is called the triploid reaction or the triple fission.

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.