Question

define double fertilization with the diagram justify the above definition

Answer 1

Double fertilization is a characteristic feature of flowering plants. In the process of double fertilization out of the two sperm nucleus, one sperm nucleus fuses with the egg nucleus to form an embryo ( process is called syngamy) and another fuses with polar nuclei to form endosperm ( process is clled triple fusion).
Since two kinds of fusion—syngamy and triple fusion—take place, the process is known as double fertilisation.
Hope you find this answer helpful!
in plants pollination is followed by fertilization.The pollen lands on the stigma ,germinates and gives out a pollen tube.The male gamete divides into 2 and both the nuclei move into the pollen tube .The pollen tube grows throught the style .ovary and reaches the ovule .The ovule contains the embryo sac which consists of the egg cell (female gamete) ,the 2 nuclei are released into the embryo sac .One of them fuses with the egg cell and this is called syngamy .The product of syngamy is the zygote.The other male gamete fuses with 2 polar nuclei in the embryo sac .This is called triple fusion because 3 nuclei are taking part in fusion(2 polar nuclei and one male gamete).