37. What is double fertilization? Describe fertilized embryo sac with a neat labelled diagram.

Ans:

As syngamy and triple fusion take place simultaneously in the embryo sac, it is termed as double fertilisation.

Fertilized embryosac exhibit degenerating synergids towards micropylar end and a fertilized egg cell called diploid zygote.

Antipodals towards the chalazal end also degenerate. Central cell becomes primary endosperm cell with a triploid primary endosperm nucleus. Primary endosperm cell develops in to the endospetm by repeated mitotic division. The cells of endosperm are filled with food reserves and thereby nourish the developing embryo.