question_answer

                Double fertilisation (or triple fusion) leading to initiation of endosperm in angiosperms, requires:

A)                                                                                                                                                                                         fusion of 4 or more polar nuclei and the second male gamete only

B)                 fusion of 2 polar nuclei and second male gamete only

C)                 fusion of one polar nucleus and second male gamete only

D)                 all the above type of fusions in different types of angiosperms

Correct Answer: B

Solution :

                Nawaschin (1898) was first to show that both the male gametes released by a pollen tube are involved in fertilization. Nucleus of one gamete fuses with egg nucleus (syngamy). Nucleus of the other gamete fuses with the polar nuclei or their fusion product (secondary nucleus). Most of the plants have two polar nuclei; hence second fertilization involves the fusion of three nuclei (triple fusion).