Question

Double fertilization

• A. forms embyo only
• B. forms endosperm only
• C. is a characteristic feature of flowering plants
• D. involves five nuclei

Answer 1

Answer: (C), (D)

involves five nuclei

The pollen grains germinate on the stigma and the resulting pollen tubes grow through the tissues of stigma and style and reach the ovule. The pollen tubes enter the embryo-sac where two male gametes are discharged. One of the male gamete fuses with the egg cell to form a zygote (syngamy). The other male gamete fuses with the diploid secondary nucleus to produce the triploid primary endosperm nucleus (PEN). Because of the involvement of two fusions, this event is termed as double fertilisation. Double fertilization is a characteristic feature of angiosperms and involves five nuclei.