Question

(a) Explain the phenomenon of double fertilization.
(b) Draw a labelled diagram of a typical anatropous ovule.

Answer 1

(a) When the pollen grains get transferred from the anther to the stigma, the pollen tube enters one of the synergids and releases two male gametes. One of them moves towards the egg cell and fuses with it to complete the syngamy to form the zygote. The other fuses with the two polar nuclei and forms triploid primary endosperm nucleus (PEN). This fusion of one male gamete with two polar nuclei is termed as triple fusion. Since two kinds of fusion—syngamy and triple fusion—take place during fertilisation in a flower, the process is known as double fertilisation.
(b) Labelled diagram of a typical anatropous ovule is given.