Question
Explain why sexual reproduction in angiosperms is said to take place through double fertilization and triple fusion.
Solution
In angiosperms, one male gamete fuses with the female gamete. In addition to this, another male gamete fuses with the secondary nucleus. Fusion between male and female gametes result in the formation of zygote. While the fusion of the male gamete and the secondary nucleus forms the primary endosperm nucleus or (PEN).
Since two instances of fusion of nuclei take place hence the phenomenon is known as Double fertilisation.
The phenomenon is called triple fusion as the male gamete fuses with the secondary nucleus having two polar nuclei and results in the formation of endosperm which has 3n chromosome.
