Question

In angiosperm, double fertilisation occurs, but a single zygote is formed. Explain how is it taking place. What happens after fertilisation that results in a fruit?

Answer 1

• Fertilisation in angiosperms takes place twice.
• The pollen tube releases two sperm nuclei.
• One of the sperm nucleus fuses with the egg cell to form the zygote.
• Another, fuses with the two polar nuclei to form the endosperm.
• As the second fertilisation involves three nuclei, one sperm nuclei and two polar nuclei, it is referred to as triple fusion.
• Since two types of fusions, syngamy and triple fusion take place in an embryo sac the phenomenon is termed double fertilisation.
• After fertilization, most of the floral parts wither and fall off, the ovary enlarges to form the fruit, and the ovule becomes the seed