Question

Define the term 'double fertilisation'.

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.