Question

A unique phenomenon observed in the embryo sac of angiosperms is

• A. Triple fusion
• B. Fusion of gametes
• C. Triple fusion and double fertilisation
• D. Double fusion

Answer 1

The correct option is C Triple fusion and double fertilisation

Triple fusion and double fertilisation
Two haploid male gametes are released from the same pollen tube in the embryo sac of the ovule in angiosperms.

• One of these fuses with the haploid egg cell to form a diploid zygote. This fusion of gametes is known as syngamy.
• The other one fuses with the diploid central cell to form the triploid primary endosperm cell containing the triploid primary endosperm nucleus. Since this process involves the fusion of three nuclei, hence it is known as triple fusion or vegetative fertilisation.

This entire process involving two fertilisation events is known as double fertilisation. Triple fusion and double fertilisation are unique characteristics of angiosperms or flowering plants.
Non- flowering plants such as gymnosperms, bryophytes, pteridophytes and thallophytes do not undergo double fertilisation.

Final answer
(d) Triple fusion and double fertilisation