(a) Trace the development of an endosperm after fertilisation with reference to coconut. Mention the importance of endosperm development.

(b) Write the importance of ‘pollen bank’.

(a)

• Fertilization is a distinctive feature of the angiosperm life cycle. Out of 2 sperm, one fertilizes the egg to form the zygote.

• The other sperm combines with the secondary nucleus to form a triploid (3n) nucleus called the primary endosperm nucleus (PEN) in the large central cell of the embryo sac.

• The union of two male gametes with different nuclei of the embryo sac is termed double fertilization.

• The fertilized egg becomes the zygote and develops into an embryo. The primary endosperm nucleus after division gives endosperm.

• The endosperm is rich in nutrients, which it provides to the developing embryo.

• In case of coconut, endosperm is the most important economic part that provides a refreshing health drink during the immature stage and edible oil during the mature stage.

(b)

• Pollen banks are used to store pollen grains for a short as well as very long period of time at different conditions.

• Pollen grains are stored through cryopreservation techniques.

• The most important application of pollen bank is that it preserves the biodiversity in the form of valuable genetic resources. The preserved pollen grains can then be used for crop breeding programmes.