91. Draw a diagram of a male gametophyte of an angiosperm. Label any four parts. Why sporopollenin is considered the most resistant organic material?

State what is apomixis. Comment on its significance. How can it be commercially used?

Name the part of the flower which the tassels of the corn-cob represent.

(a) Explain the different ways apomictic seeds can develop. Give an example of each.

(b) Mention one advantage of apomictic seeds to farmers.

How do the pollen grains of Vallisneria protect themselves? 

Out of many papaya plants growing in your garden, only a few bear fruits. Give reason.

(a) Explain the post-pollination events leading to seed production in angiosperms.

(b) List the different types of pollination depending upon the source of pollen grains.

A. Draw a labelled diagram of L.S. of an embryo of grass (any six labels).

B, Give reason for each of the following:

(i) Anthers of angiosperm flowers are described as dithecous.
(ii) Hybrid seeds have to be produced year after year.

State the importance of water to plants.