1. Unisexuality. The Plants bear unisexual flowers i.e. stamens and carpels occur in different flowers. They may be present on same plant e.g., in maize or on different plants e.g. in Papaya. The first condition is called monoecious and second is called dioecious. Since the male and female flowers are different the chances of self pollination are less.
2. Dichogamy. When stamens and carpels of bisexual flowers mature at different times, it is called as dichogamy. If stamens mature first it is called protandrous condition, or if carpels mature first it is called protogynous condition. since the stamens and the carpels mature at different time they cannot self pollinate.
(a) hypocotyl and epicotyl
(b) Coleoptile and coleorhiza
(c) Integument and testa
(d) Perisperm and pericarp.
With a neat labelled diagram, describe the parts of a typical angiosperm ovule.
What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?
Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
(a) Draw a diagrammatic sectional view of a mature anatropous ovule and label the following parts in it:
(i) that develops into seed coat.
(ii) that develops into an embryo after fertilization.
(iii) that develops into an endosperm in an albuminous seed.
(iv) through which the pollen tube grains entry into the embryo sac.
(v) that attaches the ovule to the placenta.
(b) Describe the characteristic features of wind pollinated flowers.(a) Explain the different ways apomictic seeds can develop. Give an example of each.
(b) Mention one advantage of apomictic seeds to farmers.
(c) Draw a labelled mature stage of a dicotyledonous embryo.(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.