It occurs in embryo sac. Triple fusion occurs when during fertilization the other male nuclei moves towards the central two polar nuclei and fuse with them forming 3n primary endosperm nucleus.
Nuclei involved are two polar nuclei and one nucleus of male gamete.
(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.