|
Microsporogenesis |
Megasporogenesis |
|
1. Formation of microspores and production of male gametophyte is termed micro-sporogenesis. 3. Many microspore mother cells are differentiated in a microsporangium. 4. All the four cells of the microspore tetrads are functional. |
1. Formation of megaspores , female gametophyte from megaspore mother cells is called megasporogenesis. 2. It occurs in the nucellus of the ovule/megasporangium. 3. Only one megaspore mother cell is differentiated in a megasporangium. 4. Only one of the four cells in the megaspore tetrad continues to grow. |
The type of cell division that occurs during these events is Meiosis or Reduction division which produces haploid gametes from diploid cells.
The structures formed at the end of the two events are(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.