Q. How are the female gametes of gymnosperms formed? What is the relationship between this process and the concept of alternation of generations?
In the female strobiles (cones) there are megasporophylls (fertile leaves of the strobile) that restrain megasporangia. In the megasporangium the spore mother cell undergoes meiosis generating four haploid cells of which three revert and one gives birth to the functional megaspore. The functional megaspore by several mitosis forms the female gametophyte that restrain the oospheres (female gametes) of the plant. The female gametophyte is located within the megasporangium that has the micropyle, a tiny opening, all through which the pollen tube enters.
The procedure is related to the diplobiontic life cycle (alternation of generations) since the efficient megaspore generates the haploid stage of the plant (the female gametophyte).