Question

why in most of the flowering plant only one megaspore is functional and other three are degenerated while in microspore all the four cells are functional

Answer 1

In flowering plants the megaspore mother cell undergoes meiotic division to form four megaspores. out of these 3 degenerates and one if left function which further develops into embryo sac.

Possible reasons behind the degeneracy of 3 megaspores are-

• The position of megaspore is fixed,it would not be possible to accommodate 4 embryo sac at one point.
• If the remaining 3 are functional then there is a division of nutrients among them which can cause nutrient shortage.
• Its the pollen grain which need to travel to megaspores so there are chances of them to get affected or lost while travelling, hence they are more in numbers.
• If all 4 megaspore would be functional it need 4 pollen to fuse with them resulting in the formation of 4 pollen tubes which becomes very complex for the plant.