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In majority of angiosperms the pollen grains are shed from the anther at bi-celled stage (one generative cell and one vegetative cell) but in some angiosperms the generative cell divides forming 2 sperms prior to the dehiscence of anther & pollen grains are shed at 3 celled stage.
- Spores are formed in lower plants by mitotic division and they may be diploid but gametes are always made by meiosis & they are always haploid.
- In majority of angiosperms the pollen grains are shed from the anther at bi-celled stage (one generative cell and one vegetative cell) but in some angiosperms the generative cell divides forming 2 sperms prior to the dehiscence of anther & pollen grains are shed at 3 celled stage.
- 100 zygotes requires 100 pollen grains and 100 embryo sacs. 100 pollen grains are formed from 25 microspore mother cells while 100 embryo sacs are formed from 100 functional megaspores which in turn are produced by 100 megaspore mother cells since three out of four megaspores degenerate in each case.
- Double fertilization is a unique phenomenon that occurs in angiosperms only.
Correct answer: In majority of angiosperms the pollen grains are shed from the anther at bi-celled stage (one generative cell and one vegetative cell) but in some angiosperms the generative cell divides forming 2 sperms prior to the dehiscence of anther & pollen grains are shed at 3 celled stage.
Solution
The correct statement describes the normal condition in most angiosperms: pollen is released at the bicelled stage. It also correctly notes the exception where the generative cell divides earlier, so pollen is shed as a tricelled grain.
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