describe the structure of a mature male gametophyte answer for 5 marks
Answers
Answer:
Mature male gametophyte in angiosperms is a three-celled structure i.e., the 3-celled germinated pollen grain. The terminal poistion is occupied by cytoplasm and nucleus of tube cell and two male gametes remain in back side of tube nucleus. In 40% of angiosperms, pollen is released at the 3-celled stage while in other 60% in the 2-celled immature stage.
So, the correct answer is 'Three celled'.
Answer:
Microspore or the pollen grain represents the initial cell of male gametophyte.
During germination, the cytoplasm of the pollen grain comes out in the form of a tube like structure called pollen tube through the germ pore.
The pollen tube carries the tube nucleus cytoplasm and generative cell.
The pollen tube grows through the style towards the ovule due to some chemical stimulus inside the ovary.
The generative cell of the pollen grain divides by mitosis and forms two haploid non motile gametes.
Pollen tube consisting of the two male gametes and a degenerating tube nucleus represents the male gametophyte.