development of male plant gametes

Question 1

outline the structure of an anther

Answer 1

1) contains 4 chambers called pollen sacs
2) each pollen sac is enclosed by a protective epidermis and fibrous layer
3) within this fibrous layer is the tapetum which acts as a food store and provides energy for future divisions
4) each pollen sac is filled with large numbers of diploid pollen mother cells
5) as the anther grows each of the cells goes through meiosis I and II forming a tetrad
6) each tetrad eventually becomes a pollen grain

Question 2

what is a tapetum

Answer 2

within the fibrous layer of the anther, it provides nutrients and regulatory molecules to developing pollen grains and provides energy for future cell division

Question 3

what is a tetrad

Answer 3

aka microspores
the product of mother cells after meiosis I and II. Each tetrad contains 4 haploid cells they eventually develop into pollen grains

Question 4

outline the formation of a pollen grain

Answer 4

1) inside the pollen grain the nucleus goes through mitosis producing 2 haploid nuclei
2) one of these nuclei is a generative nucleus and the other a tube nucleus
3) the generative nucleus produces two male nuclei by mitosis
4) when the pollen is mature the outer layer drys and splits open along a line of weakness via dehiscence
5) this allows the release of pollen grains

Question 5

define dehiscence

Answer 5

the opening of the anther and release of mature pollen grains

Question 6

what are the male gametes of a plant

Answer 6

the male nuclei within the pollen not the pollen grains themselves