gamete formation

Question 1

outline how pollen is formed

Answer 1

1) each pollen sac is filled with diploid cells called mother cells which are produced by mitosis
2) each mother cell undergoes 2 meiotic divisions forming a tetrad made up 4 microspores, each of which will develop to produce 4 mature pollen grains
3) the microspores divide by mitosis and differentiate into pollen grains
4) within each pollen grain the haploid nucleus undergoes further mitosis producing 2 haploid nuclei- the generative and tube nucleus

Question 2

define dehiscence

Answer 2

the splitting of anthers down a line of weakness releasing the pollen

Question 3

what are the diploid cells within anthers called

Answer 3

mother cells

Question 4

what are tetrads made up of

Answer 4

4 microspores as a result of 2 meiotic divisions from the mother cell

Question 5

outline the formation of an ovule

Answer 5

1) a mother diploid cell (mother megaspore) divides by meiosis producing 4 haploid megaspores
2) 3/4 of these megaspores degenerate leaving only 1 surviving

3) the haploid nucleus of the surviving megaspore undergoes three mitotic divisions producing 8 haploid nuclei
- 3 antipodal cells
- 2 polar nuclei
- 2 synergids
- 1 oosphere

Question 6

what are the 8 haploid nuclei produced by the mitotic division of the surviving megaspore nuclei

Answer 6

1) 3 antipodal cells
2) 2 polar nuclei
3) 2 synergids
4) 1 oosphere