Unit 4.2 - Gametogenesis in flowering plants

Question 1

where does male gamete formation take place?

Answer 1

The Anthers

Question 2

what is the ploidy of the pollen mother cell

Answer 2

diploid (2n)

Question 3

what is the ploidy of the pollen daughter cells

Answer 3

haploid (1n)

Question 4

explain pollen grain development

Answer 4

1. diploid(2n) mother cell x1
   -> meiosis
2. Haploid(n) pollen cells x4
   -> mitosis
3. Two Haploid(n) nuclei in 1 cell
   (= pollen grain. no cytokinesis
   occurs)

During pollination, generative nucleus divides by mitosis = 2 male nuclei.

Question 5

what are the 2 haploid nuclei called in the pollen grain after 1st mitosis

Answer 5

• tube nucleus
• generative nucleus

Question 5

what is the cells in pollen cells called

Answer 5

microspores

Question 6

what are the parts of a mature pollen grain

Answer 6

• Cell wall (intine + extine)
• tube nucleus
• generative nucleus

Question 7

what is the ploidy of the tube nucleus

Answer 7

n (haploid)

Question 8

what is the ploidy of the generative nucleus

Answer 8

n (haploid)

Question 9

what is the purpose of the gaps in the exine of the pollen grain

Answer 9

gaps for pollen tube growth

Question 10

how many meiosis divisions occur in pollen grain

Answer 10

1

Question 11

how many mitosis divisions occur in pollen grain

Answer 11

2

Question 12

what is the cells in ovule cells called

Answer 12

spore

Question 13

explain ovule development

Answer 13

1. diploid(2n) mother cell x1
   -> meiosis
2. Haploid(n) megaspore cells x4
   
   • 3 degenerate, 1=embrosac
     -> mitosis + grows
3. Two Haploid(n) nuclei in 1 cell
   -> mitosis
4. four haploid(n) nuclei in 1 cell
   ->mitosis
5. eight haploid(n) nuclei in 1 cell
6. Centre 2 = polar nuclei.
   Top 3 = antipodal
   Bottom outer 2 = synergids
   Bottom middle = female gamet

Question 14

how many mitosis in ovule

Answer 14

3

Question 15

how many meiosis in ovule

Answer 15

1