2.5 Sexual Reproduction in Plants

Question 1

what is pollination

Answer 1

pollen lands on stigma of a flower

Question 2

what is fertilisation in plants

Answer 2

pollen nuclei fuse with nuclei of egg sac

Question 3

describe the production of pollen grains

Answer 3

1. diploid microspore mother cell divides by meiosis
2. four haploid microspores are formed
3. microspores mature into pollen grains
4. haploid microspore undergoes one mitotic division to form a pollen grain with 2 haploid nuclei: tube and generative

Question 4

describe the production of embryo sac in plants

Answer 4

1. diploid megaspore mother cells in ovary divide into a haploid megaspore and a polar body
2. megaspore mother divides by meiosis to form 4 haploid cells, 3 of which degenerate
3. remaining haploid megaspore (ootid) undergoes 3 mitotic divisions, resulting in an embryo sac

Question 5

define pollination

Answer 5

pollen grain falls onto stigma of a flower of the same species

Question 6

describe the process of producing 2 male gametes in a plant

Answer 6

1. pollen tube grows a pollen tube - growth in directed y tube nucleus
2. tube nucleus secretes digestive enzymes to break down cells of the style
3. tube nucleus degenerates when it reaches the embryo sac
4. generative divides by mitosis to produce 2 male gametes

Question 7

describe the process of double fertilisation

Answer 7

1. once the tube enters the ovule in the ovary, two male gamete nuclei pass in and double fertilisation occurs
2. one male haploid nucleus fuses with the haploid female egg cell to produce a diploid zygote
3. the other male haploid nucleus fuses with the 2 haploid polar nuclei to form the triploid endosperm
4. the triploid endosperm will go on to form the starch store in the seed