fertilisation

Question 1

outline the formation of the pollen tube

Answer 1

1) the stigma of a plant of the same species produces a sugary solution in which the pollen grain germinates producing a pollen tube

Question 2

outline how the pollen tube reaches the ovule

Answer 2

1) the pollen tube secretes hydrolase enzymes as it grows, production coded by the tube nucleus
2) the pollen tube digests its may down the tissues of the style following a gradient if chemoattracts called GABA secreted by the ovule
3) behind the tube nucleus the generative nucleus divides by mitosis producing 2 more haploid nuclei- 3 now in the pollen tube

Question 3

outline what occurs when the pollen tube reaches the ovule

Answer 3

1) the pollen tube enters the micropyle and the tube nucleus disintegrates
2) the tip of the pollen tube bursts releasing the two haploid male gametes
3) one of the male gametes fuses with the oosphere forming a diploid zygote
4) the other fuses with the 2 polar nuclei forming a triploid endosperm

Question 4

what does the triploid endosperm develop into

Answer 4

divides by mitosis to produce an endosperm tissue

Question 5

what does the zygote develop into

Answer 5

the embryo of the new plant

Question 6

what happens to the fertilised ovule

Answer 6

develops into a seed

Question 7

what happens to the fertilised ovary

Answer 7

develops into a fruit

Question 8

what happens to the integuments of the ovule

Answer 8

develop into a tough protective outer covering of the seed

Question 9

what does the embryo of the seed produce

Answer 9

1) a radicle shoot which develops into the roots

2) a plumule which develops into the shoot