Fertilisation in Plants

Question 1

double fertilisation

Answer 1

one of the male gametes fuses with the female nucleus to form a diploid zygote and the other male gamete fuses with two polar nuclei to form a triploid endosperm nucleus which serves as a source of nutrients for the embryo.

Question 2

male gametes

Answer 2

Male gamete is called pollen and its produced in the anthers
Anthers contain four pollen sacs where meiosis occurs to produce 4 haploid nuclei

Question 3

Describe the role of enzymes in the growth of the pollen tube.

Answer 3

enzymes digest the tissue
provides energy for pollen tube growth
allows pollen tube to enter ovule

Question 4

pollen formation

Answer 4

Diploid microspore mother cells in the anther undergo meiosis. They form four haploid microspores. Haploid microspores undergo mitosis to mature into pollen grains. Pollen grains consist of two nuclei – the generative nucleus and the pollen tube nucleus – and a protective coating.

Question 5

Describe what happens to the polar nuclei once the pollen tube has grown
into the embryo sac.

Answer 5

polar nuclei fuse (1)
* to form a {diploid nucleus / primary endosperm nucleus} (1)
* which is then fertilised by one of the male {nuclei / gametes} (1)
* to form a (triploid) endosperm nucleus / which will result in the
formation of {endosperm / nutrients} (1)

Question 6

Fertilisation in Plants – Key Steps

Answer 6

Fertilisation in Plants – Key Steps
Pollen lands on stigma (pollination).

A pollen tube grows down the style toward the ovary.

The pollen tube enters the ovule through the micropyle.

The male nucleus travels down the tube and fuses with the female nucleus (egg cell) in the ovule.
This forms a diploid zygote.
the other fuses with the two polar nuclei to make a triploid endosperm