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)