3.4

3.4 Understand that the growth of the pollen tube followed by fertilisation leads to seed and fruit formation

Pollen grains land on the stigma. Tubes grow down the plant and it is species specific, which means that the pollen would germinate only if it lands on the same kind of plant. They grown down to the ovule.

1)     The male nucleus travels down the pollen tube into the ovule à fertilisation. It forms the zygote, which grows into an embryo.

2)     Outside the ovule is the testa, the seed coat.

3)     Inside the ovule is the cotyletons, the food store for the seedlings. The food is supplied until the first leaf grows.

4)     The wall of the ovary thickens (lots of energy is put into this). It contains sugar and protein. This turns into the fruit of the plant.