3.4 Plant Fertilisation

- The pollen grains germinate: a tube begins to grow downwards. (note: the pollen tubes will only complete if they are from the same species)
- The tube goes all the way down and around into the yellow ovule
- Traveling down the pollen tubes are the male nucleus which goes into the ovule
1. Pollen nucleus will fertilise the ovule --> formation of Zygote and this will grow into the embryonic plant.
2. Outside the ovule forms the Testa (seed coat).
3. Formation of cotyledons = food stores for the seedling which will support the plant until it develops its first set of leaves.
4. Plant will put a lot of energy (sugars, protein) into the walls of the ovary / carpel. It will build up and form the fruit.

3.3a Insect Pollination

- Process of pollinating flower = there has to be a transfer of pollen (pollen - small structure containing the male nuclei) from the anther to the stigma of another flower
- The transfer of this takes place by insects. Therefore, necessary for the first flower to attract the insect
- When pollen goes from one plant to another = cross pollination
- adaptation to attract insect:
     - signals: colour petals, scents
     - value: food = nectaries / fructose, pollen (as protein)
- stamen = male part of the plant composed of the anther which produces the pollen grains
- anther and filament form the stamen
- female part: stigma - where pollen grains fall, style - connects stigma to ovary, ovaries - which contain eggs called ovules.
- The whole female structure is called the carpel
- The stamen is the male part