3.4 Plant Fertilisation.

Understand that the growth of the pollen tube followed by fertilisation leads to seed and fruit formation.
- pollen grains on stigma germinates and a tube begins to grow.
- the male nucleus travels down the pollen tube in to the ovule.
- pollen nucleus will fertilise the ovule- leads to formation of a zygote -> later grows into and embryonic plant.
- outside of the forms seed coat called testa.
- inside of seed forms cotyledons. food storage for the seedling, this supports the plant until it develops leaves.
- thickening of walls of the ovary occurs- plant uses lots of energy (like sugar and protein) this will form fruit which is developed from the wall of the ovary.

3.3b Wind Pollination

describe the structures of an insect-pollinated and a wind-pollinated flower and explain how each is adapted for pollination.



-transfer of pollen grain from anther to stigma.


adaptations
-light weight pollen grain some sort of wing feature to move through the air efficiently,
- anther will hang well clear out of any basic flower structure so it is exposed to the wind.
-stigma- large surface area, feather like structure to catch pollen grain.
- grass- no colour in petal, no scent, no nectaries to attract insects as it is a waste of energy and it is wind pollenated.

3.3a Insect Pollination

describe the structures of an insect-pollinated and a wind-pollinated flower and explain how each is adapted for pollination.


-Pollination: transfer of pollen grain from anther to stigma.
-Pollen contains nuclei
-Cross pollination: when pollen goes from one plant to another.
-Attract insects.
 Signal- Colour Petals
           - Scent
 Valve- Food (nectaries) producing Fructose.
           - Pollen- Source of protein.
-Structure
 Petals
 Stamen- male part of the plant. Anther and Filament.
 Carpel- female part of plant- Stigma, Style and Ovary.