3.4 - Plant Fertilisation

Pollen grain on the stigma ->germinate( the tube grows - only the same species)

The pollen tube will go down to the ovule where the  pollen nucleus will travel there.

These things will occur :

1. Fertilisation Pollen nucleust will fertilise the Ovule -> will lead to Zygote  -> Embryonic plant

2. Outside Ovule forms a seed coast ( TESTA) 

3.Formation of the Cotyledons - food store for the seedling which will surpport the plant

4. Thickness of the walls of ovary -> plant will put alot of energy in here eg. sugar , protein ->build these up and form the fruit

3.3b - Wind Pollination

Process of wind pollination - Transfering pollen from anther to another flower's stigma by wind

Pollen grain adaptation
- light weight ( wing feature) travel through the air more effieciently
- Anther will hang well clear so they exposed to the wind
- stigma - very large surface area to catch the pollen grain through the wind ( feather like structure)

Some plants like Grass do not need to attract the insects so they don't need colour , scents or food ;  No point, only wasting energy because they are the wind pollinated plant.

Example : The Grass flower diagram

3.3a - Insect Pollination

1.Process of pollinating flower - transfer of pollen grains from the anther from one plant to a stigma of another.
2. Pollen small structure which contains the male nuclei and the transfer by the insects

3.The flower must attract the insects into the flower and have the reason to go to the second
Cross pollination = when pollen goes from one plant to another


Adaptation of flower to attract Insect : 
Signals - Colour petals
            - Scents
Value - Food nectaries / Fructose
          - Pollen Protein


Structure
Stamen ( male) = anther -> makes the pollen & filaments ( stalk)
Carpel ( female) = stigma ( where the pollen falls) , style ( connects stigma to the ovary)
eggs in the plant are called Ovules

         

2.81 Phototropism

KEY POINTS
 Growth in response to light and the positive suggest towards the light



The stem grow towards the light =positive
away from the light = negative 


The plants bends to the lateral light causes the opposit side of a compoud ( austin : plants hormones) causes more growth than the other side = Bend

2.80 Geotropism

Key Points
 Geotropism = growth responses togravity



Example of a seed:


Embrionic root ->grows downwards = positive geotropisim


Embrionic shoot->grows upwards to the surface = negative geotropism


Rotate it to sideways 
The shoot grows upwards= negative
root-> Grows down =positive

2.79 Plants and stimuli

KEY POINTS

1.stimuli are changes in the environment eg. temperature, light


2.Plants have receptor which detect stimuli


3.This turns into response - Growth
(Tropism)


4.Tropism involvle light which involve phototropism and geotropism ( gravity)


5.Connection between receptor and response usually takes the form plants hormones

2.54 Transpiration

5 Key points

1. transpiration will occur where H20 liquid change into Gas
2. This is created by the sunlight where light energy transfer to heat and absorb by the structure of the leaf
3. Water from the roots travel to the leaf by the osmosis
4. Heat from the sunlight causes the water to become a vapour where it is 100% humidity in leaf spaces
5. The phase change occured and the gas diffuses out of the leaf through the stomatl pore by the steep diffusion gradient and also to the lower humidity outside