Video: 2.81 Phototropism

- Phototropism. Photo = Light. Tropism = Growth in response to light. Shows towards the light
- If light comes from all directions the stem will grow forwards and upwards.
- If light comes from lateral light source the stem will start growing towards the light.
- Light on one side, causes movement of opposite side of a compound, Auxin (plant hormone).
- Auxin causes more growth to the plant which makes the plant grow in the other direction an also causes the plant to bend.
- Cell division is called mitosis which means that the cells multiply.

Video: 2.80 Geotropism

Geo of Geotropism stands for gravity and tropism stands for growth response.
- Geotropic. Geo = Gravity. Tropic = Growth response
- Embryonic root grows downwards in a seed.
- It SHOULD grow upwards.
- If you take the same seed but rotated the shoot then grows upwards and the Embryonic root will grow downwards.

Video: 2.79 Plants and stimuli

- Stimuli are changes in the environment, Temperature or light.
- Plants have receptors that detect stimuli and turn into response
- Response - Take form of growth - Tropism, involving light (phototropism)
- Tropism, involving Gravity (Geotropism)
The light comes in all directions meaning that the light will grow forward.
If light comes into the plant sideways that means that the plant will grow in the direction the light is coming in.
The light on one side causes the plant to move to the opposite side.
Auxin causes more growth to the plant which makes the plant grow in the other direction an also causes the plant to bend.
Cell division is called mitosis which means that the cells multiply

2.55 Rate of Transpiration

- Transpiration is the loss of water through the leaf (caused by evaporation and diffusion through stomatal pore) 
- absorption of sunshine generates heat - transforms the water into heat 
- Concentration gradient for Water Vapour 
- if big difference then high rate of transpiration - factors: low humidity, high winds (wind blows away water vapour), high temperature (more evaporation), high light intensity ( higher rates of Photosynthesis) All result in FAST DIFFUSION 
- if small difference then low rate of transpiration - factors: high humidity, low wind speed (water vapour builds up around pore - gradient shallow), low temperature (less evaporation), low light intensity (rate of photosynthesis will be low and slow so water movement will be low and slow) 

2.54 Transpiration

• Transpiration is a process like evaporation.
• it is the loss of water vapor from parts of the plants. (similar to sweating)
• Leaf transpiration occurs through stomata.
• The openings in the stomata are what allows the vapor to escape and to allow other things in such as C02.
• Transpiration also cools plants and allows mass flow of mineral nutrients and water from the roots.

Parts of the plant and functions

- Branching root pattern increases surface area, which speeds up the rate of absorption.

- Cell wall extends, which creates a greater surface area for more intake of water.

- Epidermal also specialised to maximise surface area, again for absorption of Water.

- Active Transport of minerals at the bottom of the root hair to the xylem.

- Osmosis - from dilute region (outside) to a concentrated region (inside where the cells are full of minerals)

Images: Animal and Plant Cell table

In a write up investigation we found this graph.
This shoes the different levels of light intensity and how it affected the rate of reaction with the enzymes that are used in photosynthesis. Because the more heated light the more heat.

As you can see the blue line which is not the highest intensity gave the enzymes the most energy, but the brown line (which is the highest) is too much which is de naturing the enzyme which then doesn’t allow the enzyme to use the lock and key mechanism which slows down the reaction.

Here you can see the lock and key mechanism which is used to create the end result: sugar.
But when the heat from the sunlight reacts on this it changes its speed and the quicker the lock and key collide together the quicker it can create the sugar which then fuels photosynthesis quicker. But when it gets to hot which it shows in the first graph its starts to de nature the lock and key edges shown in this diagram:

Conclusion:
To conclude the more heat the faster the enzymes react but too much it denatures.

2.53 T1

10/10
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2.53 Root Structure

Root Hair cell:


Root Hair cell
These cells are found near to the tip of the roots.
Most water enters the root through them.
The thin hair-like extension of each cell gives a large surface for water to enter across.