2.81 Phototropism: Describing Positive phototropism of stems

Photo referring to light.

Tropism referred to growth in response to light. Positive suggest that the growth is towards the light.

Light comes in from all direction therefore it will grow forwards.

If the light comes from the side (lateral) then the plants will bends in the growth towards the lights. (This is an example of positive tropism growth of the stems towards the lights) the light will then moves to the opposite side. This is know as  auxin which causes more growth. 

2.80 Geotropism: describing the geotropic responses of roots and stems

Geotropic referred to gravity and growth responses.
An embryonic root grows downward. This process is called Positive geotropism.
An embryonic roots grows upward is called Negative Geotropism
Shoots grow upwards and the roots grow downwards.

2.55 Rate of transpiration - Explain how the rate of transportation is effected by changes in humidity, wind speed and temperature and light intensity

Transpirtion  is a loss of water through the leaf. This is cause by evaporation.
For this process to occur its need to be change from a liquid to a gas. Diffusion will then go through the stomatal pore.
The sunshine generates the heat. The heat will then transform the water of the leaf then into the gas.
Concentration of the gradient in the water is a big difference then then it will be high rate of transpiration.
If the humidity is low then the transpiration slows down. If the humidity is high you will get more evaporation.

2.79 Plants and stimuli

stimuli: changes in the environment e.g temperature or light changes.
Receptor: Is in a plant. Its function is to detect the stimuli. After this process will turn into response.
Response: often takes the form of growth. The response between stimuli and the growth is called the tropism.
Tropism: Involves light. This process is called phototropism. 
This involves response to gravity. This process is called geotropism. 

2 54 Transpiration

Recall the transpiration in the evaporation of water from a surface of a plant. 

Evaporation will occur when go from liquid to gas. We will need Heat for this process. In addition to this heat is provided by sunlight.

Sunlight absorbed the leaf structure. So the light energy will be converted into hear.

The evaporation is through the stomatol pore.

Sunlight will have to go through the process of photosynthesis. + Not all lights will be absorbed in the chloroplast.

Above the stomatol pore there is phases change from liquid to gas à gas diffuses through the pore by a fairly steep diffusion gradient. 

2.53 How water is obsorbed by root hair cells

water uptake in the roots

• ·      Branches increase the surface area. It also absorbs water.
• ·      There are root hairs at the end of each root. You have to use microspores to see them. These roots are epidermis cell.
• ·      Root hair creates the surface area for absorption
• ·      Involves active transport of mineral + encourage plants to take up water by osmosis/ water moves from dilute to concentrated solution
• ·      Dilute is a soil of water surrounded the roots + concentrated creates to built up mineral in the cells
• ·      Water then moves in the plants to the xylem by osmosis. 

Here is an example of a root structure: