Phototropism: example

2.79-2.81

Stimuli = changes in the environment (temperature, light etc.)
-The plant has receptors which can detect the stimuli.
-The response takes the form of growth
                  This type of response is called a tropism
1) Photo tropism
- This is the growth response due to light (the plant grows towards the light)
- Auxin is a hormone which causes more growth on the side of the plant which causes bending
2). Geotropism
-This is the growth response due to gravity
-        Positive Geotropism= the embryonic root grows down into the ground
         Negative Geotropism= the embryonic shoot grows upwards

-To prove this, if you turn the seed sideways the shoot will still grow upwards and the root downwards

2.54 Transpiration

                heat
Liquid    -------->     Gas
              sunlight


-Evaporation happens through the stomatal pores


-Not all of the light is absorbed by the chloroplast, some will be absorbed by the other cell structure and generates heat


-The water is brought in by the xylem


-Just above the stomatal pores is where the liquid changes into a gas


-Gas diffuses through the stomatal pores (by steep diffusion gradient)

2.53 the uptake of water

Water is absorbed by root hair cells which have a branching pattern
The roots have root hairs which are designed to have a large surface area therefore it is more efficient for water intake
Minerals go into the plant via active transport
Water goes into the plant via Osmosis
Water moves across the cortex of the root to the xylem (through osmosis)