Multicellular Organisms - Transpiration Flashcards
1
Q
Explain the process of transpiration
A
- Water molecules move cell to cell by osmosis.
1. Water enters root hairs, crosses the root cortex by osmosis.
2. Water enters xylem then is drawn up the xylem in the transpiration stream
3. Water moves along the xylem into the leaf, where it evapourates into airspaces between the spongy mesophyll cells, creating vapour
4. Stomata open for the vapour to diffuse in the air.
water loss = transpiration
2
Q
- Define transpiration
- List the parts of plants involved in transpiration
- What do plants use water for?
A
Process of water moving through a plant and its evapouration through the stomata on the underside of the leaves
* Root hairs
* Xylem
* Spongy mesophyll
* Guard cells
* Stomata
First stage of photosynthesis, keeping cool in the sun
3
Q
List the 5 factors that affect the rate of transpiration
A
- Light
- Temperature
- Wind Speed
- Humidity
- Surface area
4
Q
Describe light as a factor that affects the rate of transpiration
A
- Increased light intensity? → rate increases
- Stomata opens wider for more CO2 to enter the leaf for photosynthesis
5
Q
Describe temperature as a factor that affects the rate of transpiration
A
- Increased temperature? → rate increases
- Evapouration and diffusion are faster at high temperatures
6
Q
Describe wind speed as a factor that affects the rate of transpiration
A
- Increased wind speed? → rate increases
- Water vapour is removed quickly by the air movement, speeding up diffusion of water vapour out the leaf
7
Q
Describe humidity as a factor that affects the rate of transpiration
A
- Increased humidity? → rate decreases
- Diffusion of water vapour slows if the leaf is already surrounded by moist air
8
Q
Describe surface area as a factor that affects the rate of transpiration
A
- Increased surface area? → rate increases
- Larger leaf area = more stomata, so more water will be evapourating and diffusing away from the plant.
