Transpiration Rates Flashcards
How does light intensity affect transpiration rate
The brighter the light, the greater the transpiration rate
- This is because in brighter light the stomata are open wider to let more carbon dioxide in for photosynethesus so more water is able to evaporate and transpiration increases
- In lower light intenisty photosynthesis cant happen so stomata dont need to be open to let co2 in so transpiration rate decreases
What is the affect of temperature on the rate of transpiration
- The warmer it is the fatser transpiration happens
- This is because when it is warmer water molecules have more energy to diffuse out of the stomata and evaporate out
How does humidity affect transpiration
The less humid the air the faster transpiration happens
-This is because if the air is less humid there is a lower water potential ouyptside the leaf so lots of water can move from the higher water potential inside the leaf to the lower water potential outside the leaf
How does wind intensity affect transpiration rate
As wind intensity increases the transpiration rate increases
-This is because the high wind intesnity removes water molecules wuickly from outside the leaf so there is a lower water potential outside the leaf. This means that water can diffuse from inside the plant to outside as there is a low water potential outside the leaf
What happens when the plant has lots of water
When the plant has lots of water the gaurd cells fill will water and become turgid . This makes the stomata open so gasses can be exchanged for photosynthesis
What happens when the plant is short of water
When the plant is short of water the guard cells lose water and become flaccid , making the stomata close. This helps to stop too much water vapour escaping
How do guard cells open and close
Guard cells have unevenely thickened cell walls(thin outer walls and thick inner walls )
This allows them to change shape/ bend when they gain water by osmosis
Where are most stomata located and why are they located here
Most of the stomata are located on the underside of the leaf.This is because it is cooler here and the stomata are nit exposed to direct sunlight so temperature is not as high and therefore transpiration rate is not as high
What mechanisms might the plant use to prevent water loss
- The whole plant may wilt . Wilting is a protection measure against water loss.Tjhe leaves all may collapse and hng down.This greatly reduces the surface area avaliable for water loss by evaporation
- stomata may also close
