4.9Factors affecting transpiration Flashcards
Parts of the leaf that help the plant reduce water loss under normal conditions are (2)
waxy cuticle
guard cells
Explain the effects of a fan blowing onto the leaves of the plant
-better airflow = greater transpiration rate
-water vapours are swept away maintaining a low concentration in the air outside the leaf.
Diffusion will happen quickly from an area of high concentration to an area of low concentration
Describe the effect on transpiration if the TOP of a left is coated with petroleum jelly?
rate of transpiration slightly reduced. Petroleum jelly on top surface has little effect as few stomata covered (most are on the bottom of the leaf).
Describe the effect on transpiration if the BOTTOM of a left is coated with petroleum jelly?
-rate of transpiration greatly reduced.
-Most stomata are found on the bottom of leaves therefor transpiration is greatly reduced as most of stomata would be covered, allowing little diffusion to take place. Rate of evaporation from cell surfaces would be reduced as surrounding air would become saturated with water vapour (decreasing
concentration gradient)..
Why do water lilies have stomata on the top of their leaves?
Stomata on underside would be under water and water could not be lost through them.
Stomata on top surface enable effective gas exchange for photosynthesis through direct exposure to sunlight
What does a photometer do?
Investigates the effects of different factors on the rate of transpiration in plants.
What happens if plants lose water faster than it is replaced by the roots?
- It will wilt
2 Stomata close= stop photosynthesis and risk overheating
What effect does humidity have on transpiration?
Drier air around the leaf=faster transpiration happens.
If the air is humid there is a lot of water in it already so not much difference between inside and outside of the leaf.
Diffusion happens faster if there is high concentration in one place and low in other.
What happens to water vapours in regards to transpiration if the airflow is poor?
Water vapours just surround the leaf and don’t move = high concentration of water outside and inside leaf so diffusion doesn’t happen quickly.
What effect does the airflow have on transpiration?
better airflow around the leaf (eg. stronger winds) the greater transpiration rate
What happens to stomata at night time and what is the result?
Stomata close
- little water can escape the plant
What are the 4 factors that affect transpiration?
Light intensity
temperature
air flow
humidity
What effect does temperature have on transpiration?
warmer it is faster transpiration happens as it gets warmer
-water particles =more energy to evaporate and diffuse out of the stomata
What happens as the light gets brighter in transpiration?
- greater transpiration rate
- stomata close as it gets dark and photosynthesis can’t happen in the dark.
- which result in little water escaping
