B4.9 Factors affecting transpiration Flashcards
What are the factors that affect the rate of transpiration?
Temperature
Humidity
Amount of air movement
Light intensity
How does an effect on the rate of photosynthesis affect the rate of transpiration?
Increasing the photosynthesis will increase the rate of transpiration because more stomata open up to let in carbon dioxide - therefore more water lose by evaporation and diffusion increases
Why does hot and dry conditions increase the rate of transpiration?
More water evaporates from the cells and diffusion happens quickly
Water vapour diffuses more rapidly into dry air than into humid air because the concentration gradient is steeper
How do windy conditions increase the rate of transpiration?
Windy conditions increase the rate of evaporation and also maintain a steep concentration gradient from the inside of the leaf to the outside by removing water vapour as it diffuses out
How does temperature affect the rate of transpiration?
More molecules move faster as temperature increases - so rate of diffusion increase and rate of photosynthesis increases as temperature goes up so more stomata will be open for gas exchange - therefore more water lost
How does the waxy cuticle reduce uncontrolled water loss?
It is very thick and shiny so prevents light reaching the chloroplasts
Why are most stomata found on the underside of the leaves?
Protects them from the direct light and energy of the sun
What are the problems if a plants begins to lose water faster than it is replaced?
Whole plant may wilt - wilting is a protection mechanism against further water loss. Leaves all collapse and hang down - greatly reduces the surface area available for water loss by evaporation
Stomata close which stops photosynthesis and risk overheating
What can a potometer do?
Measure the rate of transpiration in plants?
What can a potometer show?
Show the uptake of water by a plant changes in different conditions
