2.57B Understand how the rate of transpiration is affected by changes in humidity, wind speed, temperature and light intensity

how does light intensity affect rate of transpiration

• increased light intensity = increased rate of transpiration

• brighter the light —> more photosynthesis

• more of the stomata open = to let in CO2 for photosynthesis so more H2O evaporate

how does temperature affect the rate of transpiration

• higher temp = faster the rate of transpiration

• particles have more kinetic energy

• so more are likely to evaporate out the stomata

how does air flow affect rate of transpiration

• higher airflow = higher rate of transpiration

• water = continually brought up from root so high conc of water INside than OUT side

  • this provides a conc grad which means the rate of transpiration = depends on strength of conc grad

• HIGH airflow = WINDY

  • water particles = swept away once evaporated

  • conc grad is kept high

how does humidity affect rate of transpiration

• higher humidity levels = slower rate of transpiration

• humidity = measure of volume of H2O vapour in air

• more humidity = MORE H2O in the air outside the plant

  • lower conc grad so less H2O diffused