transpiration

Question 1

Name the 5 factors affecting the rate of transpiration

Answer 1

light intensity
Temperature
Humidity
Air movement
Water availability

Question 2

Light intensity

Answer 2

high light intensity will increase the rate of transpiration
In light, the stomata open (wider) to allow gaseous exchange for photosynthesis

Question 3

Temperature

Answer 3

High temperatures increase the rate of transpiration
-increases the rate of evaporation from the cell surface so the water vapour potential in the leaf increases and the relative water vapour potential in the air decreases which allows for more rapid diffusion of molecules out of the leaf
-increases the rate of diffusion through the stomata because water molecules have more kinetic energy

Question 4

Humidity

Answer 4

-lower relative humidity increases the rate of transpiration
-there will be a larger water potential gradient between the air spaces in the leaf and the air outside

Question 5

Air movement

Answer 5

more air movement increases the rate of transpiration
-air moving outside the leaf will carry away water vapour that has just diffused out of the leaf which will maintain a high water vapour potential gradient.

Question 6

Water availability

Answer 6

-A greater water availability will increase the rate of transpiration
-The plant can easily replace the water lost
-If there is insufficient water in the soil than the stomata close, and the leaves wilt
-guard cells remain turgid, and the stomata remain open

Question 7

Why is transpiration slower/lower at night?

Answer 7

-low light intensity so the stomata will be closed because of plant cannot photosynthesise when light is not present
-lower temperatures because a lower rate of evaporation mean to water molecules have less kinetic energy so diffusion is slower

Question 8

Process of transpiration