4.9 Factors affecting transpiration

Question 1

What factors affect transpiration

Answer 1

Temperature, humidity, wind and light intensity

Question 2

How does temperature affect transpiration

Answer 2

Increasing temperature increases the kinetic energy of the molecules. this makes diffusion, osmosis and evaporation happen faster

Question 3

How does wind affect transpiration

Answer 3

Wind blows water vapour away from stoma keeping conc gradient high

Question 4

How does humidity affect transpiration

Answer 4

When the air is humid there is more water vapour in it. Humaid air is less able to accept more water molecules by evap

Question 5

How does light intensity affect transpiration

Answer 5

Light causes stoma to open. wider stroma can allow faster diffusion of water out of the leaf

Question 6

what is transpiration

Answer 6

loss of water by evap from plants

Question 7

How to work out transpiration rate

Answer 7

distance travelled by the bubble/ time taken

Question 8

How are plants adapted to help lose as little water as possible?

Answer 8

• waxy waterproof layer to prevent uncontrolled water loss
• in hot environments, cuticle may be thick and shiny
• stomata found on the underside of the leaf to protect them from the direct light and heat of the sun

Question 9

What happens if plant loses water faster than it is being replaced?

Answer 9

• whole plant may wilt. Wilting is a protection mechanism against further water loss. Leaves collapse and hang down which greatly reduces the surface area available for water loss by evaporation
• stomata close, which stops photosynthesis and risks overheating. This prevents most water loss and any further wilting