Factors affecting the rate of transpiration

Question 1

High temperature

Answer 1

• Increases transpiration
• Evaporation and diffusion are faster at high temperatures
• Can be varied using a fan

Question 2

High humidity

Answer 2

• Decreases transpiration
• Diffusion of water vapour out of leaves slows down if the leaf is surrounded by moist air
• Plastic bag over plant varies this factor

Question 3

Greater Air movement

Answer 3

• Increases transpiration
• Water vapour is removed quickly by air movement, speeding up diffusion
• Fan with varying speeds/distances can change this factor during experiments

Question 4

Larger Surface area

Answer 4

• Increases transpiration
• More stomata for water to evaporate/diffuse through
• Remove leaves on one plant to vary

Question 5

Light intensity

Answer 5

• increases transpiration

0 Stomata opens when it’s light, therefore allowing evaporation

• Lamp with varying bulb strength or distance can vary the factor