Transpiration Practical

Question 1

Factors affecting transpiration: Light intensity

Answer 1

• Lighter it is, faster the transpiration rate.
• More light means more photosynthesis so stomata is open as oxygen is required.
• But water leaves so transpiration increases.

Question 2

Factors affecting transpiration: Temperature

Answer 2

• Higher the temp. faster the transpiration rate.
• Warmer water mol. have more energy so they evaporate faster.
• This increases water pot. between leaf and outside of leaf so water diffuses faster.

Question 3

Factors affecting transpiration: Humidity

Answer 3

• Lower the humidity, faster the transpiration.
• More humid the environment, lower the water pot. gradient between inside and outside leaf so less transp. as diffusion is lower.

Question 4

Factors affecting transpiration: Wind

Answer 4

• More windier it is, faster the transpiration rate.
• Lots of sir movement blows away water molecules from around the stomata.
• This increases water pot. gradient.

Question 5

Using potometers

Answer 5

• Potometer measures water uptake by a plant and it is assumed that water uptake is directly related to water loss.
• Potometer creates a sealed environment with water which can be used to measure water uptake based on how far an air water meniscus moves over time.
• Must be assembled underwater and sealed with waterproof jelly like Vaseline to keep it airtight.
• Any air that gets it will break transpiration stream’s cohesive forces and stops transpiration pull.
• Dry the leaves
• Only change one factor and keep other condition constant
• Cut at slant to increase SA for water uptake