Chapter 4.9 Factors affecting transpiration

Question 1

What do factors that increase the rate of photosynthesis or increase stomatal opening also increase? and what do they include?

Answer 1

They will increase the rate of transpiration. They include:

• Temperature
• Humidity
• Air flow
• Light intensity

Question 2

When is transpiration quickest?

Answer 2

Transpiration is more rapid in hot, dry, windy, or bright conditions.

Question 3

What is the definition of transpiration?

Answer 3

The exhalation of water vapour through the stomata.

Question 4

What type of protection does the plant make when it loses water fast?

Answer 4

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

Question 5

What is the waxy waterproof layer on the leaf of the plant? and what does it prevent?

Answer 5

This is called the cuticle which prevents uncontrolled water loss.

Question 6

How can we measure transpiration rates?

Answer 6

We can use a piece of equipment called a potometer which can be used to show how the uptake of water by a plant changes in different conditions.