Gas Exchange in Plants

Question 1

Explain why plants have a reduced need for gas exchange with the air than animals

Answer 1

they produce oxygen during photosynthesis which can be used in respiration

Question 2

Describe gas exchange in a plant when photosynthesis is taking place

Answer 2

carbon dioxide enters from the air, oxygen diffuses out of the plant

Question 3

Describe gas exchange in a plant when photosynthesis is not taking place

Answer 3

oxygen diffuses into the leaf for respiration, carbon dioxide diffuses out

Question 4

Explain how there is a short, fast diffusion pathway in plants

Answer 4

short - cells are close to external air

fast - diffusion takes place in gas phase (not liquid)

Question 5

How do plants ensure a large surface area:volume?

Answer 5

air spaces inside the leaf

Question 6

Describe 3 adaptations of a leaf for rapid diffusion

Answer 6

many stomata - short diffusion pathway
air spaces in mesophyll - gases in close contact with cell
large surface area of mesophyll cells

Question 7

Describe the conflict between gas exchange and water loss in plants

Answer 7

plants need stomata open to exchange gases during photosynthesis but also loss more water when stomata are open