13.4 Gas exchange in the leaf of a plant

Question 1

Two beneficial features for gas exchange?

Answer 1

• No living cell is far from surface.

- Diffusion takes place in air rather than water - more rapid.

Question 2

Three leaf features for gas exchange?

Answer 2

• Thin, flat shape providing a large surface area.
• Many small pores called STOMATA.
• Lots of interconnecting air spaces throughout the mesophyll.

Question 3

STOMATA. Where do they occur?

Answer 3

Mostly on lower epidermis of leaves.

Question 4

STOMATA. Why are guard cells important?

Answer 4

Because they can open and close the stomata to control rate of gas exchange. Plants also lose water by evaporation, this means they can shut stomata at times where water loss would be excessive.