Gas exchange in plants

Question 1

What is the process of gas exchange in leaves?

Answer 1

-Carbon dioxide/oxygen diffuses through the stomata
-Stomata is opened by guard cells
-Carbon dioxide/oxygen diffuse into the mesophyll layer into air spaces
-Carbon dioxide/oxygen diffuse down concentration gradient

Question 2

What are the adaptations of leaves for efficient gas exchange?

Answer 2

-Lots of stomata
-large surface area for gas exchange → gases do not have to pass through cells to reach the mesophyll
-Thin → short diffusion pathway
-Mesophyll cells have large surface area → rapid diffusion

Question 3

Structure of xerophytic plants that are needed for efficient gas exchange and the limitation of water loss

Answer 3

-Thick waxy cuticle → increases diffusion distance and less evaporation
-Rolled leaves → traps water vapour, water potential gradient decreases, less evaporation
-Stomata in pits/grooves → traps water vapour → water potential decreased →less evaporation

Question 4

Structural and functional compromises between opposing needs for efficient gas exchange and the limitation of water loss by insects

Answer 4

-Thick waxy cuticle → increased diffusion distance →less evaporation
- spiracles can open and close → open to let oxygen in, close when water loss too much