Limiting water loss in plants

Question 1

Describe xerophytic adaptations

Answer 1

The leaves are covered in waxy waterproof layers to reduce water loss, the stomata can close and structural adaptations which allows them to survive in dry conditions by reducing transpiration or storage. Such as marram grass.

Question 2

How is the stomata adapted?

Answer 2

Closes in the daylight and at higher temperatures, they’re confined to the underside of the leaf where it’s cooler and less heat vaporisation. They’re sunken in pits so that water vapour is held above the stomatal pore, reducing wp gradient between air spaces and the atmosphere. Lower rate of diffusion, less transpiration occurs.

Question 3

How does a reduction in SA:V of leaves limit water loss?

Answer 3

Smaller ratio= slower rate of diffusion. Some have spines rather than broad, flat leaves

Question 4

How does the waxy cuticle limit water loss?

Answer 4

The wax reduces water loss from the epidermis so there’s greater thickness which increases the diffusion pathway and decreases rate of diffusion through water cuticle.

Question 5

How does trapped humid air with high water potential limit water loss?

Answer 5

Reduces water potential between air spaces and atmosphere, lower rate of diffusion from stomata

Question 6

What’s on the lower epidermis of the leaf and why does it limit water loss?

Answer 6

Hairs, which trap water vapour and reduce wp gradient between air and the atmosphere, lower rate of diffusion, less transpiration