Reducing Water Loss
- Created by: Eleanor Izzard
- Created on: 02-01-13 13:28
View mindmap
- Reducing Water Loss
- Xerophytes
- some plants are well adapted to living in very dry or arid conditions
- Many Adaptations to reduce water loss from their leaves
- densely packed spongy mesophyll reduces the cell surface area that is exposed to the air inside the leaves, less water will evaporate into theleaf air spaces
- smaller leaves, particularly shaped like needles, reducing the total surface area of the leaves, so less water is lost
- thicker waxy cuticle
- hair on the surface of the leaves trap a layer of air close to the surface
- this air can become saturated with moisture and will reduce the diffusion of water vapour out of the stomata (water potential vapour gradient reduced)
- Pits with stomata at their base trap air too
- this air can become saturated with moisture and will reduce the diffusion of water vapour out of the stomata (water potential vapour gradient reduced)
- Pits with stomata at their base trap air too
- Rolling the leaves so the lower epidermis is not exposed to the atmosphere can trap saturated air
- this air can become saturated with moisture and will reduce the diffusion of water vapour out of the stomata (water potential vapour gradient reduced)
- this air can become saturated with moisture and will reduce the diffusion of water vapour out of the stomata (water potential vapour gradient reduced)
- some plants have a low water potential in their leaves, by maintaining high salt concentration in the cells
- reduces the evaporation of water from the cell surfaces as the water potential gradient between the cells and the leaf air spaces is reduced
- Marram Grass
- specialises in living in sand dunes, where the water in the sand drains away quickly and may be salty, leaves may be exposed to very windy conditions
- leaf rolled up to trap air inside
- hairs on lower surface reduce movement of air
- thick waxy cuticle to reduce water evaporation from surface
- trapped air in centre with high vapour potential
- stomata in pits to trap air with moisture close to stomata
- Unavoidable Loss
- Plants exchange gases with their environments via stomata, so water can always be lost through them when they are open during the day
- most plants can reduce losses by structural and behavioural adaptations
- stomata are often found on the underneath of the leaf, not the top. Reducing Evaporation due to direct heating from the sun
- a waxy cuticle on the leaf
- most stomata are closed at night, when there is no light for photo-synthesis
- deciduous plants lose their leaves during winter, when the ground may be frozen (less water available) or when temperatures may be too low for photo-synthesis
- Xerophytes
Comments
No comments have yet been made