Transpiration Flashcards
What features of a plant affect the rate of transpiration?
Number of leaves
Number, size and position of the stomata
Presence of cuticle
What environmental factors affect the rate of transpiration?
Light Temperature Relative humidity Air movement or wind Water availability
What are the special type of plants called?
Xerophytes
What adaptations do xerophytes have to live in arid conditions? (8)
Leaves shaped like needles Densely packed spongy mesophyll Thick waxy cuticles Closing stomata when water availability is low Hairs on the surface of the leaf Pits containing stomata at their base Rolled leaves Low water potential in the leaf
Needle shaped leaves
Reduces total SA of the leaves- less water is lost by transpiration.
Densely packed spongy mesophyll
Reduces cell SA that is exposed to the air inside the leaves. Less water will evaporate into the leaf air space.
Thick waxy cuticle
Reduces evaporation further.
Closing the stomata when water availability is low
Reduce the water loss and so reduce the need to take up water.
Hairs on the surface of the leaf
Traps a layer of air close to the surface. This air can become saturated with moisture and will reduce the diffusion of water vapour out through the stomata.
Pits
Trap air that can become saturated with water vapour. Reduces water potential gradient.
Rolled leaves
Lower epidermis is not exposed to the atmosphere can trap air that becomes saturated.
Low water potential inside the leaf
Maintaining a high salt concentration in the cells.
