B2.2.5 - Transpiration stream Flashcards
What is transpiration?
The loss of water from the leaves of a plant
What is the transpiration stream?
The constant flow of water from the roots, through the xylems and out of the leaves
How does water enter the xylem?
Water diffuses from the soil into the root hairs by osmosis
What allows the stomata to open and close?
Guard Cells
How is water lost from leaves?
When the stomata is open, water evaporates from cells inside the leaf into the leaf’s air spaces. This creates a concentration gradient which leads to water vapour diffusing out
When water is lost, what happens to the pressure in the xylem vessels?
It reduces
Why do plants wilt?
If a plant loses water faster than it takes in water it may wilt
Why are the upper surface of many leaves covered in a waxy waterproof leayer?
To prevent uncontrolled water loss
