Describe transpiration in three steps.
Reveal answer
Water evaporates from mesophyll cells → into air spaces → water vapour diffuses out through stomata.
Key words: evaporates · stomata
3(h) TRANSPORT · RECALL
3.6B Transpiration
15 recall questions · Biology only (B): not in Science (Double Award). Answer from memory, reveal the answer, then rate yourself. Ratings stay on this device.
Ratings are saved in this browser on this device, under a KS4 key kept separate from International A Level recall. Written answers are temporary and cleared when you leave the page. Use Reset to clear the ratings on this device.
What is the flow of water from roots to leaves called?
Reveal answer
The transpiration stream.
Key words: transpiration stream
What apparatus measures water uptake by a shoot?
Reveal answer
A potometer.
Key words: potometer
Why is the potometer shoot cut underwater?
Reveal answer
Stops air entering xylem → no air lock → water uptake continues.
Key words: air · xylem
Which leaf surface loses most water?
Reveal answer
The lower surface (more stomata).
Key words: lower
How does transpiration cool a leaf?
Reveal answer
Water evaporates → takes heat energy from the leaf → leaf cools.
Key words: evaporates
Why does a potometer not measure transpiration exactly?
Reveal answer
Some water taken up is used in photosynthesis or kept in cells → uptake ≠ loss.
Key words: photosynthesis
What is meant by the term transpiration stream?
Reveal answer
Continuous movement of water from roots through xylem to leaves.
Key words: transpiration stream
Stages of leaf water loss: for Xylem to mesophyll, give the state/process and the location.
Reveal answer
State/process: Liquid water movement. Location: Leaf veins and cells.
Key words: Xylem to mesophyll
Stages of leaf water loss: for Cell wall to air space, give the state/process and the location.
Reveal answer
State/process: Evaporation. Location: Moist mesophyll surface.
Key words: Cell wall to air space
Stages of leaf water loss: for Air space to atmosphere, give the state/process and the location.
Reveal answer
State/process: Diffusion of water vapour. Location: Through stomata.
Key words: Air space to atmosphere
Stages of leaf water loss: for Replacement from roots, give the state/process and the location.
Reveal answer
State/process: Mass flow under tension. Location: Xylem.
Key words: Replacement from roots
True or false, and why? “Transpiration is water moving up xylem.”
Reveal answer
False. It is evaporation from plant surfaces; xylem flow replaces lost water.
True or false, and why? “Water leaves as liquid droplets through stomata.”
Reveal answer
False. It normally leaves as water vapour.
True or false, and why? “All water loss is useless.”
Reveal answer
False. It accompanies gas exchange, moves minerals and can cool leaves.