IGCSE Biology glossary
Transpiration
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
The loss of water vapour from the leaves of a plant, mainly through the stomata, as water evaporates from the surfaces of mesophyll cells.
What to include in an exam answer
Two details earn marks: water vapour (not liquid water) and through stomata. Factor questions (temperature, humidity, wind speed) want explanations in terms of evaporation rate and diffusion gradients, not just 'it gets faster'.
Example in context
Explaining water loss on a hot day: 'Water evaporates from the mesophyll cell surfaces and the water vapour diffuses out through the open stomata. This is transpiration.'
Related syllabus topic
Transport in plants