IGCSE Biology glossary
Limiting factor
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
Something present in the environment in such short supply that it restricts life processes, such as the rate of photosynthesis.
What to include in an exam answer
The paying idea is that the factor is in short supply and so limits the rate; the three limiting factors for photosynthesis are light intensity, carbon dioxide concentration, and temperature. On a rate graph, the plateau means a different factor has become limiting, and naming which one earns the mark. Students lose marks saying a factor 'speeds up' the reaction rather than explaining it is the factor restricting the rate.
Example in context
Interpreting a photosynthesis graph: 'On the flat part of the curve light is no longer the limiting factor, so increasing it has no effect; carbon dioxide concentration or temperature must now be the limiting factor.'
Related syllabus topic
Plant nutrition