Why does the rate of photosynthesis fall at high temperatures?
At high temperatures the rate of photosynthesis falls because the enzymes that control the reactions denature.
GCSE Biology
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In more detail
Photosynthesis is controlled by enzymes. As temperature rises the rate increases at first, but above the optimum the extra heat breaks the bonds holding the enzymes’ active sites in shape. The enzymes denature, so the reactions slow down and the rate of photosynthesis falls.
Key points for the exam
- Photosynthesis is enzyme-controlled.
- Above the optimum, enzymes denature → active site changes shape → rate falls.
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