The lower leaves in a dense crop canopy are shaded by the leaves above them. At midday, a grower increases the carbon dioxide concentration around the lower leaves without changing the light intensity or temperature.
The grower concludes: 'Extra carbon dioxide will make these shaded leaves photosynthesise faster.'
Which is the best evaluation of the grower's conclusion?
Correct, because carbon dioxide is joined with hydrogen when glucose is built.
Incorrect, because shaded leaves only respire and do not photosynthesise at all.
Correct, because carbon dioxide is normally the limiting factor at midday.
Incorrect, because light may remain limiting in the shaded lower leaves.
117 exam-style questions on OCR GCSE Biology 1.4 Photosynthesis, covering 1.4.1 Photosynthesisers as biomass producers, 1.4.2 Factors affecting the rate of photosynthesis, and 1.4.3 Limiting factors in photosynthesis. Each one has a worked solution and a mark scheme showing where the marks go.