Practise identifying the limiting factor from graph gradients, plateaus and paired conditions, then justify whether light, carbon dioxide or temperature constrains the rate.
The effect of carbon dioxide concentration on the rate of oxygen production in an aquatic plant was measured.
- A lamp was used to keep the light intensity constant.
- The oxygen gas released by the plant was collected in a gas syringe.
- The plant was placed in water that was kept constant at 20∘C.
Fig. 4.2 shows the results.
Explain the results shown in Fig. 4.2.
1 carbon dioxide is required for photosynthesis ;
2 initially carbon dioxide concentration is limiting the rate of photosynthesis ;
3 (after 500μ mol per dm3 ) carbon dioxide concentration is not limiting the rate of photosynthesis / other factors are limiting the rate of photosynthesis ;
4 ref. to named limiting factor ;