CAIE A-Level Biology 13.2 Investigation of Limiting Factors Question Bank

Practise limiting-factor questions by interpreting photosynthesis rate graphs, explaining light, carbon dioxide and temperature effects, and judging controls.

Exam points

identify light, carbon dioxide or temperature as limiting factors from graph plateaus
explain rate changes using photophosphorylation, Calvin-cycle CO2 fixation or enzymes
judge photosynthesis investigations using controls, oxygen output and net CO2 uptake

Covered syllabus points

13.2.1—Limiting factors 13.2.2—Effects of limiting factors 13.2.3—Chloroplast suspension investigation 13.2.4—Whole-plant photosynthesis investigation

[Maximum number: 4]

(a)

Fig. 8.1 shows how the rate of uptake of carbon dioxide by a plant varies with temperature, at an optimum intensity of light on a clear day.
rate of uptake of carbon dioxide / arbitrary units (au)

Fig. 8.1

[ 4 ]

(i)

Suggest why the rate of carbon dioxide uptake levels off and then decreases after $20^{\circ} \mathrm{C}$ .

[ 3 ]

(ii)

On Fig. 8.1, draw a curve to show the uptake of carbon dioxide on a cloudy day.

[ 1 ]

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Covered syllabus points

13.2 Investigation of Limiting Factors question 1

Question (a)

Question (i)

Question (ii)