AQA practicals – Effect of light intensity on the rate of photosynthesis

Investigate the effect of light intensity on the rate of photosynthesis using an aquatic organism such as pondweed.

Use appropriate apparatus to record the rate of production of oxygen gas produced.
Measure and control the temperature of water in a large beaker that acts as a ‘heat shield’.
Use a thermometer to measure and control temperature of water bath.
Use appropriate apparatus and techniques to observe and measure the process of oxygen gas production.
Safe and ethical use and disposal of living pondweed to measure physiological functions and responses to light.
Measuring rate of reaction by oxygen gas production.


Plan experiments to test hypotheses.
Recognise that multiple samples will be needed at each light intensity.
Make and record observations of gas production.
Present a graph of light intensity against rate of photosynthesis.
Translate numeric data into graphical form.
Measure and understand the rate of photosynthesis reactions.
Plot and draw appropriate graphs of rate of photosynthesis against light intensity selecting appropriate scale for axes.
(HT) – Understand and use inverse proportion: the inverse square law and light intensity in the context of photosynthesis.

Typical questions