A student investigated the effect of light intensity on the rate of photosynthesis by changing the distance between a lamp and some pondweed. Which variable must be kept the same in this investigation?
The distance between the lamp and the pondweed
The number of bubbles released in each minute
The temperature of the water around the pondweed
The volume of the gas collected from the pondweed
54 exam-style questions on AQA GCSE Biology 4.1 Photosynthesis, covering 4.1.1 Photosynthetic reaction, 4.1.2 Rate of photosynthesis, and 4.1.3 Uses of glucose from photosynthesis. Each one has a worked solution and a mark scheme showing where the marks go.