A technician compares the rate of photosynthesis of matching bean leaves. Each leaf is sealed inside a transparent flask, and the volume of carbon dioxide used in five minutes is measured at several distances from a lamp. Which modification should the technician make to stop heating by the lamp affecting the comparison?
stand each flask in a large beaker of water and check the temperature at every distance
carry out every measurement in a darkened room so that no daylight reaches the leaves
keep the lamp at the greatest distance throughout so that it heats each leaf less
wrap each flask in aluminium foil so that heat from the lamp is reflected away
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.