A loose mat of filamentous green algae lies at the bottom of a transparent tank containing water. In darkness, the mat remains at the bottom. After a bright light is switched on, small gas pockets form between the strands and the mat gradually rises to the surface.
Explain why the mat moves upwards after the light is switched on.
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.