Light intensity is the only limiting factor for pondweed at both lamp positions. At 30 cm, the shoot produces 2.0 cm3 of gas in 5 minutes. The lamp is moved to 20 cm.
What volume of gas is expected in 10 minutes at 20 cm?
9.0 cm39.0\ \text{cm}^39.0 cm3
4.5 cm34.5\ \text{cm}^34.5 cm3
6.0 cm36.0\ \text{cm}^36.0 cm3
3.0 cm33.0\ \text{cm}^33.0 cm3
87 exam-style questions on Edexcel GCSE Biology 6.1 Photosynthesis, covering 6.1.1 Photosynthetic organisms as producers, 6.1.2a Limiting factors on the rate of photosynthesis, 6.1.2b Interactions of limiting factors on photosynthesis, and 6.1.3 Inverse square law and light intensity. Each one has a worked solution and a mark scheme showing where the marks go.