A technician shines a lamp on an algal culture. The lamp is initially 18 cm from the culture, which produces oxygen at a rate of 0.48 cm3 min-1.
The technician moves the lamp until the rate of oxygen production is 0.12 cm3 min-1.
Light is the limiting factor at both distances, and the rate of oxygen production is directly proportional to the light intensity. Temperature and carbon dioxide concentration remain constant.
Light intensity is inversely proportional to the square of the distance from the lamp.
Calculate the new distance between the lamp and the algal culture.
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.