Two pondweed shoots, P and Q, are tested at a lamp distance of 20 cm. Each releases 3.0 cm3 of gas in 5 minutes. P has twice the mass of Q. All other conditions are controlled.
The lamp is moved to 40 cm. Light intensity is the only limiting factor at both distances.
Which prediction is correct for gas produced in 5 minutes at 40 cm?
Each releases 0.75 cubic centimetres; P has twice the rate per gram.
Each releases 1.50 cubic centimetres; P has twice the rate per gram.
Each releases 0.75 cubic centimetres; Q has twice the rate per gram.
Each releases 1.50 cubic centimetres; Q has twice the rate per gram.
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.