A fish hatchery grows small floating plants called duckweed in shallow indoor tanks. The water is cooler than the optimum temperature for photosynthesis and the lamps provide low light intensity. The hatchery warms the water towards the optimum and increases the light intensity.
Explain how these two changes increase the rate of photosynthesis of the duckweed.
The hatchery also increases the carbon dioxide concentration in the air above the tanks.
Explain how this can increase the mass of duckweed harvested.
Later, the lamps provide high light intensity. The hatchery raises the water temperature slightly while it remains below the optimum, but the rate of photosynthesis does not increase.
Suggest why.
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.