Hydrogencarbonate indicator changes colour when the carbon dioxide concentration changes. It is red at a normal carbon dioxide concentration. It turns purple when the concentration decreases and yellow when the concentration increases. A student puts a leaf in a sealed tube of red hydrogencarbonate indicator and places the tube in bright light. After 2 hours, the indicator is purple. Which statement explains this result?
The leaf used more carbon dioxide in photosynthesis than it made in respiration.
The leaf made carbon dioxide in photosynthesis, which turned the indicator purple.
The leaf respired faster in bright light, so more carbon dioxide was made.
The leaf made oxygen in respiration, which reacted with the indicator.
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.