Hydrogencarbonate indicator is purple when the carbon dioxide concentration is below normal, red at a normal carbon dioxide concentration and yellow when the concentration is above normal.
Several green pea shoots are sealed in a flask containing red hydrogencarbonate indicator. The flask is kept in dim light for 40 minutes. The indicator remains red.
Which statement explains this result?
The shoots stopped both photosynthesis and respiration because the light was dim.
The shoots only respired, because photosynthesis cannot happen in dim light.
The shoots removed carbon dioxide in photosynthesis at the same rate as they released it in respiration.
Oxygen released in photosynthesis replaced the carbon dioxide used, keeping the carbon dioxide concentration normal.
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.