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.
A moist moss plant and some red hydrogencarbonate indicator are placed in an airtight jar. The jar is kept at a low light intensity. After two hours, the indicator is yellow.
Which statement explains this result?
The first stage of photosynthesis split water and released carbon dioxide into the jar.
The moss broke down stored starch into carbon dioxide during photosynthesis.
The moss stopped respiring in low light, so carbon dioxide was no longer being used up.
Respiration added carbon dioxide to the jar faster than photosynthesis removed it.
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.