Living onion bulb cells were placed in a sealed flask containing glucose solution. The concentrations of oxygen and carbon dioxide in the flask were measured.
| Time / hours | Oxygen concentration / % | Carbon dioxide concentration / % |
|---|---|---|
| 0 | 20.9 | 0.0 |
| 4 | 0.0 | 19.8 |
| 6 | 0.0 | 22.6 |
A student says that the cells respired only aerobically, because carbon dioxide was detected.
Explain why the student is wrong. Use the results to explain whether aerobic and anaerobic respiration could have occurred during the six hours, and suggest one substance that could be tested for as further evidence of anaerobic respiration.
98 exam-style questions on Edexcel GCSE Biology 8.3 Respiration, covering 8.3.1 Aerobic and anaerobic respiration. Each one has a worked solution and a mark scheme showing where the marks go.