The respiratory quotient (RQ) of different respiratory substrates can be calculated using the formula:
RQ=Volume of carbon dioxide producedVolume of oxygen consumed \text{RQ} = \frac{\text{Volume of carbon dioxide produced}}{\text{Volume of oxygen consumed}} RQ=Volume of oxygen consumedVolume of carbon dioxide producedThe table below gives the standard RQ values for three pure respiratory substrates:
| Substrate | Standard RQ value |
|---|---|
| Carbohydrate | 1.0 |
| Protein | 0.8 |
| Lipid | 0.7 |
During an investigation into the respiration of a culture of germinating pea seeds, the following volumes of gases were recorded over a 24-hour period:
Calculate the RQ for this seed sample and suggest which combinations of respiratory substrates were being used.
113 exam-style questions on OCR GCSE Biology 1.3 Respiration, covering 1.3.1 Cellular respiration supplies ATP, 1.3.2 Aerobic and anaerobic respiration, 1.3.3 Sugars and carbohydrates, 1.3.4 Amino acids and proteins, and 1.3.5 Fatty acids and lipids. Each one has a worked solution and a mark scheme showing where the marks go.