Scientists investigate how a substance affects the control of breathing. They vary the concentration of dissolved carbon dioxide in each participant's blood and measure the mean breathing rate before and after giving the substance.
| Dissolved carbon dioxide concentration in mmol/dm³ | Mean breathing rate before the substance in breaths per minute | Mean breathing rate after the substance in breaths per minute |
|---|---|---|
| 0.9 | 10 | 10 |
| 1.2 | 14 | 11 |
| 1.5 | 20 | 12 |
A scientist concludes that the substance acts directly on the medulla and reduces its response to changes in dissolved carbon dioxide.
Evaluate the scientist's conclusion. In your answer, use the data and suggest how the substance would affect the control of breathing while a participant is asleep.
135 exam-style questions on OCR GCSE Biology 3.1 Coordination and control – the nervous system, covering 3.1.1 Structure of the nervous system, 3.1.2 Coordinated response, 3.1.3 The reflex arc, 3.1.4 Structure of the eye, 3.1.5 Defects of the eye, 3.1.6 Structure and function of the brain, 3.1.7 Difficulties of investigating brain function, and 3.1.8 Limitations in treating nervous system damage. Each one has a worked solution and a mark scheme showing where the marks go.