CAIE A Level Biology 9700 · Homeostasis
The table below shows the blood glucose concentration of a healthy individual after eating a meal at time 0.
| Time (minutes) | Blood glucose concentration (mmol dm⁻³) |
|---|---|
| 0 | 5.0 |
| 30 | 7.5 |
| 60 | 6.5 |
| 90 | 5.5 |
| 120 | 5.0 |
Explain how homeostatic mechanisms restore blood glucose concentration to its set point after this meal. In your answer, describe the roles of insulin and glucagon, and outline the cell signalling pathway by which glucagon stimulates liver cells to release glucose.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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