Explain how the body maintains blood glucose concentration within a narrow range after a carbohydrate-rich meal.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Rising blood glucose after a carbohydrate‑rich meal is detected by beta cells in the islets of Langerhans in the pancreas.
Beta cells secrete insulin into the blood in response to the elevated glucose.
Insulin acts on body cells, especially liver and muscle cells, to take up glucose and stimulate glycogenesis (conversion of glucose to glycogen).
This negative‑feedback loop restores blood glucose to the set point, reducing the stimulus for further insulin release.
Beta cells secrete insulin into the blood in response to the elevated glucose.
Insulin acts on body cells, especially liver and muscle cells, to take up glucose and stimulate glycogenesis (conversion of glucose to glycogen).
This negative‑feedback loop restores blood glucose to the set point, reducing the stimulus for further insulin release.
Examiner tips
- Use the word ‘negative feedback’ to show understanding of the control mechanism.
- Mention the key organs (pancreas, liver, muscle) and the hormone (insulin).
- Show the sequence: detection → hormone release → cellular response → return to set point.
Common mistakes
- Failing to name the beta cells or the pancreas as the detector.
- Omitting the role of insulin or the conversion to glycogen.
- Not identifying the process as negative feedback.
Mark scheme (4 marks)
- Rising blood glucose is detected by beta cells in the islets of Langerhans in the pancreas
- Beta cells secrete insulin into the blood in response to elevated blood glucose
- Insulin causes body cells (particularly liver and muscle cells) to take up glucose / stimulates conversion of glucose to glycogen (glycogenesis)
- This is an example of negative feedback — blood glucose is restored to the set point / normal range, reducing the stimulus for further insulin release
Key terms in this question
Related
- All IB DP Biology Standard Level (2023 syllabus) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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