Describe the roles of insulin and glucagon in maintaining a stable blood glucose concentration. Include in your answer how each hormone brings about its effect.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
The pancreas produces hormones that work together to keep blood glucose levels within a narrow range. This is an example of homeostasis.
Model answer (5 marks)
Insulin is released by the pancreas when blood glucose is high.
1. It stimulates cells, especially muscle and adipose, to take up glucose from the blood.
2. It promotes the conversion of glucose into glycogen in the liver for storage.
Glucagon is released when blood glucose is low.
3. It signals the liver to break down glycogen into glucose.
4. The glucose is released into the blood, raising its concentration.
These actions keep blood glucose within a narrow range.
1. It stimulates cells, especially muscle and adipose, to take up glucose from the blood.
2. It promotes the conversion of glucose into glycogen in the liver for storage.
Glucagon is released when blood glucose is low.
3. It signals the liver to break down glycogen into glucose.
4. The glucose is released into the blood, raising its concentration.
These actions keep blood glucose within a narrow range.
Examiner tips
- Use the exact terms ‘insulin’ and ‘glucagon’ and state when each is released. Show the two main effects of insulin and the single effect of glucagon. Keep the answer concise – 5 marks can be earned with 4–5 short points.
Common mistakes
- Mixing up the timing of hormone release (e.g. saying glucagon is released when glucose is high). Failing to mention the liver’s role in glycogen storage or breakdown. Using vague language such as ‘helps cells’ without specifying glucose uptake.
Mark scheme (5 marks)
- Insulin is produced/released by the pancreas when blood glucose concentration is too high
- Insulin causes glucose to be taken up into cells / allows cells to absorb more glucose
- Insulin causes the liver to convert glucose into glycogen for storage
- Glucagon is produced/released by the pancreas when blood glucose concentration is too low
- Glucagon causes the liver to convert glycogen back into glucose, increasing blood glucose concentration
Key terms in this question
insulin · glucagon · blood glucose concentration
Related
- All WJEC A-Level Biology (Wales) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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