A teenager is diagnosed with Type 1 diabetes. Their pancreas no longer produces insulin. Explain why the absence of insulin causes blood glucose levels to remain dangerously high after eating a meal, and describe how insulin injections help to restore normal blood glucose levels.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Type 1 diabetes is an autoimmune condition in which the immune system destroys the insulin-producing cells of the pancreas. People with Type 1 diabetes must inject insulin before meals to manage their blood glucose levels.
Model answer (5 marks)
After a meal glucose is absorbed into the blood, raising glucose concentration.
Normally the pancreas releases insulin when blood glucose is high.
Insulin binds to receptors on liver and muscle cells, stimulating glucose uptake and conversion to glycogen, thereby lowering blood glucose.
Without insulin, cells cannot take up glucose, so glucose remains in the blood and is not stored as glycogen.
Injecting insulin replaces the missing hormone, enabling cells to absorb glucose and return the blood glucose level to normal.
Normally the pancreas releases insulin when blood glucose is high.
Insulin binds to receptors on liver and muscle cells, stimulating glucose uptake and conversion to glycogen, thereby lowering blood glucose.
Without insulin, cells cannot take up glucose, so glucose remains in the blood and is not stored as glycogen.
Injecting insulin replaces the missing hormone, enabling cells to absorb glucose and return the blood glucose level to normal.
Examiner tips
- Use the exact sequence: absorption → insulin release → uptake & storage → effect of absence → injection restores function.
- Show cause–effect links and mention specific tissues (liver/muscle).
Common mistakes
- Confusing insulin with glucagon; writing that insulin raises glucose.
- Failing to mention that glucose cannot be stored as glycogen without insulin.
Mark scheme (5 marks)
- After eating, glucose from digested food is absorbed into the blood, raising blood glucose levels
- Normally insulin is released from the pancreas in response to high blood glucose
- Insulin causes cells (liver / muscle cells) to take up glucose from the blood, lowering blood glucose concentration
- Without insulin, cells cannot take up glucose, so blood glucose remains high / glucose is not converted to glycogen
- Injecting insulin acts as a replacement hormone, allowing cells to take up glucose and blood glucose levels to return to normal
Key terms in this question
insulin · pancreas · blood glucose
Related
- All OCR A-Level Biology B — Advancing Biology (H422) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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