A patient with type 1 diabetes cannot produce insulin. Explain how insulin normally controls blood glucose concentration in a healthy person, and why maintaining a constant blood glucose concentration is important for the body's cells.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Blood glucose concentration in a healthy person is kept within a narrow range. In type 1 diabetes, the cells of the pancreas that produce insulin are destroyed by the immune system.
Model answer (5 marks)
After a meal blood glucose rises. The pancreas senses this and secretes insulin into the blood. Insulin signals the liver (and muscle cells) to take up glucose and convert it into glycogen for storage. This reduces the glucose level back to normal – a negative‑feedback loop. Cells require a constant supply of glucose for respiration; too much or too little glucose would disturb cellular processes and damage cells.
Examiner tips
- Use the sequence: rise → detection → insulin release → glycogen synthesis → return to normal. Include the negative‑feedback phrase. Mention cells need glucose for respiration and that imbalance causes damage.
Common mistakes
- Failing to mention insulin’s role in glycogen synthesis. Writing that glucose is "used up" without specifying storage. Omitting the negative‑feedback explanation.
Mark scheme (5 marks)
- After a meal, blood glucose concentration rises / increases
- The pancreas detects the rise and releases / secretes insulin into the blood
- Insulin causes the liver (and muscle cells) to convert excess glucose into glycogen for storage
- This lowers / returns blood glucose concentration to the normal level (negative feedback)
- Cells need a constant supply of glucose for respiration to release energy; too much or too little glucose would disrupt cell processes / damage cells
Key terms in this question
insulin · blood glucose concentration
Related
- All Pearson Edexcel A-Level Biology A (9BI0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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