Describe the role of glucagon in maintaining a constant blood glucose concentration when a person has not eaten for several hours.

Eduqas GCSE Biology — 2.5.2 Hormonal coordination · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Blood glucose concentration must be kept within narrow limits to ensure cells have a constant supply of glucose for respiration. The hormone glucagon plays a key role in this process.

Model answer (4 marks)

Low blood glucose is detected by the pancreas.
The pancreas releases glucagon into the blood.
Glucagon stimulates the liver to break down glycogen into glucose.
Glucose is released into the bloodstream, raising the blood glucose level back to normal.

Examiner tips

Use the exact sequence: detection → release → action on liver → glucose release.
Show the hormone’s name and its target organ (liver).

Common mistakes

Confusing glucagon with insulin.
Omitting the step that glucagon acts on the liver to break down glycogen.

Mark scheme (4 marks)

Low blood glucose concentration is detected by the pancreas
The pancreas secretes/releases glucagon into the blood
Glucagon causes the liver to convert glycogen into glucose (glycogen breakdown)
Glucose is released into the blood, raising blood glucose concentration back to normal

Key terms in this question

glucagon · blood glucose concentration