IGCSE Biology glossary
Glycogen
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A complex carbohydrate (polysaccharide) used as the main energy storage molecule in animals and fungi. It is stored in the liver and muscles and can be rapidly broken down into glucose when energy is needed.
What to include in an exam answer
In homeostasis questions about blood glucose regulation, always distinguish glycogen (storage form) from glucose (usable form). Insulin causes glucose to be converted to glycogen, not the other way around.
Example in context
Describe the role of glycogen in blood glucose regulation (2 marks): When blood glucose is high, insulin stimulates liver cells to convert excess glucose into glycogen for storage. When blood glucose is low, glucagon stimulates conversion of glycogen back into glucose.
Related syllabus topic
Biological molecules