Describe the roles of starch and glycogen as energy storage molecules in living organisms.

Pearson Edexcel International GCSE Biology (4BI1) — 2.3 Biological molecules · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Starch is an energy storage carbohydrate found in plants, consisting of many glucose units linked together.
Glycogen is an energy storage carbohydrate found in animals, also made up of many glucose units joined together.

Examiner tips

Use the word ‘consisting’ or ‘made up of’ to show structure. Mention the organism type (plants/animals) to hit both points. Keep sentences short – one for starch, one for glycogen. Use the term ‘glucose units’ rather than just ‘glucose’.

Common mistakes

Mixing up which molecule is in plants vs animals. Forgetting to state that both are large carbohydrates. Using vague terms like ‘sugar’ instead of ‘glucose units’.

Mark scheme (4 marks)

Starch is an energy storage molecule found in plants
Starch is a large carbohydrate / made up of many glucose molecules
Glycogen is an energy storage molecule found in animals
Glycogen is a large carbohydrate made from many glucose molecules joined together

Key terms in this question

starch · glycogen