Cellulose and glycogen are both polymers found in living organisms. Explain what is meant by a polymer, name the monomer used to build both cellulose and glycogen, and explain how monomers are joined together to form a polymer.

AQA A-Level Biology (7402) — 3.1.1 Monomers and Polymers · Explain · 5 marks · View as Markdown

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

Model answer (5 marks)

A polymer is a large molecule made from many smaller units (monomers) joined together.
The monomer used to build both cellulose and glycogen is glucose.
Monomers are joined together by condensation reactions, in which a water molecule is released when a glycosidic bond is formed, allowing a long chain of glucose units to be built.

Examiner tips

  • Use the term "polymer" and "monomer" explicitly. Mention "glucose" as the common monomer. Explain that a condensation (dehydration) reaction releases water to form a glycosidic bond. Show the chain‑forming process to hit all points.

Common mistakes

  • Confusing polymer with monomer. Using the wrong monomer (e.g. fructose). Forgetting that a water molecule is released during bond formation.

Mark scheme (5 marks)

  1. A polymer is a large molecule made from many smaller units (monomers) joined together
  2. The monomer for both cellulose and glycogen is glucose
  3. Monomers are joined together by chemical reactions
  4. Water is released / removed when monomers are joined (condensation)
  5. This forms a long chain / many monomers can be added to form a polymer of any length

Key terms in this question

monomer · polymer

Related

More Monomers and Polymers questions

▶ Try answering this question with AI marking (free) →