Compare the roles of monomers and polymers in living organisms, and explain how a polymer can be converted back into its monomers.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
Monomers are small individual molecules that act as the building blocks of polymers.
Polymers are large molecules formed by linking many monomers together.
In living organisms polymers serve storage and structural roles – for example, starch stores energy, DNA stores genetic information and proteins provide structural support.
Polymers can be converted back into their monomers by hydrolysis, a reaction that uses water to break the bonds between monomers.
Polymers are large molecules formed by linking many monomers together.
In living organisms polymers serve storage and structural roles – for example, starch stores energy, DNA stores genetic information and proteins provide structural support.
Polymers can be converted back into their monomers by hydrolysis, a reaction that uses water to break the bonds between monomers.
Examiner tips
- Use the word ‘compare’ to show similarities and differences; list monomer vs polymer traits. Show the hydrolysis mechanism – mention water and bond cleavage. Use specific examples (starch, DNA, protein).
Common mistakes
- Confusing monomers with polymers; writing that monomers are large. Omitting the role of water in hydrolysis. Failing to give examples of polymer functions.
Mark scheme (5 marks)
- Monomers are small / individual molecules that are the building blocks (of polymers)
- Polymers are large molecules made up of many monomers joined together
- Polymers are used for storage / structural purposes in living organisms (e.g. starch stores energy / DNA stores genetic information / proteins form structures)
- Polymers are broken down into monomers by hydrolysis
- Water is used / added during hydrolysis to break the bonds between monomers
Key terms in this question
Related
- All AQA A-Level Biology (7402) revision notes →
- How to answer a "Compare" question →
- Decode the mark scheme abbreviations →
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