Explain why DNA and proteins are described as naturally occurring polymers. Include in your answer the names of the monomers that make up each of these molecules.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
DNA and proteins are naturally occurring polymers because they are large, long‑chain molecules made from many smaller monomers joined together. The monomers that make up DNA are nucleotides, and the monomers that make up proteins are amino acids. Both DNA and proteins are produced by living organisms, not synthesised by humans.
Examiner tips
- Use the term ‘naturally occurring polymer’ and explain size and monomer linkage; name the monomers; mention biological origin; keep answer concise to fit 4 marks.
Common mistakes
- Confusing nucleotides with nucleobases; writing ‘proteins are made of sugars’; omitting the biological origin of the polymers.
Mark scheme (4 marks)
- DNA / proteins are polymers because they are large long-chain molecules made from many smaller monomers joined together
- The monomers that make up DNA are nucleotides
- The monomers that make up proteins are amino acids
- They are naturally occurring because they are produced by living organisms (not synthesised / manufactured by humans)
Key terms in this question
Related
- All AQA GCSE Chemistry (8462) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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