Explain why the sequence of bases in a DNA molecule is important for a living organism.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
The sequence of bases in DNA forms a genetic code that carries the information required for life.
1. The order of A, T, C and G determines the sequence of codons.
2. Each codon specifies a particular amino‑acid.
3. The amino‑acid sequence dictates the structure of a protein or enzyme.
4. Proteins/enzymes control the organism’s traits and biochemical reactions.
1. The order of A, T, C and G determines the sequence of codons.
2. Each codon specifies a particular amino‑acid.
3. The amino‑acid sequence dictates the structure of a protein or enzyme.
4. Proteins/enzymes control the organism’s traits and biochemical reactions.
Examiner tips
- Use the exact phrase ‘sequence of bases’ and ‘genetic code’.
- Show the chain: base sequence → codons → amino acids → proteins → traits.
- Keep each point short and directly linked to the marks.
Common mistakes
- Confusing DNA with RNA or saying ‘sequence of bases is random’.
- Failing to mention that proteins determine traits or reactions.
Mark scheme (4 marks)
- The sequence of bases forms a code / carries genetic information
- The base sequence codes for the order of amino acids in a protein
- This determines which protein / enzyme is made
- Proteins / enzymes control the characteristics / chemical reactions of an organism
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →