A3.1.10—Comparison of genome sizes
Genome size is the total DNA amount in one chromosome set, and it does not reliably measure organism complexity or gene number.
- Syllabus
- First assessment 2025
- Objective
- A3.1.10
- Level
- SL
Exam analysis
Chance of appearing2%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1
Typical marks1–2
Common command terms
- Discuss
Scoring notes
- Common mistake
- Equating genome size with gene number or chromosome number.
Recent exam appearances
May 2025Paper1B ["SL"] · TZ14(d)[ 2 ]A3.1.10—Comparison of genome sizes
November 2023Paper1 ["SL"] · TZ214[ 1 ]A3.1.10—Comparison of genome sizes
May 2018Paper1 ["SL"] · TZ213[ 1 ]A3.1.10—Comparison of genome sizes
Practice this objective
Coverage 2018–2025 · Updated 15 Jul 2026
Concept essentials
- Genome size means total DNA amount, not total gene number.
- Genome size can vary greatly between species.
- Large genomes do not necessarily indicate greater organism complexity.
- Claims about genome size and complexity must be evaluated from the data provided.