D1.3.1—Gene mutations
Gene mutations change DNA base sequences through substitution, insertion, deletion or duplication, creating altered alleles and potential protein effects in organisms.
- Syllabus
- First assessment 2025
- Objective
- D1.3.1
- Level
- HL
Exam analysis
Chance of appearing3%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper2
Typical marks1
Common command terms
- Define
- Identify
- Distinguish
- Compare
Scoring notes
- Common mistake
- Naming a disease such as sickle-cell anemia instead of naming a mutation type.
Recent exam appearances
November 2025Paper1A ["HL"] · TZ111[ 1 ]D1.3.1—Gene mutations
May 2025Paper2 ["HL"] · TZ27(b)[ 1 ]D1.3.1—Gene mutations
May 2017Paper2 ["HL"] · TZ25(a)(ii)[ 1 ]D1.3.1—Gene mutations
Practice this objective
Coverage 2017–2025 · Updated 16 Jul 2026
Concept essentials
- Gene mutations are changes in DNA nucleotide sequence.
- Substitution, insertion, deletion and duplication are common gene mutation types.
- Mutation can produce new alleles in a population.
- Insertion and deletion add or remove bases rather than replacing one base.