D2.1.10—Down syndrome
Down syndrome usually results when non-disjunction produces a gamete with an extra chromosome 21, causing trisomy after fertilization occurs in reproduction.
- Syllabus
- First assessment 2025
- Objective
- D2.1.10
- Level
- SL
Exam analysis
Chance of appearing11%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper1
Typical marks1
Common command terms
- Explain
- Outline
- Determine
- State
- Identify
- Describe
Scoring notes
- Common mistake
- Calling Down syndrome a gene mutation instead of a chromosome-number abnormality.
Recent exam appearances
November 2024Paper1 ["SL"] · TZ214[ 1 ]D2.1.10—Down syndrome
November 2024Paper1 ["SL"] · TZ113[ 1 ]D2.1.10—Down syndrome
May 2024Paper2 ["SL"] · TZ14(c)[ 3 ]D2.1.10—Down syndrome
May 2019Paper2 ["SL"] · TZ16(b)[ 1 ]D2.1.10—Down syndrome
May 2019Paper1 ["SL"] · TZ213[ 1 ]D2.1.10—Down syndrome
Practice this objective
Coverage 2010–2024 · Updated 16 Jul 2026
Concept essentials
- Non-disjunction is failed chromosome separation during meiosis.
- Non-disjunction can produce gametes with extra or missing chromosomes.
- Down syndrome is usually caused by trisomy 21.
- A karyogram can identify the chromosome affected by trisomy.