Q BankQuestion BankDocsDocuments

D3.2.7—Phenylketonuria (PKU)

PKU is an inherited recessive condition affecting phenylalanine metabolism, managed by identifying affected individuals and controlling diet in inheritance problems.

Syllabus
First assessment 2025
Objective
D3.2.7
Level
SL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper3
Typical marks3–4

Common command terms

  • Explain
  • Outline

Recent exam appearances

May 2023Paper3 ["SL"] · TZ116(c)[ 3 ]D3.2.7—Phenylketonuria (PKU)
May 2017Paper3 ["SL"] · TZ121[ 4 ]D3.2.7—Phenylketonuria (PKU)
May 2015Paper3 ["SL"] · TZ23(b)[ 4 ]D3.2.7—Phenylketonuria (PKU)
November 2013Paper3 ["SL"] · TZ02(b)[ 3 ]D3.2.7—Phenylketonuria (PKU)
May 2012Paper3 ["SL"] · TZ1A2(c)[ 3 ]D3.2.7—Phenylketonuria (PKU)
Practice this objective

Coverage 2011–2023 · Updated 16 Jul 2026

Concept essentials

  • PKU is usually autosomal recessive, so carriers can be unaffected.
  • Diet can influence the PKU phenotype by limiting phenylalanine intake.
  • The condition links an allele to an enzyme defect and a metabolic outcome.
ConceptIB Biology SL