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IB Biology HL 2.5.7 Phenylketonuria genotypes and treatment data Question Bank

Practise IB Biology HL 2.5.7 by analysing PKU genotypes and evidence for treatment effectiveness.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Deduce PKU genotype outcomes from inheritance data.
  • Evaluate treatment data and explain effects of untreated PKU.

D3.2.7—Phenylketonuria (PKU) question 1

[Maximum number: 1]

The table summarizes the relative content of essential amino acids in different foods. Cysteine and tyrosine are classified as being "conditionally essential". The quantity of each amino acid in a hen egg is set as 1.0 and all other values are relative to the hen egg standard.

Table for Question D3.2.7—Phenylketonuria (PKU) question 1 — IB Biology HL

Phenylalanine is converted to tyrosine by the enzyme phenylalanine hydroxylase.

Figure for Question D3.2.7—Phenylketonuria (PKU) question 1 — IB Biology HL

When infants with the condition phenylketonuria (PKU) are left untreated, they have a build-up of phenylalanine in the blood and high levels of phenylalanine in the urine. State the cause of this condition.

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