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IB Biology SL 1.3.2 Base substitution consequences Question Bank

Practise IB Biology SL 1.3.2 by tracing how a base substitution can change a codon, amino acid and protein function.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Trace a base substitution from DNA sequence to codon and amino-acid change.
  • Explain how the sickle-cell mutation changes haemoglobin structure or function.
  • Distinguish a silent, missense or other possible consequence of a base substitution.

D1.3.2—Base substitution consequences question 1

[Maximum number: 2]

Thrombophilia is a human genetic condition where the blood has an increased tendency to clot. The condition is caused by a single base substitution mutation in DNA. If a person is homozygous for the gene, they are at greater risk for developing a blood clot than an individual who is heterozygous. The pedigree chart shows the inheritance of thrombophilia in a family.

Figure for Question D1.3.2—Base substitution consequences question 1 — IB Biology SL

Explain how a single base substitution mutation in DNA can cause a change to a protein.

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