IB Biology SL D1.3 Mutation and gene editing Questions

Practise IB Biology SL D1.3 by classifying mutations, predicting molecular consequences and linking germ-line changes to inheritance.

26 questions in this syllabus scope, with question parts counted together.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam analysis

SL · 2010–2025
Papers with this topic25 / 141in the analysed sample
Latest appearanceNovember 2025
Tagged question parts29
Paper types5

Most tested objectives

  1. D1.3.2—Base substitution consequences7 papers
  2. D1.3.1—Gene mutations6 papers
  3. D1.3.4—Causes of mutation5 papers
  4. D1.3.7—Mutation as source of variation5 papers
  5. D1.3.6—Consequences in germ vs. somatic cells4 papers

Common question formats

  • Definition or recall
  • Process explanation
  • Comparison
  • Evaluation
  • Diagram interpretation
  • Calculation

Recent exam appearances

November 2025Paper 1B SL · TZ1Q4(b), 4(d)(i), 4(d)(ii)[ 3 ]
November 2025Paper 1A SL · TZ1Q7[ 1 ]
May 2025Paper 1B SL · TZ1Q2(c)[ 2 ]

141 papers analysed · Tagging incomplete

Exam points

  • define a gene mutation and distinguish substitution, insertion and deletion from DNA sequence evidence
  • trace a base substitution through a codon to silent, altered or sickle-cell protein outcomes
  • identify UV, radiation and chemical mutagens and explain how they raise mutation rates
  • explain random mutation as a source of new alleles and genetic variation
  • distinguish germ-line from somatic changes and identify which can be inherited

Covered syllabus points

D1.3.1—Gene mutationsD1.3.2—Base substitution consequencesD1.3.3—Insertion and deletion consequencesD1.3.4—Causes of mutationD1.3.5—Randomness in mutationD1.3.6—Consequences in germ vs. somatic cellsD1.3.7—Mutation as source of variation

Exam points

  • Define a gene mutation as a change in the DNA nucleotide or base sequence.
  • Identify and contrast substitution, insertion, and deletion as changes to bases or nucleotides within a gene sequence.

Question 1

[Maximum number: 1]

Define mutation.

Exam points

  • Trace a base substitution from a DNA triplet through the mRNA codon to a changed amino acid or polypeptide.
  • Explain how the sickle-cell substitution changes glutamic acid to valine and affects haemoglobin or red-cell function.
  • Compare substitution outcomes to decide whether the translated amino-acid sequence changes or remains the same.

Question 1

[Maximum number: 4]

Inheritance of one sickle cell allele is known as sickle cell trait, while inheritance of two causes sickle cell anemia.

Outline how a base substitution leads to sickle cell anemia.

No public sample questions are available for this syllabus point yet.

Exam points

  • Explain that replication errors can cause mutations and that radiation or chemical mutagens can affect DNA bases or increase mutation frequency.
  • Use UV exposure or SPF-treatment evidence to describe changes in mutation frequency or damage by comparing the relevant control or treatment groups.

Question 1

[Maximum number: 2]

Explain one cause of mutation.

Exam points

  • Explain that mutations occur randomly with respect to an organism’s need or advantage.

Question 1

[Maximum number: 1]

What is a feature of mutations?

A

They occur randomly.

B

They only occur in germ cells.

C

The frequency cannot be increased by external factors.

D

They only occur in certain base sequences of the genome.

Exam points

  • Distinguish germ-line changes in gametes from somatic changes in body cells.
  • Explain that germ-line changes can be inherited by offspring, whereas somatic changes affect only the treated individual’s body cells.

Question 1

[Maximum number: 3]

Gene therapy is a new technology which can be used to treat hereditary diseases.

Distinguish between somatic and germ line therapy.

Exam points

  • Explain that mutations produce new alleles and are an original source of genetic variation.

Question 1

[Maximum number: 1]

How is a new allele produced?

A

Cloning

B

Mutation

C

Differentiation

D

Natural selection