Lesson 3.8.1.1

3.8.1.1 Gene mutations and their effects Quiz: AQA Biology, Unit 8

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.8.1.1, Gene mutations and their effects: 20 multiple choice questions for the AQA Biology (7402), Unit 8: The control of gene expression, written with Revision Ninja.

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The 20 questions

  1. Which of these is NOT a type of gene mutation?

    • Substitution
    • Inversion
    • Duplication
    • Crossing over

  2. Which type of mutation causes a frame shift in a coding sequence?

    • Inversion of bases
    • Silent mutation
    • Base substitution
    • Insertion or deletion

  3. Which term describes any factor that increases the rate of gene mutation?

    • Oncogene
    • Morphogen
    • Mutagen
    • Carcinogen

  4. What feature of the genetic code means multiple codons encode the same amino acid?

    • Degeneracy
    • Universality
    • Non-overlapping
    • Colinearity

  5. During which cell cycle process do spontaneous gene mutations most frequently occur?

    • DNA replication
    • Cytokinesis
    • Translation
    • Anaphase

  6. A mutation changes a codon but the amino acid stays the same. Which term describes this?

    • A frame shift mutation
    • A nonsense mutation
    • A silent mutation
    • A translocation mutation

  7. In sickle cell anaemia, which amino acid is replaced by valine in haemoglobin?

    • Alanine
    • Lysine
    • Aspartic acid
    • Glutamic acid

  8. A codon CTT mutates to CTC, both coding for leucine. What is the effect?

    • Frameshift mutation
    • Altered shape
    • Truncated protein
    • No change

  9. The codon GAG mutates to GTG in a gene. What type of mutation is this?

    • Duplication
    • Insertion
    • Deletion
    • Substitution

  10. What is the most likely result of a single base deletion near a gene's start?

    • Longer protein
    • Non-functional protein
    • Unchanged protein
    • Enhanced activity

  11. What process alters every codon downstream of a single base addition?

    • Frame shift
    • Inversion
    • Substitution
    • Translocation

  12. Which form of radiation acts as a physical mutagenic agent?

    • Infrared radiation
    • Ultraviolet radiation
    • Radio waves
    • Microwaves

  13. Why might a base substitution in a gene cause no change to the phenotype?

    • Degenerate code
    • Transcription factors
    • DNA proofreading
    • Exon splicing

  14. Which process describes a translocation mutation?

    • Bases are duplicated
    • Bases are deleted
    • DNA segment moves
    • Base sequence inverted

  15. What happens to DNA during a duplication mutation?

    • Bases are swapped
    • Bases are repeated
    • Bases are deleted
    • Sequence is inverted

  16. What happens to the reading frame between a deletion and downstream insertion?

    • Translation stops completely
    • Frame remains unchanged
    • Frame is inverted
    • Frameshift occurs

  17. What determines whether a random gene mutation becomes beneficial?

    • High mutation rate
    • Selective breeding
    • Natural selection
    • Genetic drift

  18. A mutation rate of 1 in 10^6 per gene copy per generation is applied to 10^7 gene copies. How many mutations are expected per generation?

    • 1
    • 100
    • 10
    • 1000000

  19. Why is a base mutation altering an active site usually harmful?

    • Stops DNA replication
    • Prevents mRNA transcription
    • Prevents substrate binding
    • Destroys all ribosomes

  20. What is directly altered first when a gene mutation occurs?

    • Polypeptide chain length
    • Protein tertiary structure
    • mRNA codon sequence
    • Organism phenotype

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