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IBBiologyHLExam QuestionsContinuity & ChangeMutations & Gene Editing

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First teaching 2023

First exams 2025

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Mutations & Gene Editing (HL IB Biology)

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Mutations & Gene Editing

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Mutations & Gene Editing

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11 mark

Which of the following are mutagenic agents?

  • X-rays, benzo(a)pyrene, radio waves

  • X-rays, microwaves, radio waves

  • X-rays, benzo(a)pyrene, gamma rays

  • X-rays, benzo(a)pyrene, microwaves

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21 mark

Which of the following statements, correctly describes the impact of the substitution mutation shown below?

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  • The codon encoding an amino acid was changed to a stop codon, truncating the polypeptide

  • The sequence of amino acids may code for a different protein structure

  • The resulting polypeptide chain will be elongated

  • There will be no change in the polypeptide chain

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31 mark

What is the function of the enzyme Cas9? 

  • Guides the new DNA into the correct space during a gene editing insertion

  • Cuts the DNA that is being edited

  • Repairs the cut DNA after editing

  • Enables the gene editing mechanism to bind to the target DNA

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11 mark

A base substitution mutation has caused a single change to the mRNA transcript of a section of a gene, as shown below. 

Original sequence

AUGGAAAUACCGCCAGGA

Mutated sequence

AUGGAAAUACUGCCAGGA

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Using the table above, what is the change in amino acid sequence caused by this mutation?

  • Pro → Leu

  • Met → Glu

  • Pro → Gln

  • No change

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21 mark

The risk of developing a cancerous tumour is increased by exposure to which of the following?

  Ultraviolet light Benzo[a]pyrene Carbon monoxide X-rays
A. ✓ ✓ ✗ ✓
B. ✓ ✗ ✗ ✓
C. ✗ ✓ ✓ ✗
D. ✓ ✗ ✓ ✗

Key: ✓ = increases risk, ✗ = does not increase risk

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    31 mark

    Sickle cell anaemia is caused by the following mutation in the gene that codes for haemoglobin:

    3-1-biology-q3-ib-hl

    Which of the following correctly explains how this mutation causes sickle cell anaemia?

    • It causes valine to be replaced by glutamic acid, altering the structure of the haemoglobin protein.

    • It produces an allele known as HbA.

    • It causes glutamic acid to be replaced by valine, altering the structure of the final haemoglobin protein.

    • It causes an amino acid substitution at the 8th position in the polypeptide.

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    1
    Sme Calculator    1 mark

    The nucleotide base sequence and the associated sequence of four amino acids can be seen below:

    AGG   ACA   CCT   GGA

    Serine   Tyrosine   Glycine   Proline

    The table shows the mRNA codons and their associated amino acids.

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    A single mutation occurred in the original base sequence of the DNA which resulted in only one amino acid from the sequence being produced.

    Which of the following would represent the correct nucleotide base sequence which was found in the DNA after the mutation occurred?

    • AGT   ACA   CCT   GGA

    • AGG   ACT   CCT   GGA

    • AGG   ACC   CCT   GGA

    • AGG   ACA   UGA   GGA

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