Lesson 3.8.4.2.1

3.8.4.2.1 DNA probes, hybridisation and genetic counselling Quiz: AQA Biology, Unit 8

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.8.4.2.1, DNA probes, hybridisation and genetic counselling: 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 phrase best describes a functional DNA probe?

    • Unlabelled double-stranded RNA
    • Circular plasmid vector
    • Restriction endonuclease enzyme
    • Labelled single-stranded DNA

  2. Which process occurs during DNA hybridisation?

    • Histone proteins detach
    • Complementary strands bind
    • Nucleotides undergo hydrolysis
    • Covalent bonds form

  3. Which tag is commonly used to label a DNA probe?

    • Heavy nitrogen isotope
    • Fluorescent tag
    • Sodium ion tag
    • Glucose molecule

  4. What can DNA probes be used to screen for in patients?

    • Antibody levels
    • Blood glucose concentrations
    • Mutant alleles
    • Bacterial infections

  5. How do genetic counsellors use results from DNA probe screening?

    • Assessing inheritance risk
    • Synthesising viral vaccines
    • Determining blood type
    • Calculating heart rate

  6. What factor determines treatment choice in personalised medicine?

    • Patient's age group
    • Patient's diet preferences
    • Standard medical guidelines
    • Patient's genetic profile

  7. Why does a DNA probe bind to a target sequence?

    • Ionic attraction
    • Covalent peptide bonding
    • Hydrophobic interaction
    • Complementary base pairing

  8. What does successful hybridisation of a DNA probe indicate?

    • Enzyme active
    • Mutation absent
    • Target allele present
    • Protein expressed

  9. Why must a DNA probe be single-stranded?

    • Prevent enzyme action
    • Stop self-folding
    • Allow complementary binding
    • Increase thermal stability

  10. Why is patient DNA sometimes screened before prescribing drugs?

    • Measure blood pressure
    • Determine diet needs
    • Predict drug efficacy
    • Calculate body mass

  11. Which genetic screening result is most critical in counselling?

    • White cell count
    • Blood glucose level
    • Tissue type
    • Carrier status

  12. A probe screen tests 1000 people. If 2 per cent carry the allele, how many carriers are expected?

    • 50
    • 200
    • 2
    • 20

  13. What does a positive DNA probe result confirm about an individual?

    • Allele presence
    • Protein production
    • Gene transcription
    • Disease expression

  14. What patient information is needed to design personalised medicine?

    • Immune status
    • Genetic profile
    • Enzyme level
    • Blood pressure

  15. DNA probe screening is used to identify susceptibility to what type of condition?

    • Genetic conditions
    • Nutritional deficiencies
    • Environmental diseases
    • Bacterial infections

  16. Which ethical issue is associated with genetic screening results?

    • Insurance discrimination
    • Organ rejection
    • Bacterial resistance
    • Viral mutation

  17. A recessive disorder occurs in 1 in 10 000 births. How many affected births are expected in 50 000 births?

    • 50
    • 1
    • 5
    • 0.5

  18. Why is a DNA probe complementary to a specific allele rather than the whole gene?

    • Target sequence differences
    • Increase DNA length
    • Measure protein size
    • Prevent PCR replication

  19. Put these steps in the most likely order: 1 extract DNA, 2 denature the DNA into single strands, 3 apply the labelled probe, 4 wash and detect the hybridised probe. Which sequence is correct?

    • 2, 1, 3, 4
    • 4, 1, 2, 3
    • 1, 2, 3, 4
    • 1, 3, 2, 4

  20. What is a major limitation of using DNA probes for genetic screening?

    • Only known alleles
    • Destroys sample DNA
    • Takes several months
    • Requires live cells

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