Lesson 4.1.1.6

4.1.1.6 Culturing microorganisms (biology only) Quiz: AQA Biology, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.1.1.6, Culturing microorganisms (biology only): 20 multiple choice questions for the AQA GCSE Biology (8461), Unit 1: Cell biology, written with Revision Ninja.

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The 20 questions

  1. How often can bacteria divide under ideal conditions?

    • Once every 24 hours
    • Once every 20 minutes
    • Once every 2 hours
    • Once every 2 minutes

  2. What primary nutrient source is typically added to agar to support bacterial growth?

    • Protein
    • Lipid
    • Vitamin
    • Carbohydrate

  3. What is the main purpose of sterilising culture media and Petri dishes before use?

    • Provide nutrients
    • Speed up division
    • Increase temperature
    • Prevent contamination

  4. Why is an inoculating loop passed through a Bunsen burner flame?

    • To warm it up
    • To sterilise it
    • To dry it quickly
    • To sharpen the tip

  5. Why is an agar plate stored upside down during incubation?

    • Prevents condensation dripping
    • Prevents oxygen entering
    • Stops bacterial growth
    • Increases light exposure

  6. In school laboratories, cultures should generally be incubated at:

    • 25°C
    • 4°C
    • 37°C
    • 60°C

  7. What is the main purpose of using aseptic techniques in microbiology?

    • Speed up division
    • Increase agar area
    • Kill all bacteria
    • Prevent contamination

  8. Why are uncontaminated bacterial cultures needed when testing antibiotics?

    • Increase clear zones
    • Ensure valid results
    • Prevent mutations
    • Speed up growth

  9. A population starts from 1 bacterium that divides every 20 minutes. How many bacteria are present after 2 hours?

    • 120
    • 12
    • 128
    • 64

  10. 500 bacteria divide every 20 minutes. How many are present after 1 hour?

    • 2000
    • 1000
    • 4000
    • 8000

  11. A clear zone around a disc has a radius of 10 mm. What is its cross-sectional area?

    • 628 mm²
    • 62.8 mm²
    • 31.4 mm²
    • 314 mm²

  12. A clear zone has a radius of 7 mm. What is its area?

    • 21.99 mm²
    • 43.98 mm²
    • 307.9 mm²
    • 153.9 mm²

  13. A population of 100 bacteria divides every 20 minutes. How many are there after 3 hours?

    • 9,000
    • 25,600
    • 51,200
    • 1,600

  14. The mean division time is 30 minutes and starting population is 1 bacterium. How many bacteria after 90 minutes?

    • 4
    • 8
    • 9
    • 6

  15. Two clear zones have radii of 6 mm and 3 mm. What is the ratio of their areas?

    • 36 : 3
    • 2 : 1
    • 4 : 1
    • 1 : 4

  16. What does a larger clear zone around an antiseptic disc indicate?

    • Less effective antiseptic
    • More effective antiseptic
    • Faster bacterial reproduction
    • Higher agar concentration

  17. A population grows from 1000 to 16000 bacteria by simple division. How many divisions occurred?

    • 5
    • 3
    • 8
    • 4

  18. What is the process of simple cell division by which bacteria multiply?

    • Meiosis
    • Spore formation
    • Mitosis
    • Binary fission

  19. An agar plate shows colonies of varied shapes and colours. What caused this?

    • Nutrient shortage
    • High temperature
    • Rapid binary fission
    • Bacterial contamination

  20. Which formula should be used to calculate the cross-sectional area of a circular colony?

    • 2πr
    • πr²
    • πd
    • 4/3 πr³

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