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Microbiology: Eduqas A‑Level Biology questions

Every Eduqas A-Level Biology exam question on 1.4 Microbiology, 2016–2025, with its mark scheme and examiner’s report.

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2,061 questions

  1. Q2(c)(i)

    June 2025 · Component 1

    3 marks1.4 Microbiology
    The whole paper ↗
    June 2025 Component 1, question 2(c)(i): With reference to the habitat of this species of bacteria and its metabolism of sugars, conclude whether S. mutans is an aerobe, an obligate anaerobe or a facul

  2. Q2(c)(ii)

    June 2025 · Component 1

    2 marks1.4 Microbiology
    The whole paper ↗
    June 2025 Component 1, question 2(c)(ii): Use the information provided to explain why not brushing your teeth can increase the risk of cavity formation. [2]

  3. Q6

    June 2024 · Component 1

    9 marks1.4 Microbiology
    The whole paper ↗
    June 2024 Component 1, question 6: In 2004, it was estimated that approximately 18% of the human population lacked access to safe drinking water. In most industrialised nations, samples of drinki

  4. Q5(a)

    June 2023 · Component 1

    2 marks1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(a): Calculate the length of one bacterium along the line marked X–Y on Image 5.1. Give your answer in µm to one decimal place. [2] Length of bacterium = ……… …….. µm

  5. Q5(b)(i)

    June 2023 · Component 1

    1 mark1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(b)(i): State the term used to describe rod-shaped bacteria. [1]

  6. Q5(b)(ii)

    June 2023 · Component 1

    1 mark1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(b)(ii): Explain what is meant by the term facultative anaerobe. [1]

  7. Q5(b)(iii)

    June 2023 · Component 1

    1 mark1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(b)(iii): Explain what information about the structure of Salmonella bacteria is provided by the result of Gram-staining. [1] Salmonella enterica is an intracellular path

  8. Q5(d)

    June 2023 · Component 1

    2 marks1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(d): Salmonella can be highly pathogenic and so strict aseptic conditions must be used when transferring samples containing this bacterium from the container with a

  9. Q5(e)

    June 2023 · Component 1

    2 marks1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(e): Salmonella infections are estimated to affect up to 1.3 billion people and are responsible for nearly 3 million deaths each year. Many foods have been found to

  10. Q5(f)(i)

    June 2023 · Component 1

    1 mark1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(f)(i): Explain why this is a method of producing a viable count. [1]

  11. Q5(f)(ii)

    June 2023 · Component 1

    3 marks1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(f)(ii): A total of 1010 tubes were prepared from the 101 samples of nuts that tested positive for Salmonella. Of these, 260 tubes tested positive for the presence of Sa

  12. Q5(f)(iii)

    June 2023 · Component 1

    2 marks1.4 Microbiology
    The whole paper ↗
    June 2023 Component 1, question 5(f)(iii): It has been estimated that a person needs to ingest 106 Salmonella bacteria to cause the symptoms of food poisoning. Use your calculated value of the MPN of Sal

  13. Q1(a)(i)

    June 2022 · Component 1

    3 marks1.4 Microbiology
    The whole paper ↗
    June 2022 Component 1, question 1(a)(i): Complete the table below to name stages A, B and C of the population growth curve shown in Image 1.1 and explain the shape of the growth curve in each stage. [3

  14. Q1(a)(ii)

    June 2022 · Component 1

    1 mark1.4 Microbiology
    The whole paper ↗
    June 2022 Component 1, question 1(a)(ii): Explain the difference between the shape of the decline phase obtained using a total count and a viable count. [1]

  15. Q1(a)(iii)

    June 2022 · Component 1

    1 mark1.4 Microbiology
    The whole paper ↗
    June 2022 Component 1, question 1(a)(iii): One method of estimating the number of bacteria is to dilute a sample of the bacterial culture, plate out known volumes onto agar plates and count the number of

  16. Q1(b)(i)

    June 2022 · Component 1

    1 mark1.4 Microbiology
    The whole paper ↗
    June 2022 Component 1, question 1(b)(i): State two environmental conditions that could affect the rate of bacterial cell division. [1]

  17. Q1(b)(ii)

    June 2022 · Component 1

    2 marks1.4 Microbiology
    The whole paper ↗
    June 2022 Component 1, question 1(b)(ii): For a culture in which cells divide every 20 minutes, calculate how many cells will be produced after eight hours from a single bacterium. Express your answer i

  18. Q1(c)(i)

    June 2022 · Component 1

    3 marks1.4 Microbiology
    The whole paper ↗
    June 2022 Component 1, question 1(c)(i): Use the graph in Image 1.2 and the formula given below to calculate the number of generations produced per hour between 2.5 hours and 6 hours. Express your answ

  19. Q1(c)(ii)

    June 2022 · Component 1

    2 marks1.4 Microbiology
    The whole paper ↗
    June 2022 Component 1, question 1(c)(ii): Under optimum conditions this species of bacteria should have a generation time of 30 minutes. Using your calculated figure for the number of generations per ho

  20. Q7(c)(i)

    June 2022 · Component 3

    2 marks3.A Immunology and Disease1.4 Microbiology
    The whole paper ↗
    June 2022 Component 3, question 7(c)(i): Name the type of bacterium indicated by the purple colour and describe what this indicates about the structure of the cell wall of Streptococcus pyogenes. [2] T
All 54 questions on Microbiology, as a list
  1. June 2025, Component 1, Q2(c)(i) (3 marks): With reference to the habitat of this species of bacteria and its metabolism of sugars, conclude whether S. mutans is an aerobe, an obligate anaerobe or a facul
  2. June 2025, Component 1, Q2(c)(ii) (2 marks): Use the information provided to explain why not brushing your teeth can increase the risk of cavity formation. [2]
  3. June 2024, Component 1, Q6 (9 marks): In 2004, it was estimated that approximately 18% of the human population lacked access to safe drinking water. In most industrialised nations, samples of drinki
  4. June 2023, Component 1, Q5(a) (2 marks): Calculate the length of one bacterium along the line marked X–Y on Image 5.1. Give your answer in µm to one decimal place. [2] Length of bacterium = ……… …….. µm
  5. June 2023, Component 1, Q5(b)(i) (1 mark): State the term used to describe rod-shaped bacteria. [1]
  6. June 2023, Component 1, Q5(b)(ii) (1 mark): Explain what is meant by the term facultative anaerobe. [1]
  7. June 2023, Component 1, Q5(b)(iii) (1 mark): Explain what information about the structure of Salmonella bacteria is provided by the result of Gram-staining. [1] Salmonella enterica is an intracellular path
  8. June 2023, Component 1, Q5(d) (2 marks): Salmonella can be highly pathogenic and so strict aseptic conditions must be used when transferring samples containing this bacterium from the container with a
  9. June 2023, Component 1, Q5(e) (2 marks): Salmonella infections are estimated to affect up to 1.3 billion people and are responsible for nearly 3 million deaths each year. Many foods have been found to
  10. June 2023, Component 1, Q5(f)(i) (1 mark): Explain why this is a method of producing a viable count. [1]
  11. June 2023, Component 1, Q5(f)(ii) (3 marks): A total of 1010 tubes were prepared from the 101 samples of nuts that tested positive for Salmonella. Of these, 260 tubes tested positive for the presence of Sa
  12. June 2023, Component 1, Q5(f)(iii) (2 marks): It has been estimated that a person needs to ingest 106 Salmonella bacteria to cause the symptoms of food poisoning. Use your calculated value of the MPN of Sal
  13. June 2022, Component 1, Q1(a)(i) (3 marks): Complete the table below to name stages A, B and C of the population growth curve shown in Image 1.1 and explain the shape of the growth curve in each stage. [3
  14. June 2022, Component 1, Q1(a)(ii) (1 mark): Explain the difference between the shape of the decline phase obtained using a total count and a viable count. [1]
  15. June 2022, Component 1, Q1(a)(iii) (1 mark): One method of estimating the number of bacteria is to dilute a sample of the bacterial culture, plate out known volumes onto agar plates and count the number of
  16. June 2022, Component 1, Q1(b)(i) (1 mark): State two environmental conditions that could affect the rate of bacterial cell division. [1]
  17. June 2022, Component 1, Q1(b)(ii) (2 marks): For a culture in which cells divide every 20 minutes, calculate how many cells will be produced after eight hours from a single bacterium. Express your answer i
  18. June 2022, Component 1, Q1(c)(i) (3 marks): Use the graph in Image 1.2 and the formula given below to calculate the number of generations produced per hour between 2.5 hours and 6 hours. Express your answ
  19. June 2022, Component 1, Q1(c)(ii) (2 marks): Under optimum conditions this species of bacteria should have a generation time of 30 minutes. Using your calculated figure for the number of generations per ho
  20. June 2022, Component 3, Q7(c)(i) (2 marks): Name the type of bacterium indicated by the purple colour and describe what this indicates about the structure of the cell wall of Streptococcus pyogenes. [2] T
  21. Autumn 2021, Component 1, Q2(a)(i) (1 mark): State the names given to the shapes of bacteria, A, B and C shown in image 2.1.  [1] A B C
  22. Autumn 2021, Component 1, Q2(a)(ii) (2 marks): State and explain what the results of the staining shown in image 2.2 indicates about the structure of the cell walls of bacteria D and E. [2]
  23. Autumn 2021, Component 1, Q2(b) (3 marks): Nutrient agars can be modified so that only particular types or species of bacteria can grow in them. MacConkey’s mannitol salt agar contains a chemical called
  24. Autumn 2021, Component 3, Q7(b)(i) (1 mark): One bacterium will produce one visible colony after 24 hours’ incubation. Explain why the original sample needed to be diluted before transferring 1 cm3 to an a
  25. Autumn 2020, Component 1, Q1(f)(i) (2 marks): Complete the flow chart below which shows the stages in the Gram staining technique. [2] Fixation Stain with ………… ………… Iodine treatment Washed and decolourised
  26. Autumn 2020, Component 1, Q1(f)(ii) (1 mark): Explain what this staining technique indicates about the structure of the cell wall of Prochlorococcus. [1]
  27. Autumn 2020, Component 1, Q5(a)(i) (1 mark): Use the number of colonies on plate D to calculate how many bacteria there are in 1 cm3 of the original sample of water. [1] Number of colonies = ………… ………….
  28. Autumn 2020, Component 1, Q5(a)(ii) (2 marks): Explain why the number of colonies on plates C and E would not be used to calculate the number of bacteria. [2] C ………… …………. E ………… ………….
  29. Autumn 2020, Component 1, Q5(b) (2 marks): Explain why it is essential that the plates are all cultured using exactly the same culture medium and incubation period. [2]
  30. Autumn 2020, Component 1, Q5(c) (1 mark): At the end of the investigation all plates were autoclaved. State one condition produced by the autoclave which results in the sterilisation of the plates. [1]
  31. Autumn 2020, Component 1, Q5(d) (2 marks): Water quality can be determined by the number of human gut bacteria present. Suggest two suitable conditions for incubation in order to culture human gut bacter
  32. Autumn 2020, Component 3, Q8(e)(i) (2 marks): Scientists investigated the effect of penicillin on the number of C.diphtheria cells growing in a nutrient broth in a laboratory. A culture of C. diphtheria was
  33. Autumn 2020, Component 3, Q8(e)(ii) (1 mark): The nutrient broth used to grow each C.diphtheria population contained compounds called peptones which provide a source of organic nitrogen. Explain why a sourc
  34. June 2019, Component 1, Q2(a) (4 marks): Using the key provided, identify the four bacteria in the images. [4] A B C D Each bacterial species has its own particular heat tolerance. During a process suc
  35. June 2019, Component 1, Q2(b) (3 marks): Follow the method shown on graph 1 to calculate the D value for 62 °C (graph 2). [3] D Value =
  36. June 2019, Component 1, Q2(c) (4 marks): Describe a method that you could use to determine the number of living bacteria in the original sample prior to heat treatment. No reference to aseptic techniqu
  37. June 2019, Component 3, Q8(d)(i) (2 marks): On the plate shown in figure 8.6 there are 25 plaques. Calculate the number of bacteriophages per cm3 in the original sample. [2] Number of bacteriophages =
  38. June 2019, Component 3, Q8(d)(ii) (2 marks): Describe two techniques that could have been used to maintain sterile conditions when inoculating the plates. [2]
  39. June 2019, Component 3, Q8(d)(iii) (1 mark): Explain why 37 °C was used as the incubation temperature. [1]
  40. June 2018, Component 1, Q2(a)(ii) (2 marks): Apart from the lack of peptidoglycan, describe how the cell walls of Gram negative bacteria would differ from those of Archaea. [2]
  41. June 2018, Component 1, Q2(b)(ii) (3 marks): Identify species A-C giving reasons for your conclusions. [3] A B C
  42. June 2018, Component 1, Q2(b)(iii) (3 marks): Enterococcus faecalis is a Gram-positive bacterium which also inhabits the gastro- intestinal tracts of humans and other mammals. Briefly describe two ways in w
  43. June 2018, Component 1, Q2(c)(i) (3 marks): Calculate the missing standard deviation (SD) using the following formula. [3] Σ(x – x) 2 s = n – 1 s = standard deviation Σ = sum of x = each value in the data
  44. June 2018, Component 1, Q2(c)(ii) (1 mark): Suggest why the mean values for the first two dilutions were so close despite there being a 100 times difference in the dilutions. [1]
  45. June 2018, Component 1, Q2(c)(iii) (1 mark): State what the standard deviations of the first two dilutions tell you about the data. [1]
  46. June 2018, Component 1, Q2(c)(iv) (3 marks): Calculate the number of bacteria in 1 cm3 of the original sample using the 10–9 dilution. Give your answer in standard form. [3] Number of bacteria =
  47. June 2017, Component 1, Q5(a) (2 marks): What is meant by a total viable count? [2]
  48. June 2017, Component 1, Q5(b) (2 marks): Explain why the numbers of colonies were converted to logarithms before they were plotted on the graph. [2]
  49. June 2017, Component 1, Q5(c) (2 marks): Explain the importance of standard deviations and how the researchers have used them in this experiment to conclude that there was no significant difference bet
  50. June 2017, Component 1, Q5(d) (4 marks): Using the information provided, what conclusions could you draw from the treatment of shrimp paste with tea extract and ginger extract and what advice would you
  51. June 2017, Component 1, Q5(e) (2 marks): What further investigations would need to be carried out before you could use tea and ginger extracts to preserve shrimp paste on a commercial basis? [2]
  52. June 2017, Component 3, Q5(c)(iii) (2 marks): Suggest why the bacteria were cultured at 37 °C and explain why an unmodified strain of E.coli was included. [2]
  53. June 2017, Component 3, Q5(c)(iv) (5 marks): The agar contained 0.02 g cm–3 milk protein. The clear zone surrounding bacterial colonies was due to the digestion of milk protein. The clear zone surrounding
  54. June 2017, Component 3, Q7(b) (3 marks): Pseudomonas aeruginosa is a Gram-negative bacterium that can be easily spread by hands as a type of direct contact. P. aeruginosa infections can be treated with

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