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Flashcards · Biology · Natural Selection and Evolution

Antibiotic Resistance in Bacteria

17 cards

  1. What does an antibiotic do?

    It kills bacteria or stops them growing, without harming the person's cells.

  2. Do antibiotics work on viruses?

    No. Viruses are not cells, so antibiotics cannot affect them.

  3. What is antibiotic resistance?

    A bacterium not being killed by an antibiotic, because of an allele that it carries.

  4. How does a resistant bacterium first arise?

    By a random mutation, before the antibiotic is used.

  5. What is the selection pressure in antibiotic resistance?

    The antibiotic, which kills non-resistant bacteria.

  6. What happens to the non-resistant bacteria?

    They are killed by the antibiotic.

  7. What happens to the resistant bacteria?

    They survive, reproduce and pass on the resistance allele.

  8. Why do bacteria evolve resistance quickly?

    They reproduce very quickly, they are present in huge numbers and they clone themselves.

  9. How often can some bacteria divide?

    About every 20 minutes in good conditions.

  10. What does MRSA stand for?

    Methicillin-resistant Staphylococcus aureus.

  11. Why is MRSA a problem in hospitals?

    It spreads to patients with wounds and weak defences, and few antibiotics will treat it.

  12. Why should a patient finish the whole course of antibiotics?

    So that all of the bacteria are killed and none survive to breed.

  13. Why should antibiotics not be given for a cold?

    A cold is caused by a virus, and the use would only select for resistant bacteria.

  14. Why is the use of antibiotics in farming a concern?

    It selects for resistant bacteria that may pass to humans.

  15. Name two ways to stop MRSA spreading.

    Washing hands and cleaning equipment, and isolating infected patients.

  16. Why is antibiotic resistance evidence for evolution?

    Natural selection can be seen happening in a short time, in a population of bacteria.

  17. Four stages in a bacterial population exposed to an antibiotic, with no labels. Describe what happens at each of stages 1 to 4 in the diagram. The same four stages with the headings and the labels for the bacteria and the antibiotic.

    1 A mutation makes one bacterium resistant. 2 The antibiotic kills the non-resistant bacteria. 3 The resistant survivors reproduce and pass on the allele. 4 The population is now mostly resistant, so the antibiotic no longer works.