Antibiotic resistance: selection acts on bacteria
הוצג| English | משמעות |
|---|---|
| strain/streɪn/ | זן |
| antibiotic resistance/ˌæntɪbaɪˈɒtɪk rɪˈzɪstəns/ | עמידות לאנטיביוטיקה |
What would explain this observation?
- It is the bacteria that become resistant to a drug, rather than the patient becoming resistant. Antibiotic exposure changes which bacterial variants survive.
Build the model
- Mutations produce bacterial variants, some resistant to a particular antibiotic.
- Susceptible bacteria are killed or inhibited while resistant ones survive and reproduce.
- Fast reproduction can rapidly increase the resistant strain 菌株’s population, and it can spread between hosts.
- MRSA is the specification’s example of antibiotic resistance 抗生素耐药性; resistance to one antibiotic does not automatically mean resistance to every possible treatment.
- antibiotic resistance: Ability of a bacterial strain to survive or grow despite a particular antibiotic.
- strain: A form within a bacterial species with particular inherited features.
Which explanation accounts for increasing resistance frequency?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Antibiotic exposure kills the susceptible bacteria, so the resistant minority survives and reproduces, and its frequency rises. Patients do not transform, and bacteria never change their DNA intentionally.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- The specification calls for avoiding inappropriate antibiotic prescribing, including use against viral infections, restricting agricultural antibiotic use and completing prescribed treatment.
- Current NHS information likewise says to follow the healthcare professional’s directions.
- New antibiotic development is slow and expensive.
- The selection explanation must not say bacteria mutate deliberately because treatment was stopped or that every resistant infection has no treatment.
In the lab: Analyse supplied before/after counts and distinguish resistant frequency from total bacterial number. Use paper models or prepared data, never culture resistant pathogens. This teaching task does not set treatment length or advise medication changes; the NHS stewardship reference provides the clinical wording alongside the exam specification.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: a model has 10 resistant and 90 susceptible bacteria before exposure.
- Afterwards, 10 resistant and 10 susceptible remain.
- Resistant number stays 10, but frequency rises from 10% to 50%.
- This selection event alone changes frequency without requiring a new mutation during exposure.
- Later reproduction can increase absolute numbers.
Your turn: Eight resistant and 12 susceptible bacteria remain in a supplied model. Find resistant percentage.
Eight resistant and 12 susceptible bacteria remain in a supplied model. Find resistant percentage.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 40 %. Known: 8 resistant and 12 susceptible remain. Total = 20. Resistant percentage = 8/20 x 100 = 40%. The same resistant count can give a higher frequency when susceptibles are removed.
Check the conclusion and its limits
- Antibiotics do not treat viral infection.
- Finishing a prescribed course does not guarantee that every bacterium in every real infection is killed.
- Mutation supplies variants and selection changes their representation; these processes must not be confused. NHS stewardship reference.
Not true: A patient’s own body becomes the resistant bacterial strain. Resistance is a property of the bacterial strain, evolved by selection in the bacterial population. The patient's body does not become a bacterium and does not become resistant.
- Mutations produce bacterial variants, some resistant to a particular antibiotic.
- The specification calls for avoiding inappropriate antibiotic prescribing, including use against viral infections, restricting agricultural antibiotic use and completing prescribed treatment.
- Watch for: antibiotics do not treat viral infection.
A patient’s own body becomes the resistant bacterial strain.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Resistance is a property of the bacterial strain, evolved by selection in the bacterial population. The patient's body does not become a bacterium and does not become resistant.
Ability of a bacterial strain to survive or grow despite a particular antibiotic: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
antibiotic resistance means Ability of a bacterial strain to survive or grow despite a particular antibiotic.