Two dental clinics reviewed patients who had the same type of tooth removed.
Clinic A gave every patient antibiotics immediately after the procedure. Clinic B gave antibiotics only when a bacterial infection was diagnosed.
| Antibiotic policy | Patients who developed a bacterial infection per 100 patients | Samples containing resistant bacteria per 100 mouth bacterial samples |
|---|---|---|
| Antibiotics given to every patient | 4 | 22 |
| Antibiotics given after diagnosis | 9 | 6 |
Compare the results for the two clinics.
A random mutation has given one bacterium an allele that provides resistance before the antibiotic is used.
Explain how repeated use of the antibiotic can increase the proportion of resistant bacteria in the population.
85 exam-style questions on Edexcel GCSE Biology 4.1 Evolution and natural selection, covering 4.1.1 Work of Darwin and Wallace and 4.1.2 Resistant organisms and evolution. Each one has a worked solution and a mark scheme showing where the marks go.