Staphylococcus aureus is a bacterium that can cause infections. MRSA is a strain of Staphylococcus aureus that is resistant to the antibiotic methicillin.
The Table shows the percentage of Staphylococcus aureus infections in one hospital that were caused by MRSA.
Table
| Year | Percentage of infections caused by MRSA |
|---|---|
| 1995 | 4 |
| 2000 | 18 |
| 2005 | 32 |
| 2010 | 25 |
In 2005, the hospital treated 450 patients with Staphylococcus aureus infections. Calculate the number of these infections that were caused by MRSA.
Explain how MRSA evolved from bacteria that were not resistant to methicillin.
Suggest one reason for the change in the percentage of infections caused by MRSA between 2005 and 2010.
Explain why doctors are told not to prescribe antibiotics for mild bacterial infections.
44 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.