MRSA is a strain of the bacterium Staphylococcus aureus. MRSA is resistant to many antibiotics. The figure shows the number of cases of MRSA infection reported in the hospitals of one country between 2005 and 2020.
Figure: The number of cases of MRSA infection reported in the hospitals of one country between 2005 and 2020

Describe the trend shown in the figure.
Use the figure to calculate the percentage decrease in the number of reported cases between 2005 and 2011.
Explain how a strain of bacterium such as MRSA becomes resistant to an antibiotic and then becomes common.
Explain why developing new antibiotics is unlikely to solve the problem of resistant strains of bacteria.
40 exam-style questions on AQA GCSE Biology 6.3 The development of understanding of genetics and evolution, covering 6.3.1 Theory of evolution, 6.3.2 Speciation, 6.3.3 The understanding of genetics, 6.3.4 Evidence for evolution, 6.3.5 Fossils, 6.3.6 Extinction, and 6.3.7 Resistant bacteria. Each one has a worked solution and a mark scheme showing where the marks go.