A hospital laboratory tests one antibiotic against four species of bacteria, W, X, Y and Z, each isolated from a different patient. A lawn of each species is grown on its own agar plate. A paper disc soaked in the same volume of the antibiotic is placed in the centre of each plate.
The table shows the clear-zone diameters after incubation.
| Species of bacterium | Clear-zone diameter in mm |
|---|---|
| W | 9 |
| X | 17 |
| Y | 12 |
| Z | 6 |
Against which species of bacterium was the antibiotic most effective?
Species W
Species Y
Species Z
Species X
282 exam-style questions on AQA GCSE Biology 1.1 Cell structure, covering 1.1.1 Eukaryotes and prokaryotes, 1.1.2 Animal and plant cells, 1.1.3 Cell specialisation, 1.1.4 Cell differentiation, 1.1.5 Microscopy, and 1.1.6 Culturing microorganisms. Each one has a worked solution and a mark scheme showing where the marks go.