A student measured the diameter of the clear zone produced by four disinfectants, W, X, Y and Z, on plates of the same species of bacterium.
Table: The diameter of the clear zone produced by each of four disinfectants
| Disinfectant | Diameter of clear zone / mm |
|---|---|
| W | 10 |
| X | 22 |
| Y | 16 |
| Z | 4 |
Figure: Grid for plotting the data in the Table

Complete the Figure. You should:
The bar for disinfectant W has been drawn for you.
Give the letter of the least effective disinfectant.
The student concluded that disinfectant X should be used in a hospital. Give two other pieces of information the student would need before making this conclusion.
163 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.