A student uses a light microscope to find and observe cells on a prepared slide of fungal cells.
The student considers four plans.
| Plan | Position of slide | First objective lens used | Focusing with the first objective lens | Focusing with the ×40 \times40\,×40 objective lens |
|---|---|---|---|---|
| W | secured with stage clips | ×4\times4×4 | coarse focus, then fine focus | fine focus |
| X | resting on the stage without clips | ×4\times4×4 | coarse focus, then fine focus | fine focus |
| Y | secured with stage clips | ×40\times40×40 | fine focus | fine focus |
| Z | secured with stage clips | ×4\times4×4 | coarse focus, then fine focus | coarse focus |
Which plan should the student use?
Explain why each of the other plans could cause a problem.
130 exam-style questions on OCR GCSE Biology 1.1 Cell structures, covering 1.1.1 Viewing cells with light microscopes, 1.1.2 Sub-cellular structures and functions, and 1.1.3 Electron microscopy and resolution. Each one has a worked solution and a mark scheme showing where the marks go.