A student lowers a cover slip flat onto a drop containing a specimen. After focusing the microscope, the student sees circular areas with thick dark rims, and cells cannot be seen beneath these areas.
Explain why these areas formed and describe how the student should lower the cover slip to stop them forming.
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.