A student prepares a slide of onion epidermis cells. The cells are colourless.
The student adds a drop of iodine solution to the slide.
Why does the student add iodine solution?
to hold the specimen flat on the slide
to make structures in the cells visible
to increase the magnification of the image
to stop the cells on the slide drying out
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.