Explain4 marksStandard
A student obtained a photomicrograph of onion root tip cells. The image includes a scale bar that is labeled as 20 μm. On the printed photomicrograph, the scale bar measures 10 mm in length. A particular cell in the image measures 45 mm along its longest axis on the print.
Explain how the student can use the scale bar to determine the actual length of this cell. Set out the method as a sequence of steps, and state why the two lengths must be converted to the same unit before they can be compared.