From time to time the SAT II Biology tests your knowledge of the various parts of the compound microscope, usually by showing you an image and asking you to identify the parts.

 

 

    Many parts of the cell are hard to see under microscopes because they are colorless. In order to view them, scientists sometimes employ stains that mark various cell parts differently. One alternative to staining is a technique called phase contrast microscopy, which uses filters to emphasize the contrast between different parts of the cell.

 

 

    At high magnifications, light microscopes produce blurry images. In the 1950s, scientists invented a new type of microscope called the electron microscope, which offers increased image clarity, or resolving power. Electron microscopes are powerful enough to resolve individual fats and proteins. Light microscopes are still widely used, however, because electron microscopes are expensive and can only be used to view matter that is not living.