Describe how a student could use a microscope to compare the size of frog skin cells to the size of human skin cells.

The use of the fine lens and the light source.

A light microscope uses focused light and lenses to magnify an object. Light microscopes come in several forms. (1) Simple light microscopes use a single lens to magnify an object and cannot reach high magnification just like a handheld lens whose highest clear magnification in the best conditions is 25x. (2) Compound light microscopes use two sets of lenses - an objective lens and an eye piece. This is the type of light microscope whose magnification power reaches between 1000x and 2000x.

Louis Pasteur designed an experiment to test whether sterile nutrient broth could spontaneously generate microbial life.