Yeast

False color scanning electron micrograph of the unicellular yeast Saccharomyces cerevisiae, or Baker's yeast. Cells with the appearance of pinched in waistlines are in the process of dividing. The circular areas on some of the cells are bud scars where former daughter cells have broken away at the completion of cell division. Yeast, a form of fungus, multiplies rapidly by a process of budding or by fission. They have the ability to ferment sugars and in so doing produce alcohol and carbon dioxide. These properties are used in the production of wines, beers, distilled spirits and in the baking of leavened bread. Magnification: X1,930 at 35mm size.
Credit: David Scharf / Photo Researchers, Inc.

Algae

Volvox are spherical colonies of green algae cells clinging to a semi-transparent hollow ball of mucilage. A single colony may consist of over 500 cells, each one with a tiny pair of whip-like tails (flagella) - and all cells undulating their flagella in unison, propelling the colony through the water. Very large colonies can exceed 1 mm in diameter and are easily visible to the naked eye. Many will be found to contain daughter cells, and sometime even grand-daughter cells in various stages of development, within the hollow interior of the globe. Here the daughter cells can be seen as green developing colonial spheres within the hollow interior of the larger sphere. Darkfield microscopy. Mag: X75 @35mm.
Credit: Michael Abbey / Photo Researchers, Inc.