Exploring the world of microscopic life, this program begins by discussing viruses and explaining how these cause disease. Bacterial cells are described, highlighting the important roles they play on Earth. Special attention is paid to protists, comparing the structure and function of plant-like, animal-like, and fungus-like protists. Concepts and terminology include: microscope, vaccine, moneran, decomposition, amoeba, phytoplankton, yeast, algae, paramecium, and protozoa. .