A microorganism is an organism that can be seen only with the aid of a microscope. They include bacteria, protozoans, algae, and fungi. Microorganisms can be harmful or beneficial. Billions of __________ in our bodies live in our intestines. They help us digest our food and some help make vitamins that support good health. What are these microorganisms? A) algae B) bacteria C) fungi D) protozoan
