Colorado Esthetician Written Practice Exam 2026 – Complete Test Prep

Single-cell microorganisms are known as bacteria. Bacteria are unicellular organisms that can be found virtually everywhere and can have both harmful and beneficial effects on humans. Viruses are not considered cells but rather infectious agents that need a host cell to replicate. Fungi are multicellular organisms, and parasites are multicellular organisms that live on or in a host organism.