TEAS® Science Study Guide
Classification & Microorganisms
Taxonomy is the system for naming and grouping living things. From broadest to most specific: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species. A common mnemonic is "Dear King Philip Came Over For Good Soup."
Three domains — Bacteria, Archaea, and Eukarya (everything with eukaryotic cells).
Microorganisms worth knowing
- Bacteria — Single-celled, prokaryotic. Living organisms; some cause disease, many are harmless or helpful.
- Viruses — Not made of cells and generally not considered alive. They can’t reproduce on their own; they must hijack a host cell to make copies. This is why antibiotics work on bacteria but not on viruses.
- Fungi — Include yeasts and molds. Absorb nutrients from their surroundings.
- Protists — A catch-all group of simple eukaryotes, such as amoebas and algae.
Terms to know
- Prokaryote — Cell without a nucleus (bacteria).
- Host — The cell or organism a virus infects to reproduce.
- Species — The most specific level of classification.
What the TEAS asks most
- What’s the correct order of classification? Domain → Kingdom → … → Species.
- Are viruses alive? Generally considered non-living; they need a host to reproduce.
- Why don’t antibiotics work on viruses? Antibiotics target bacteria, which are living cells; viruses aren’t.
- What is the most specific classification level? Species.