Biology / Unit 8: Classification and Diversity of Life
8.2 Domains and Kingdoms
Notes
All life is grouped into three domains: Bacteria, Archaea and Eukarya.
- Bacteria: prokaryotes with cell walls containing peptidoglycan. Found almost everywhere.
- Archaea: prokaryotes without peptidoglycan; many live in extreme places (hot springs, very salty lakes). They are more closely related to eukaryotes than bacteria are.
- Eukarya: all eukaryotes, in four kingdoms: Protista, Fungi, Plantae, Animalia.
| Kingdom | Cells | Food |
|---|---|---|
| Protista | Mostly unicellular | Autotroph or heterotroph |
| Fungi | Mostly multicellular, cell walls of chitin | Heterotroph (absorbs food) |
| Plantae | Multicellular, cell walls of cellulose | Autotroph |
| Animalia | Multicellular, no cell walls | Heterotroph (ingests food) |
Practice
A single-celled prokaryote is found living in a boiling hot spring, and its cell wall has no peptidoglycan. Which domain does it most likely belong to?
Archaea are prokaryotes without peptidoglycan, often in extreme environments.
A multicellular organism has cell walls made of chitin and absorbs nutrients from dead material. It belongs to kingdom:
Chitin cell walls and absorbing food are features of fungi.
Which kingdom contains organisms that are multicellular, lack cell walls, and eat other organisms?
Animals are multicellular heterotrophs without cell walls.
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