Domain is the taxonomic level that is just above kingdom in the Linnean system of classification. According to whatever agreed upon nomenclature that you have in front of you, how many kingdoms are recognized? Try looking up the following keywords: prokaryotes, *eu*bacteria, monerans . . . et cetera. You should memorize the categories: Kingdom, Phylum, Class, Order, family, genus, species. King Phillip calls on fifty girls Saturday.
