Texas A&M University (TAMU) BIOL 351 Fundamentals of Microbiology Exam 1 Practice

Organisms are grouped in a way that goes from broad similarities to very specific ones. The widest category is domain, which splits all life into large groups. Within each domain, the next level is kingdom, then phylum, followed by class, order, family, genus, and finally species. This progression shows how each step narrows down the shared traits until you reach a single species. So the correct sequence starts with domain and ends with species: domain, kingdom, phylum, class, order, family, genus, species. Other sequences misplace domain or swap or mix up levels like phylum and kingdom, which doesn’t align with how organisms are hierarchically organized.