Organisms with prokaryotic cells are separated into two ________, Bacteria and Archaea.

• A. kingdoms
• B. phyla
• C. domains
• D. families

Answer: (C)

Taxonomic classification uses domains as the highest rank in the modern three-domain system. Organisms with prokaryotic cells are separated into two domains: Bacteria and Archaea. This split reflects deep evolutionary differences shown by genetic analyses, such as ribosomal RNA sequences, which reveal that these two lineages diverged long ago and are as distinct from each other as either is from Eukarya. Because of that, the term that fits is domains. Using kingdoms would reflect an older framework, and phyla or families are lower ranks that wouldn’t capture the two primary prokaryotic lineages.