Final answer:
Living organisms are classified into three domains: Bacteria, Archaea, and Eukarya. The domain Bacteria includes prokaryotes, while the domain Eukarya includes eukaryotes. Within Eukarya, organisms are further classified into the kingdoms Animalia, Plantae, Fungi, and Protista.
Step-by-step explanation:
In the past, living things were grouped into five kingdoms: animals, plants, fungi, protists, and prokaryotes. However, in the late 20th century, scientists proposed a more fundamental way to group organisms based on differences in the structure of cell membranes and in ribosomal RNA sequences.
According to this new classification system, all living organisms can be categorized into three domains: Bacteria, Archaea, and Eukarya. The domain Bacteria includes prokaryotes, which are unicellular organisms without a nucleus or membrane-bound organelles. The domain Eukarya includes eukaryotes, which are multicellular organisms with a nucleus and membrane-bound organelles. Within the domain Eukarya, organisms are further classified into the kingdoms Animalia, Plantae, Fungi, and Protista.