The organization of similar organisms into groups scientists understand how living things are related. it also allows scientists to communicate about all forms of life. scientists organize the living world using a process called taxonomy, which is the science classifying organisms based on shared structures, functions, and relationships to other organisms. scientists use a branching system of classification, and over the years, due to new discoveries, the branching system has changed and grown. all living organisms are classified into one of three domains: bacteria, archaea, and eukarya. compare and contrast the domains bacteria and archaea. how are they alike? how are they different? a. they are both composed of prokaryotic organisms. bacteria are parasites and archaea are free- living. b. both domains contain parasitic organisms composed of one cell. the archaea are the disease- causing parasites. c. both are composed of prokaryotic organisms. the archaea live in very extreme environments, like hot springs, bacteria do not. d. both are unicellular, prokaryotes. the archaea live as parasites while the bacteria live in extreme environments, like the salt flats and hot springs.