The science for classifying living things, is called (4)__________. (5)_______ is the process of grouping things based on similarities. Today, organisms are classified into three different domains. (6)__________ is unicellular, prokaryotic and live in extreme environments. The eukaryotic organisms fall into the domain (8) and are found everywhere. (7)_________ are found everywhere, are normally unicellular and are prokaryotic.​