The document describes characteristics of living things and how dichotomous keys are used to identify organisms. It outlines the 7 main characteristics of living things: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. It then discusses viruses and how they differ from living cells in their inability to reproduce without a host. The document also defines what a species is and how dichotomous keys work through a series of binary choices to determine the identity of an organism based on its observable traits.