The simplest level of biological organization at which something can considered "life" is? a. atoms b. molecules c. cells d. tissues e. ecosystems 2. the main purpose of any single experiment is to a. explains an observation. b. prove unambiguously that a particular hypothesis is correct. c. gives know-it-all college professors something to do. d. answer as many key questions as possible. e. tests a prediction that is based on a hypothesis.