Biologists are able to study life at multiple levels of organization.[1] From the molecular biology of a cell to the anatomy and physiology of plants and animals, and to the evolution of populations.[1][6] Thus, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they used.[7][8][9] Like other scientists, biologists use the scientific method to make observations, pose questions, generate hypotheses, and perform experiments to satisfy their curiosity about the world around them.[1]