Biology is the branch of science that deals with the study of living things. It studies any species that is considered to be alive, including minute bacteria that are made up of a single cell. This sect of science aims to discover how the systems of an organism work, how organisms behave in their environments, how species have evolved and how different ecosystems affect one another.
Biology is divided into more precise areas of study that focus on particular items. For example, the discipline of genetics studies how genetic material is passed down from parent to child and how an organism's genes control its existence. Evolutionary biology focuses on the evolution of species both on small and large scales.