<Ol> <Li> All known living things are made up of one or more cells </Li> <Li> All living cells arise from pre-existing cells by division . </Li> <Li> The cell is the fundamental unit of structure and function in all living organisms . </Li> <Li> The activity of an organism depends on the total activity of independent cells . </Li> <Li> Energy flow (metabolism and biochemistry) occurs within cells . </Li> <Li> Cells contain DNA which is found specifically in the chromosome and RNA found in the cell nucleus and cytoplasm . </Li> <Li> All cells are basically the same in chemical composition in organisms of similar species . </Li> </Ol> <Li> All known living things are made up of one or more cells </Li> <Li> All living cells arise from pre-existing cells by division . </Li> <Li> The cell is the fundamental unit of structure and function in all living organisms . </Li>

When did biologists confirm that living things are composed of cells