Are all living things made up of one or more cells and all cells come from pre-existing cells?

Yes, all living things are composed of one or more cells, which are the fundamental units of life. This principle is a key component of the cell theory, which also states that all cells arise from pre-existing cells through processes like cell division. This means that new cells are produced from the division of existing cells, rather than spontaneously generating. Thus, both statements reflect essential concepts in Biology.