All processes in organisms, from the interaction of molecules to complex functions
of the brain and other organs, obey physical laws. Mathematical modeling is an
important step towards uncovering the organizational principles and dynamic behavior
of biological systems. In general mathematical models can take many forms
depending on the time scale and the space structure of the problem. For example, in
population dynamics, if there is a complete overlap between generations, then the
population changes in a continuous manner and studies of such systems involve the
use of differential equations. For example, the equation