In many systems biology applications prior knowledge exists as to the nature of the biology underlying the collected data. This knowledge can be formalized in models of different nature and - ideally - these models describe the essential biological processes in a concise way. Such models can range from first-principles biochemical models, to agent-based models and grey models.
Lumped systems biology model of the fate of polyphenols in the human body as used in Nutrikinetics studies (from the thesis of Ewoud van Velzen).