Abstract
The present Chapter relates and summarizes the main features of biological systems. Contrary to molecular biology, systems biology does not attempt at explaining biological events in terms of the properties of biomolecules but in terms of systems of biomolecules. As these systems are abstract entities it follows that systems biology has an abstract character that can only be approached by the use of mathematics. Exactly as for physics, this situation raises the question of the concrete reality of the theoretical concepts.
Keywords: Systems and emergent properties, Systems and information, Systems and Plato’s metaphysics, Systems and mathematics, Reality and objectivity of mathematical concepts, Systems and artificial life.