Is that right? (From an article, Using graph theory to analyze biological networks.)
Things flow in biological systems: energy, nutrients, blood, air, as examples.
A graph is a set of points with connections.
A graph is like a photograph. Biological systems are like movies. If that analogy is valid (well, maybe it is not?), then graphs are not the optimal way to model biological system; it is necessary to also model flow.
Your views?