Significance of Inflection Points in Biological Application

Question

This problem appears in our calculus book. It asks to compute the maximum concentration of drug in the blood and the time when the maximum occurs as well as to find the number of inflection points and then it asks for the time at which the inflection points occur and finally the "significance" of the inflection points. The model given is $$C(t)=0.5t^2e^{-0.6t}$$ where $C(t)$ is the concentration. It was very easy to find that the maximum concentration of $\frac{50}{9}e^{-2}$ occurs at $t=10/3$ and that there are two inflection points, occurring at $t=\frac{10\pm 5\sqrt{2}}{3}$. But when the author asks for the "significance" of the inflection points I'm not sure what he means. An inflection point is a zero of the second derivative occurs. It is where the graph is "flat" (i.e. the curvature is zero) but in this case I believe the author wants the "biological" significance, and there I am stuck. Is it when the drug is being absorbed and excreted? Perhaps there is something about drug metabolism that I need to know and do not? Thank you in advance for any help!