Under the conditions existing in biological systems (including constant temperature and pressure), changes in free energy, enthalpy, and entropy are related to each other quantitatively by the equation: △ G = __________ in which Δ G is the change in Gibbs free energy of the reacting system, Δ H is the change in enthalpy of the system, T is the absolute temperature, and Δ S is the change in entropy of the system.