Exploitable energy gain is equal to the overall energy gain lessened by the not exploitable energy gain, which latter depends on the temperature during reaction and the number and nature of the present and participating substances.
Our expositions about energy distribution hardly if at all refer to the functional cycles proceeding according to unequivocal formulae and equations, and in which free energy, kept within moderate limits, appears as simple little exploitable unspecific heat.
Because in the metabolic cycles (being good examples of partition of an overall reaction with high energy potential at a safely low energetic level) the conditions of the strictly chemical reaction are very sharp and the execution at almost all stages steered by enzymes, the selecting agents may unequivocally attack, and, as surviving entity, an absolutely securely functioning, robust and strictly heritable reaction scheme can be preserved.
If one, now, says on the one hand : the many stages and cycles provide small attunable portions, to which the organismic objects could easily adapt, then one may say with even more confidence that possibly the cycles, which we, of course, now know only in the form of something complete, have phylogenetically evolved through attunable and appropriate stages. The inserted ATP reactions in the energetic coupling of glycogene-"combustion" [i.e. the transition from anaerobic energy extraction in the organism, "glycolysis", to aerobic energy extraction through oxygen, the "combustion" [of energy-containing compounds], ], and new-formation of ATP, represent a good example of how a chemical transformation does proceed with a substance [glycogene] that can udergo a reversible reaction in two reaction-kinetically different ways. If one wishes to be very exact, then one certainly must say that the change [from anaerobic to aerobic], as a summed-up happening, is reversible only on paper, and not so [reversible] if one takes into account the true nature of the real reactions. ["ATP", adenine triphosphate, is an energy-bearing molecule. When it subsequently transforms into ADP, andenine diphosphate, it releases this energy. So energy can, in the organismic body, be transported from one place to another by ATP.].