Calculate the energy cost of the Calvin cycle combined with glycolysis and oxidative phosphorylation, that is, the ratio of the energy spent synthesizing starch from CO2 and photosynthetically produced NADPH and ATP to the energy generated by the complete oxidation of starch. Assume that each NADPH is energetically equivalent to 2.5 ATP and that starch biosynthesis and breakdown are mechanistically identical to glycogen synthesis and breakdown.