Bioenergetics of Photophosphorylation The steady-state concentrations of ATP, ADP, and P; in isolated spinach chloroplasts under full illumination at pH 7.0 are 120.0, 6.0, and 700.0 M, respectively. (a) What is the free-energy requirement for the synthesis of 1 mol of ATP under these conditions? (b) The energy for ATP synthesis is furnished by light-induced electron transfer in the chloroplasts. What is the minimum voltage drop necessary (during transfer of a pair of electrons) to synthe- size ATP under these conditions? (You may need to refer to Eqn 13-7, p. 515.)