n the reoxidation of QH2 by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH2 because: Group of answer choices cytochrome c is a one-electron acceptor, whereas QH2 is a two-electron donor. cytochrome c is a two-electron acceptor, whereas QH2 is a one-electron donor. cytochrome c is water soluble and operates between the inner and outer mitochondrial membranes. heart muscle has a high rate of oxidative metabolism, and therefore requires twice as much cytochrome c as QH2 for electron transfer to proceed normally. two molecules of cytochrome c must first combine physically before they are catalytically active.