Which of the following statements about the H+ gradient are correct?
I. The H⁺ gradient is primarily established by the decarboxylation reactions of the citric acid cycle.
II. The flow of protons through ATP synthase from the intermembrane space to the matrix drives the synthesis of ATP.
III. The H⁺ gradient is maintained by the transfer of electrons from NADH and FADH₂ through the electron transport chain.
IV. The dissipation of the H⁺ gradient without ATP synthesis can lead to the production of heat instead of ATP.