Final answer:
The redox potential changes down the electron transport chain as electrons are transferred from substances with higher reduction potentials to those with lower reduction potentials. This transfer releases energy that is converted into electrochemical potential energy.
Step-by-step explanation:
The redox potential, also known as the reduction potential, changes down the electron transport chain in a specific manner. In each step of the chain, electrons are transferred from a substance with a higher reduction potential to one with a lower reduction potential. This transfer results in the release of energy proportionate to the difference in reduction potential between the substances. The energy released is then converted into electrochemical potential energy by pumping protons from the matrix to the intermembrane spaces through enzymes called complexes. This electrochemical energy is used by ATP synthase to generate ATP through oxidative phosphorylation.