Which of the Following is the Source for the Energy

Question

Which of the following is the source for the energy that drives ATP synthesis?
A)the proton gradient
B)NAD⁺ and FAD
C)the electron gradient
D)molecular oxygen

Accepted Answer

The source of energy that drives ATP synthesis is the proton gradient - this is established by the electron transport chain in the mitochondria. As protons are pumped across the inner mitochondrial membrane, they create a gradient which can be harvested to drive the synthesis of ATP. NAD⁺ and FAD are coenzymes involved in the electron transport chain, but they are not the direct source of energy for ATP synthesis. The electron gradient is also involved in the electron transport chain and indirectly contributes to the establishment of the proton gradient, but it is not the direct source of energy. Molecular oxygen is the final electron acceptor in the electron transport chain, but it is not the direct source of energy for ATP synthesis.