AP BIOLOGY

Detailed explanation-1: -During oxidative phosphorylation, electrons derived from NADH and FADH2 combine with O2, and the energy released from these oxidation/ reduction reactions is used to drive the synthesis of ATP from ADP.

Detailed explanation-2: -Oxidative phosphorylation. Protons flow back into the matrix through an enzyme called ATP synthase, making ATP. At the end of the electron transport chain, oxygen accepts electrons and takes up protons to form water.

Detailed explanation-3: -The electron transport chain and ATP synthase are embedded in the inner mitochondrial membrane. NADH and FADH2 made in the citric acid cycle (in the mitochondrial matrix) deposit their electrons into the electron transport chain at complexes I and II, respectively.

Detailed explanation-4: -The ETC is a collection of proteins bound to the inner mitochondrial membrane and organic molecules, which electrons pass through in a series of redox reactions, and release energy. The energy released forms a proton gradient, which is used in chemiosmosis to make a large amount of ATP by the protein ATP-synthase.