Which organelle is primarily responsible for ATP production through oxidative phosphorylation?

• A. Nucleus
• B. Chloroplast
• C. Ribosome
• D. Mitochondrion.

Answer: (D)

Energy production via oxidative phosphorylation happens in the mitochondria because this process uses a protein chain of electron carriers and ATP synthase embedded in the inner mitochondrial membrane. Electrons carried by NADH and FADH2 move through this chain, releasing energy that pumps protons across the membrane and creates a gradient. As protons flow back through ATP synthase, the enzyme drives the synthesis of ATP from ADP and inorganic phosphate. Nuclei store genetic material, ribosomes build proteins, and chloroplasts in plants generate ATP through photosynthesis via photophosphorylation, not oxidative phosphorylation. So the organelle responsible for ATP production through oxidative phosphorylation is the mitochondrion.