Cell Respiration · Paper 1 — Free Biology SL Practice Questions

A eukaryotic cell contains a bean-shaped organelle with a highly folded inner membrane that is the primary site of aerobic cell respiration. During aerobic cell respiration, pyruvate is converted to acetyl-CoA before entering a cyclic series of reactions that produce $\text{CO}_2$ and reduced coenzymes. In which location within this organelle does this cyclic series of reactions occur?

Isolated yeast mitochondria are suspended in a buffered solution containing pyruvate, ADP, and inorganic phosphate, and oxygen consumption is monitored with an oxygen electrode. After 5 minutes, a specific inhibitor of the pyruvate dehydrogenase complex is added. What is the immediate effect on the rate of oxygen consumption and on the NADH concentration in the mitochondrial matrix?