This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Chain, Subject name: Biochemistry
Enzyme responsible for complete oxidation of glucose to CO2 to water is present in 
Select and explain. 
A. Cytosol, B. Mitochondria, C. Lysosomes, D. Endoplasmic reticulum
B: Mitochondria
Answer: B: Mitochondria 
Explanation: Ans. is 'b' i.e. Mitochondria The fate of pyruvate formed at the end of glycolysis (glucose metabolism) is as follows :Under anaerobic conditions : Pyruvate is reduced by the NADH to lactate in the presence of Lactate dehydrogenaseUnder aerobic conditions : Pyruvate is taken up into mitochondria & is converted to Acetyl-CoA in the presence of pyruvate dehydrogenase complex. Now this Acetyl-CoA enters Krebs cycle.* Kreb's cycle is the final pathway where oxidative metabolism of carbohydrates, amino acids & fatty acids converge, their carbon skeleton being converted to CO2 and H20.