The standard free energy for the complete oxidation of glucose to CO₂ and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced? A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis. B) Glycolysis is a very inefficient process, with much of the energy of glucose released as heat. C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. D) There is no CO₂ or water produced as products of glycolysis.

Question

Quizplus · Accepted Answer

Most of the free energy available from the oxidation of glucose remains in pyruvate, the end product of glycolysis, which is why only two molecules of NADH are formed during this process. The remaining energy is conserved in pyruvate for further processing in the mitochondria during the citric acid cycle.

The Standard Free Energy for the Complete Oxidation of Glucose