10 . Oxidation of organic substances is accompanied by reductior of: (indicate one or more answers) tetrahydrofolate thiamine pyrophosphate FAD ascorbic acid NAD^+

The correct answers are:<br /><br />- FAD (Flavin Adenine Dinucleotide)<br />- $NAD^{+}$ (Nicotinamide Adenine Dinucleotide)<br /><br />Explanation:<br />During the oxidation of organic substances, certain cofactors and coenzymes are reduced. FAD and $NAD^{+}$ are two such cofactors that are reduced during the oxidation process. FAD is reduced to FADH2, and $NAD^{+}$ is reduced to NADH. These reduced forms then carry the electrons to the electron transport chain for ATP production.