Final answer:
The correct statement related to the Citric Acid Cycle is B: Oxidation of a sugar releases a molecule of CO2 as the coenzyme NAD+ captures electrons. This cycle plays a critical role in cellular respiration, generating high-energy electron carriers for ATP production.
Step-by-step explanation:
Understanding the Citric Acid Cycle
The student's question pertains to the metabolic pathways involved in the breakdown of glucose during cellular respiration, specifically the Citric Acid Cycle (also known as the Krebs Cycle). The Citric Acid Cycle is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates, fats, and proteins into carbon dioxide. In the presence of oxygen, pyruvate from glycolysis is converted into acetyl CoA, which then enters the Citric Acid Cycle. Every turn of the cycle generates high-energy electron carriers in the form of NADH and FADH2 and releases carbon dioxide as a byproduct.
The cycle starts with the combination of acetyl CoA and a four-carbon oxaloacetate molecule to form a six-carbon citrate molecule. Then, through a series of steps, citrate is oxidized, releasing two carbon dioxide molecules for each acetyl group fed into the cycle. Simultaneously, NAD+ is reduced to NADH, FAD to FADH2, and ATP is produced through substrate-level phosphorylation. Contrary to the statement in option C, CO2 does not capture electrons; rather, NAD+ captures them. Thus, option A is incorrect because the oxidation of the 5-carbon sugar does not release CO2, and option D correctly describes ATP synthesis independent of sugar oxidation.
Thus, the correct statement related to the Citric Acid Cycle, among the given options, is B: Oxidation of a sugar releases a molecule of CO2 as the coenzyme NAD+ captures electrons.