What is NOT one of the products formed in the Krebs cycle?

• A. NADH
• B. Fumarate
• C. ATP
• D. Glucose

Answer: (D)

In the context of the Krebs cycle, glucose is not one of the products formed. The Krebs cycle, also known as the citric acid cycle or TCA cycle, is primarily involved in the oxidative metabolism of acetyl-CoA, which is derived from carbohydrates, fats, and proteins.

During the cycle, acetyl-CoA reacts with oxaloacetate to form citrate, leading to a series of reactions that produce key products such as NADH, FADH2, and ATP (or GTP, depending on the organism) as well as carbon dioxide. These NADH and FADH2 molecules are crucial electron carriers that feed into the electron transport chain to produce more ATP through oxidative phosphorylation.

Fumarate is one of the intermediates formed during the Krebs cycle, making it a product of this metabolic pathway. While glucose plays a critical role as a starting substrate for glycolysis, which produces pyruvate that is subsequently converted into acetyl-CoA, it is not directly generated or produced during the Krebs cycle itself. Thus, recognizing that glucose is not a product of the cycle is essential to understanding the distinctions between glycolysis, the Krebs cycle, and the overall metabolism of carbohydrates.