What is the primary product of the Krebs cycle?

The primary product of the Krebs cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle, is carbon dioxide. This cycle is a crucial part of cellular respiration and occurs in the mitochondria of cells.

During the Krebs cycle, acetyl-CoA, derived from carbohydrates, fats, and proteins, enters the cycle and undergoes a series of enzymatic transformations. These transformations lead to the release of energy in the form of ATP and reduced coenzymes, NADH and FADH2, which carry high-energy electrons to the electron transport chain. One of the essential outcomes of these biochemical reactions is the decarboxylation process where carbon atoms from acetyl-CoA are released as carbon dioxide. This carbon dioxide is then expelled from the cell and ultimately exhaled by organisms, making it a key byproduct of the Krebs cycle.

The other choices do not accurately represent the primary product of the Krebs cycle. While glucose is a substrate entered into cellular respiration before entering the Krebs cycle, it is not a product of it. Lactic acid and alcohol are products of anaerobic respiration and fermentation processes, not of the aerobic Krebs cycle. Hence, the correct identification of carbon dioxide emphasizes