How many times does the Krebs cycle turn for each molecule of glucose that enters cellular respiration?

The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle, is a central metabolic pathway that plays a critical role in cellular respiration. For each molecule of glucose that undergoes cellular respiration, the Krebs cycle turns twice.

When glucose is metabolized, it is first broken down into two molecules of pyruvate during glycolysis. Each pyruvate is then converted into acetyl-CoA, which enters the Krebs cycle. Since one molecule of glucose produces two molecules of acetyl-CoA, the Krebs cycle turns two times, once for each acetyl-CoA. During these turns, substrates are processed through a series of reactions that result in the production of electron carriers (NADH and FADH2) and ATP, as well as the release of carbon dioxide as a waste product.

Therefore, the correct answer is that the Krebs cycle turns twice for each molecule of glucose that enters cellular respiration.