The Krebs cycle, also known as the citric acid cycle, produces six molecules of carbon dioxide (CO2) per molecule of glucose.

Here's why:

* Glucose (C6H12O6) is a 6-carbon molecule that is broken down into two 3-carbon molecules of pyruvate during glycolysis.

* Each pyruvate enters the Krebs cycle and is decarboxylated twice (losing a carbon atom as CO2).

* Therefore, two turns of the Krebs cycle (one for each pyruvate) produce a total of 6 CO2 molecules.