Most CO₂ from Catabolism is Released During

Question

Most CO₂ from catabolism is released during
A) glycolysis.
B) the citric acid cycle.
C) lactate fermentation.
D) electron transport.
E) oxidative phosphorylation.

Accepted Answer

During the citric acid cycle (also known as the Krebs cycle), the majority of CO₂ molecules are released as a byproduct of the oxidative breakdown of acetyl-CoA. This cycle takes place in the mitochondria of cells and is the final common pathway for the oxidation of carbohydrates, fats, and amino acids. The other choices (glycolysis, lactate fermentation, and electron transport) do not directly produce CO₂ as a byproduct. Although oxidative phosphorylation does involve the transfer of electrons and the generation of a proton gradient, it occurs in conjunction with electron transport and does not produce CO₂ as a byproduct.