AP BIOLOGY

Detailed explanation-1: -So 1 molecule of pyruvate is responsible for the release of 2 CO2 molecules during 1 Krebs cycle. Since 1 glucose molecule gives 2 pyruvate molecules. There will be two cycles to utilize both the pyruvate molecules. Thus, 1 glucose molecule is responsible for the release of 4 CO2 molecules during Krebs cycle.

Detailed explanation-2: -Step 3. Isocitrate is converted into -ketoglutarate in a reaction catalyzed by isocitrate dehydrogenase. An NAD+ molecule is reduced to NADH + H+ in this reaction, and a carbon dioxide molecule is released as a product.

Detailed explanation-3: -For each acetyl CoA that enters the citric acid cycle, two carbon dioxide molecules are released in reactions that are coupled with the production of NADH molecules from the reduction of NAD+ molecules.

Detailed explanation-4: -The molecules of carbon dioxide are produced in the second stage of cellular respiration, that is, in the Krebs cycle. These molecules of carbon dioxide are carried by the circulating blood to the alveolar tissues; from there, it is expelled out of the body via a breathing mechanism.