Most of the \( \mathrm{CO}_2 \) from the catabolism of glucose is released during which stage of cellular respiration?

• A. The citric acid cycle (Krebs cycle)
• B. Oxidative phosphorylation
• C. Lactic acid fermentation
• D. Glycolysis

Answer: (A)

Verified step by step guidance

1. Understand the process of cellular respiration, which consists of three main stages: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation. Each stage has a specific role in breaking down glucose and releasing energy.
2. Recall that glycolysis occurs in the cytoplasm and breaks down one molecule of glucose into two molecules of pyruvate. This process produces a small amount of ATP and NADH but does not release significant amounts of carbon dioxide ( \( \mathrm{CO}_2 \) ).
3. Next, consider the citric acid cycle (Krebs cycle), which occurs in the mitochondrial matrix. During this stage, the pyruvate from glycolysis is further broken down, and most of the carbon dioxide ( \( \mathrm{CO}_2 \) ) from glucose catabolism is released as a byproduct.
4. Understand that oxidative phosphorylation, which occurs in the inner mitochondrial membrane, involves the electron transport chain and chemiosmosis. This stage generates the majority of ATP but does not release carbon dioxide ( \( \mathrm{CO}_2 \) ).
5. Finally, eliminate lactic acid fermentation as it is an anaerobic process that occurs when oxygen is not available. It does not involve the release of carbon dioxide ( \( \mathrm{CO}_2 \) ) and is not part of the main stages of cellular respiration.