During which phase of cellular respiration can a person typically hold their breath longer, and why?

• A. During the Krebs cycle, because oxygen is not required at this stage.
• B. During glycolysis, because less carbon dioxide is produced and the urge to breathe is lower.
• C. During the electron transport chain, because ATP is produced without generating carbon dioxide.
• D. During fermentation, because lactic acid buildup increases oxygen demand.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the phases of cellular respiration. Cellular respiration consists of glycolysis, the Krebs cycle (citric acid cycle), and the electron transport chain. Fermentation is an alternative pathway that occurs in the absence of oxygen.
2. Step 2: Analyze the role of oxygen in each phase. Oxygen is not required during glycolysis or fermentation, but it is essential for the electron transport chain, where it acts as the final electron acceptor.
3. Step 3: Consider carbon dioxide production. Carbon dioxide is produced during the Krebs cycle, which can increase the urge to breathe. Glycolysis produces less carbon dioxide, which may allow a person to hold their breath longer.
4. Step 4: Evaluate ATP production. The electron transport chain produces the most ATP, but it requires oxygen. Fermentation produces ATP without oxygen but leads to lactic acid buildup, which increases oxygen demand.
5. Step 5: Conclude based on physiological factors. Holding breath is influenced by carbon dioxide levels and oxygen demand. Glycolysis may allow longer breath-holding due to lower carbon dioxide production and reduced urge to breathe.