In animal cells, what happens to the carbon dioxide (\(\mathrm{CO_2}\)) produced during the link reaction of cellular respiration?

• A. It is transported to the lungs and exhaled as a waste product.
• B. It is converted into glucose through gluconeogenesis.
• C. It is stored in the mitochondria for later use.
• D. It is used directly in the electron transport chain.

Answer: (A)

Verified step by step guidance

1. Understand the context of the problem: The link reaction is a step in cellular respiration that occurs in the mitochondria. During this process, pyruvate is converted into acetyl-CoA, and carbon dioxide (\(\mathrm{CO_2}\)) is released as a byproduct.
2. Recall the fate of carbon dioxide (\(\mathrm{CO_2}\)) in animal cells: It is a waste product of cellular respiration and is not stored or reused in the mitochondria. Instead, it is transported out of the cell.
3. Consider the transport mechanism: Carbon dioxide (\(\mathrm{CO_2}\)) diffuses out of the mitochondria into the cytoplasm and then into the bloodstream. It is carried by the blood to the lungs.
4. Understand the role of the lungs: In the lungs, carbon dioxide (\(\mathrm{CO_2}\)) is exchanged for oxygen during gas exchange. The carbon dioxide is then exhaled as a waste product.
5. Eliminate incorrect options: Carbon dioxide (\(\mathrm{CO_2}\)) is not converted into glucose through gluconeogenesis, stored in the mitochondria, or used directly in the electron transport chain. The correct answer is that it is transported to the lungs and exhaled as a waste product.