Which gas is a byproduct of aerobic respiration?

During aerobic respiration, glucose is broken down in the presence of oxygen to produce energy. This process occurs in the mitochondria of cells and results in a few key products: energy in the form of ATP (adenosine triphosphate), water, and carbon dioxide. The carbon dioxide produced is a byproduct of the metabolic processes that occur when glucose is oxidized.

Oxygen, while essential for aerobic respiration, is consumed in the process rather than being produced. The other gases listed, such as nitrogen and hydrogen, are not significant byproducts of aerobic respiration in living organisms under normal conditions. Therefore, carbon dioxide is correctly identified as the byproduct, reflecting the overall equation for aerobic respiration: glucose + oxygen → carbon dioxide + water + energy.