Which of the following compounds is a byproduct of cellular respiration?

Water is considered a byproduct of cellular respiration because it is produced during the metabolic processes that convert glucose and oxygen into energy. In cellular respiration, glucose is oxidized through a series of biochemical reactions, primarily during the citric acid cycle (Krebs cycle) and oxidative phosphorylation. One of the final steps involves the transfer of electrons through the electron transport chain, which ultimately combines with oxygen to form water. This reaction is essential as it helps maintain the flow of electrons and protons, allowing ATP, the energy currency of the cell, to be produced efficiently.

In contrast, oxygen is a reactant needed for aerobic respiration, glucose is the primary fuel source that gets broken down, and nitrogen does not play a direct role in cellular respiration, making water the clear byproduct of the process.