Which of the following is NOT a product of respiration?

Respiration is a biochemical process that occurs in living organisms where organic substances, primarily glucose, are broken down to produce energy. The primary end products of this metabolic process are energy in the form of ATP (adenosine triphosphate), carbon dioxide, and water.

During respiration, glucose is oxidized, and as a result, ATP is generated for cellular activities, carbon dioxide is produced as a waste product, and water is also formed. The process of respiration can be summarized by the following general equation:

[ \text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water} + \text{Energy (ATP)} ]

In this equation, oxygen is not a product; rather, it is required as a reactant in aerobic respiration to help oxidize glucose. Therefore, it is correct to say that oxygen is not a product of respiration, as it is consumed in the process. This differentiates it from the other substances listed, which are generated as a result of physiological processes within the cells during respiration.