Which gas is essential for cellular respiration?

Oxygen is essential for cellular respiration because it plays a critical role in the process of converting nutrients into energy. During cellular respiration, cells use oxygen to help break down glucose, which occurs primarily in the mitochondria. This process results in the production of adenosine triphosphate (ATP), the energy currency of the cell, as well as water and carbon dioxide as byproducts.

The presence of oxygen allows for aerobic respiration, which is significantly more efficient than anaerobic processes that occur without oxygen. In aerobic respiration, a large amount of energy (up to 36 molecules of ATP) can be harvested from a single molecule of glucose. In contrast, anaerobic processes yield much less energy. This efficiency highlights why oxygen is vital for the energy metabolism of most living organisms, especially in complex multicellular forms like humans and animals.