What distinguishes aerobic respiration from anaerobic respiration?

Aerobic respiration is characterized by its use of oxygen to fully oxidize glucose or other substrates, resulting in the production of carbon dioxide, water, and a significant amount of energy in the form of ATP. This process occurs in the mitochondria of cells and involves several stages, including glycolysis, the citric acid cycle, and oxidative phosphorylation.

In contrast, anaerobic respiration occurs in the absence of oxygen. This process allows organisms to generate energy through fermentation or other anaerobic pathways, but it typically results in the incomplete breakdown of glucose, producing byproducts such as lactic acid or ethanol, along with a smaller yield of ATP compared to aerobic respiration.

This key difference in oxygen usage is fundamental to the metabolic pathways of aerobic versus anaerobic organisms and influences the efficiency and types of energy production that can occur in various environments. The other options presented do not accurately represent the key distinctions between these two forms of respiration, as they either confuse the requirements or the products of the processes involved.