The molecules produced as a result of anaerobic respiration vary depending on the organism but often include lactic acid or ethanol along with carbon dioxide. In the absence of oxygen, cells rely on this metabolic process to generate ATP energy. In humans, anaerobic respiration occurs during strenuous exercise, leading to temporary lactic acid accumulation. Meanwhile, yeast utilizes anaerobic respiration to ferment sugars into ethanol, which is significant for both baking and alcohol production.