Anatomy and Physiology II Practice Test

The step in carbohydrate metabolism that occurs without the requirement of oxygen is glycolysis. Glycolysis is the anaerobic process that breaks down glucose into pyruvate, producing a small amount of ATP in the process. This pathway is essential for the initial stages of glucose metabolism and does not require oxygen, making it crucial for energy production in both aerobic and anaerobic organisms, especially in conditions where oxygen is scarce. While other processes listed, like the Citric Acid Cycle and Oxidative Phosphorylation, require oxygen to proceed effectively, glycolysis can happen in its absence. Glycogenesis, on the other hand, is the process of converting glucose to glycogen for storage, which does not directly involve carbohydrate breakdown for energy. Thus, glycolysis stands out as the correct answer in this context.