Final answer:
Glucose and glycerol can be metabolized anaerobically through the process of glycolysis, while amino acids and free fatty acids are not directly utilized in anaerobic metabolism.
Step-by-step explanation:
The substances among glycerol, glucose, amino acids, and free fatty acids that can be metabolized anaerobically are glucose and glycerol. The process of glycolysis allows for the anaerobic metabolism of glucose to produce ATP. During glycolysis, glucose is broken down to pyruvate, yielding energy. Glycerol, which originates from the decomposition of triglycerides, can be converted to Glyceraldehyde 3-Phosphate (G3P) and fed into the glycolysis pathway, further supporting the production of energy under anaerobic conditions. Glucose can be synthesized from lactate, pyruvate, glycerol, alanine, or glutamate through the process of gluconeogenesis. Amino acids can be used as an energy source and processed through the Krebs cycle.
Conversely, amino acids and free fatty acids are not directly utilized in anaerobic metabolism. While amino acids can be used as energy sources, they often require conversion into other intermediates before they enter metabolic pathways like the Krebs cycle or are used in gluconeogenesis, processes that are not considered anaerobic. Free fatty acids are primarily metabolized aerobically via ß-oxidation to produce acetyl CoA, which then enters the Krebs cycle to generate ATP in the presence of oxygen.