What are the potential energy substrate byproducts of glycolysis?

The byproducts of glycolysis include lactic acid and pyruvate, making this choice the correct one. Glycolysis is a metabolic pathway that converts glucose into pyruvate while producing energy in the form of ATP and NADH. This process occurs in the cytoplasm of cells and can function under both aerobic and anaerobic conditions.

Under aerobic conditions, pyruvate is typically transported into the mitochondria for further energy production through the Krebs cycle. However, under anaerobic conditions or when there is insufficient oxygen, pyruvate is converted into lactic acid. This conversion is essential for regenerating NAD+, which is necessary for glycolysis to continue and produce ATP.

The other options do not accurately represent the byproducts of glycolysis: glucose is a substrate rather than a byproduct, oxygen and carbon dioxide are associated with aerobic respiration rather than glycolysis itself, and fatty acids and ketones are related to lipid metabolism, not carbohydrate metabolism. Therefore, recognizing that lactic acid and pyruvate are the primary byproducts of glycolysis highlights an essential aspect of cellular energy metabolism.