Final answer:
Under anaerobic conditions, lactate or lactic acid is the fermentation product necessary for glycolysis to continue.
Step-by-step explanation:
Under anaerobic (anoxic) conditions, the fermentation product that is necessary for glycolysis to continue is lactate or lactic acid. Lactate is produced when pyruvate, the end product of glycolysis, is converted to lactate using the electrons from NADH. This allows NAD+ to be regenerated, which is essential for glycolysis to continue. Fermentation is important in anaerobic conditions as it allows cells to continue producing ATP in the absence of oxygen.