Final answer:
The two pathways that might follow glycolysis are lactic acid fermentation and alcoholic fermentation, and the factor that determines which pathway a cell might follow is the presence of oxygen.
Step-by-step explanation:
Glycolysis is the first pathway used in the breakdown of glucose to extract free energy. After glycolysis, there are two pathways that might follow:
- Lactic acid fermentation: In the absence of oxygen, a cell can undergo lactic acid fermentation. This pathway converts pyruvate (the end product of glycolysis) into lactic acid and regenerates NAD+ to keep glycolysis going. This occurs in cells like muscle cells during strenuous exercise.
- Alcoholic fermentation: In the absence of oxygen, some microorganisms like yeast can undergo alcoholic fermentation. This pathway converts pyruvate into ethanol, carbon dioxide, and regenerates NAD+ for glycolysis to continue. This is the process used in the production of alcoholic beverages.
The factor that determines which pathway a cell might follow is the presence of oxygen. If oxygen is present, the cell will continue with aerobic respiration. If oxygen is absent, fermentation is used to generate ATP.