Where does carbon dioxide come from during alcohol fermatiom?

During alcohol fermentation, carbon dioxide is produced as a byproduct when yeast converts sugars into ethanol and energy. This process, known as anaerobic respiration, occurs in the absence of oxygen and involves the breakdown of glucose through glycolysis and subsequent fermentation pathways. As the sugars are metabolized, carbon dioxide is released, contributing to the carbonation in beverages like beer and sparkling wine.