The correct option is **B. zymase**. ### Detailed Explanation: 1. **Understanding the Process**: The conversion of glucose to ethyl alcohol (ethanol) is a key process in fermentation, which is primarily carried out by yeast. During fermentation, yeast cells metabolize glucose in the absence of oxygen (anaerobic conditions) to produce ethanol and carbon dioxide. 2. **Role of Zymase**: Zymase is a complex of enzymes found in yeast that facilitates the fermentation process. It catalyzes the breakdown of glucose through a series of biochemical reactions, ultimately leading to the production of ethanol. The key steps in this process include glycolysis (the breakdown of glucose into pyruvate) and the subsequent conversion of pyruvate into ethanol and carbon dioxide. 3. **Why Other Options Are Incorrect**: - **A. Maltase**: Maltase is an enzyme that specifically breaks down maltose (a disaccharide) into two glucose molecules. While it plays a role in carbohydrate digestion, it does not directly convert glucose to ethanol. - **C. Diastase**: Diastase is a term that generally refers to a group of enzymes that break down starch into sugars, including maltose and glucose. However, it does not specifically refer to the enzymes involved in the fermentation process that converts glucose to ethanol. - **D. Invertase**: Invertase is an enzyme that hydrolyzes sucrose (table sugar) into glucose and fructose. While it is involved in sugar metabolism, it does not convert glucose to ethanol. ### Summary of the Fermentation Process: - **Glycolysis**: Glucose (C6H12O6) is converted into pyruvate (C3H4O3) through a series of enzymatic reactions, producing a small amount of ATP (energy). - **Alcoholic Fermentation**: Pyruvate is then converted into ethanol (C2H5OH) and carbon dioxide (CO2) by the action of zymase and other enzymes in anaerobic conditions. ### Common Pitfalls: - Confusing the roles of different enzymes: It's important to understand that while many enzymes are involved in carbohydrate metabolism, only zymase is specifically responsible for the conversion of glucose to ethanol during fermentation. - Misunderstanding the fermentation process: Remember that fermentation occurs in the absence of oxygen, which distinguishes it from aerobic respiration. ### Revision Summary: - The enzyme that converts glucose to ethyl alcohol is **zymase**. - Zymase catalyzes the fermentation process in yeast, converting glucose into ethanol and carbon dioxide. - Other options (maltase, diastase, invertase) do not directly facilitate the conversion of glucose to ethanol. - Understanding the specific roles of enzymes in metabolic pathways is crucial for mastering biochemical processes.