Correct Option: A. Carbon dioxide and ethanol Detailed Explanation: 1. Understanding Anaerobic Respiration: Anaerobic respiration is a type of cellular respiration that occurs in the absence of oxygen. It allows organisms, such as yeast, to generate energy when oxygen is scarce. The process primarily involves the breakdown of glucose to produce energy, but instead of using oxygen, it relies on fermentation pathways. 2. The Process in Yeast: In yeast, anaerobic respiration is commonly referred to as alcoholic fermentation. The overall reaction can be summarized as follows:

• Glucose (C₆H₁₂O₆) is broken down into ethanol (C₂H₅OH) and carbon dioxide (CO₂).

The simplified equation for this process is: [ \text{C}6\text{H}{12}\text{O}_6 \rightarrow 2 \text{C}_2\text{H}_5\text{OH} + 2 \text{CO}_2 ] This means that for every molecule of glucose, two molecules of ethanol and two molecules of carbon dioxide are produced. 3. Why Option A is Correct: - Ethanol Production: Yeast converts glucose into ethanol, which is the primary alcohol produced during fermentation. This is why alcoholic beverages are made using yeast. - Carbon Dioxide Production: The carbon dioxide produced during this process is what causes bread to rise and is also a byproduct in the production of alcoholic drinks. Analysis of Other Options: Option B: Carbon dioxide and water - This option is incorrect because water is not a primary product of anaerobic respiration in yeast. Instead, water is produced during aerobic respiration, where oxygen is used to fully oxidize glucose. Option C: Carbon dioxide and oxygen - This option is incorrect because oxygen is not produced during anaerobic respiration. In fact, the defining characteristic of anaerobic respiration is that it occurs without oxygen. Oxygen is a reactant in aerobic respiration, not a product in anaerobic processes. Option D: Carbon dioxide and glucose - This option is incorrect because glucose is not produced as a byproduct of anaerobic respiration. Instead, glucose is consumed during the process to generate energy, ethanol, and carbon dioxide. Summary of Key Points:

• Anaerobic respiration in yeast produces carbon dioxide and ethanol through the process of alcoholic fermentation.
• The overall reaction involves the breakdown of glucose without oxygen, resulting in energy production and the release of byproducts.
• Other options are incorrect as they either include water or oxygen, which are not produced in anaerobic conditions.

Revision Summary:

• Anaerobic respiration in yeast results in the production of carbon dioxide and ethanol.
• The process is known as alcoholic fermentation.
• Glucose is consumed, not produced, during this process.
• Oxygen is not involved in anaerobic respiration, distinguishing it from aerobic respiration.