Final answer:
Yeast, being facultative anaerobes, can respire both aerobically and anaerobically. The product of their anaerobic respiration or fermentation is alcohol and CO2, useful in food and beverage industries. The effectiveness of different sugars, as respiratory fuels, may vary and can be measured through the production rate of fermentation products.
Step-by-step explanation:
In relation to your question, yeast are facultative anaerobes. This means they can perform both aerobic and anaerobic respiration. The effectiveness of different respiratory fuels on yeast respiration can be measured by the rate of production of carbon dioxide and ethyl alcohol. These products result from alcoholic fermentation which yeast carry out in the absence of oxygen. The glucose from sugars serves as the starting material.
During aerobic respiration, which normally occurs when oxygen is present, yeast convert glucose into energy (in the form of ATP), carbon dioxide and water. Under anaerobic conditions (when oxygen is not sufficient or absent), the yeast switch to anaerobic respiration or fermentation. They convert glucose into energy, carbon dioxide and ethyl alcohol. This fermentation process is what makes bread rise and is also used in wine and beer production.
Learn more about Yeast Respiration