The correct answer is: B. Anaerobic respiration in yeasts
Ethanol is produced by yeasts during anaerobic respiration. This is a process that occurs when there is not enough oxygen available for the yeast to carry out aerobic respiration. In anaerobic respiration, yeasts break down glucose to produce pyruvate, which is then converted to ethanol and carbon dioxide.
Aerobic respiration is a process that occurs when there is enough oxygen available. In aerobic respiration, glucose is broken down to produce pyruvate, which is then converted to carbon dioxide and water. This process is much more efficient than anaerobic respiration, and it produces more energy.
Muscles use both aerobic and anaerobic respiration to produce energy. When there is enough oxygen available, muscles use aerobic respiration. However, when there is not enough oxygen available, muscles switch to anaerobic respiration. Anaerobic respiration produces less energy than aerobic respiration, and it also produces lactic acid, which can cause muscle fatigue.
Yeasts are single-celled organisms that are found in many different environments. They are used in the production of bread, beer, and wine. Yeasts are also used in the production of biofuels, such as ethanol.