The correct option is (c).
Explanation
Respiration is the biochemical process by which cells break down glucose to release energy. In yeast, a unicellular fungus, this process often occurs in the absence of oxygen, a specific type of respiration known as anaerobic respiration or fermentation.
Statement-wise Analysis:
- Statement 1 is Incorrect: Anaerobic respiration, by definition, takes place in the absence of oxygen. In the presence of oxygen, yeast performs aerobic respiration, breaking glucose down completely into carbon dioxide and water.
- Statement 2 is Correct: During anaerobic respiration in yeast, the partial breakdown of glucose results in the formation of ethanol (ethyl alcohol) and carbon dioxide, releasing a small amount of energy (2 ATP).
- Statement 3 is Correct: This metabolic pathway is commercially utilized in the brewing industry. The ethanol produced is the alcohol content in wine and beer, while the carbon dioxide is often used to carbonate beverages or raise dough in baking.
Key Takeaway:
Anaerobic respiration in yeast (alcoholic fermentation) occurs without oxygen and converts glucose into ethanol and carbon dioxide.