The students concluded that the yeast respired aerobically at first and then switched to anaerobic respiration. Which two pieces of evidence support their conclusion?
A. The glucose was used up by the end of the experiment.
B. Carbon dioxide was released and made the balloon expand.
C. Water was still present in the flask at the end.
D. Alcohol was produced during the experiment.
E. Oxygen was present at the beginning but not at the end.
The students concluded that the yeast respired aerobically at first and then switched to anaerobic respiration. Which two pieces of evidence support their conclusion?
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The two pieces of evidence that support the conclusion that yeast respired aerobically at first and then switched to anaerobic respiration are:
B. Carbon dioxide was released and made the balloon expand.
D. Alcohol was produced during the experiment.
Explanation:
Initially, during aerobic respiration, yeast uses oxygen to break down glucose, which produces carbon dioxide and water. The expansion of the balloon indicates that carbon dioxide was produced. When the oxygen is depleted, yeast then switches to anaerobic respiration (fermentation), which produces alcohol and carbon dioxide. The production of alcohol confirms that anaerobic respiration occurred after the aerobic phase.