First, the experimental purpose

1, understand the anaerobic respiration and aerobic respiration of yeast.

2. Learn to design experiments by means of comparative experiments.

Second, the experimental principle

1. Yeast is a unicellular fungus, which can survive under aerobic and anaerobic conditions, and belongs to facultative anaerobic bacteria, which is convenient for studying different ways of cell respiration.

2.CO2 can make clear limewater turbid, and also make bromothymol blue water solution turn from blue to green and then yellow. According to the turbidity of limewater or the time when bromothymol blue solution turns yellow, the production of CO2 in yeast culture can be detected.

3. The orange potassium dichromate solution reacts with ethanol (alcohol) under acidic conditions.