Question 17
Work in groups. Wear eye protection and gloves; handle yeast carefully and avoid contact with eyes, skin and clothing. Mix 5 g of active dry yeast with 30 cm³ of warm water (35–40 °C). Label two clear plastic bottles mixture 1 and mixture 2. Mixture 1: 100 cm³ water + 15 cm³ yeast mixture. Mixture 2: 10 g sugar + 100 cm³ water + 15 cm³ yeast mixture. Cap and shake each bottle, then remove the caps and fit a balloon over each opening (stretch its opening if needed). Start a timer. Yeast is unicellular and releases carbon dioxide during respiration. Respiration releases energy; it is not breathing.
What is the purpose of the sugar solution?
What is the purpose of the sugar solution?
