Task #1- BLOW UP A BALLOON WITH YEAST (group) Yeast Fermentation Lab Purpose: To Observe anaerobic respiration in yeast (Fermentation) and to test for the presence of carbon dioxide. Materials: 1 packet of yeast 2 Erlenmeyer Flask Sugar Scale Warm water 110 ° F Spoon Balloon Directions: 1. Use the scale, filter paper and spoon to weigh 3 grams of sugar. 2. Pour 100 ml of warm water to the flask. (When yeast is cold or dry the micro-organisms are resting) 3. Add one packet of yeast to the flask and give it a gentle swirl the flask for a few seconds. (As the yeast dissolves, it becomes active – it comes to life!) 4. Add the sugar and swirl it around some more. (Life people, yeast needs energy (food) to be active. Now the yeast is eating!) 5. Place the balloon over the neck of the flask. 6. Let the flask sit in a warm place for 20 minutes. The yeast uses the sugar and warm water to grow. Warm water provides heat to the yeast reaction and accelerates it. As yeast grows it expands and gets bubbly. By being “bubbly” the yeast gives off carbon dioxide, the same gas that your body produces when you breathe, and the gas inflates the balloon. The yeast also produces ethanol. Respiration provides organisms with the energy to do cellular work that helps them grow, function, and live. People use yeast to bake because during fermentation carbon dioxide forms bubbles in the dough and expand it. Since baking is done at high temperatures, yeast ultimately dies and nearly all the ethanol evaporates. Ethanol fermentation is used to produce alcoholic beverages. People also use yeast fermentation to make ethanol for fuel.
