You have decided to try to make your own wine by adding yeast to a sweet grape juice. After allowing plenty of time for the yeast to grow, you find that although the sugar levels in the juice are decreased, there is no alcohol in the mixture. What could have been the reason fermentation did not occur?
A) More sugar needs to be added. Yeast needs a lot of energy before it produces alcohol.
B) Less sugar is needed in the juice. High sugar concentration causes cellular respiration to occur instead of fermentation.
C) Yeast cannot ferment grapes, only bacteria can.
D) The mixture needs less oxygen. Yeast only produces alcohol in the absence of oxygen.
E) The mixture needs more carbon dioxide.

Question

Quizplus · Accepted Answer

Yeasts are good examples of microorganisms that generate ethyl alcohol and CO₂ when they go through fermentation, which occurs in anaerobic environments. If they are in an aerobic environment, they will completely oxidize glucose to carbon dioxide and water.

You Have Decided to Try to Make Your Own Wine