A student measures alcoholic fermentation by yeast. Yeast and 5% glucose are placed in a flask connected to an inverted graduated cylinder filled with water. CO2 produced by yeast displaces water, and the volume is read every 5 minutes for 30 minutes. The flask is held at 30 C. Three flasks differ only in whether they contain glucose, sucrose, or starch.
Which result is predicted?
- A
No CO2 is produced from any sugar
- Bcheck_circle
Glucose produces CO2 fastest, sucrose slower (after hydrolysis), starch very little
- C
Starch produces CO2 fastest because it is the largest molecule
- D
All three produce CO2 at the same rate
Explanation
Yeast can ferment glucose directly. Sucrose must first be hydrolyzed by invertase, slowing initial CO2 production. Yeast typically lacks amylase to break down starch, producing little CO2.