Question

Mr. Miller's biology class is studying cellular respiration. To model cellular respiration, they used stopped flasks, setting one up as the control. This flask contained a package of yeast and
C water. The rate of cellular respiration was gauged by the height of carbon dioxide bubbles produced in the flask. Review the diagrams in Step 2 and compare this to the schematic of aerobic respiration. Elaborate on a conclusion for Step 2 of their experiments.
Responses
A Maximum respiration occurs in the presence of starch and oxygen.Maximum respiration occurs in the presence of starch and oxygen.
B The cell's food source of choice for maximum respiration is glucose.The cell's food source of choice for maximum respiration is glucose.
C It is more difficult to break down artificial sugars than natural sugars.It is more difficult to break down artificial sugars than natural sugars.
D Maximum respiration takes place using sugars rather than artificial sweeteners.

Answer 1

B — The cell's food source of choice for maximum respiration is glucose.

Reason: Aerobic respiration uses glucose as the primary substrate (glycolysis → pyruvate → Krebs → ETC) producing CO2. In the experiment the flask with glucose produced the most CO2 (highest bubble column). Starch must first be hydrolyzed to glucose (slower for yeast) and artificial sweeteners are not metabolized as sugars, so they give much less respiration.