Question

As a control for an experiment, you add a disk impregnated with a relatively low amount of alcohol to a plate on which you had streaked a large quantity of bacteria. After incubating this at 37°C for 2 days, you are surprised by the small zone of inhibition. Which of the following could explain these data?

A. This was a poor control. Alcohol is not a disinfectant.
B. The small amount of alcohol evaporated and, therefore, could not kill the bacteria.
C. You added too much alcohol to the disk.
D. None of the above is correct.

Answer 1

The small zone of inhibition in the experiment could be due to a poor control and the ineffectiveness of alcohol as a disinfectant.

Step-by-step explanation:

The small zone of inhibition in the experiment could be explained by option A: This was a poor control. Alcohol is not a disinfectant. Alcohol, especially at low concentrations, is not as effective at killing bacteria compared to other disinfectants. Additionally, alcohol can evaporate quickly, which could further reduce its effectiveness in killing the bacteria. Therefore, the small zone of inhibition could be due to the poor control and the inadequacy of alcohol as a disinfectant.