Question

Think about those household cleaners that claim to kill 99.99% of germs. Which of the following experiments would best test this claim?

A. -Inoculate a broth with bacteria swabbed off of a desk. Determine the number of bacteria in the tube. Subject the contents to the disinfectant. Determine the number of bacteria still in the tube.
B. -Impregnate a disk with the disinfectant. Place this disk on an agar plate which has been fully inoculated with a particular bacterium. Determine the zone of inhibition.
C. -Swab an entire desk. Determine the number of bacteria on the swab. Disinfect the desk, and reswab. Determine the number of bacteria remaining.
D. -Swab a desk before and after you disinfect it. Place the swabs in broth, and see if they grow.

Answer 1

To test the efficency of a household cleaner that claims to kill 99.99% of germs, conducting an experiment that involves swabbing a desk, applying the disinfectant, and then reswabbing to measure the bacteria reduction is most effective.

Step-by-step explanation:

The best experiment to test the claim that a household cleaner kills 99.99% of germs would be option C, which is swabbing an entire desk, determining the number of bacteria on the swab, then disinfecting the desk, and reswabbing to determine the number of bacteria remaining. This method directly tests the efficacy of the cleaner in a real-world setting, where the number of bacteria present before and after the application of the disinfectant is measured to assess the percentage reduction in bacterial count.

Option A, while controlled, only measures bacteria in a broth which does not simulate a surface found within a household setting. Option B tests the zone of inhibition but is more applicable for assessing antibiotics suitability and not household cleaners on surfaces. Option D does not quantify the bacteria but rather looks for the presence or absence of growth in broth, which may not accurately reflect the effectiveness of the cleaner.