You perform a Kirby-Bauer assay with two antibiotics. Antibiotic X has a zone of inhibition of 3 mm. Antibiotic Y has a zone of inhibition of 5 mm. Which antibiotic is better at killing this particular microorganism?

A. Antibiotic Y
B. It is impossible to tell from the information given.
C. Antibiotic X and Y, which have identical antimicrobial activities
D. Antibiotic X

A. Antibiotic Y

Explanation:

Kirby-Bauer assay is used to determine the susceptibility of an organism to the given antibiotics. It determines susceptibility by the diameter of zone of inhibition around antibiotic disks. Since the zone of inhibition of Antibiotic Y is greater than the Antibiotic X so Antibiotic is better or more powerful in killing this particular microorganism.

b. the carbon cycle ensures living things have a source of hydrogen