A student investigated the effectiveness of three different antibiotics (X, Y, and Z) against a specific bacterium grown on an agar plate.
The student measured the diameter of the circular zone of inhibition (the clear area where no bacteria grew) around each antibiotic paper disc:
Describe one aseptic technique the student should have used to prevent contamination of the agar plate when preparing this experiment.
Which antibiotic is the most effective? Give a reason for your answer.
Calculate the area of the zone of inhibition for antibiotic Y. Use π=3.14\pi = 3.14π=3.14. Give your answer to 1 decimal place and include the unit in your final answer.
Suggest one way the student could improve the reliability of this investigation.