O-LevelBiologyEcology & Environment5090/11 · May/June 2010 · Q251 Mark
Bacteria were grown on an agar plate, until the plate was covered with visible yellow bacterial colonies. Four discs containing equal amounts of different antibiotics were then placed on the agar plate. After two days, clear areas had formed around some of the discs, as shown in the diagram. Which conclusion about this experiment is correct? [Figure 25.1]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
AAntibiotic W is more effective against these bacteria than antibiotic X.
BAntibiotic Y is more effective against these bacteria than antibiotic W.
CDisc W has a higher concentration of antibiotic than disc Y.
DDisc Z contains no antibiotic.
✓ Correct answer
A: Antibiotic W is more effective against these bacteria than antibiotic X.
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