Passage III
Scientists studied the effects of Drug X on various strains of bacteria in the Staphylococcus genus. Table 1 shows the bacteria that were
tested and the ED 50 (the dosage necessary to achieve a therapeutic effect for 50% of the population that is given the medication) of each
bacterial strain.
Six flasks containing 500 mL of nutrient broth were prepared, each with 10,000 cells of Staphylococcus aureus. Drug X was then addedto five of the flasks in different concentrations, and all six flasks were incubated at 37oC for 24 hours. This procedure was then repeated for
the four other bacterial strains. Figure 1 shows the percentage of cells killed for each bacterial strain at each concentration of Drug X.