Passage I
Scientists studied the effects of Drug A on cancer Cell Lines V-Z. Table 1 shows the organ of origin and the LD50 (the concentration necessary to kill 50% of cells) of Drug A for each cell line.
Six petri dishes were prepared, each with 1,000 cells from Cell Line V. Drug A was added to 5 of the dishes in different concentrations, and all 6 dishes were incubated for 72 hr. Then the drug was removed, and the surviving cells were incubated for 10 days. This procedure was repeated for Cell Lines W-Z. Figure 1 shows the percent colony formation (percent of the surviving cells that divided to form colonies) for each cell line at each concentration of Drug A.
Table 1 and Figure 1 adapted from Debra Ferguson et al, “Anti-tumor Activity of Orally Bioavailable Farnesyltransferase Inhibitor, ABT-100, ls Mediated by Antiproliferative, Proapoptotic, and Antiangiogenic Effects in Xenograft Models." ©2005 by American Association for Cancer Research.
5. At which of the following concentrations was Drug A completely ineffective in preventing the surviving Cell Line V cells from dividing to form colonies?
Your Answer is
Correct Answer is A
Explanation
Corresponding to figure 1, when the abscissa Drug A concentration of cell line V is 0, 0.1 and 1, the ordinate percent colony formation is 100%, so at this time drag A cannot prevent Cell line V from splitting to form colonies