Passage II

Urushiols are the oils in poison ivy that cause allergic reactions in humans. The higher the U: S ratio－the ratio of unsaturated (U) urushiols to saturated (S) urushiols—the more severe the reaction.

From 1999 to 2004, poison ivy plants (PIPs) were grown in 2 identical outdoor plots under identical conditions except for the atmospheric CO2 concentration.

Figure 1 shows, for each plot, the yearly dry biomass per plant. Figure 2 shows the yearly percent of original PIPs surviving in each plot. Figure 3 shows, for each plot in 2004, the percent of U urushiols per plant, the percent of S urushiols per plant, and the U: S ratio per plant.

Figures adapted from "Biomass and Toxicity Responses of Poison Ivy (Toxicodendron radicans) to Elevated Atmospheric CO2." @2006 by the National Academy of Sciences.

8. According to Figure 2, which plot had the higher percent of original PIPs surviving at the end of the study ?

Answer and Explanation

Your Answer is

Correct Answer is J

Explanation

The at the end of the study mentioned in the question stem corresponds to the abscissa in figure 2 being 2004. At this time, the elvated ordinate represented by the dotted line is higher, about 40%, while the present-day represented by the solid line The vertical axis of is lower, about 35%. The difference between the two is 40%-35%=5%, so option J is more suitable