SCIENCE PRACTICE TEST EXPLANATIONS
Passage I
1 . B This question asks about Study 1, so we’ll need to look at Figure 2. The color intensity for
the moths in City Y is shown on the right side of the second graph in black, and the highest
percentage of these moths had a color intensity of 8. Eliminate (C) and (D). The color
intensity for the moths in City X is shown on the left side of the third graph in gray, and the
highest percentage of these moths had a color intensity of 5. Eliminate (A), and the only
remaining answer is (B).
2 . J The blurb in Study 2 contains the following information: During dry years, pollutants are
more likely to concentrate on tree bark, and the tree bark itself tends to become thicker.
Therefore, bark is thickest during dry years, and of the years listed on Figure 3, only 2003 is
listed as a “dry” year, so (J) is the best answer from the given choices.
3 . A Study 1 contains the following information: Scientists captured 100 B. betularia f. typica
and 100 B. betularia f. carbonaria in City X. Study 2 contains the following information:
During each visit [from 1983 to 1992], they captured at least 50 B. betularia f. typica
moths and measured their body color intensities. Therefore, it can be assumed that they did
not catch B. bethularia f. carbonaria in Study 2, making (A) the best answer. For color
intensity, note the axes of each of the graphs. Color intensity is a variable plotted along the x-
axis in Figure 2 and along the y-axis in Figure 3, meaning that it was measured in both
studies.
4 . H Choices (H) and (J) are direct opposites, which means that one of them is likely to be true.
You’ll need to use a bit of science common sense here to choose between these two. In Study
1, the scientists are trying to count the number of moths in these various cities; therefore, in
order to make this count accurate, they will need to make sure that each moth is only counted
once, as in (H). Choice (F) is incorrect because pollution is measured in Study 2, and (G) is
incorrect because wingspan is not measured in either study.
5 . C Figure 3 shows that 2005 was a wet year, and the average color intensity was 10. First, it is
clear that moths with higher color intensities are more likely to survive in the wet years than
the dry years, so the moth with a color intensity of 9.5 is more likely to survive than the moth
with a color intensity of 6.5. Eliminate (A) and (B). Then, notice that Study 2 contains the
following information: During wet years, pollutants tend to be washed from the surfaces of
tree bark. This information agrees with (C).
