ACT Science

SAT Question of the Day

The SAT question of the day is a Sentence Completion Question that has already been addressed on this blog: click here to see an explanation.

ACT Science Question of the Day

ACT science questions often ask you to read charts and graphs, but you do not have to understand all of the information that is provided in order to answer the question correctly.  Take a look at today's question before wading through the images.

Abandoned cornfields have been the sites of investigations concerning ecological succession, the orderly progression of changes in the plant and/or animal life of an area over time (see Figure 1).

(Note: The plants are ordered according to their appearance during ecological succession.)

During the early stages of succession, the principal community (living unit) that dominates is the pioneer community. Pioneer plants are depicted in Figure 2.

The final stage of ecological succession is characterized by the presence of the climax community, the oak-hickory forest. Figure 3 depicts the gradual change from pine to hardwoods.

Figures adapted from Eugene P. Odum, Fundamentals of Ecology. ©1971 by Saunders College Publishing/Holt, Rinehart, and Winston, Inc.

On the basis of the data depicting the gradual change from pine forest to an oak-hickory forest, after 100 years, as the density of the pine trees:

You can tell from the description of the figures that Figure 3 concerns forests, and its description even includes the words “gradual change.”  You do not need any of the other figures.  You first need to know what happens to the pine trees.  The line labeled “pine” goes down, so the pine trees are decreasing over the years.  Then notice that the line labeled “oak-hickory” goes up.  These trees are increasing during the same period.  Look down at your answer choices.

. . . as the density of the pine trees:

A. increases, the density of the oak-hickory trees increases.
B. increases, the density of the oak-hickory trees decreases.
C. decreases, the density of the oak-hickory trees increases.
D. decreases, the density of the oak-hickory trees decreases.

The correct answer is (C).


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