SAT Subject Biology Practice Question 248: Answer and Explanation
18. Ecologists surveyed the composition of three different forest plots. They measured the frequency of occurrence of 13 different tree species and the basal area of each species. The basal area is calculated by measuring tree circumference at breast height and calculating the area occupied by a particular species in square meters per hectare.
The data shows a negative, or inverse, correlation between which two tree species?
A. Strobe pine and paper birch
B. Red maple and sugar maple
C. Paper birch and yellow birch
D. Quaking aspen and paper birch
E. White spruce and American elm
Correct Answer: B
Red maple and sugar maple are inversely correlated in the forest area studied. In plots where red maple occurs more frequently, sugar maple occurs less frequently, and vice versa.