SAT Subject Biology Practice Question 246: Answer and Explanation
16. 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.
Which is the most common tree species in Plot 3?
A. Red pine
B. Red maple
C. Strobe pine
D. Paper birch
E. Sugar maple
Correct Answer: B
The frequency measures how often a particular tree species occurred in a plot. The tree with the highest frequency in plot 3 is Acer rubum, or red maple, with a frequency of 0.76.