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Biology · FRQ Trainer

Free-response 1 of 58 · Natural Selection

4 pts our rubric

The real Biology Section II is 6 free-response questions in 90 minutes, 50% of your score. 2 long questions worth 9 points each and 4 short questions worth 4 points each — 34 raw points. This prompt is ours, written to the same skills — score it against the rubric below, not against that structure.

Prompt

A beetle population varies from light to dark. A researcher introduces a bird predator that hunts by sight on dark bark. Over 20 generations, allele frequencies for the color gene (D = dark, dominant; d = light, recessive) are tracked.

aPredict how the frequency of D will change and explain the mechanism of natural selection.2 pts

bIn generation 1 the recessive light phenotype has frequency 0.16. Assuming Hardy–Weinberg equilibrium, calculate the D and d allele frequencies and the frequency of heterozygotes.1 pt

cDescribe ONE Hardy–Weinberg condition being violated and justify.1 pt

Keep writing to unlock scoring (0/120)

Write your response first — then grade it with AI or self-score against the rubric.