The evolution unit — and the single most heavily weighted unit on the exam. How natural and artificial selection change populations over time, how Hardy-Weinberg equilibrium models allele frequencies, and how phylogenies, speciation, and the fossil/molecular record provide evidence for evolution.
Six ways to master Unit 7 — pick whichever fits how you like to study.
Twelve topics from the College Board CED, in order.
Unit 7 is the evolution unit — and the single most heavily weighted unit on the entire AP Biology exam. You'll learn how natural selection acts on heritable variation within a population, how Hardy-Weinberg equilibrium gives you a mathematical baseline for "no evolution happening," and what actually changes allele frequencies when a population IS evolving (selection, drift, gene flow, mutation). You'll also study the evidence for evolution — fossils, biogeography, comparative anatomy, and molecular data — and how that evidence is used to build phylogenetic trees and identify new species.
This unit is 13–20% of the AP Bio exam and takes about 19–21 class periods — by far the largest single chunk of the course. The most-tested topics are Hardy-Weinberg calculations, interpreting phylogenetic trees/cladograms, distinguishing types of evidence for evolution, and real-world examples of ongoing evolution like antibiotic resistance.
The College Board ties Unit 7 to three of the four Big Ideas: