AP Biology · Unit 7: Natural Selection
7.5 Hardy–Weinberg Equilibrium
In short
You must understand the Hardy-Weinberg equilibrium as a theoretical model and a null hypothesis for non-evolving populations. You are required to know the five specific conditions that must be met for equilibrium (large population size, no migration, no new mutations, random mating, and no natural selection).
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What else do you need to know about Hardy–Weinberg Equilibrium?
You must be able to apply the Hardy-Weinberg equations (p^2 + 2pq + q^2 = 1 and p + q = 1) to calculate allele and genotype frequencies for a specific gene. A critical depth requirement is the conceptual distinction between allele frequencies and genotype frequencies. You must understand that while the principle clarifies factors that alter allele frequency, it does not imply that allele frequencies are static in nature; rather, the model is used to make predictions about changes in a population and to justify reasoning for those predictions.
Can you do these?
- I can list the five conditions required for a population to be in Hardy-Weinberg equilibrium and explain how it serves as a null hypothesis.
- I can calculate allele and genotype frequencies in a nonevolving population using the Hardy-Weinberg equations.
How is Hardy–Weinberg Equilibrium tested on the exam?
This topic is heavily assessed through mathematical calculations (Skill 5.A) and explaining biological concepts in applied contexts (Skill 1.C). You will be expected to perform calculations using the Hardy-Weinberg equations, which may include calculating means, rates, ratios, and percentages. A common pitfall is failing to distinguish between allele and genotype frequencies when setting up equations. Exam questions often require you to calculate allele frequencies from given data, compare them to expected Hardy-Weinberg equilibrium values, and then construct an argument or justify a prediction about whether and how the population is evolving.
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Hardy–Weinberg Equilibrium: common questions
What do you need to know about Hardy–Weinberg Equilibrium for AP Biology?
You must understand the Hardy-Weinberg equilibrium as a theoretical model and a null hypothesis for non-evolving populations. You are required to know the five specific conditions that must be met for equilibrium (large population size, no migration, no new mutations, random mating, and no natural selection).
How is Hardy–Weinberg Equilibrium tested on the AP Biology exam?
This topic is heavily assessed through mathematical calculations (Skill 5.A) and explaining biological concepts in applied contexts (Skill 1.C). You will be expected to perform calculations using the Hardy-Weinberg equations, which may include calculating means, rates, ratios, and percentages.
How do I know I have mastered Hardy–Weinberg Equilibrium?
Check you can do each of these: list the five conditions required for a population to be in Hardy-Weinberg equilibrium and explain how it serves as a null hypothesis; calculate allele and genotype frequencies in a nonevolving population using the Hardy-Weinberg equations.
Where does Hardy–Weinberg Equilibrium fit in AP Biology?
Hardy–Weinberg Equilibrium is topic 7.5 in Unit 7: Natural Selection of AP Biology.
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