Mr. Gleicher – AP Biology
Name: __________________
How to Solve Hardy-Weinberg Problems
THE BASICS
p2 + 2pq + q2
Frequency of
Homozygous
Dominant
Individuals
Frequency of
Heterozygous
Individuals
Frequency of
Homozygous
Recessive
Individuals
p+q=1
Frequency of
Dominant
Allele
Frequency of
Recessive
Allele
SOLVING PROBLEMS
Most problems require similar steps. Here’s a list of things (usually) that need to be done in
order to solve most problems:
1. Find number of recessive phenotype individuals OR homozygous recessive individuals in
a population.
2. Convert to a frequency (percent as a decimal). This is q2.
3. Take the square root. This is q.
4. Subtract q from 1. This is p.
5. Square p. This is p2 and represents the frequency of homozygous dominant individuals.
6. Find 2pq. This represents the frequency of heterozygous individuals.
7. Multiply each value (p2, 2pq, q2) by the overall population size to find numbers of
individuals with these traits, if necessary.