Cold Spring Harbor Laboratory
Dna From the Beginning: Genetic Inheritance Follows Certain Rules
Find out what happened when Mendel crossed two hybrid pea plants. The animations do a good job explaining why these crosses produce a 3:1 ratio of traits.
Other
Evolution: The Theory of Natural Selection (Part 1)
These pages are part of a site called Evolution that accompany a textbook by the same name. Mark Ridley is the author. This section has an advanced discussion of determining allele and genotype frequencies using the Hardy-Weinberg ratio.