Visit this site to explore examples and significance of polymorphic loci. When you're done, take the quiz.

Polymorphisms
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Polymorphisms.html

Think about: Why is the threshold definition for a polymorphism set at 1 percent of a population?

Phenylketonuria
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Phenylketonuria.html#PKUallele

Think about: What does it mean to say that the PKU allele shows partial dominance?

DNA as Legal Evidence
http://www.geocities.com/geneinfo/facts/evidencefr.html

Think about: When testing DNA, why is it necessary to sample multiple loci? What does it mean to say that a match exists?

1			Polymorphism analysis is useful for evaluating the degree of genetic variability in a population.
			A)	True
			B)	False
2			The ABO and Rh blood systems are examples of polymorphisms.
			A)	True
			B)	False
3			Analysis of polymorphisms cannot be used to determine if two animal populations represent different species.
			A)	True
			B)	False
4			A balanced polymorphism occurs when selection favors individuals who are heterozygous for a given pair of alleles.
			A)	True
			B)	False
5			Phenylketonuria is an example of a balanced polymorphism.
			A)	True
			B)	False
6			Because phenylketonuria is a disease of liver function, a liver transplant can correct the underlying genetic cause.
			A)	True
			B)	False
7			Genetic drift tends to reduce or eliminate a polymorphism in a small population.
			A)	True
			B)	False
8			Mutation causes polymorphisms to persist in a population.
			A)	True
			B)	False
9			The use of DNA evidence is based on the fact that except for identical twins, each person is genetically unique.
			A)	True
			B)	False
10			Examining three loci is sufficient for determining whether a suspect committed a crime.
			A)	True
			B)	False