View the animation below, then complete the quiz to test your knowledge of the concept.

1	The Meselson-Stahl experiment demonstrated that DNA replication produces two DNA molecules each composed of
	A)	two old strands.
	B)	two new strands.
	C)	one old and one new strand.
	D)	two strands with variable proportions of new and old DNA.
	E)	a variable number of old and new strands.
2	Starting with 15N15N (heavy) DNA, and after TWO generations in the 14N medium, Escherichia coli cells will contain
	A)	25% 15N15N DNA, 50% 15N14N DNA, and 25% 14N14N DNA.
	B)	50% 15N15N DNA and 50% 14N14N DNA.
	C)	50% 15N15N DNA and 50% 15N14N DNA.
	D)	50% 15N14N DNA and 50% 14N14N DNA.
	E)	25% 15N14N DNA and 75% 14N14N DNA.
3	Starting with 15N15N (heavy) DNA, and after THREE generations in the 14N medium, E. coli cells will produce the following band(s) in density-gradient centrifugation:
	A)	a single band of DNA with medium density.
	B)	one band of light DNA and one band of DNA with medium density.
	C)	one band of heavy DNA and one band of DNA with medium density.
	D)	one band of heavy DNA and one band of light DNA.
	E)	three bands corresponding to DNA of light, medium and heavy density.
4	Meselson and Stahl performed the density-gradient centrifugation of DNA in a solution of calcium chloride.
	A)	True
	B)	False
5	Starting with 15N15N (heavy) DNA, and after ONE generation in the 14N medium, E. coli cells subjected to density-gradient centrifugation will produce a single band of DNA with medium density.
	A)	True
	B)	False