Final answer:
The Meselson-Stahl experiment confirmed that DNA replication is semi-conservative, meaning that each new DNA molecule consists of one original and one new strand.
Step-by-step explanation:
The Meselson-Stahl experiment demonstrated that DNA replication is semi-conservative. During this process, each strand of the parental DNA molecule serves as a template for the synthesis of a new, complementary strand. Therefore, each resulting DNA molecule consists of one original, or 'parental', DNA strand and one newly synthesized DNA strand.
The experiment conducted by Matthew Meselson and Franklin Stahl in 1958 provided clear evidence supporting this model. They used isotopes of nitrogen to distinguish between old and new strands of DNA, finding an intermediate band after one generation, and bands corresponding to both light (14N) and intermediate densities after two generations, confirming the semi-conservative model.