Final answer:
The Meselson and Stahl's experiment confirmed the semi-conservative model of DNA replication and supported Watson and Crick's model of the double helix, as it showed that DNA replicates with one parental and one new strand.
Step-by-step explanation:
The results of the Meselson and Stahl experiment supported the semi-conservative model of DNA replication. This model was one of three proposed mechanisms: conservative, semi-conservative, and dispersive. Their use of different isotopes of nitrogen (¹⁵N and ¹⁴N) to label DNA during replication allowed them to distinguish between these models. After one generation in ¹⁴N medium, the single DNA band observed in the middle density ruled out the conservative model. After two generations, the appearance of two bands—one at the intermediate density and one at the ¹⁴N density—ruled out the dispersive model and confirmed the semi-conservative model where each DNA molecule consists of one parental and one new strand.
Meselson and Stahl's work not only supported Watson and Crick's double-helix structure but also provided essential insights into the fundamental process of DNA replication during cell division.