Final answer:
After two rounds of dispersive replication, one would expect one band in the Meselson and Stahl experiment, but the experiment actually showed two bands supporting the semiconservative model of DNA replication.
Step-by-step explanation:
According to Meselson and Stahl's experiment, after two rounds of dispersive replication, one would expect to see just one band of DNA on a density gradient. However, Meselson and Stahl's experiment did not support the dispersive model of replication. They showed that after two rounds of replication, the DNA exhibited two bands: one corresponding to DNA consisting of one heavy (¹5N) and one light (¹4N) strand, and one corresponding to DNA with two light strands (¹4N only). This finding was consistent with the semiconservative model of DNA replication, where each new DNA molecule consists of one old and one new strand.