If DNA replication was conservative, after one generation how many bands in the Meselson & Stahl experiments would you expect?

Two bands-one light and one heavy band

Explanation:

Conservative mode of replication was the hypothetical mode of replication which proposed that DNA replication results in the formation of new DNA molecule in which the one DNA molecule is the parent molecule and one DNA molecule are the synthesised DNA molecule with the exact sequence as of the original DNA.

In the given question, in the Meselson & Stahl experiments if the population is undergoing conservative mode of replication then it would result in two bands during centrifugation after generation 1. The one band will be of ¹⁵ N (original strand) and one band will be of ¹⁴N.

Thus, Two bands-one light and one heavy band are correct.