A scientist Investigated DNA replication in two groups of cells, labeled A and B. She Injected radioactively labeled nucleotides Into cells of each group and allowed DNA replication to begin. When replication was halfway completed, she Injected a drug into the cells to stop replication. She
then examined the cells to determine the distribution of the newly-synthestzed DNA. She found each cell of group A had many segments of new
DNA In Its nucleus, while each cell of group B had a single segment of new DNA in Its cytoplasm.
What can the researcher conclude about the cells?