Researchers design experiments so that only one variable is different between the two treatments being compared. In the Hershey-Chase Experiment, what is this single variable? Why was the experiment set up this way?

Recombinant dna is the merging of dna from unrelated organisms to create new genetic varieties is assembled in the lab from mononucleotides was part of the green revolution of the 1960s is pollination of one plant by another of the same species is cross-pollination of one plant by a different species