Chapter 7, Problem 7P

In a genetics lab, Kim and Maria infected a sample from an E. coli culture with a particular virulent bacteriophage. They noticed that most of the cells were lysed, but a few survived. The survival rate in their sample was about 1 × 10^-4. Kim was sure the bacteriophage induced the resistance in the cells, while Maria thought that resistant mutants probably already existed in the sample of cells they used. Earlier, for a different

experiment, they had spread a dilute suspension of E. coli onto solid medium in a large petri dish, and, after seeing that about 10⁵ colonies were growing up, they had replica-plated that plate onto three other plates. Kim and Maria decide to use these plates to test their theories. They pipette a suspension of the bacteriophage onto each of the three replica plates. What should they see if Kim is right? What should they see if Maria is right?