In the Experiments Described in the Text, Jacob and Monad

Short Answer

In the experiments described in the text, Jacob and Monad deciphered that the lacI⁺ gene product can function in trans and regulate the lac operon either on the plasmid or on the chromosome. What genotype of the partial diploid bacterial strain was key to their experiments and led them to such a conclusion? Explain why this strain helped them to reach that conclusion.