Regarding horizontal gene transfer between bacteria by conjugation, transduction, or transformation:
a. which mechanism has the broadest host range? explain.
b. which has the narrowest host range? explain.

Distinct mechanisms are used by bacteria in order to transfer the gene from one bacteria to another. These are transformation, transduction, and conjugation. Transformation refers to the process of uptaking extracellular DNA by the recipient of the other bacterial cell.  

In the process of transduction, the donor DNA gets packed within the bacteriophage and infects the recipient bacteria. In the process of conjugation, the genetic substance is transferred by the donor bacteria to the recipient via the process of mating.  

a. Of all these three mechanisms, transformation is the process that exhibits a broad range and can be easily performed in the lab. As in the process, there is a slight chance of rejection or failure due to direct compatibility between the bacteria.  

b. While the narrowest broad range is found in the process of conjugation, as in order to transfer the genetic substance between the two bacterial species, there should be a similarity between the two species so that they can mate and exchange the genetic substance in between them.