Two agar plates, one containing the antibiotic streptomycin and one without antibiotics, are inoculated with E. coli. After incubation, the streptomycin negative plate has many bacterial colonies, while the streptomycin positive plate has only a few colonies. Samples of the colonies from the positive plate are placed on another positive plate, and after incubation many colonies grow. In this experiment, what is the selective agent?

The selective agent according to the scenario of the experiment is the antibiotic streptomycin.

Explanation:

A selective agent is an environmental factor that has a dramatic impact on the mortality rate of any organism. In this scenario of the experiment, the antibiotic streptomycin is the selective agent because as described, after the incubation period of the two agar plates, the plate with antibiotic streptomycin only has a few colonies which proves that the antibiotic streptomycin since it had an impact on the mortality rate of the E. Coli bacteria.

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