Question

10 selecting a resistant strain of bacteria
how will you select and grow a resistant strain of e. coli in this experiment?
multiple choice
expose a sample of e. coli to streptomycin by inoculating it onto a streptomycin - positive plate. any colonies that grow will carry a mutation for resistance.
expose a sample of e. coli to streptomycin by inoculating it onto a streptomycin - negative plate. any colonies that grow will carry a mutation for resistance.
a culture of e. coli will be treated with streptomycin so that new antibiotic can alter the genetic composition of the bacteria.
samples of bacteria are taken from the culture and observed under a microscope for signs of susceptibility or resistance. those bacteria resistant are isolated and cloned.

Explanation:

To select a resistant strain of E. coli, one exposes a sample of E. coli to an antibiotic (in this case streptomycin). By inoculating it onto a streptomycin - positive plate, only the E. coli with a mutation for resistance will be able to grow and form colonies. Other options are incorrect as inoculating on a streptomycin - negative plate won't select for resistance, and the other descriptions don't accurately describe the standard process of selecting for antibiotic - resistant strains.

Answer:

Expose a sample of E. coli to streptomycin by inoculating it onto a streptomycin positive plate. Any colonies that grow will carry a mutation for resistance.