Which one is correct?

The population of bacteria in a petri dish doubles every 40 seconds. the population of the bacteria is initially 400 organisms. what unit is most appropriate for the time at which the number of bacteria is 300? hour bacteria per hour second bacteria per second

Ronald wants to see if a new shower cleaner works better in removing soap than his old cleaner. he uses the new cleaner on one half of the shower tiles and his old cleaner on the other half. identify the independent and dependent variables in this experiment. enter your answer in the space provided.

Jason adds the antibiotic penicillin to a bacterial culture. the bacteria develop genetic modifications in their genome, which gives them resistance to the antibiotic penicillin. what caused this genetic modification?