You have some old plastic Petri dishes that you would like to use for pouring bacteriological agar plates. The only method of physical sterilization is ultraviolet radiation sterilization with your UV light (you cannot use the autoclave because it will dis?gure and melt the plastic). After sterilizing the
Plates, pouring the sterilized agar medium, and then leaving the plates out at room temperature for a day or two to let them solidify and dry, you ?nd contaminating bacterial colonies growing on the agar. Predict what has happened in this situation.

Question

Quizplus · Accepted Answer

UV light sterilization is effective only on surfaces directly exposed to the UV light. If the lids were left on the Petri dishes during sterilization, the UV light would not penetrate the lids, leaving the inside surfaces of the dishes, including the agar, unsterilized and susceptible to bacterial contamination.

You Have Some Old Plastic Petri Dishes That You Would