A wild-type culture of yeast is exposed to the mutagen ethyl methanesulfonate (EMS). Yeast cells are plated on a complete medium, and 6 colonies are transferred to a new complete medium plate for further study. Seven replica plates are made from the complete medium plate to plates containing minimal medium or minimal medium plus one or two amino acid with the following results. Determine which colonies are prototrophic (wild-type), auxotrophic for one amino acid, or auxotrophic for more than one amino acid.