Question

in a dihybrid cross, r is normal for adenine, r is mutant for adenine and shows red color. t is normal for tryptophan and t is mutant for tryptophan. which of the following combinations is expected to grow and show a red color on mv medium?
ha rt/hb rt
ha rt/hb rt
ha rt/hb rt
hart/hart

Explanation:

To grow on MV medium and show red color, the organism needs to be mutant for adenine (r) for the red - color trait and have at least one normal allele for tryptophan (T) to be able to synthesize tryptophan and grow. In the combination HArT/HBRt, one allele combination has r (mutant for adenine) and also has T (normal for tryptophan).

Answer:

C. HArT/HBRt