Anthocyanin is a pigment that gives flowers and leaves purple colors. The M gene codes for a transcription factor (Myb) that promotes expression of an enzyme that produces anthocyanin. The W gene codes for a different enzyme (Chs) that allows anthocyanin to be deposited in plant leaves and flowers. The dominant phenotype is the production of functional Myb and Chs. Use this information to answer the following question. Plants that have the mm genotype do not show any purple color. What is the best explanation for why this is?

Anthocyanin is not produced in the plant cells

Explanation:

Anthocyanin is not produced in plant cells with the genotype mm.

As you can see from the question above, anthocyanin is responsible for the purple color of the flowers. Anthocyanin is encoded by the M gene, which is a dominant gene. Because it is a dominant gene, we know that it will be expressed in plants with the Mm and MM genotype, but will not be encoded by plants with the mm genotype. With this we can conclude that plants that have the mm genotype do not have purple color, because anthocyanin is not produced in the plant cells of these plants, since they do not have the M gene.