Answer:
No
Explanation:
According to the given information, the L gene is required to start the pathway as its product starts the pathway of synthesis of black pigment. A mutant cell lacking the L gene would not be able to carry out the conversion of D into Y since it lacks the L gene and L would not be converted into the D.
A metabolic pathway with multiple steps requires the presence of substrate for the downstream reactions to occur. In the absence of a substrate or gene for any of the steps, the downstream reactions of the pathway would not occur and the cell would not form the final product of the pathway. Therefore, the mutant cell would not be able to form black pigment.