Final answer:
The result of a mutation that eliminates the repressor protein in a negative inducible gene control system is that gene expression becomes constitutive, meaning it occurs continuously without regulation.
Step-by-step explanation:
When a structural gene is under negative inducible control, the presence of a repressor protein prevents gene expression until an inducer molecule binds to the repressor and inactivates it. If a mutation eliminates the repressor protein altogether, the natural consequence is that the gene would be expressed continuously because there is no repressor to inhibit its expression.
The correct answer is d) Gene expression becomes constitutive. This means that the gene is expressed at a constant rate without regulation. In the absence of the repressor protein, negative regulation cannot occur, thereby allowing the gene to be continually transcribed and translated into its protein product. This can often be beneficial in scenarios where constant production of a protein is desired, but may have detrimental effects if the protein needs to be regulated in response to the cell's environment or other cellular signals.