The enzyme beta-galactosidase acts on lactose to form galactose. In turn, the presence of galactose leads to expression of the enzymes responsible for the metabolism of galactose. In this case, lactose is serving as a carbon source and as a(n)

A. repressor.
B. operon.
C. inducer.
D. DNA-binding protein.


Answer: C

Biology & Microbiology

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