Answer:
by c. allowing an organism to adjust to changes in environmental conditions like the presence of certain nutrients like sugars.
Step-by-step explanation:
A repressible operon is an operon that is normally active, but can be turned off in response to a specific signal. An example of a repressible operon is the trp operon in E. coli, which is responsible for the synthesis of the amino acid tryptophan. This operon is normally active, but can be turned off when tryptophan is present in the environment. This is achieved through a repressor protein that binds to a specific site on the DNA, preventing the operon from being transcribed.
An inducible operon is an operon that is normally inactive, but can be turned on in response to a specific signal. An example of an inducible operon is the lac operon in E. coli, which is responsible for the metabolism of lactose. This operon is normally inactive, but can be turned on when lactose is present in the environment. This is achieved through the binding of a specific protein called the lac repressor to the operator site on the DNA, which prevents the operon from being transcribed. When lactose is present, it binds to the repressor protein and causes a conformational change, releasing the repressor protein from the operator site, allowing the operon to be transcribed.
In summary, the repressible operon is normally active but can be turned off in response to a specific signal. The inducible operon is normally inactive but can be turned on in response to a specific signal. The mechanism by which the operon responds to an environmental cue is through the binding of a specific protein, the repressor protein, to the operator site on the DNA.