Which of the following statements about regulation of the lac operon is true? select all that apply. when glucose is present but lactose is absent, gene expression is activated at the lac operon. the presence of glucose in the growth medium does not affect the level of gene expression activated by the presence of lactose. the lac repressor can dissociate from the operator in the presence of glucose. gene expression is high when the lac repressor is not bound to the operator and glucose is unavailable. gene expression is high when the lac repressor is not bound to the operator and glucose and lactose are available?