(南京大学2008年考研试题)E.Coli cells are growing in a medium containing lactose but no glucose，indicate whether each of the following changes or conditions would increase，decrease，or not change the expression of the lac opern．It may be helpful to draw a model depicting what is happening in each situation． (a)addition of a high concentration of glucose (b)a mutation that prevents dissociation ofthe Lac repressor form the operator (c)a mutation that completely inactivates β-galactosidase (d)a mutation that completely inactivates galactosied permease (e)a mutation that prevents binding of CRP to its binding site near the lac promoter