Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 5

Positive and Negative Control. Assume you have a culture of E. coli cells growing on medium B, which contains both lactose and glucose. At time f, 33% of the cells are transferred to medium L, which contains lactose but not glucose;
33% are transferred to medium G, which contains glucose but not lactose; and the remaining cells are left in medium B. For each of the following statements, indicate with an L if it is true of the cells transferred to medium L, with a G if it is true of the cells transferred to medium G, with a B if it is true of the cells left in medium B, and with an N if it is true of none of the cells. In some cases, more than one letter may be appropriate.
(a)The rate of glucose consumption per cell is approximately the same after time t as before.
(b)The rate of lactose consumption is higher after time t than before.
(c)The intracellular cAMP level is lower after time t than before.
(d)Most of the lac operator sites have lac repressor proteins bound to them.
(e)Most of the catabolite activator proteins exist as CAP-cAMP complexes.
(f)Most of the lac repressor proteins exist as repressor-glucose complexes.
(g)The rate of transcription of the lac operon is greater after time t than before.
(h)The lac operon has both CAP and the repressor protein bound to it.