Glucose is the preferred carbon source for Escherichia coli bacteria. Researchers isolated E. coli-M, a strain of E. coli with a single mutation that inactivates a key enzyme in one of the three glycolytic pathways E. coli bacteria use to break down glucose. In an initial experiment to study the effect of the mutation on glucose utilization and ATP production by the bacteria, the researchers add 2×104 E. coli-M bacteria to 400 mL of a growth medium that contains glucose. To measure the rate of bacterial growth, they monitor the optical density of the culture as a measure of the bacterial concentration over time.

(a) Describe why monitoring the growth rate of the E. coli-M bacteria is a useful indicator of the effect of the glycolytic enzyme mutation on the bacteria.

(b) Identify the most appropriate control the researchers should use when determining whether the mutation affects the growth rate of the E. coli-M bacteria.

(c) Predict the growth rate pattern of the E. coli-M bacteria when they are initially added to the growth medium if the mutation does not interfere with glucose utilization.

(d) Provide reasoning to justify your prediction.