Two strains of E. coli-one of which can turn on its lactase production and one that cannot-are grown together with lactose in the medium. If all other conditions are equal, what will occur?
A) Both strains will continue to be present in equal amounts.
B) The two strains will kill each other off.
C) The strain that can turn on lactase production will outcompete the other strain.
D) The strain that cannot turn on lactase production will outcompete the other strain.
E) The two strains will work cooperatively and share the lactose.

Question

Quizplus · Accepted Answer

The strain that can turn on lactase production will have an advantage over the strain that cannot. This is because it will be able to use lactose as a source of energy more efficiently, and therefore grow and reproduce at a faster rate. Over time, the lactase-producing strain will outcompete and eventually replace the lactase-nonproducing strain.

Two Strains of E