The following questions refer to Figure 27.1.
In this eight-year experiment, 12 populations of E. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population.

Figure 27.1
-If new genetic variation in the experimental populations arose solely by spontaneous mutations, then the most effective process for subsequently increasing the prevalence of the beneficial mutations in the population over the course of generations is
A) transduction.
B) binary fission.
C) conjugation.
D) transformation.
E) meiosis.

Question

The following questions refer to Figure 27.1.
In this eight-year experiment, 12 populations of E. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population.
  
Figure 27.1
-If new genetic variation in the experimental populations arose solely by spontaneous mutations, then the most effective process for subsequently increasing the prevalence of the beneficial mutations in the population over the course of generations is
A) transduction. 
B) binary fission. 
C) conjugation. 
D) transformation. 
E) meiosis.

Quizplus · Accepted Answer

Binary fission is the process by which E. coli cells reproduce and pass on their genetic information to daughter cells. If a beneficial mutation arises in a cell during binary fission, it will be present in both daughter cells, and the prevalence of the mutation in the population will increase over time as more and more cells acquire it through reproduction. Transduction, conjugation, and transformation are all mechanisms of horizontal gene transfer that can introduce new genetic variation into a population, but they are not as efficient for increasing the prevalence of beneficial mutations as binary fission. Meiosis is a process that occurs in sexual reproduction and would not be relevant in this experiment where E. coli is reproducing asexually through binary fission.

The Following Questions Refer to Figure 27.1