The following questions refer to Figure 27.1 below, which is the same as Figure 27.10 in the textbook.
In this 8-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 the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophage are excluded from the bacterial cultures, then which of these is a means by which beneficial mutations might be transmitted horizontally to other E. coli cells?
A)via sex pili
B)via transduction
C)via conjugation
D)via transformation
E)both A and C above

Question

The following questions refer to Figure 27.1 below, which is the same as Figure 27.10 in the textbook.
In this 8-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 the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophage are excluded from the bacterial cultures, then which of these is a means by which beneficial mutations might be transmitted horizontally to other E. coli cells?
A)via sex pili 
B)via transduction 
C)via conjugation 
D)via transformation 
E)both A and C above

Quizplus · Accepted Answer

In this experimental setup, the absence of F factor or F plasmid and exclusion of bacteriophage eliminate the possibilities of horizontal gene transfer through sex pili and transduction. However, transformation (option D) can still occur, as E. coli can take up DNA fragments from their environment and incorporate them into their genome. Therefore, option D is the best choice for horizontal transmission of beneficial mutations in this scenario.

The Following Questions Refer to Figure 27