The following question refers to the figure.
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.

If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophages are excluded from the bacterial cultures, then beneficial mutations might be transmitted horizontally to other E. coli cells via ________.
A) sex pili
B) transduction
C) conjugation
D) transformation

Question

The following question refers to the figure.
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.

If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophages are excluded from the bacterial cultures, then beneficial mutations might be transmitted horizontally to other E. coli cells via ________.
A) sex pili 
B) transduction 
C) conjugation 
D) transformation

Quizplus · Accepted Answer

If the population of E. coli lacks an F factor or F plasmid, and bacteriophages are excluded from the bacterial cultures, then beneficial mutations might be transmitted horizontally to other E. coli cells via transformation, which is the process by which DNA is released into the environment, taken up by a recipient cell, and integrated into the recipient cell's genome. Sex pili are involved in conjugation, and transduction involves the transfer of DNA mediated by bacteriophages. However, in this experiment, bacteriophages are excluded, so transduction is not a possible mechanism of transfer.

The Following Question Refers to the Figure