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

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 experimental population of E. coli lacks an F factor or F plasmid, it cannot participate in conjugation, and bacteriophages are excluded from the bacterial cultures, so horizontal gene transfer can only occur via transformation. This process involves the uptake and incorporation of DNA from the environment into the bacterial genome. Sex pili are structures involved in conjugation, and transduction involves the transfer of genetic material via bacteriophages.

In This Eight-Year Experiment, 12 Populations of E