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.
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Compare the bacteria in the figure above in generation 1 and generation 20,000. The bacteria in generation 1 have a greater ________.
A) efficiency at exporting glucose from the cell to the environment
B) ability to survive on simple sugars, other than glucose
C) ability to synthesise glucose from amino acid precursors
D) reliance on glycolytic enzymes

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. 
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Compare the bacteria in the figure above in generation 1 and generation 20,000. The bacteria in generation 1 have a greater ________.
A) efficiency at exporting glucose from the cell to the environment 
B) ability to survive on simple sugars, other than glucose 
C) ability to synthesise glucose from amino acid precursors 
D) reliance on glycolytic enzymes

Quizplus · Accepted Answer

The figure shows that the bacteria in generation 1 have a higher growth rate but a lower fitness compared to the bacteria in generation 20,000. This indicates that the bacteria in generation 1 are relying more on glycolytic enzymes to metabolize glucose, which allows them to grow faster but also makes them less fit in low-glucose conditions. In contrast, the bacteria in generation 20,000 have evolved to rely less on glycolytic enzymes and more on other metabolic pathways, which may allow them to better survive in low-glucose conditions. Therefore, choice D is the best answer.

In This Eight-Year Experiment, 12 Populations of E