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
-Which of the following, if it occurs in the absence of any other type of adaptation listed here, is least reasonable in terms of promoting bacterial survival over evolutionary time in a low-glucose environment?
A) increased efficiency at transporting glucose into the cell from the environment
B) increased ability to survive on simple sugars, other than glucose
C) increased ability to synthesize glucose from amino acid precursors
D) increased reliance on glycolytic enzymes
E) increased sensitivity to, and ability to move toward, whatever glucose is present in its habitat

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
-Which of the following, if it occurs in the absence of any other type of adaptation listed here, is least reasonable in terms of promoting bacterial survival over evolutionary time in a low-glucose environment?
A) increased efficiency at transporting glucose into the cell from the environment 
B) increased ability to survive on simple sugars, other than glucose 
C) increased ability to synthesize glucose from amino acid precursors 
D) increased reliance on glycolytic enzymes 
E) increased sensitivity to, and ability to move toward, whatever glucose is present in its habitat

Quizplus · Accepted Answer

Increased reliance on glycolytic enzymes would not be the least reasonable adaptation for promoting bacterial survival in a low-glucose environment. Glycolytic enzymes are involved in the breakdown of glucose to extract energy. If glucose is scarce, enhancing the pathway that directly depends on glucose does not address the fundamental challenge of its scarcity. Adaptations that allow the organism to either utilize alternative energy sources, improve glucose acquisition efficiency, or synthesize glucose from non-glucose precursors would be more beneficial.

The Following Questions Refer to Figure 27.1