In This Eight-Year Experiment, 12 Populations of E

question 63

Multiple Choice

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.
-Imagine that after generation 20,000, the experimental cells were grown in high-glucose conditions for 20,000 generations (using the same transfer process described) . Refer to the y-axis on the graph and predict the fitness of the new lines when tested in low- and high-glucose conditions.

• A) low: 1.0; high: 1.0
• B) low: 1.6; high: 1.6
• C) low: 1.0; high: 1.6
• D) low: 1.6; high: 1.0

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Definitions:

pH

A measure of the acidity or alkalinity of a solution, determined by the concentration of hydrogen ions, with lower values being more acidic and higher values more alkaline.

Chemical Digestion

The breakdown of food into smaller molecules, facilitated by enzymes, so they can be absorbed by the body.

Ileum

The final and longest segment of the small intestine, where most of the absorption of nutrients and water takes place.

Duodenum

The first and shortest section of the small intestine, where a significant part of digestion occurs.