SAT Reading & Writing · Command of Evidence (textual)
In a decades-long laboratory evolution experiment, one population of E. coli bacteria evolved the ability to use citrate as a food source…
In a decades-long laboratory evolution experiment, one population of E. coli bacteria evolved the ability to use citrate as a food source under oxygen-rich conditions, a trait that took tens of thousands of generations to appear. A textbook claims this shows the key mutation could have arisen and produced the same beneficial trait at any point during the experiment, given enough luck. Which finding would most directly undermine the textbook's claim?
Answer and explanation
Answer: B: Researchers found that the key mutation only produced its beneficial effect because of earlier, seemingly unrelated mutations that had already accumulated in that specific population's genetic…
The textbook's claim assumes the mutation's effect was independent of when it arose or what other genetic changes had already occurred. B directly refutes that by showing the mutation's benefit depended entirely on a specific prior genetic background that took time to accumulate, meaning the same mutation could not have produced the same result "at any point," contrary to the textbook's claim. A restates the timing fact without explaining why the timing mattered. C and D are background facts about the experiment and organism that don't address the contingency question.
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