PSAT Writing and Language Question 343: Answer and Explanation

Question: 343

The author wants a conclusion that summarizes the main finding of Gause's experiment. Which choice best accomplishes this goal?

• A. NO CHANGE
• B. two species can coexist without competing for resources.
• C. competition for resources causes both organisms to go extinct.
• D. when two species compete, one will adapt to find a new niche.

Correct Answer: A

Explanation:

Note the question! The question asks which choice summarizes the main finding of Gause's experiment, so it's testing consistency of ideas. Determine the main finding of Gause's experiment, and find the answer that is consistent with that idea. According to the text, in Gause's experiment, one organism became dominant and had a high population, while the other decreased in population until becoming wiped out. Keep (A) because it is consistent with the text. Eliminate (B) because the passage indicates that competitive exclusion means that one species becomes dominant—the two don't coexist without competing. Gause's findings matched with competitive exclusion, so this answer isn't supported. Eliminate (C) because only one species in the experiment went extinct, not both. Eliminate (D) because, though the first paragraph says that a species threatened by competition may adapt to find a new niche, this was not proven by Gause's experiment. The correct answer is (A).