LSAT 104 | Section 4 | Logical Reasoning: Q24

LR Question 24 Explanation

QUESTION TEXT: Scientists, puzzled about the development of…

QUESTION TYPE: Role in Argument

CONCLUSION: Scientists think that dental fillings with mercury cause penicillin resistant bacteria to develop.

REASONING: Mercury fillings cause mercury resistant bacteria. There may be a link between mercury resistance and penicillin resistance.

ANALYSIS: Normally, a bacteria develops resistance to a drug when we try to kill bacteria using that substance. So some people take penicillin, the bacteria don’t die completely, and penicillin resistant bacteria develop.

The unstated assumption serves to show that it’s unusual for bacteria to develop penicillin resistance if a person hasn’t taken penicillin.

The first sentence shows that scientists do think this is unusual. They’re puzzled that some people who don’t take penicillin can have penicillin resistant bacteria.

On this question, the wrong answers are mostly nonsense, more so than usual. They’re masked in scientific language. There’s hardly anything to explain, because the words don’t mean much, or directly contradict the stimulus. On science questions, be sure you understand the stimulus. It’s the only way to get past the nonsense answers.

___________

1. This describes answer describes the hypothesis that mercury fillings cause penicillin resistance. The scientists didn’t say anything about the normal way bacteria resist penicillin.
2. The author spends the entire passage proving that bacteria can resist penicillin even if their host never took penicillin.
3. CORRECT. The first sentence shows that scientists think it is strange that people can have penicillin resistant bacteria without having taken penicillin.
4. There’s no previous research mentioned; that’s enough to eliminate this answer. But the main problem is that the passage doesn’t say that only mercury fillings can cause penicillin resistance.
5. The unstated assumption just describes the normal development of penicillin resistance. It can’t prove anything about abnormal penicillin resistance.

Recap: The question begins with “Scientists, puzzled about the development of”. It is a Role in Argument question. Learn more about LSAT Role questions in our guide to LSAT Logical Reasoning question types.