PrepTest 154

[lcid:3714] Prep Test 154 LSAT — Reading Comp — S3 Reading comp

Passage

 For nearly a century after the discovery in the 1880s that a bacterium, Vibrio cholerae , causes cholera, scientists believed Remaining source text redacted.
Passage walkthrough
Passage SummaryTopic: Science

Paragraph 1
  • Paragraph note
    • A common scientific belief is discussed, and a question it leaves open is raised
  • Views, minor Meta-Structures, and the author's attitude
    • Common belief - Cholera travels via human hosts (waste into food and water supplies)
    • Question - How do spontaneous outbreaks in areas cholera was eliminated happen?
Paragraph 2.1 (Lines 12-25)
  • Paragraph note
    • A new belief is brought up and skepticism is discussed
  • Views, minor Meta-Structures, and the author's attitude
    • Rita Colwell (1970s) - Claimed to have found cholera in seawater and it can go undetected by common culture tests
    • Skepticism - "No" biologist thought it could live outside of humans, and there were no outbreaks since 1911
Paragraph 2.2 (Lines 25-39)
  • Paragraph note
    • Colwell's hypothesis is put to the test
  • Views, minor Meta-Structures, and the author's attitude
    • Colwell used a new test (antibodies/UV) and found cholera bacteria in bayous that traditional tests missed
Paragraph 3
  • Paragraph note
    • Further studies backing up/expanding on Colwell's hypothesis, and a future course of inquiry
  • Views, minor Meta-Structures, and the author's attitude
    • Tests show bacteria go into sporelike state that can't be detected using traditional tests
    • That state is more survivable
    • Question - What gets them out of sporelike state? Potential answer - Sea-surface temp spikes (e.g., Bay of Bengal)
Main Point:
There is evidence suggesting that Rita Colwell's hypothesis about "viable but nonculturable" cholera bacteria surviving in the ocean and in a sporelike state is correct, as it explains seemingly spontaneous outbreaks of the disease in areas where it has been eradicated.

Key Lines:
Lines 3-6 - Traditional scientific theory is discussed
Lines 9-11 - A question left open by this theory
Lines 12-14 - A new scientist/theory is introduced
Lines 21-24 - More on that theory
Lines 25-30 - The new theory is tested
Lines 40-42 - The new theory is expanded
Lines 49-51 - A question is posed for the new theory
Lines 51-54 - An answer is put forward

Meta-Structure:
Old Theory/New Theory - The old theory concerning the spread of cholera is shown to leave open a question that a new theory answers.

Question/Answer - Two questions are posed. The first (Lines 9-11) is broad and leads to the main point - Colwell's new theory. The second (Lines 49-50) is limited and leads to a hypothesis to be tested under Colwell's theory.

Last Thoughts:
Normally, the Author is a bit more on board with a new theory being presented. Here, there's a mix. She states that Colwell's studies "revealed" some things about V. cholerae (Line 40), but also poses Colwell's water theory as being something that isn't 100% certain ("If, as Colwell believes" in Line 54).

So we need to be careful in selecting answers that don't overshoot the Author's feelings towards Colwell's theory and pick an answer that reflects a certainty that doesn't exist.

Also, note that we split Paragraph 2 up. It was pretty long, and there was a natural breaking point between where Colwell raised her claim and people expressed skepticism, and the specific situation that allowed her to discover evidence for her hypothesis.

Question prompt

The passage suggests that Remaining source text redacted.
Why the credited answer is right

Credited answer: E

The notes below walk through why it fits the stem and how to eliminate the rest.

Question Type

Science

Answer choices

  1. A
    Human antibodies that usually Remaining source text redacted.
    Why choice A is not credited
    Incorrect. (Lines 30-32) The antibodies that latch onto the membrane are related to Colwell's test, not the awakening of dormant bacteria.
  2. B
    The human body's temperature Remaining source text redacted.
    Why choice B is not credited
    Incorrect. (Lines 55-59) The Author notes that it's possible that changes in seawater temperature or salinity causes the dormant bacteria to wake up. That statement is too weak to address this question stem that asks for something that's ""most likely"" true, and it provides an option other than temperature, anyway.
  3. C
    In their dormant state, Remaining source text redacted.
    Why choice C is not credited
    Incorrect. (Line 7) Paragraph 1 notes that the old theory believed cholera was transmitted by human waste in nonchlorinated water supplies, but it never discusses chlorinated water.
  4. D
    The infected humans had Remaining source text redacted.
    Why choice D is not credited
    Incorrect. There's no indication that an earlier infection with cholera is a prerequisite for dorman bacteria waking up in a person.
  5. E
    The human body is Remaining source text redacted.
    Why choice E matches the stem
    Correct. Question Type:
    Must Be True

    Strategy Overview:
    Head back to the passage to learn about this specific bacteria and then anticipate an answer

    Answer Anticipation/Relevant Lines:
    As we just saw in Question #16, this undetectable bacteria was first brought up in the second half of Paragraph 2. It ""could not always be cultured,"" explaining why it didn't show up in traditional tests.

    However, why couldn't it always be detected? That question isn't answered until Paragraph 3. There, it's noted that this bacteria goes into a dormant state—""viable but nonculturable"" (Line 46). If this bacteria is causing cholera in people, then it must be leaving that dormant state.

    How does that happen? ""[N]o one knows"" (Line 50), but Colwell hypothesizes that it might be temperature or salinity, which would explain the seasonal cases that coincide with sea temperature spikes.

    That latter hypothesis is speculative, though, so we should look for an answer that says this bacteria is brought out of the dormant state.

    Answer Explanation:
    (Lines 24-25; Line 46) The passage notes that V. cholerae that can't be cultured are in a dormant state, but that they can be awakened—it's just that no one knows the conditions wherein that happens. However, if humans that are ingesting this dormant bacteria are getting cholera, then it must be awakening inside them. We still don't know what, in particular, is allowing that to happen, but if the humans are getting sick, it must be something in their bodies, supporting this answer.

    Key Takeaway:
    This RC question definitely required drawing information in from several different locations, which can make it hard to anticipate or answer correctly. However, note that the correct answer does line up with a key element in Paragraph 3, in that it discusses dormant bacteria awakening and making people sick. In fact, the more places a correct answer draws from, the more likely it is to line up with the overall view of the passage!

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