PrepTest 106

[lcid:3523] Prep Test 106 LSAT — Reading Comp — S4 Reading comp

Passage

Questions 6-13  .        Long after the lava has cooled, the effects of a  . major volcanic eruption may linger Remaining source text redacted.
Passage walkthrough
Passage Summary

Topic: Science


Paragraph 1

  • Paragraph note
    • Atmospheric debris produced by a major volcanic eruption has been hypothesized to have a cooling effect on Earth’s climate.
  • Views, minor Meta-Structures, and the author's attitude
    • Fine dust and sulfuric acid droplets from an eruption can block sunlight, which is believed to result in a drop in Earth’s temperature.
    • Example: many believe the Tambora eruption in 1815 for the Earth’s “year without a summer” of 1816.
    • Author’s attitude: “may linger on” (first sentence); “persist for years” (first sentence); “researchers have generally thought” (second sentence); “many blame” (third sentence)

Paragraph 2

  • Paragraph note
    • According to Clifford Mass and Davit Portman, volcanic eruptions don’t cause as much cooling as previously believed.
  • Views, minor Meta-Structures, and the author's attitude
    • Mass and Portman conducted an analysis of nine volcanic eruptions, tracking global climate data for the years before and after
      • Examples: El Chichon in 1982 and Krakatau in 1883
      • Filtered out effect of El Nino-Southern Oscillation
        • El Nino warms the atmosphere - can mask cooling from an eruption but can also mimic cooling effect of an eruption if it ends as an eruption occurs
      • Author’s attitude: “seems plausible” (first sentence); “not as strong” (first sentence); “can mask the cooling” (fourth sentence); “can also mimic volcanic cooling” (fourth sentence)

Paragraph 3

  • Paragraph note
    • Mass and Portman: minor eruptions have no effect on global temperature, while major eruptions cause a smaller drop than expected.
  • Views, minor Meta-Structures, and the author's attitude
    • Mass and Portman’s analysis:
      • Accounted for El Nino
      • Major explosions that spit dust lower average temperature by half a degree centigrade or less in the hemisphere (northern or southern) where eruption occurred and in the opposite hemisphere
    • Author’s attitude: “came through more clearly” (first sentence); “contrary to what earlier studies had suggested” (second sentence); “no discernible effect” (second sentence); “cause a smaller drop than expected” (third sentence); “only half a degree” (third sentence)

Paragraph 4

  • Paragraph note
    • Other researchers argue that a small temperature drop from an eruption can cause a significant decrease in regional temperature due to feedback loops.
  • Views, minor Meta-Structures, and the author's attitude
    • Example of feedback loop: small temperature drop in NE US in early spring delays melting of snow, which leads to increased reflection of sunlight, which increases cooling.
      • Unusually cool air causes jetstream to move farther south than normal, causing more cold air to come in behind it, which further deepens cooling
      • This effect could cause the “year without a summer”
    • Author’s attitude: “could result in a significant regional fluctuation” (first sentence) “amplified by climatic feedback loops” (first sentence); “could, in turn, affect the jet stream” (third sentence); “could cause the stream to wander” (fifth sentence); “could be blown up” (sixth sentence)

Main Point: According to new research, major volcanic eruptions cause a smaller decrease in global temperature than previously hypothesized, but can have a significant depressive impact on regional temperature via feedback loops.

Key Lines?

Paragraph 1, Sentence 2 (P1, S2) - Introduces volcano-climate hypothesis

P3, S3 - Mass and Portman show eruptions cause small decrease in global temperature

P4, S2 - Small decrease hypothesized to lead to significant regional decrease due to feedback loops

Meta-Structure?

Reporting a Viewpoint: This passage uses a “Reporting a Viewpoint” Meta-Structure. The first paragraph introduces the topic of the passage: the hypothesis that dust thrown up by a volcanic eruption blocks sunlight and leads to a decrease in Earth’s average temperature (P1 S2). The author summarizes the research of Clifford Mass and Davit Portman, whose analysis shows that, contrary to earlier research, the effect of a major volcanic eruption on global temperature would be small (P2 S1, P3 S3). Finally, the author relates that other researchers hypothesize that climatic feedback loops could amplify even a small decrease in temperature to cause significant drops in regional temperature (P4 S1).

The main point in a Reporting A Viewpoint passage is the view held by the subject, in this case, Mass, Portman, and the other group of researchers mentioned in the fourth paragraph who posit the feedback loop hypothesis. The author does a clear and neutral job of tracing the volcano-climate hypothesis from its origins, through Mass and Portman’s research, to the feedback loop hypothesis. The author’s own opinion is largely absent from the passage.

Last Thoughts?

Initially, this passage begins with the idea that scientists have believed the cooling effect of a volcanic eruption on global temperature to be significant. In fact, the author writes, people believe an eruption could cause a year without a summer. Then the author describes the research of Mass and Portman, stating that they believe the global effect of a major eruption is much less significant than previously believed. This statement seems to counter the original belief that eruptions have a significant climatic effect. Finally, the author discusses the hypothesis that climatic feedback loops can cause a large decrease in regional temperature, which could result in a year without a summer.

So the key distinction the author makes in the passage seems to be between the global effect of a major volcanic eruption and the regional effect of such an eruption. This distinction is key, and is something the careful test-taker should make note of.

Question prompt

Which one of the Remaining source text redacted.
Why the credited answer is right

Credited answer: D

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

Question Type

Science

Strategy Overview

Review the purpose of the paragraph in which the expression is found, including the expression in question, then use the purpose and the immediate context to define the expression's meaning.

Answer Anticipation

This question asks what the author meant when they used the phrase “minor” volcanic eruption. This phrase appeared in the third paragraph, so we should start by defining the role of that paragraph, as that can sometimes provide contextual clues about the author's meaning. Our note for the third paragraph is, “Mass and Portman: minor eruptions have no effect on global temperature, while major eruptions cause a smaller drop than expected.” So, the third paragraph talked about Mass and Portman’s findings about how minor and major volcanic eruptions affect global temperature.Now, turning our attention to the phrase “minor” eruption, which is in P3 S2, we find that the author does not define it explicitly. It is important to note, though, that our summary for P3 distinguished minor eruptions from major ones, because Mass and Portman found that there was a difference between the way in which minor and major eruptions affected global temperature. So, if we look at P3 S3, where “major” eruptions are discussed, we find that the author uses the phrase “dust-spitting explosions.” This brings to mind the initial point the author made in the first paragraph, that the volcano-climate hypothesis is based on the notion that dust and sulfuric acid droplets from an explosion block sunlight and thereby decrease Earth’s temperature (P1 S2). So the author seems to be saying that a “major” eruption spits much more dust and debris into the atmosphere than a “minor” one.Let’s look for language making this distinction in the answer choices.

Answer choices

  1. A
    an eruption that produces Remaining source text redacted.
    Why choice A is not credited

    (A) Does this answer choice define “minor” in terms of the quantity of dust and debris it emits?

    No. This answer choice references lava, which is entirely irrelevant to the volcano-climate hypothesis that the passage talks about. The only place where lava is mentioned is P1 S1, where the author says the effects of a volcanic explosion linger long after the lava has cooled. The rest of the passage is about the dust and debris emitted by an eruption (P1 S2), and this is the aspect of volcanic eruptions that is relevant here.

  2. B
    an eruption that has Remaining source text redacted.
    Why choice B is not credited

    (B) Does this answer choice define “minor” in terms of the quantity of dust and debris it emits?

    No. This answer choice talks about an eruption that has less of an effect on global temperature than either Krakatau or El Chichon. This sounds like an appealing answer choice, because the author does indeed distinguish these two explosions from “minor” eruptions (P3 S3), and states that they have a larger effect on temperature than “minor” eruptions, but what this question has asked is that we find the phrase that “most accurately characterizes what the author of the passage means.” Because the point of the passage is to analyze the effect of volcanic eruptions on climate, and because that relationship is in flux throughout the passage, it would be premature to characterize “minor” explosions just in terms of the drop in temperature that they cause.

    The author began discussing the volcano-climate hypothesis by talking about the debris released by volcanic eruptions (P1 S2), and because P3 S3 describes major eruptions as being “dust-spitting,” it is more likely that the author is characterizing “minor” eruptions as ones that don’t spit as much dust or debris.

    For this reason, this is not the right answer.

  3. C
    an eruption whose effect Remaining source text redacted.
    Why choice C is not credited

    (C) Does this answer choice define “minor” in terms of the quantity of dust and debris it emits?

    No. This answer choice brings up a point that is not made by the passage. Mass and Portman’s findings were that minor eruptions had no effect on temperature. Neither they nor the author asserted that this lack of effect was in fact due to hemispheric conditions that masked a drop in temperature.

    This answer choice is a good example of how the test writers rearrange the terminology in the relevant paragraph in order to make a point that sounds superficially good and may confuse some test-takers who rush or who did not fully grasp the argument being made in P3, but the careful test-taker will stick to their answer anticipation and eliminate this answer choice.

  4. D
    an eruption that introduces Remaining source text redacted.
    Why choice D matches the stem

    (D) Does this answer choice define “minor” in terms of the quantity of dust and debris it emits?

    Yes. This answer choice defines “minor” eruption with respect to the amount of debris it vents into the atmosphere, which is an exact match of our anticipation and an echo of the way in which the author describes “major” eruptions in P3 S3 only one sentence after the reference that is cited in the question stem.

  5. E
    an eruption that causes Remaining source text redacted.
    Why choice E is not credited

    (E) Does this answer choice define “minor” in terms of the quantity of dust and debris it emits?

    No. This answer choice directly contradicts the passage. Mass and Portman found that minor eruptions “had no discernible effect on temperature” (P3 S2), not that they simply had less of an effect than major eruptions. Major eruptions, they found, caused average temperature in the hemisphere in which they occurred to drop half a degree or less (P3 S3).

    As this answer choice not only fails to match our anticipation but is directly contradicted by the passage, we can eliminate it.

What this tests

Discussion

  • Confusion 1 reply

    Started by Sallyanne-Tejan

View all discussions Start a discussion