Reading comp PrepTest 124 · Section 4 · Question 21

Passage

Questions 20-27  .        Sometimes there is no more effective means of  . controlling an agricultural pest than giving free Remaining source text redacted.
Passage walkthrough
Passage Summary

Topic: Science


Paragraph 1

  • Paragraph note
    • A generalization and an example
  • Views, minor Meta-Structures, and the author's attitude
    • Generalization - Sometimes, best pest control is using a predator
    • Example - Cyclamen (Cyc) (pest)/Typhlodromus (Typh) (predator mite)
    • Usual cycle - Cyc infest, get out of control year 2, Typh move in and control them

Paragraph 2

  • Paragraph note
    • Features of Typh that make them work
  • Views, minor Meta-Structures, and the author's attitude
    • Hungry
    • Reproduction - method and rate (Similar to Cyc)
    • Seasonal and population densities
    • Reproduce only when there’s cyc
    • Similar - Other predators that can control prey

Paragraph 3

  • Paragraph note
    • Study - Typh works
  • Views, minor Meta-Structures, and the author's attitude
    • Study - Greenhouse experiments - Strawberries (one with both, one with just Cyc and insecticide)
    • Results - Just Cyc = out of control; Both = Cyc under control

Paragraph 4

  • Paragraph note
    • Study backed up in real world
  • Views, minor Meta-Structures, and the author's attitude
    • In study, insecticide more harm than good
    • Real-world studies show same thing
    • Average - Cyc population 25x with no predators

Main Point: In some cases, the most effective means of controlling an agricultural pest is by using its predator, as is exemplified by the Cyclamen/Typhlodromus relationship.

Key Lines?

Lines 1-3 - A generalization is presented

Lines 4-6 - A specific example is noted

Lines 15-16 - List of factors owing to effectiveness introduced

Lines 33-37 - Features generalized to other predators

Lines 37-40 - Studies verify generalization

Lines 52-54 - Studies backed up in real world

Meta-Structure?

Generalization/Example - This question is one of the best examples (pun intended) of the Generalization/Example Meta-Structures in the history of the exam. It starts out by making a very general - yet strong - statement about a particularly effective means of controlling a pest population. It then goes into “[a] case in point” that it spends the rest of the passage exploring. When this Meta-Structure is present, the main point is the generalization, and the correct answer to any main point question will generally reference the example, as well - though it sometimes doesn’t.

List - Paragraph 2 is a list of “several factors” that explain why Typh is such an effective predator and can keep Cyc in check. That paragraph even generalizes from Typh to other predators in the last sentence (Lines 33-37), which reinforces the Generalization/Example Meta-Structure above.

Similarities - Paragraph 2 has a lot of comparisons in its list of factors. There are similarities between Typh and Cyc that makes Typh such an effective predator, and similarities between Typh and other predators that show a pattern to what makes for an effective predator.

Last Thoughts?

Paragraph 2 is difficult. There are a lot of details in there, and so we should be sure to head back there for any question that talks about similarities, any of the individual points of comparison/factors, or anything that sounds sciency, as that paragraph is the scienciest paragraph in the passage (yes, we just made up those words).

Paragraph 4 is interesting - it takes the studies from Paragraph 3 and shows that they pan out in the real world. One inherent flaw in any study is that it doesn’t necessarily represent the real world, but this passage gets around that to an extent by showing that the results can be found outside of a lab setting.

Question prompt

Based on the passage, 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 big-picture argument made by the Author about predator/prey control success, then find an answer that bolsters the connection

Answer Anticipation

We’re treating this as a Principle (Strengthen) question because the question is tasking us with identifying a principle that underlies the Author’s argument. When the answer choices are the principles, we view it as a Principle (Strengthen) question.Specifically, this question is asking about what the Author thinks is a principle underlying long-term predatory control of pests - in other words, what principle must be followed if predators are to successfully control prey. We know that Paragraph 2 is where the Author discusses what features allow Typh to successfully control Cyc, so the answer is likely to reflect one of those features.That said, the paragraph lists a large number of features that lead to the success of Typh, so we shouldn’t do too much work ahead of looking at the answer choices. With a focus on Paragraph 2, and a general knowledge of how the Author thinks this control relationship works, let’s head to the answers.

Answer choices

  1. A
    The reproduction of the Remaining source text redacted.
    Why choice A is not credited

    (A) (Lines 32-33) The first half of this answer definitely reflects the passage, but the second half is more questionable - does the predator population surge before the prey population? The passage suggests that the predator population grows in response to that population, not the other way around, as this answer suggests.

  2. B
    The effectiveness of the Remaining source text redacted.
    Why choice B is not credited

    (B) While the Author does use greenhouse and field experiments to support the effectiveness of this relationship, the passage never claims that these studies are both “fundamental” to the success of the relationship. In fact, that doesn’t even make sense - things happen whether or not there are experiments verifying them!

  3. C
    The prey population should Remaining source text redacted.
    Why choice C is not credited

    (C) (Lines 27-32) The passage notes that the Cyc population effectively disappears in winter (when there would be low crop productivity), and that Typh can survive on other food sources, so this answer doesn’t represent a fundamental principle to the long-term success of predator-prey control.

  4. D
    The predator population's level Remaining source text redacted.
    Why choice D matches the stem

    (D) (Lines 17-18; Lines 32-33) First, this answer just makes sense - if the predator isn’t eating more when there are more pests, then it wouldn’t be able to keep those pests under control. And second, the passage spends time talking about how the predator population size is responsive to the prey population size, and that they only reproduce when there are pests to eat. This answer underlies the relationship from the passage and several features of the predator population discussed, making it the correct answer.

  5. E
    The predator population should Remaining source text redacted.
    Why choice E is not credited

    (E) The Author argues that predators should sometimes be used instead of pesticides, so whether the prey and predators are or aren’t susceptible to the same pesticides is immaterial.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 30%
  2. B 6%
  3. C 6%
  4. D Credited 53%
  5. E 4%

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