Reading comp PrepTest 124 · Section 4 · Question 23

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

Suppose that pesticide X Remaining source text redacted.
Why the credited answer is right

Credited answer: A

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

Question Type

Science

Strategy Overview

Review the experiments from the passage, then infer what would have happened had this different pesticide been used

Answer Anticipation

The experiments in the passage are discussed in Paragraph 3 (Paragraph 4 includes real-world observations - there’s no indication that an experiment was done, which would have involved conscious decisions to test something).Checking Paragraph 3, we see that there were two groups of strawberry plants. In one, Cyc and Typh were both present, and Cyc populations remained low. In the other, Cyc was present without Typh because a pesticide that killed just the Typh was used, and Cyc populations grew out of control and hurt the crops.Now, we need to infer what would have happened if the pesticide in the second set of crops was swapped from the one that killed just the Typh to one that slows down the reproduction of Cyc.For the first set of crops, nothing would have changed, as the pesticide wasn’t used there. The Cyc population still would have been under control.For the second set of crops, Typh would not have been killed off by the parathion, so they would have been around to keep the Cyc under control. On top of that, the new pesticide would also have worked to keep the pest population under control by slowing their reproductive cycle. That’s a one-two punch against the pest population, so we can infer that, in this case, the Cyc population would have been kept under control in both sets of crops. Let’s find an answer reflecting that.

Answer choices

  1. A
    In both treated and Remaining source text redacted.
    Why choice A matches the stem

    (A) The untreated plots would have the same outcome as in the initial experiment, as nothing changed there - the Cyc population would have been kept under control. In the treated plots, instead of killing off the Typh, the pesticide would slow down the reproduction of the Cyc. That means Typh would be present, eating the Cyc, and the Cyc population would grow more slowly because of their slowed-down reproductive cycle. Therefore, both sets of plots would see the Cyc population kept under control, making this the correct answer.

  2. B
    Cyclamen mite populations in Remaining source text redacted.
    Why choice B is not credited

    (B) (Lines 1-3) This is a convoluted answer, so let’s rephrase it to make what is being compared easier to see. The first set of plots is treated plots with no predator. The second set of plots is untreated plots with predators. Both have something controlling the Cyc population - either the new insecticide, or the predators. However, there’s no way for us to directly compare which is more effective. If anything, the generalization that kicks the entire passage off and which the Author says is exemplified by the Typh/Cyc relationship suggests that the predators should be more effective, not the other way around, as this answer has it.

  3. C
    In the treated plots, Remaining source text redacted.
    Why choice C is not credited

    (C) (Lines 23-27) The passage refers to the synchrony as seasonal, not related to reproductive speeds, so there’s no indication that a slowing of the prey population’s reproductive cycle would throw this synchrony off.

  4. D
    In the treated plots, Remaining source text redacted.
    Why choice D is not credited

    (D) This answer is interesting in how it’s trying to trick you. It talks about the predator population dropping but then increasing. That makes sense if you think that the insecticide, in slowing the Cyc’s reproductive cycle, would cause their population to go down and then up once the slower cycle results in new Cyc babies. And, in responding to this change in population, the Typh population also goes down and then up. However, let’s think that through. The Typh and Cyc are both present, so the Typh is keeping Cyc in check. An insecticide is added that slows down the Cyc reproductive cycle, but it has no effect on Typh. That would mean the Typh population doesn’t change, but the increase in Cyc slows down, so those Typhs would end up eating a higher proportion of the Cyc population, leading to a decrease, which would then cause the Typh population to go down. But even that’s a bit of a leap, and when you feel yourself jumping through this many hoops to figure out if an answer is right or wrong, you’re probably looking at a quicksand answer - one that’s meant to eat up your time while not actually being correct.

  5. E
    In the treated plots, Remaining source text redacted.
    Why choice E is not credited

    (E) (Lines 42-45) The passage says that, in the actual experiment, the second set of plots were kept Typh-free by using the insecticide. That implies that with a different insecticide that doesn’t kill Typh, there would be a Typh population present. So these treated plots would now have an insecticide working to control the Cyc population and Typh doing the same, so there’s a good chance that the pests wouldn’t grow to the point where they were damaging the crops.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A Credited 45%
  2. B 8%
  3. C 24%
  4. D 13%
  5. E 10%

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