PrepTest 138

[lcid:3648] Prep Test 138 LSAT — Reading Comp — S1 Reading comp

Passage

Questions 8-14  .        The characteristic smell or taste of a plant, to  . insects as well as to humans, Remaining source text redacted.
Passage walkthrough
Passage Summary

Topic: Science


Paragraph 1

  • Paragraph note
    • Distinction between primary substances (required for plant growth) and secondary substances (give plants taste/smell)
  • Views, minor Meta-Structures, and the author's attitude
    • List of two different chemicals in plants, according to the author:
      • Primary substances: required for growth and functioning, found in all plants (third sentence)
      • Secondary substances: No known internal function, different in different plant families, give plants taste and smell (fourth through last sentences)
    • Examples of primary substances, according to the author:
      • Proteins, carbs, vitamins, hormones (third sentence)
    • Author's attitude: "depends" (first sentence); "required" (third sentence); "found in all plants" (third sentence); "diverse and multitudinous array of chemicals" (fourth sentence); "no known role" (fourth sentence); "Only a few" (fifth sentence); "give plants their distinctive tastes and smells" (last sentence)

Paragraph 2

  • Paragraph note
    • Insects' role in the diversity of secondary substances developed (some attract helpful insets, others defend against harmful insects)
  • Views, minor Meta-Structures, and the author's attitude
    • Cause-and-effect relationships, according to the author:
      • Mutations cause the emergence of secondary substances (second sentence)
      • Some secondary substances' ability to attract pollinating insects causes the secondary substances to survive via natural selection (fourth sentence)
      • Some secondary substances' biochemical defenses against harmful insects cause the secondary substances to survive via natural selection (sixth sentence)
      • Some secondary substances cause harm or death to insects (seventh sentence)
      • Some secondary substances cause insects to avoid feeding on the plant (last sentence)
    • Author's attitude: "appear to have played a major role" (first sentence); "undoubtedly" (second sentence); "must pass the muster of natural selection" (third sentence); "must increase" (third sentence)

Paragraph 3

  • Paragraph note
    • Progression of evolution after insects (insects evade defenses and become associated with few plants)
  • Views, minor Meta-Structures, and the author's attitude
    • Cause-and-effect relationship, according to the author:
      • Plants' defenses cause insects to either develop ways avoid defenses (second sentence)
      • These defenses cause insects to become associated with very few plants (fourth and last sentences)
    • Examples of ways insects avoid plants' defenses, according to the author:
      • Detoxification and storing toxins so the insects aren't harmed (third sentence)
    • Author's attitude: "there has been an evolutionary competition" (first sentence); "must" (second sentence); "fewer and fewer" (last sentence)

Main Point: While secondary substances in plants start out from random mutations, it's a back-and-forth evolutionary "battle" with insects that has resulted in a variety of secondary substances across species of plants.

Key Lines?

Paragraph 1, Sentences 4 (P1, S4) - Definition of "secondary substances"

P2, S3 - How secondary substances emerge

P2, S4 - How secondary substances survive

P2, S6 - How secondary substances survive

P3, S5 - Outcome of secondary substances

Meta-Structure?

Phenomenon/Explanation: This passage uses a Phenomenon/Explanation Meta-Structure.* The passage spends Paragraph 1 building up to the statement about diverse secondary substances, which give plants their taste and smell but don't help the plant function. That poses a question that needs explaining — if they don't help a plant function, then why do they exist? The passage answers that question/explains the phenomenon in the rest of the passage. Secondary substances exist because random mutations cause them to develop, and then an evolutionary competition with insects causes the beneficial ones (either because they hurt insects or attract pollinating insects) to proliferate.

When a passage falls into the Phenomenon/Explanation Meta-Structure, the author's explanation serves as the passage's main point. Here, the author provides a multi-faceted explanation, which is how we got to our main point above.

*You could also characterize this passage as a Question/Answer passage (Q: How do secondary structures emerge and survive in plants? A: Through natural selection and by attracting/defending insects).

Cause and Effect: The most prominent minor Meta-Structure is the cause-and-effect relationship, most prominently featured in the second paragraph. Make sure you understand these cause-and-effect relationships because we're bound to get a question or two about them — perhaps even a difficult Strengthen or Weaken question.

Last Thoughts?

This passage includes a lot of science, but we can simplify it to a few basic cause-and-effect relationships to help us understand what's going on. If you don't find memorizing a few basic facts too onerous, keeping these in mind can save you some fact-finding missions as you answer the questions:

  • Mutations cause secondary substances to first appear
  • Some secondary substances survive because they attract pollinating insects
  • Some secondary substances survive because they defend against harmful insects
  • Plants' evolutions and insects' adaptations cause insects to become associated with very few plants

Question prompt

The passage provides the 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

Remind ourselves of the main point of the passage, then head to the answers, focusing on those that line up with the main point and then using our notes/the passage to find the correct answer

Answer Anticipation

This question asks us to infer, based on the entire passage, a statement that must be true. Such questions can be very challenging. These questions provide little indication as to the topic of the correct answer or where it’ll show up in the passage. Moreover, the correct answer probably won't restate something from the passage. Instead, the question will likely require us to draw a connection between a few different pieces of information.We’ll need to rely on our big-picture understanding of the passage to answer these questions. We should start by reminding ourselves of the main point (either by reviewing what we said after reading the passage or by rereading our answer to the main point question). From there, we can head to the answer choices. If something in an answer choice doesn't seem familiar and isn’t reflected in our notes on each paragraph, we shouldn’t check the passage to see if it was mentioned. Instead, we’ll table it and move on to the next answer choice. If something seems inconsistent with the main point, we can eliminate it. If something seems familiar, consistent with the main point, or reflected in our notes, we’ll use our notes/highlights/underlines to find the part of the passage that proves the answer choice must be true. If we can find that confirmation, we’ll select that answer choice and move on.

Answer choices

  1. A
    Some chemicals that are Remaining source text redacted.
    Why choice A matches the stem

    (A) Is this consistent with the passage's main point or reflected in our notes?

    Yes! This answer lines up with the passage's main point — the importance that secondary substances play in the lives of plants. It also has weak, easy-to-support language ("some," "various kinds") we like in a Must Be True answer choice.

    Therefore, we should review the passage to see if we can support the claim that secondary substances have no known role in growth or metabolism. We can review the first paragraph, which provides the background information that distinguishes primary and secondary substances.

    Checking the first paragraph, we can see that secondary substances have "no known role in the internal chemical processes of plants' growth or metabolism" (P1, S4). And do these substances play vital roles in the lives of plants? That's the whole rest of the passage, but at the very least, we know that secondary substances only persist in a population if they contribute to the likelihood of survival and reproduction (P2, S3), which surely counts as playing a vital role in the plants' lives. This answer is, therefore, correct. We can justifiably select it, skip past (B) through (E), and advance to the next question.

  2. B
    Most plants that have Remaining source text redacted.
    Why choice B is not credited

    (B) Is this consistent with the passage's main point or reflected in our notes?

    No. Our note for the third paragraph is, "Progression of evolution after insects (insects evade defenses and become associated with few plants)." This suggests that "most plants" are not "used as food by a wide variety of insects." We can cross off (B) since it contradicts our note.

  3. C
    Most insects that feed Remaining source text redacted.
    Why choice C is not credited

    (C) Is this consistent with the passage's main point or reflected in our notes?

    Neither our notes nor the main point mentions how insects identify plants. For this reason, it's best to table (C) without reviewing the passage and move on to the next answer choice.

    If we had to review the passage to eliminate (C), we'd see that this answer also deals with the outcome of the evolutionary "battle" between insects and plants, so we should check Paragraph 3. There, it tells us that insects come to identify the plants they eat by taste and smell (P3, S4), so this answer about other characteristics is unsupported.

  4. D
    Many secondary substances that Remaining source text redacted.
    Why choice D is not credited

    (D) Is this consistent with the passage's main point or reflected in our notes?

    No. Neither our notes nor the main point says whether secondary substances evolved independently among unrelated species of plants. For this reason, it's best to table (D) without reviewing the passage and move on to the next answer choice.

    If we had to review the passage to eliminate (D), we'd see that the development of secondary substances is the topic of Paragraph 2. There, teh author talks about random mutations leading to secondary substances but doesn't say the same substances developed independently in different species (P2, S2). Therefore, this answer choice is unsupported.

  5. E
    Some toxic substances that Remaining source text redacted.
    Why choice E is not credited

    (E) Is this consistent with the passage's main point or reflected in our notes?

    Neither our notes nor the main point discusses toxic substances that are not secondary substances. For this reason, it's best to table (E) without reviewing the passage and circle back to any answer choices you haven't yet eliminated.

    If we had to review the passage to eliminate (E), the passage establishes that there are, broadly speaking, two types of chemicals in plants — primary and secondary — and so this answer would have to deal with primary substances. But those are discussed only in the first half of Paragraph 1 and are not related to evolution or toxicity at all.

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