PrepTest 107

[lcid:3525] Prep Test 107 LSAT — Reading Comp — S2 Reading comp

Passage

Questions 16-21  .        Scientists have long known that the soft surface of  . the bill of the platypus is Remaining source text redacted.
Passage walkthrough
Passage Summary

Topic: Science


Paragraph 1

  • Paragraph note
    • New evidence from scientists including Bohringer shows that the platypus uses its bill to sense and snap at prey by while underwater.
  • Views, minor Meta-Structures, and the author's attitude
    • Platypus’s bill has sensitive nerve endings (first sentence)
    • Explanation of phenomenon: Platypus uses bill to locate prey while underwater (second sentence)
      • Eyes, ears, and nostrils sealed while underwater (second sentence)
    • New evidence: neurophysiological studies showed bill has mechanoreceptors, which detect touch, and electroreceptors, which sense electric fields (third sentence)
      • Bohringer: strength of input from mechanoreceptors indicates that bill is platypus’s primary sensory organ (fourth sentence)
        • Supported by studies showing touch on the bill induces snapping movement of jaws (fifth sentence)
      • These findings don’t explain how platypuses locate prey at a distance (sixth sentence)
      • Author’s attitude: “long known” (first sentence); “new evidence” (second sentence); “suggested by the fact” (second sentence); “recently revealed” (third sentence); “extraordinarily sensitive” (fifth sentence)

Paragraph 2

  • Paragraph note
    • The work of Scheich shows that platypuses use electroreceptors to locate prey at a distance via the weak electrical fields that the prey emit underwater.
  • Views, minor Meta-Structures, and the author's attitude
    • Schech’s studies: platypuses, when feeding, exhibit patrolling behavior until an electrical field is detected, then switch to searching behavior along the bottom of a body of water until they locate and seize prey (second-third sentences)
      • Hypothesis: platypus differentiates prey from other objects using electrosensory system (fourth sentence)
      • Scheich’s study: induced platypuses to switch from patrolling to searching behavior using a battery that emitted a weak electrical current (fifth sentence)
        • Platypus could detect and locate the battery at a distance of up to 30 cm (sixth sentence)
        • Platypus attacked battery as if it were food (seventh sentence)
      • Tail flicks of freshwater shrimp create an electric field similar to that emitted by the battery (eighth sentence)
        • Hypothesis: platypus’s common prey, underwater invertebrates, all emit electrical fields (ninth sentence)
      • Author’s attitude: “contribute to solving this mystery” (first sentence); “Scheich hypothesized” (fourth sentence); “rapidly oriented” (sixth sentence); “identical response” (eighth sentence); “reasonable to assume” (ninth sentence)

Main Point: New scientific research by Bohringer, Scheich, and others strongly suggests that the platypus uses its bill to locate prey underwater.

Key Lines?

Paragraph 1, Sentence 2 (P1 S2) - Thesis: platypus uses bill to locate prey underwater

P1 S3 - Bill has mechanoreceptors and electroreceptors

P1 S4 - Bohringer: bill is primary sensory organ

P1 S6 - Stimulating mechanoreceptors leads to snapping of bill

P2 S4 - Scheich: platypus senses prey at a distance using electroreceptors

Meta-Structure?

Phenomenon/Explanation: This passage uses a Phenomenon/Explanation Meta-Structure. The phenomenon under investigation is the ability of the platypus to locate prey while underwater. The author presents the hypothesis that the animal’s bill, which contains mechanoreceptors and electroreceptors and seems to be the only sensory organ in operation while the platypus is underwater, is the means by which it locates prey. The research and hypotheses of scientists Bohringer and Scheich is presented as evidence to support the author’s contention. Bohringer determined that stimulation of the mechanoreceptors on the platypus’s bill induced the jaws to snap, and Scheich showed that stimulation of the electroreceptors on the bill attracted the animal to the source of an electric current, suggesting that the platypus senses the weak electric fields emitted by prey.

The author seems to endorse the views of both Bohringer and Scheich, whose research is complementary and seems to explain the behavior and sensory abilities of the platypus.

Last Thoughts?

There are no hidden agendas in this passage. The author presents and tacitly endorses the views of two scientists, Bohringer and Scheich, and describes their experiments as evidence to back up an explanation of how the platypus senses prey underwater.

Question prompt

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

Credited answer: C

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

Question Type

Science

Strategy Overview

Review the relevant part of the passage and notes, if necessary, to anticipate key features of Scheich’s experimental strategy.

Answer Anticipation

These Application/Analogous Situation questions closely resemble Parallel Reasoning questions in Logical Reasoning. We want to find the answer choice that is structurally similar to the element we're asked to analogize. The correct answer won't have the same subject matter as the passage; instead, it will feature similar characteristics or themes as the element from the passage. Therefore, we should start by reviewing the key features of the element we're asked to parallel.The passage initially describes Scheich’s early findings without elaborating on his experimental strategy (P2 S1-3). The passage doesn’t discuss a specific experiment that Scheich conducted until P2 S5-7, where the author explains that Scheich placed a battery in water to mimic the weak electrical fields created by the platypus’s prey in order to stimulate the animal to change behavior and home in on the battery (P2 S5-7). So we are looking for an answer choice that involves someone mimicking a natural phenomenon in order to study whether an animal will respond in a certain way.

Answer choices

  1. A
    To determine the mating Remaining source text redacted.
    Why choice A is not credited

    (A) Does this answer choice show someone mimicking a natural phenomenon in order to study whether an animal will respond in a certain way?

    It’s impossible to be sure. True, the scientist uses a decoy that resembles the birds in appearance, but the answer choice doesn’t say the decoy emits the same bird calls as the birds they are studying. This point is rather significant, because if the bird calls are just from random birds, it’s unclear how the scientist hypothesized the birds would respond.

    It is not clear that this situation matches the situation we are trying to parallel, because we don’t know how the bird calls the decoys emit compare with the birds the scientist is trying to study, and we don’t know what hypothesis the scientist is testing. How do the bird calls figure in the scientist’s experiment? Until we know the answer to that question, we can’t say that this situation is like the one in the passage.

  2. B
    To determine whether certain Remaining source text redacted.
    Why choice B is not credited

    (B) Does this answer choice show someone mimicking a natural phenomenon in order to study whether an animal will respond in a certain way?

    Again, it’s not clear. Though the scientist is trying to study the way animals navigate, and plays a tape of the animals’ cries, it isn’t clear where the echoes come in. The scientist hypothesizes that the animals use the echoes of their cries to navigate, but does the tape that the scientist is playing create echoes? Are there recordings of echoes already on it? Until we know this critical information about the echoes, it’s impossible to determine whether this situation parallels the one in the passage.

  3. C
    To determine whether an Remaining source text redacted.
    Why choice C matches the stem

    (C) Does this answer choice show someone mimicking a natural phenomenon in order to study whether an animal will respond in a certain way?

    Yes. Here, we know what hypothesis the scientist is testing (an animal uses heat sensitivity to detect prey), and how that test is being carried out (a heat-generating object mimicking the prey is placed near the animal’s home). Presumably, the scientist is waiting to see how the animal will respond to the heat, and if it responds in the way the scientist expects, they will know the animal uses heat sensitivity to locate their prey.

    The situation described in the answer choice exactly matches the situation described in the passage; in fact, the only element that is different is the fact that Scheich used an electrical field to stimulate the platypus, while the scientist in the answer choice is using a heat-generating object.

  4. D
    A fisherman catches fish Remaining source text redacted.
    Why choice D is not credited

    (D) Does this answer choice show someone mimicking a natural phenomenon in order to study whether an animal will respond in a certain way?

    We can’t be sure. Because though the fisherman scents the replicas of the prey with fish oil, we’re not sure if the prey are fish themselves, or if the oil matches the scent the prey would normally give off. Perhaps the prey replicas are made to resemble flies, in which case the fish oil wouldn’t make much sense and certainly wouldn’t mimic a natural phenomenon.

  5. E
    A game warden captures Remaining source text redacted.
    Why choice E is not credited

    (E) Does this answer choice show someone mimicking a natural phenomenon in order to study whether an animal will respond in a certain way?

    Not necessarily. In the situation described in the answer choice, it isn’t clear what hypothesis the game warden is testing, if any. And there is no mimicry taking place. In the situation we’re trying to parallel, the battery is mimicking the electrical fields generated by moving shrimp tails to see how the platypus will respond. What is the piece of meat mimicking, if anything?

    The situation in the answer choice doesn’t match the one in the passage.

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