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

It can be inferred 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

Refer to notes or what you highlighted/underline to locate where the passage discusses the platypus’s patrolling behavior, and refer to the relevant part of the passage as needed to find that answer choice that must be true.

Answer Anticipation

For questions that ask us to infer, from a few details in the passage, an answer choice that must be true, quickly finding and reviewing those details is critical. That is why we make brief notes describing the role of each paragraph and highlight or underline definitions and the minor Meta-Structures — doing so helps us find the salient information efficiently and reliably. Once we review that part of the passage, we can look through the answer choices to see which one is best supported by what we reviewed. Since the question stem asks us to make an inference, 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.Here, the question asks about the patrolling behavior of the platypus. This topic showed up in P2 S2-3 and P2 S5. In these sentences, the author states that Scheich’s research showed patrolling behavior is the first stage of feeding, in which the platypus swims steadily, wagging its bill from side to side until prey is “encountered” (P2 S2). Then, it switches to searching behavior at the bottom of a body of water (P2 S3). So, the question is, what is the platypus doing during its patrol? It would seem, since patrolling is followed by specific searching at the bottom of the river or pond, that during patrolling, the platypus is attempting to sense prey from a distance so the “search” can be more accurate.Let’s look for this idea in the answer choices.

Answer choices

  1. A
    capture prey that it Remaining source text redacted.
    Why choice A is not credited

    (A) Does this answer choice line up with our anticipation of what the platypus is trying to do during patrolling behavior?

    No. “Patrolling,” as we know from P2 S2, means the platypus is swimming steadily with its bill wagging from side to side. It is only after prey is “encountered” during patrolling that the platypus drops down to the bottom of the lake or river and attempts to seize the prey (P2 S3). So patrolling definitely precedes the attempt to capture prey, and we anticipated that the platypus is trying to sense the prey at a distance.

    This is not the right answer choice.

  2. B
    distinguish one kind of Remaining source text redacted.
    Why choice B is not credited

    (B) Does this answer choice line up with our anticipation of what the platypus is trying to do during patrolling behavior?

    No. The platypus may be trying to do this, but there’s no evidence in the passage to back this answer choice up. Also, this answer choice doesn’t line up with our anticipation.

  3. C
    detect electric fields produced Remaining source text redacted.
    Why choice C matches the stem

    (C) Does this answer choice line up with our anticipation of what the platypus is trying to do during patrolling behavior?

    Yes. We anticipated that the right answer choice would say something about attempting to sense prey from a distance. Detecting the electric fields produced by prey is a specific way of accomplishing this. So this is the right answer choice.

  4. D
    stimulate its mechanoreceptors
    Why choice D is not credited

    (D) Does this answer choice line up with our anticipation of what the platypus is trying to do during patrolling behavior?

    No. The mechanoreceptors are stimulated by the touches of prey on the bill, which then stimulate the platypus to snap with its jaws (P1 S7). This is a behavior that is obviously only effective when the prey is within snapping distance, and when the platypus is patrolling, it’s swimming by itself in a steady fashion (P2 S2). Its prey is generally on the bottom of the body of water (P2 S3-4), so there would be no sense in saying it is patrolling well above the bottom of the body of water to stimulate its mechanoreceptors.

  5. E
    pick up the scent Remaining source text redacted.
    Why choice E is not credited

    (E) Does this answer choice line up with our anticipation of what the platypus is trying to do during patrolling behavior?

    No. The passage doesn’t discuss the platypus’s sense of smell at all, even in connection with hunting or feeding behavior. Indeed, P1 S2 says that the animal’s nostrils are closed when it’s underwater, which would strongly suggest that it does not use its sense of smell to locate prey underwater.

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