PT107.S2.P3.Q17 > Analytics

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Scientists have long known that the soft surface of the bill of the platypus is perforated with openings that contain sensitive nerve endings. ████ █████████ ████████ ████ ██████████ █████████ ██ ███ █████ ██ ███ ████████ ████ ███ ██████ ████ ███ ████ ██ ██████ ███ ████ █████ ███████████ █ ██████████ █████████ ██ ███ ████ ████ ███ ████████ █████ █████ ███ ████████ ███ ██████ ████ ██ ██ ██████████ ███

Biologists' conclusion · Platypus uses its bill to locate prey underwater

We've known for a long time that the bill has nerve endings. Now biologists think those nerves on the bill are used for finding prey underwater.

New evidence supporting conclusion · Neurophysiological studies

Studies reveal two sensory receptors in pores on platypus bills: mechanoreceptors (respond to physical pressure), and electroreceptors (respond to electrical fields).

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Bohringer's conclusion · Bill is the primary sensory organ for the platypus

This was supported by studies showing the bill is sensitive to touch.

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Puzzle · How does platypus locate prey at a distance?

If a platypus isn't touching its prey with its bill, how can it find the prey? (Probably has to do with the electroreceptos, since we discussed the mechanoreceptors earlier.)

Set-up for Scheich's hypothesis · Platypus hunts by steadily wagging bill, then moving bill erratically after prey it finds prey

The erratic movements are called "searching behavior."

Scheich's hypothesis · Platypus distinguishes prey from non-prey by detecting electric fields

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Scheich's experiment · Confirms platypus can detect electric fields

Platypus switches to searching behavior when it encounters electric field from battery. Then platypus attacked the battery like it was food.

Scheich's speculation · All invertebrates that platypus eats produce electric fields

We already know that shrimp prey of platypus produces an electric field.

Passage Style

Phenomenon-hypothesis (RC)

Single position

17.

Which one of the following ██████████ ████ █████████ ███ ████ ████ ██ ███ ████████

Question Type

Main point

The author expresses the main point at the beginning of P1: “biologists concluded on the basis of new evidence that the animal uses its bill to locate its prey while underwater.” The rest of the passage describes the new research that supports this conclusion.

Neurophysiological studies have ███████████ ████ ███ ████ ██ ███ ████████ ██ ███ ██ ███ ███████ ███████ ███████

This is only Bohringer’s conclusion. But it’s not the biologists’ conclusion as described at the beginning of P1.

19%

Neurophysiological studies have ███████████ ████ ███ ████████ ████ ███ ████ ██ ██████ ███ ████ ███████████

This best captures the main point, which is the biologists’ conclusion at the beginning of P1.

73%

Bohringer's neurophysiological studies ████ ███████████ ████ ███████ █████████ ██ ███ ████ ██ ███ ████████ ███████ ██ ██████████ ████████████

This is too narrow to be the main point. The biologists’ conclusion at the beginning of P1 isn’t merely that the platypus responds to electrical stimulation; it’s that the platypus uses its bill to locate prey underwater. (C) ignores Scheich’s research in P2.

Biologists have concluded ████ ███ ███████ ██ ███ ████ ██ ███ ████████ ██ ██████████ ████ ████████ ████ ███████ █████████ █████ ████████

Scientists have “long known” that the bill of the platypus has sensitive nerve endings. This isn’t the biologists’ conclusion described in the passage.

Biologists have concluded ████ ███ ███████ ████████ ████████ ██ ████ ████████ ██████ ███████ ██ ██████████ ██████████████

Although Scheich speculates that the platypus responds to weak electric fields emitted by invertebrates, this isn’t the biologists’ conclusion at the beginning of P1. The main point isn’t just to express Scheich’s hypothesis.

PrepTest 107 - Section 2 - Passage 3 - Question 17

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