PrepTest 107

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.

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

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.

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.