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Test: 4th Grade Science
| 1. | Platypus have a "sixth-sense" that allows them to hunt underwater: electroreception. To find meals in the mud, it uses its bill to detect movements and subtle electric fields produced by its prey. Receptors on the bill detect changes in pressure and motion. Two types of receptors track the electrical signals produced by small prey when they contract their muscles. The platypus moves its head side-to-side to determine the direction and distance of its next meal by collecting and processing this sensory information. The platypus has about 40,000 of these special receptors. Based on the passage, which of the following sentences best describes how the platypus processes an electrical signal?
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The platypus’ tail first detects the signal and works as an oar to turn it in the right direction.
The platypus cannot process electrical signals because it is a platypus.
The platypus’ bill detects the movement of the electrical signal, which is then processed by its brain.
The platypus’ eyes see the movement of the electrical signal, which is then processed by its brain.
