#20 - Concept Reference, Must Be True

[Administrator]

Complete Question Explanation

The correct answer choice is (C).

Answer choice (A):

Answer choice (B):

Answer choice (C): This is the correct answer choice.

Answer choice (D):

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[hinarizvi]

Can you help me understand why the right answer is C? I didn't love any of the answer choices, but I thought the answer was not C because the passage tells us "[Scheich] found he could trigger the switch from patrolling to searching behavior in the platypus by creating a dipole electric field in the water...The platypus, sensitive to the weak electric current that was created, rapidly oriented toward the battery..." I thought since the electric current triggered a switch FROM patrolling TO searching behavior, the platypus isn't detecting electric fields during patrolling behavior?

[Dana D]

Hey hinarizvi,

This passage is tricky; it talks about two different ways the platapus detects prey (with mechano- and electroreceptors) and attributes proof to two different studies. With passages like this, it might be helpful to diagram or mark in shorthand by the passage which tests or traits are attributed to which sensor.

Here, when platapus' are patrolling, they are moving their bills back and forth trying to sense electronic fields with their electroreceptors. It is once they have found a electric field that they switch from patrolling to searching, and begin using their mechanoreceptors to hone in on the prey, moving their bill erratically.

Rereading the passage with that knowledge, see if that makes sense. Hope it helps!