#18 - Concept Reference, Must Be True

[Administrator]

Complete Question Explanation

The correct answer choice is (E).

Answer choice (A):

Answer choice (B):

Answer choice (C):

Answer choice (D):

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

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

[bonbon94]

why is the answer E and not C? I was able to narrow it down to answers that involved the fifth crainal nerve as sending a signal, but I had trouble trying to figure out whether it was C or E. I felt like C was more specific and so I chose it as an answer

[Luke Haqq]

Hi bonbon94!

Great question, as answer choices (C) and (E) look similar to one another in some respects. To find support for the answer to this question, I'd look to the second half of the first paragraph. We're told there that "Bohringer concluded that the bill must be the primary sensory organ for the platypus. Her finding was supported by studies showing that the bill is extraordinarily sensitive to tactile stimulation: stimulation with a fine glass stylus sent a signal by way of the fifth cranial nerve to the neocortex and from there to the motor cortex" (lines 18-24).

We're asked for what we know happens "before a nerve impulse reached the motor cortex of the platypus." Answer choice (E) states that "The fifth cranial nerve carried the nerve impulse to the neocortex." We know this from the quoted material that tells us that stimulus resulted in a signal "by way of the fifth cranial nerve to the neocortex." With respect to answer choice (C), mechanoreceptors and electroreceptors function differently and occur earlier in the paragraph. In addition, they're not specifically part of this portion of the paragraph on studies supporting Bohringer.