Solitary Passages Questions - - Question 21

Which one of the following best states the main idea of the passage?

knoxygirl May 8, 2017

Hard time identifying main point

I was having a hard time identifying the main point in this question. I chose A because the passage, while largely referring to evidence based on drugs, seemed to be making a larger claim. D seemed too specific. Why was I incorrect?

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Mehran May 16, 2017

Hi @knoxygirl, thanks for your post. This is a difficult passage, and your question is a good one.

The main point of this passage pertains to the role of serotonin in signaling to the human brain when carbs have been, or should be, consumed. This is established by the very first lines (1-5) and reaffirmed throughout the passage.

We are told, for example, that "drugs that selectively facilitate serotonin-mediated neurotransmission tend to cause weight loss, whereas drugs that block serotonin-mediated transmission often have the opposite effect" (lines 9-13).

We are also given a lot of background information on the chemistry of serotonin (lines 15-31), and then told how the level of serotonin in the brain affects the amount of carbs someone chooses to eat (lines 32-34). In other words, the passage is explaining the how "body's desire for carbs can be influenced by serotonin or serotoninlike drugs" (which is answer (D)).

By contrast, answer choice (A) is too limited--the discussion of serotonin levels in blood is really limited to paragraph 2, and so not the main point of the entire passage here.

Hope this helps! Please let us know if you have any additional questions.