PT109.S3.Q20 > Analytics

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Galanin is a protein found in the brain. ██ ██ ███████████ ████ ████ ████████████ █████ ██ ███ █████ █████ ████ ███████ █ ██████ ███████ ████ ███ █████ █████ ████ █████ ██ ████ █████████████ ██████ ██████████████ ██ ███████ ██ █████ ██████ ████ ███ ████ ████ ████████████ █████ ████ ████ █████ ██████ █████ █████ ████████ ███████ ███ ██████████ ████ ███████ ██████ ████ ██ █████ █████ ██████

Summary: Phenomenon-Hypothesis

The author comments on a phenomenon: in this experiment, rats that consistently chose fatty foods over lean foods had higher concentrations of galanin in their brains than rats that made the opposite choice. The author offers a causal hypothesis for this phenomenon: galanin causes rats to crave fatty foods.

20.

Which one of the following, ██ █████ ████ ████████ ███ █████████

Question Type

Strengthen

Notice that the author draws a causal conclusion from a correlation. All the experiment tells us is that there is a correlation between rats choosing fatty foods and them having higher galanin concentrations. But for all we know, eating fatty foods could cause higher concentrations of galanin, or craving fatty foods and having higher concentrations of galanin could both be caused by some other factor.

To strengthen the argument, then, we want an answer choice supporting the idea that galanin actually causes rats to crave fatty foods. An answer choice ruling out other potential causes, or explaining the causal mechanism by which galanin causes a craving for fatty foods, would be a good candidate.

The craving for █████ █████ ████ ███ ██████████ ██████ ██ █ █████ ████████ █████ █████ ████ ████ ██████

Incorrect. This fact about craving fatty foods doesn't tell us anything about the relationship between galanin and craving fatty foods, which is what we need to strengthen the argument.

The brains of ███ ████ ████ ████████████ █████ ██ ███ █████ █████ ███ ███ ███████ █████████████ ████ ███ ████ ███ ███ ██████ ██ ████ ████ ████████████ █████ ████ ██████

Incorrect. We're not interested in whether the rats' brains contained fat. We want to know more about the relationship between galanin and craving fatty foods. (B) doesn't help us.

Failed alternate explanation

The chemical components ██ ███████ ███ ███████ ██ ████ █████ █████ ███ ████ ██████

Incorrect. Since the chemical components of galanin are present in both fatty and lean foods, this fact applies to both groups of rats and doesn't explain anything about the different galanin concentrations in their brains. So (C) doesn't strengthen the argument.

The rats that █████████ █████ █████ ███ ███ ██████ ██████████████ ██ ███████ ██ █████ ██████ ██████ ████ ████ ███████ █████ ██████

Correct. This rules out the possibility that the fatty foods themselves caused the rats to produce higher concentrations of galanin: the galanin was there in high concentrations before the rats were offered the fatty foods. (D) strengthens the author's argument by eliminating an alternate explanation for the correlation.

Plausibility

89%

Rats that metabolize ███ ████ ███████████ ████ ██ █████ ████ ███████ ████ ██████████████ ██ ███████ ██ █████ ███████

Incorrect. Even if (E) is true, we don't know if any of these rats that metabolize fat less efficiently were in the study, or which group they were in, if so. (E) doesn't provide any information useful for strengthening the argument.

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PrepTest 109 - Section 3 - Question 20

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