PrepTest 94+, Section 2, Question 16
A recent study found that small rats were approximately twice as likely, and large rats only half as likely, to suffer from heart problems than were rats of average size.
A recent study found that small rats were approximately twice as likely, and large rats only half as likely, to suffer from heart problems than were rats of average size.
A recent study found that small rats were approximately twice as likely, and large rats only half as likely, to suffer from heart problems than were rats of average size.
A recent study found that small rats were approximately twice as likely, and large rats only half as likely, to suffer from heart problems than were rats of average size.
Each of the following, if true, contributes to an explanation of the correlation given above between size and heart disease in rats EXCEPT:
Small rats are more likely than large rats to suffer from fatal diseases that tend to strike earlier than do heart problems.
Small rats generally have smaller blood vessels than do large rats, vessels that can more easily be clogged with fatty deposits.
The larger a rat is, the more successful it will be at defending itself, and therefore the less stressful its existence will be.
In addition to being the leading cause of weak hearts in adult rats, malnutrition at early stages of development causes rats to be undersized.
Although large rats are no more active than rats of average size, they tend to be much more active than small rats, resulting in greater cardiovascular conditioning.
Explanations
The passage tells us that small rats have 2x the heart problems of average rats and that large rats have 0.5x the heart problems of average rats. So the smaller the rat, the more likely they are to develop heart disease—that's the correlation, at least.
This is a paradox except question. In other words, our job is to find the answer choice that doesn't help us better understand why as rats get smaller their risk for heart disease increases.
Let's take a look.
Yeah, this works (because it doesn't explain the heart disease correlation). The rates at which all these rats suffer from cancer, or dementia, or whatever else, doesn't matter.
Nope. This helps explain things. If small rats have small blood vessels that easily get clogged, it's easy to imagine how they'd suffer more frequently from heart disease.
No. This totally helps explain it. If big rats are more capable of defending themselves and thereby have lower stress levels, then they probably have healthier hearts.
Nope. This helps explain the issue. If a rat is malnourished, causing it to be smaller, and thereby have a weaker heart in adulthood, then it totally explains why smaller rats are more susceptible to heart disease.
Nah. This helps us understand things. We can abbreviate the information here as, "large rats...tend to be much more active than small rats, resulting in greater cardiovascular conditioning." If that's true, then of course the larger rats have less risk for heart disease.
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