Passage: Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.
Question: Which of the following experiments would yield the most useful results for evaluating the scientists' hypothesis?
A. Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids
B. Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats' immune-system activity levels again
C. Injecting rats with corticosteroids and then observing how many of the rats contracted infections
D. Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats' immune-system responses
E. Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams
Passage: Since 1990 the percentage of bacterial sinus infections in Aqadestan that are resistant to the antibiotic perxicillin has increased substantially. Bacteria can quickly develop resistance to an antibiotic when it is prescribed indiscriminately or when patients fail to take it as prescribed. Since perxicillin has not been indiscriminately prescribed, health officials hypothesize that the increase in perxicillin-resistant sinus infections is largely due to patients' failure to take this medication as prescribed.
Question: Which of the following, if true of Aqadestan, provides most support for the health officials' hypothesis?
A. Resistance to several other commonly prescribed antibiotics has not increased since 1990 in Aqadestan.
B. A large number of Aqadestanis never seek medical help when they have a sinus infection.
C. When it first became available, perxicillin was much more effective in treating bacterial sinus infections than any other antibiotic used for such infections at the time.
D. Many patients who take perxicillin experience severe side effects within the first few days of their prescribed regimen.
E. Aqadestani health clinics provide antibiotics to their patients at cost.
Question: Which of the following most logically completes the argument?
The last members of a now-extinct species of a European wild deer called the giant deer lived in Ireland about 16,000 years ago. Prehistoric cave paintings in France depict this animal as having a large hump on its back. Fossils of this animal, however, do not show any hump. Nevertheless, there is no reason to conclude that the cave paintings are therefore inaccurate in this regard, since __________.
A. some prehistoric cave paintings in France also depict other animals as having a hump
B. fossils of the giant deer are much more common in Ireland than in France
C. animal humps are composed of fatty tissue, which does not fossilize
D. the cave paintings of the giant deer were painted well before 16,000 years ago
E. only one currently existing species of deer has any anatomical feature that even remotely resembles a hump
Source: Graduate Management Admission Council
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