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题库 / OG2017V-CR-155
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.
Which of the following experiments would yield the most useful results for evaluating the scientists' hypothesis?
Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids
Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats' immune-system activity levels again
Injecting rats with corticosteroids and then observing how many of the rats contracted infections
Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats' immune-system responses
Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams
相关因果推理 M刺激分泌---导致免疫下降
D 控制变量法 切断因果链
A 无法切断，已经有高水平的C
B 没提到M ，链不成立
C 跳过了腺体 直接注射分泌物，无法知道是不是刺激腺体导致的
E M 没提到
C: morphine -- adrenal glands -- corticosterioids -- immune system.
P1: morphine -- corticosteriods -- immune system
P2: adrenal glands -- corticosteriods
strengthen: morphine --- ? --- adrenal glands -- corticosteriods -- immune system
by stimulating the “adrenal glands“ to secrete additional “corticosteroids“ into the “bloodstream"。不要被C迷惑，只说到了cor...和免疫的关系
rat注射morphine以后immune system活动减弱，adrenal glands分泌的corticosteroids升高。推测M是通过影响AG来减弱immune的。
正确选项一定含有morphine和immune system之间的某种关系
吗啡刺激肾上腺释放额外cort→降低immune response
morphine 吗啡
adrenal gland 肾上腺
secrete 分泌
contract 感染