本贴相关题目 TN-16-CR-36 (PGPE)

00:00:00

The chemical adenosine is released by brain cells when those cells are active. Adenosine then binds to more and more sites on cells in certain areas of the brain, as the total amount released gradually increases during wakefulness. During sleep, the number of sites to which adenosine is bound decreases. Some researchers have hypothesized that it is the cumulative binding of adenosine to a large number of sites that causes the onset of sleep.

Which of the following, if true, provides the most support for the researchers' hypothesis?

AEven after long periods of sleep when adenosine is at its lowest concentration in the brain, the number of brain cells bound with adenosine remains very large.
BCaffeine, which has the effect of making people remain wakeful, is known to interfere with the binding of adenosine to sites on brain cells.
CBesides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body.
DSome areas of the brain that are relatively inactive nonetheless release some adenosine.
EStress resulting from a dangerous situation can preserve wakefulness even when brain levels of bound adenosine are high.

正确答案: B

麻烦牛人们解释一下这道GWD的题。。

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shirly813

楼主

发表于 2010-9-2 18:52:37 | 显示全部楼层

(C)选项throughout the body说明了这是无关选项
(D)选项relatively inactive nonetheless release some adenosine样本不具说服力
(E)选项Stress resulting from a dangerous只说明在压力下的特例,也与题干无关
最后(A)选项是在说明即使在睡眠时adenosine浓度最低,他在脑中的浓度还是非常高,变成是在反驳了
因此只有(B)可选
但这题难在,(B)选项只提到了adenosine和Caffeine有交互关系,却没有说明是正向或负向的关系,在没有厘清其它选项绝对错误时,很难大胆选(B)