3，GWD25-Q36
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?
A. Even after long periods of sleep when adenosine is at its lowest concen-tration in the brain, the number of brain cells bound with adenosine remains very large.
B. Caffeine, which has the effect of making people remain wakeful, is known to interfere with the binding of adenosine to sites on brain cells.
C. Besides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body.
D. Some areas of the brain that are relatively inactive nonetheless release some adenosine.
E. Stress resulting from a dangerous situation can preserve wakefulness even when brain levels of bound adenosine are high.
RC JJ上的题目,说是选B,可还是不是很明白,请指教!
自己顶一下..
22号就要一战,请各位同学帮帮忙指点迷津！
可以用有关无关来判断：
A：文说的腺苷的cumulative binding 与睡眠的开始的关系，after sleep无关
C：腺苷在其他反应中的作用无关
D：对于腺苷不敏感的脑部分无关
E:stress可以抵消腺苷的作用，貌似weaken，而且weaken的作用还不大
理论上分析B正确的原因就是：咖啡因通过 阻止the binding of adenosine to sites on brain cells.来使人们保持清醒，说明这个对于睡眠的开始是有作用的
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