52 睡觉与某化学物质分泌的关系
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 concentration 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.
不做GWD 很久了 没有看出来这是哪里的题 有哪位XDJM提供一下答案吗??
b
设A为：adenosine；B为：sleep;
原文结论说的是：有A则有B：A——> B：
adenosine累积到大量的sites时，启动了睡眠；
选项B说：没有A就没有B：无A——>无 B：
Caffeine，妨碍了adenosine累积（无A），因此人保持清醒（不想睡，既无B），从反面支持了原来的结论。
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