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?
语文部分: 考之前看到CD上有之前考过的同学说感觉语法跟以前做过的不太一样,这个我还真没觉得,感觉跟GWD的很像啊,而且最后一道题还是GWD里的 Charles Darwin observed, natural selection operates whenever individuals of one genetic composition are better at reproducing than that of others A. that of others B. the other
C. another D. those of another E. that of the next
这题语法题正好是最后一题,呵呵,时间来不及了就正好立马选上 考试过程中觉得最痛苦的是逻辑,,,看不懂,脑袋之间放空啊,最后第二道逻辑题优势GWD里的 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? 答案选B
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.
Caffeine, which has the effect of making people remain wakeful, is known to interfere with the binding of adenosine to sites on brain cells.
Besides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body.
Some areas of the brain that are relatively inactive nonetheless release some adenosine.
Stress resulting from a dangerous situation can preserve wakefulness even when brain levels of bound adenosine are high.