GWD25-Q36

ambrosecelin

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.

答案选B，看了讨论贴，还是不太懂...

cathyzq

推理逻辑

wakefulness-when cells active-adenosine released-bind to sites-sites accumulated to a large number-stimulate person-sleep-adenosine decrease

Most support-

关键是最支持的这个假设，那这个假设是大量由AD形成的SITE是导致睡觉的最主要原因，那要睡觉就是要形成这些SITES。如果要支持的话，就是如果这些SITES形不成，就无法导致睡眠，从而无法导致睡眠的形成，也就从反面支持了这个假设。

A 睡觉后这个AD没有下降，所以与假设相反

B 看上面解释

C 无关

D 与题目的第一句矛盾

E 提到危险的状况，与题目无关

ambrosecelin

非常感谢！

rpch2004

以下是引用cathyzq在2008-3-25 22:41:00的发言：

推理逻辑

wakefulness-when cells active-adenosine released-bind to sites-sites accumulated to a large number-stimulate person-sleep-adenosine decrease

Most support-

关键是最支持的这个假设，那这个假设是大量由AD形成的SITE是导致睡觉的最主要原因，那要睡觉就是要形成这些SITES。如果要支持的话，就是如果这些SITES形不成，就无法导致睡眠，从而无法导致睡眠的形成，也就从反面支持了这个假设。

A 睡觉后这个AD没有下降，所以与假设相反

B 看上面解释

C 无关

D 与题目的第一句矛盾

E 提到危险的状况，与题目无关

无因无果型支持，赞一个！

tiffany1102

up

raphael1234

up

raphael1234

以下是引用cathyzq在2008-3-25 22:41:00的发言：

推理逻辑

wakefulness-when cells active-adenosine released-bind to sites-sites accumulated to a large number-stimulate person-sleep-adenosine decrease

Most support-

关键是最支持的这个假设，那这个假设是大量由AD形成的SITE是导致睡觉的最主要原因，那要睡觉就是要形成这些SITES。如果要支持的话，就是如果这些SITES形不成，就无法导致睡眠，从而无法导致睡眠的形成，也就从反面支持了这个假设。

A 睡觉后这个AD没有下降，所以与假设相反

B 看上面解释

C 无关

D 与题目的第一句矛盾

E 提到危险的状况，与题目无关

我有一点很不明白:

原文说

"醒着的时候:A被释放àA与越来越多的site结合

睡着的时候:与A结合的site减少

研究者假设:积累的大量的A与site的结合会导致睡眠"

想问一下,研究者的假设跟前文提到的睡着的时候以及醒着的时候的状况,有什么关系吗?

scarlett8327

ding

伊布拉莫维琨

skigorush