GWD25-Q36 请教刚出来的逻辑JJ一题，

anistonlucky

GWD25-Q36 请教刚出来的逻辑JJ一题，

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 tointerfere 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.

answer B???

为什么是B？

mych666666

可以参照一下以前的讨论：

1.当大脑的cells被激活的时候，A就会被这些cells释放。当在醒着的时候被释放的总数慢慢增加的时候，A然后就会邦在越来越多的cells的位置上。而当睡着的时候邦着A的的地方变少了。一些研究人员就假设

A邦定大量的site的积累的过程的时候导致了睡觉的发生
            

注意cumulative这个词，他时候过程；当邦定积累到一定的程度，邦定就会慢慢减少，那么就会导致睡觉的刚刚开始
A 无关，因为提干中的假设是说睡觉刚刚开始的时候，而A说after long periods of sleep 

B  加强，说明A的邦定确实是和wakefullness或者是sleep相关的东西
C  br无关
D inactive无关
E 说stress导致wakefullness或者是sleep的东西，否认了是A的邦定导致wakefullness或者是sleep的东西，所以削弱

2."as the total amount released gradually increases during wakefulness", 是说醒的时候释放的A增加，

"during sleepness, the nuber of sites to which a is bound decreases"是说睡的时候A可以bind的site减少。

A的释放增加，和site减少，是两回事。所谓site减少就是A物质bind to site减少，这个是在睡眠时发生的。所以科学家的假说是认为睡眠时bind这件事减少。

B就是说抑止bind这件事，刚好针对问题关键。

3.注意：

it is the cumulative binding of adenosine to a  large number of sites that causes the onset of sleep

而Caffeine能够interfere with the binding of adenosine to sites on brain cells

所以，B是合适的

zacharyzhang

每当碰上逻辑，其实还是阅读。

题目说：脑细胞活跃时释放adenosine,脑中ad与sites结合得就越来越多；sleep时结合会减少。因此有人认为是ad与sites结合的量积累引起sleep。问加强。

A sleep后ad减少但与ad结合的site仍然十分多
B caffeine可以让人清醒，可以干扰ad和site的结合。
C ad除了能和sites结合外，还参与身体中其他生化反应。
D 脑中一些不活跃的区域不产生ad
E 即使ad很多，危险带来的压力也会让人清醒。

内容理解清楚了，应该不用再多加解释了吧。

[此贴子已经被作者于2008-4-28 13:00:14编辑过]

gelan1234

我怎么觉得还是挺绕的，考试的时候很容易绕进去。

never3738

LZ加油啊！！！