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The chemical adenosine is released by brain cells when those

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The chemical adenosine is released by brain cells when those [#permalink] New post 11 Nov 2012, 05:42
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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.

[Reveal] Spoiler:
OA after some discussion.
Guys can u please confirm this -> When awake Adenosine binds to more and more sites (and the concentration level of Adenosine also increase) -> because of this extensive binding, sleepiness is induced (author's hypothesis)-> during sleep Adenosine binding decreases.
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Re: The chemical adenosine is released by brain cells when t [#permalink] New post 11 Nov 2012, 08:36
Jp27 wrote:
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.

[Reveal] Spoiler:
OA after some discussion.
Guys can u please confirm this -> When awake Adenosine binds to more and more sites (and the concentration level of Adenosine also increase) -> because of this extensive binding, sleepiness is induced (author's hypothesis)-> during sleep Adenosine binding decreases.


Hypothesis is 'cumulative binding of adenosine to a large number of sites that causes the onset of sleep'. Choice B provides evidence that caffeine interfers with binding of chemical to sites on brain cells and also that caffeine prevents sleep. This provides support to hypothesis.

Ans B it is.
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Re: The chemical adenosine is released by brain cells when t [#permalink] New post 11 Nov 2012, 11:19
Jp27 wrote:
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.

[Reveal] Spoiler:
OA after some discussion.
Guys can u please confirm this -> When awake Adenosine binds to more and more sites (and the concentration level of Adenosine also increase) -> because of this extensive binding, sleepiness is induced (author's hypothesis)-> during sleep Adenosine binding decreases.



Hi Jp

I also used the same reasoning, but i dnt find any straight answer,
all choices are either weakening the argument or out of scope

Except B
Re: The chemical adenosine is released by brain cells when t   [#permalink] 11 Nov 2012, 11:19
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