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The chemical adenosine is released by brain cells when those cells are

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The chemical adenosine is released by brain cells when those cells are  [#permalink]

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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.


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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 28 Jul 2009, 03:26
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IMO B

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. -Though the number of bindings are very large, but still the option is saying that it is at its lowest concentration. That clearly means that at higher concentration the number of bindings will be even much larger. This option doesn't support "Some researchers have hypothesized that it is the cumulative binding of adenosine to a large number of sites that causes the onset of sleep."
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. -Correct. The researchers are saying that increase in binding makes people sleepy. This option is giving an example when a decrease in binding keeps people awake. Hence supporting the researchers work.
C. Besides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body. -Irrelevant.
D. Some areas of the brain that are relatively inactive nonetheless release some adenosine. -Irrelevant. Referring to very small amount of adenosine. "Some areas...release some..."
E. Stress resulting from a dangerous situation can preserve wakefulness even
when brain levels of bound adenosine are high. -Irrelevant. Its talking about a one off case.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 28 Jul 2009, 12:51
bigoyal wrote:
IMO B
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. -Correct. The researchers are saying that increase in binding makes people sleepy. This option is giving an example when a decrease in binding keeps people awake. Hence supporting the researchers work.

B only says that caffeine 'interferes' with the binding. Can we assume that it decreases the binding for it's so-called effect? For me this option only says that caffeine has some kind of effect on brain cells.

OA pls?
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 28 Jul 2009, 13:32
Economist wrote:
bigoyal wrote:
IMO B
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. -Correct. The researchers are saying that increase in binding makes people sleepy. This option is giving an example when a decrease in binding keeps people awake. Hence supporting the researchers work.

B only says that caffeine 'interferes' with the binding. Can we assume that it decreases the binding for it's so-called effect? For me this option only says that caffeine has some kind of effect on brain cells.

OA pls?


I think in this context:
interfere is used as "Come between so as to be hindrance or obstacle"(Wordweb dictionary meaning)
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 28 Jul 2009, 20:39
Economist wrote:
bigoyal wrote:
IMO B
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. -Correct. The researchers are saying that increase in binding makes people sleepy. This option is giving an example when a decrease in binding keeps people awake. Hence supporting the researchers work.

B only says that caffeine 'interferes' with the binding. Can we assume that it decreases the binding for it's so-called effect? For me this option only says that caffeine has some kind of effect on brain cells.

OA pls?


I think so, as it is mentioned in the option that "Caffeine....is known to interfere with the binding of adenosine to sites on brain cells"
So if its interfering with the binding process, it surely will at least slow down the process of binding process, hence not letting it to increase.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 29 Jul 2009, 02:28
Thanks ankur55..good question:) and thanks all for the discussion.
Actually I did some over-engineering..
I was between C and E. ( which are almost similar )

Now that I know the OA...I can understand the subtle difference. C says that X affects the cells ( increase or decrease, but most probably decreases the binding to have its effect ) and thereby causes wakefulness. So we are sure that wakefulness or sleep is affected by the binding.

E says that Y 'preserves' wakefulness inspite of high concentration. It does not say anything about the effect of Y on the cells. So may be something else is causing sleep. This actually weakens the argument.

Nice pattern for cause-effect CRs.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 11 Nov 2012, 07:36
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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.

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 those cells are  [#permalink]

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New post 11 Nov 2012, 10:19
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.

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
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 01 Dec 2013, 18:22
I don't think E is irrelevant. It is the 2nd best option to B. It suggests that high conc of adenosine makes people sleepy but a dangerous situation keeps them awake clearly suggesting that adenosine aids in sleep.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 02 Dec 2013, 01:24
My breakdown reasoning:
Cumulative binding of adenosine ------> sleep
OTHER/ NO (adenosine) -------> NO sleep

Therefore answer B
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 30 Jun 2015, 19:32
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.
It just says that even during sleep, adenosine remains bound to large number of brain cells... does not help in argument

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.
correct.. this tells us that caffine keeps people awake and interferes in binding

C. Besides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body.
out of context

D. Some areas of the brain that are relatively inactive nonetheless release some adenosine.
again out of context

E. Stress resulting from a dangerous situation can preserve wakefulness even when brain levels of bound adenosine are high.
again out of context
ans B
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 26 Oct 2015, 04:38
Dear friend,

I would like to share some opinion on choice A and B. I choose A although OA is B. Here is my reasoning:

First, I summarize the paragraph:
Premise 1: brain cells are active -> adenosine is released.
Premise 2: adenosine binds to more cells in certain areas of the brain, more binding in the state of wakefulness. That results from more adenosine because of more active brain cells in state of wakefulness, confirming by "the total amount released gradually increases during wakefulness"
Premise 3: in sleep, the number of sites bound by adenosine decreases, less binding in the state of unwakefulness (sleep).. However, we do not know whether the number of adenosine is less. What we know is "less binding" rather than decreasing "amount" of adenosine. Thus, to fit a gap reasonably from Premise 1 and 2, it is assumed that there is less adenosine because active brain cells are less in state of sleep)
Conclusion (hypothesis): the cumulative binding of adenosine to a large number of sites (the more adenosine released) -> onset of sleep


My method of reasoning is: since the conclusion attempts to establish the CAUSALITY between the accumulative binding of adenosine (the increasing number of adenosine) and the onset of sleep, I will eliminate other causality that also leads to the onset of sleep, thus strengthening the conclusion.


In Choice 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"
- There is a correlation RATHER THAN a causality here.
- That statement is, to me, two premises (two facts) [fact 1: caffeine makes people wakeful; fact 2: caffeine is known to interfere with the binding of adenosine to brain cells) RATHER THAN a causality chain to be understood like this: "caffeine has the effect of making people remain wakeful because it interfere with the binding of adenosine to brain cells"
- EVEN IF this statement is a causality, it is understood in this way: "because caffeine interfere with the binding of adenosine to sites on brain cells, it makes people wakeful". Briefly, "less cumulative of binding (less adenosine) causes the state of wakefulness".
- Understood in this way, this statement bears no relevance to the reasoning because one CANNOT infer that because less cumulative of binding causes people to wake, so more cumulative (the opposite of less cumulative) will make them sleep (the opposite of wakefulness) . Simply, A -> B does NOT lead to "NO A -> NO B".


Choice A does a remarkable job in eliminating the reverse causality:
- The conclusion suggests that it is the cumulating binding of adenosine (the increasing number of adenosine) that causes sleep. Conclusion will be weakend tremendously if the reverse causality is true: sleep causes the cumulative binding of adenosine ( sleep "increases" the number of adenosine, thus increasing the number of cells that adenosine binds to). Statement A takes well care of this.
- By saying: "even after long periods of sleep when adenosine is at its lowest concentration in the brain, the number of brain cells with adenosine remains very large". Briefly, sleep CANNOT increase the number of adenosine/ the number of cells that adenosine binds to because adenosine is now at its lowest concentration AND the number of brain cells that adenosine binds to remains very large.


With such reasoning, to me, A is a correct answer. I know OA is B, but, until now, I find no other explanation that is persuasive enough to prove that B is the BEST choice here :)


bigoyal wrote:
IMO B

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. -Though the number of bindings are very large, but still the option is saying that it is at its lowest concentration. That clearly means that at higher concentration the number of bindings will be even much larger. This option doesn't support "Some researchers have hypothesized that it is the cumulative binding of adenosine to a large number of sites that causes the onset of sleep."
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. -Correct. The researchers are saying that increase in binding makes people sleepy. This option is giving an example when a decrease in binding keeps people awake. Hence supporting the researchers work.
C. Besides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body. -Irrelevant.
D. Some areas of the brain that are relatively inactive nonetheless release some adenosine. -Irrelevant. Referring to very small amount of adenosine. "Some areas...release some..."
E. Stress resulting from a dangerous situation can preserve wakefulness even
when brain levels of bound adenosine are high. -Irrelevant. Its talking about a one off case.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 10 Apr 2016, 13:50
Conc: cumulative binding of adenosine to a large number of sites causes the onset of sleep.

We need to strengthen this causal argument. There are several way you can strengthen a causal argument. You can suggest that whenever cause happens effect happens. No cause no effect. effect did not cause the cause and so on.

B is correct as it says no cause no effect. i.e. No cumulative binding of adenosine(because of caffeine) no sleep.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 07 Aug 2018, 10:53
I actually thought A as OA as somehow high binding causes sleep.
I am not getting any connection b/w B and hypothesis to be supported.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 07 Aug 2018, 18:31
tejyr wrote:
I actually thought A as OA as somehow high binding causes sleep.
I am not getting any connection b/w B and hypothesis to be supported.

Why?

Question is a strengthen question. With that in mind, the conclusion of the stem says "Some researchers have hypothesized that it is the cumulative binding of adenosine to a large number of sites that causes the onset of sleep." Even if you don't read anything else, what would strengthen this statement? The only choice that does not weaken it or is out of scope, and actually does strengthen it, is B because the conclusion says that it is the large binding of the chemical that promotes sleep. If anything interferes with it and keeps people awake, it strengthens the argument because the it supports that the chemical does indeed induce sleep.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 23 Sep 2018, 12:16
ankur55 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.


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bigoyal wrote:
IMO B

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. -Though the number of bindings are very large, but still the option is saying that it is at its lowest concentration. That clearly means that at higher concentration the number of bindings will be even much larger. This option doesn't support "Some researchers have hypothesized that it is the cumulative binding of adenosine to a large number of sites that causes the onset of sleep."
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. -Correct. The researchers are saying that increase in binding makes people sleepy. This option is giving an example when a decrease in binding keeps people awake. Hence supporting the researchers work.
C. Besides binding to sites in the brain, adenosine is known to be involved in biochemical reactions throughout the body. -Irrelevant.
D. Some areas of the brain that are relatively inactive nonetheless release some adenosine. -Irrelevant. Referring to very small amount of adenosine. "Some areas...release some..."
E. Stress resulting from a dangerous situation can preserve wakefulness even
when brain levels of bound adenosine are high. -Irrelevant. Its talking about a one off case.


Just to add to the discussion on top.
The argument is using cause and effect reasoning.

Conclusion: Cause (i.e. cumulative binding of adenosine to a large number of sites) -> Effect (i.e. Sleep)

Strengthener: No Cause (Caffeine interferes with the binding of adenosine to sites on brain cells) -> No Effect (No sleep = Wakefulness)
Therefore, answer is B.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 24 Sep 2018, 03:32
No doubt that Option B supports the argument but Option E also states that sleep preserves wakefulness even when the brain levels of bound adenosine are high which implies that high levels of adenosine cause the onset of sleep and stress counters it. How can we say that E is out of context?

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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 25 Sep 2018, 08:07
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Ilishar wrote:
No doubt that Option B supports the argument but Option E also states that sleep preserves wakefulness even when the brain levels of bound adenosine are high which implies that high levels of adenosine cause the onset of sleep and stress counters it. How can we say that E is out of context?

Posted from my mobile device


As you state, E informs us of a counter effect to anedosine. it is perhaps true that this is not entirely out of context, but it definitely doesn't strengthen the claim that andeosine causes sleep, which is what we are looking for. It's just informing us about the existence of an opposite force- and at that, only one which operates in very specific conditions (danger). so, no support here.
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Re: The chemical adenosine is released by brain cells when those cells are  [#permalink]

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New post 01 Dec 2018, 02:53
chetan2u wrote:
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.
correct.. this tells us that caffine keeps people awake and interferes in binding

E. Stress resulting from a dangerous situation can preserve wakefulness even when brain levels of bound adenosine are high.
again out of context
ans B



I don't fully see how you can simply say "out of context" without articulating why it's out of context.

I narrowed it down to B and E, but went with E.

Both B and E infer that Caffeine and Stress preserve wakefulness.

I really needed to understand the OG explanation to see why E was wrong and well, E actually confirms that Stress impedes the sleep inducing effect of adenosine - It doesn't "refute the hypothesis".

Speaking of which, I didn't jot this down before I answered the question, which is probably why I marked it incorrect.

Conclusion/ Hypothesis: The cumulative binding of adenosine to many sites causes the onset of sleep

Back to E - E is incorrect because it neither refutes nor validates this conclusion/hypothesis. We want something that STRENGTHENS.

B - Coffee induces wakefulness and inhibits binding of adenosine to sites on brain cells. So it is then logical to infer that because coffee inhibits binding, people remain awake and so if adenosine was bound to brain sites people would be asleep.

I found this tough to get my head around under timed conditions.
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