Find all School-related info fast with the new School-Specific MBA Forum

It is currently 26 Jul 2014, 11:37

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

The chemical adenosine is released by brain cells when those

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
User avatar
Affiliations: FRM Charter holder
Joined: 02 Dec 2006
Posts: 736
Schools: Stanford, Chicago Booth, Babson College
Followers: 6

Kudos [?]: 15 [0], given: 4

GMAT Tests User
The chemical adenosine is released by brain cells when those [#permalink] New post 31 Jan 2007, 06:28
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
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.
Senior Manager
Senior Manager
User avatar
Joined: 01 Feb 2005
Posts: 275
Followers: 1

Kudos [?]: 29 [0], given: 1

GMAT Tests User
 [#permalink] New post 31 Jan 2007, 07:59
This is a good one... Is the Answer A?
Director
Director
avatar
Joined: 28 Dec 2005
Posts: 922
Followers: 2

Kudos [?]: 37 [0], given: 0

GMAT Tests User
 [#permalink] New post 31 Jan 2007, 08:23
This would be B for me.
Manager
Manager
User avatar
Joined: 11 Dec 2006
Posts: 51
Followers: 1

Kudos [?]: 2 [0], given: 0

Re: CR: adenosine [#permalink] New post 31 Jan 2007, 08:29
B should be answer. It proves that caffeine prevents adenosine hence causing wakefulness which suggest that it is adenosine which caused sleepiness. Good argument in support of theory.

Please tell OA.

A --> If concentration of adenosine is high even after waking up from a good sleep, It refutes proposed theory.
B --> proves that caffeine prevents adenosine hence causing wakefulness
C --> Does not relate with theory. Does not matter.
D --> If inactive cells also emit adenosine, theory fails.
E ---> talks about other factor causing wakefulness.
Senior Manager
Senior Manager
avatar
Joined: 17 Aug 2005
Posts: 394
Location: Boston, MA
Followers: 1

Kudos [?]: 5 [0], given: 0

GMAT Tests User
Re: CR: adenosine [#permalink] New post 31 Jan 2007, 09:29
aurobindo 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.


Initially went for A, but I'll go with B.
Hypothesis is that during wakefulness the cumulative binding of Ad. to sites in the brain, built up from wakeful hours, is what makes you sleepy.

B supports the hyp. by saying that Caffeine makes us awake by preventing the action that makes us sleepy (binding of Adenosine to cells)

A is very close but I think that AFTER long periods of sleep the number of bound cells would decrease because you are going to wake up. I could argue for A too, and probably would have chosen A on test day.

Can anyone argue the reasons for their choice? I'm a little torn b/w A and B
SVP
SVP
User avatar
Joined: 08 Nov 2006
Posts: 1560
Location: Ann Arbor
Schools: Ross '10
Followers: 12

Kudos [?]: 160 [0], given: 1

GMAT Tests User
Re: CR: adenosine [#permalink] New post 31 Jan 2007, 09:48
aurobindo 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.


The para-phrased argument is similar to the following.

Adenosine is released by active brain cells
As adenosine level increases, they are bound to the brain cells.

Researchers say that the binding of adenosines to the brain cells in a large number of cells causes onset of sleep. --> Restated as 'Adenosine when bound to the brain makes the brain cell less active and causes the onset of sleep.'

We can substantiate the hypothesis by demonstrating that sleep can be prevented by preventing the binding of adenosines to brain cells.

According to 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.

B strengthens the hypothesis. No other answer comes close. B is my pick.
_________________

My Profile/GMAT/MBA Story
http://www.gmatclub.com/forum/111-t59345

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Director
Director
User avatar
Affiliations: FRM Charter holder
Joined: 02 Dec 2006
Posts: 736
Schools: Stanford, Chicago Booth, Babson College
Followers: 6

Kudos [?]: 15 [0], given: 4

GMAT Tests User
 [#permalink] New post 01 Feb 2007, 02:26
Thanks Guys. The OA is B.
  [#permalink] 01 Feb 2007, 02:26
    Similar topics Author Replies Last post
Similar
Topics:
The chemical adenosine is released by brain cells when those Jp27 3 11 Nov 2012, 04:42
1 Recently documentedc, the production of new brain cells, devinawilliam83 3 05 Nov 2011, 21:29
The chemical adenosine is released by brain cells when those ankur55 11 28 Jul 2009, 02:54
The chemical adenosine is released by brain cells when those jerrywu 6 18 Sep 2006, 00:32
Alcohol may interface with the ability of the brain cells as mbassmbass04 2 11 Dec 2004, 09:54
Display posts from previous: Sort by

The chemical adenosine is released by brain cells when those

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.