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Caffeine, the stimulant in coffee, has been called “the most widely us

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Caffeine, the stimulant in coffee, has been called “the most widely us  [#permalink]

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New post 05 Jun 2018, 07:23
RC Full of jargon , not that tough to understand ,with some straight forward questions , got 9/9 Correct , but took around 20min for all 9 Questions , willing to help with any understanding issues with the RC.

I did not find anything unusual with Q8 , The discrepancy in the alternate hypothesis is presented and explanation is given.
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Re: Caffeine, the stimulant in coffee, has been called “the most widely us  [#permalink]

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New post 09 Jun 2018, 21:25
RMD007 wrote:
shrupk wrote:
Hello,

Can somebody please explain Q7?

Thanks.


So here is the question --

Quote:
Which of the following, if true, would most weaken the theory proposed by Snyder et al?

(A) At very low concentrations in the human brain, both caffeine and theophylline tend to have depressive rather than stimulatory effects on human behavior.

(B) The ability of caffeine derivatives at very low concentrations to dislodge adenosine from its receptors in mouse brains correlates well with their ability to stimulate mouse locomotion at these low concentrations.

(C) The concentration of cyclic AMP in target neurons in the human brain that leads to increased neuron firing can be produced by several different phosphodiesterase inhibitors in addition to caffeine.

(D) The concentration of caffeine required to dislodge adenosine from its receptors in the human brain is much greater than the concentration that produces behavioral stimulation in humans.

(E) The concentration of IBMX required to dislodge adenosine from its receptors in mouse brains is much smaller than the concentration that stimulates locomotion in the mouse.



Okay. So we have to weaken the claim proposed by Snyder et al

Lets take these options one by one -

Quote:
(A) At very low concentrations in the human brain, both caffeine and theophylline tend to have depressive rather than stimulatory effects on human behavior.


This does not weaken the claim. In the last paragraph author says that caffeine can have mixed effects at low concentrations and this behavior is OK.

Quote:
(B) The ability of caffeine derivatives at very low concentrations to dislodge adenosine from its receptors in mouse brains correlates well with their ability to stimulate mouse locomotion at these low concentrations.


Even if this is true, it claims that caffeine at low levels stimulates the mouse locomotion. This is also in line with Snyder et al's explanations.


Quote:
(C) The concentration of cyclic AMP in target neurons in the human brain that leads to increased neuron firing can be produced by several different phosphodiesterase inhibitors in addition to caffeine.


Okay, if the said concentration of Cyclic AMP is produced by several others as well caffeine, it does not weaken any claim by Snyder et al

Quote:
(D) The concentration of caffeine required to dislodge adenosine from its receptors in the human brain is much greater than the concentration that produces behavioral stimulation in humans.


Snyder et al claims that caffeine dislodges adenosine from its receptors and that results in greater neuron firing. Thereby produces behavioral stimulation in humans. So it is a series of dependent events.

But if the concentration of caffeine that is required to dislodge adenosine to produce behavioral stimulation is much greater, then probably this behavioral stimulation is not caused by dislodging of adenosine.

This breaks the reasoning chain.

Quote:
(E) The concentration of IBMX required to dislodge adenosine from its receptors in mouse brains is much smaller than the concentration that stimulates locomotion in the mouse.

These are independent events; does not deduce anything.

Hope it helps... :)

Thanks RMD007 for the awesome explanation!

As noted by gmatexam439 several months ago (sorry gmatexam439, didn't see your question before!), questions #7-9 do not appear to be official questions. These three are not included in the OG or in the Verbal Reviews, so I wouldn't worry too much about them.

JAIN09, note that these 3 additional questions obviously skewed your timing data.

Thanks everybody!
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Re: Caffeine, the stimulant in coffee, has been called “the most widely us  [#permalink]

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New post 10 Jun 2018, 01:06
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Hello sensei.... i hope you are doing great.
Yes it doesn't make sense to attempt those unofficial questions because they aren't of great quality.

Posted from my mobile device
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Re: Caffeine, the stimulant in coffee, has been called “the most widely us  [#permalink]

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New post 10 Jun 2018, 07:49
Can an expert please help with OE for Q7,8 and 9
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Re: Caffeine, the stimulant in coffee, has been called “the most widely us  [#permalink]

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New post 05 Jul 2018, 09:25
aditya2887 wrote:
Can an expert please help with OE for Q7,8 and 9

aditya2887, can you let us know what you were thinking about these questions? The more detail you can give us about what you are struggling with, the better we can assist you (and the more likely you are to receive a timely reply!).

Please use the request verbal experts' reply button to post specific questions.

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Re: Caffeine, the stimulant in coffee, has been called “the most widely us &nbs [#permalink] 05 Jul 2018, 09:25

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