Critical Reasoning

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.

I am confused between A and B here....Can someone please explain each of the options in details...

Many thanks!

I think B is a better candidate than A. What we are talking about is onset of sleep induced by the adenosine binding to a large number of site. B says that people do not get sleep after consuming caffeine because less number of sites are bound with adenosine and hence onset of sleep does not occur. A is taking about after onset of sleep.

this_time_i_will wrote:I think B is a better candidate than A. What we are talking about is onset of sleep induced by the adenosine binding to a large number of site. B says that people do not get sleep after consuming caffeine because less number of sites are bound with adenosine and hence onset of sleep does not occur. A is taking about after onset of sleep.

Thankyou for sharing your thoughts on this one.

However, can you please explain the meaning of option A. What does it trying to convey?.

Thanks in advance!.

"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. "
so there are two things.. 1 saying: during sleep number of site decreases
2 saying ( hypothesis) large number of sites causes sleep

so i went with D.

Any taker?

We are not given a context in which to evaluate 'very large'. Thousands? Millions? Suppose we are talking about 100,000,000. 100,000,000 is a very large number, but it may pale in comparison to the number of bound sites before the onset of sleep

kevincanspain wrote:We are not given a context in which to evaluate 'very large'. Thousands? Millions? Suppose we are talking about 100,000,000. 100,000,000 is a very large number, but it may pale in comparison to the number of bound sites before the onset of sleep

I am little confused here...Please elaborate a bit more on this

Thanks

ssgmatter wrote:

this_time_i_will wrote:I think B is a better candidate than A. What we are talking about is onset of sleep induced by the adenosine binding to a large number of site. B says that people do not get sleep after consuming caffeine because less number of sites are bound with adenosine and hence onset of sleep does not occur. A is taking about after onset of sleep.

Thankyou for sharing your thoughts on this one.

However, can you please explain the meaning of option A. What does it trying to convey?.

Thanks in advance!.

A talks about adenosine bound ( it means adenosine already bound ). However, the stimulus talks about accumulating binding of adenosine which is ongoing. that's why A is wrong.

The most evident assumption in this argument is that
Abundant binding of adenosine to the cell sites ---> induces sleep and it's not the other way round.

Choice (B) strengthens this assumption - that caffeine interferes with the binding of adenosine to the sites. Because of this action, sleep is prevented from occurring. So (B) is the best choice here.

Choice (A) is not strengthening the argument. In fact in a way it already says what is stated in the argument, however in circumlocutory words. If the adenosine is still bound to the site, it means that sleep cycle will continue.

To strengthen the argument, we need to show that if large no. of adenosine are interfered or prevented from binding to the sites, does this action induce sleep or not. (B) does this best.


Thanks
Prashant

Prashant Ranjan wrote:The most evident assumption in this argument is that
Less binding of adenosine to the cell sites ---> induces sleep and it's not the other way round.
Thanks
Prashant

Prashant,

Don't you mean large amount of binding induces sleep and since caffeine interferes with the binding, it interferes with the onset of sleep and therefore keeps people awake.

Regards
Anup

Thanks Anup..
Mistake rectified...


Thanks
Prashant