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Normally , the pineal gland governs CR

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georgepaul0071987 Senior | Next Rank: 100 Posts Default Avatar
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Normally , the pineal gland governs CR

Post Tue Sep 11, 2012 5:56 pm
Normally, the pineal gland governs a person's sleep-wake cycle by secreting melatonin in response to the daily cycle of light and darkness as detected by the eye. Nonetheless, many people who are totally blind due to lesions in the visual cortex of the brain easily maintain a 24-hour sleep-wake cycle. So the neural pathway by which the pineal gland receives information from the eye probably does not pass through the visual cortex.

For purposes of evaluating the argument it would be most useful to establish which of the following?


(A) Whether melatonin supplements help people who have difficulty maintaining a 24-hour sleep cycle to establish such a pattern

(B) Whether the melatonin levels of most totally blind people who successfully maintain a 24-hour sleep-wake cycle change in response to changes in exposure to light and darkness

(C) Whether melatonin is the only substance secreted by the pineal gland

(D) Whether most people who do not have a 24-hour sleep-wake cycle nevertheless have a cycle of consistent duration

(E) Whether there are any people with normal vision whose melatonin levels respond abnormally to periods of light and darkness

Source : OG 13

OA :B

What's the best way to solve this question ?

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vikram4689 Legendary Member
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Post Wed Sep 12, 2012 9:07 am
arg. says that pineal secretes melatonin as a response to light and governs sleep cycle. but since blind people having damaged cortex have same sleep cycle, therefore light does not enter form cortex. therefore link to be evaluated: coz people with damaged cortex have same sleep cycle, pineal does not get light from cortex.

to evaluate, we need to see is melatonin is produced in blind people. if yes then light does not pass through cortex. if no then light does pass through cortex

A - difficulty maintaining sleep cycle is not discussed
C - even if pineal secretes more substances, it does not affect us
D - duration is not our concern
E - we are concerned about blind people

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akashkumar1987 Senior | Next Rank: 100 Posts Default Avatar
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Post Tue Sep 11, 2012 8:22 pm
If we go through the argument,Information we got from "totally blind" is used for making the argument.

So to evaluate the argument the best thing is to ask question from "totally blind" people only,

Answer Correct s B

If anybody is having any other best strategy then please share.

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