This topic has expert replies
User avatar
Legendary Member
Posts: 1560
Joined: 17 Nov 2009
Thanked: 137 times
Followed by:5 members

MGMAT RC

by thephoenix » Wed May 05, 2010 8:51 pm
Scientific advances in the latter half of the twentieth century have allowed researchers to study the chemical activities taking place in the human brain during the sleep cycle in more detail. In the 1970s, Jacobs employed these advances to postulate that dreams and hallucinations share a common neurochemical mechanism with respect to the neurotransmitters serotonin and norepinephrine that accounts for the observable similarities between the two states of mind. To test the theory, researchers attempted to elucidate the role of these transmitters in the normal sleep cycle and the effect of hallucinogenic drugs on them.
Although scientists still have much to discover about the chemical complexities of the brain, serotonin appears important for managing sleep, mood, and appetite, among other important functions, while neurons release norepinephrine to facilitate alertness and mental focus. Both are discharged in high quantities only during waking states. At the onset of sleep, the activity levels of neurons that release both the neurotransmitters drop, allowing the brain first to enter the four non-rapid eye movement (Non-REM) stages of sleep. When the brain is ready to enter the fifth stage, REM, which is associated with dreaming, the levels of these two chemicals drop virtually to zero. The Jacobs hypothesis held that the absence of norepinephrine was required to enable the brain to remain asleep, while the absence of serotonin was necessary to allow dreaming to occur.
Lysergic acid diethylamide, or LSD, is a semi-synthetic psychedelic drug which causes significant alteration of the senses, memories and awareness; at doses higher than 20 micrograms, it can have a hallucinogenic effect. LSD mimics serotonin well enough to be able to bind at most of the neurotransmitter's receptor sites, largely inhibiting normal transmission. In addition, the drug causes the locus ceruleus, a cluster of neurons containing norepinephrine, to greatly accelerate activity. If the drug stimulates norepinephrine, thereby precluding sleep, and inhibits serotonin, which Jacobs had postulated was a necessary condition for dreaming, then the resulting hallucinations could merely be "dreaming while awake." The research thus far is promising but inconclusive; future scientific advances should allow this theory to be tested more rigorously.

1)Which of the following, if true, would most undermine the central premise of the Jacobs hypothesis?

LSD does not completely inhibit normal transmission of serotonin.

Serotonin is only one of many chemicals that play a role in regulating sleep.

Researchers prove conclusively that the level of norepinephrine in the brain is a significant factor in enabling the brain to sleep.

Some semi-synthetic hallucinogenic drugs other than LSD do not inhibit serotonin.

The first four stages of sleep are as crucial to the process of dreaming as the fifth stage.

2)Which of the following best represents the author's primary goal in writing the passage?


to outline a theory and suggest options for further research


to act as an advocate for additional research to help elucidate a particular theory's validity


to introduce a theoretical construct that has not yet been sufficiently proven


to demonstrate the complexities involved in conducting a certain type of scientific research


to articulate a hypothesis and lay out the case for proving it

3)According to the passage, which of the following is true of the drug lysergic acid diethlyamide?


Research into the drug is promising but inconclusive.


The neuron receptor sites that normally bind serotonin will also bind the drug.


The locus ceruleus causes the drug to affect bodily systems more rapidly than normal.


The drug stimulates norepinephrine and serotonin.


A person who ingests more than 20 micrograms of the drug will have hallucinations.

[spoiler]I find this RC tougher than the RC given in OG's. Some how the options for all questions seems to be tough for me.
please help me to outline the structure of the passage[/spoiler]
Many of the great achievements of the world were accomplished by tired and discouraged men who kept on working

User avatar
Legendary Member
Posts: 758
Joined: 29 Aug 2009
Location: Bangalore,India
Thanked: 67 times
Followed by:2 members

by sumanr84 » Thu May 06, 2010 9:54 pm
1. B
B will tear apart this hypothesis as it points to only Serotonin responsible for sleep regulation.

2. C

3. B
Marker : LSD mimics serotonin well enough to be able to bind at most of the neurotransmitter..

OA ?
I am on a break !!

User avatar
Legendary Member
Posts: 1560
Joined: 17 Nov 2009
Thanked: 137 times
Followed by:5 members

by thephoenix » Thu May 06, 2010 10:39 pm
sumanr84 wrote:1. B
B will tear apart this hypothesis as it points to only Serotonin responsible for sleep regulation.

2. C

3. B
Marker : LSD mimics serotonin well enough to be able to bind at most of the neurotransmitter..

OA ?
OA is D,C,B
but pls respond to my query
strurcture?????
Many of the great achievements of the world were accomplished by tired and discouraged men who kept on working

User avatar
Legendary Member
Posts: 758
Joined: 29 Aug 2009
Location: Bangalore,India
Thanked: 67 times
Followed by:2 members

by sumanr84 » Fri May 07, 2010 9:36 am
I just read it..structuring it is very difficult task for me. I think testluv can help you in this..send a pm.
I am on a break !!

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2228
Joined: 27 Dec 2006
Location: Montreal, Canada
Thanked: 639 times
Followed by:693 members
GMAT Score:780

by Stacey Koprince » Tue May 11, 2010 1:02 pm
Received a PM asking me to respond. Yes, this is a tough one! (And that was on purpose - I wrote the passage. :))

First, the post above doesn't show the normal formatting; we can't see where the paragraph breaks are. If you can, please edit your post to include the paragraph breaks. Those breaks are very important clues in terms of how much attention to pay to various parts of the passage.

The second paragraph begins: "Although scientists still have much to discover"

The third paragraph begins: "Lysergic acid diethylamide, or LSD, is a semi-synthetic psychedelic drug"

So, here's the read-through / structure:

P1
later 20c. chemical stuff in brain while sleeping. J hypoth: dreams and hallucinations have some chemical thing in common. Researchers did some stuff to test this theory.

[Notice what I'm NOT including up there? All the hard stuff. I can still get the basic idea without the annoying stuff.]

P2
Scientists don't know everything yet. Something called serotonin has certain functions; hey that word was in the first paragraph. I'm going to call this S from now on. Something else called norepinephrine does some other stuff; that N thing was in the first para too. There are two things, S and N, that are important and do certain things. "At the onset of sleep..." okay, now they're telling me how people go to sleep... skimming... there are different stages of sleep... and when people dream, the levels of S and N drop. And then something about the J hypoth again. Whatever.

P3
LSD is a... drug. People can hallucinate when they take it. LSD mimics S in some way. LSd also does something to... the LC... that does something to N. (I really don't care what, though - I'm not getting into that!) The last two sentences aren't too bad though. LSD affects N and S, which somehow means that hallucinations might just be dreaming while you're awake. Okay, that's a lot easier to understand that all of the earlier stuff. And, finally, we need more research.

Q1: Hmm. Well, what is the central premise of the J hypothesis? Well, P1 said that J thought dreams and hallucinations had something in common. Then there was a bunch of scientific stuff till the end of P3, which kind of summarized things, so I'm going to look at that part again to see WHAT J thought the two had in common.

Let's see. LSD stimulates N, so I can't fall asleep, and LSD also inhibits S, so I can dream... so, boom, I start dreaming while I'm awake. And that's hallucinating - that's the connection that J thought was going on. This question asks us to undermine this thing, so I need something that would cause this chain of events to fall apart somewhere.

A) LSD doesn't completely inhibit S. Okay. But it could still mostly inhibit it. And that's what P3 describes, so that doesn't really change anything.

B) S is one of lots of chemicals. Okay. That doesn't change anything in the above sequence of events.

C) N is important in sleep. If anything, that reinforces the passage, which already says that N is important in sleep.

D) Other drugs also cause hallucinations. Those drugs do NOT inhibit S. Wait. They don't inhibit S, but they still cause hallucinations? Okay, so they don't support J's idea.

E) All stages of sleep are crucial to dreaming. Doesn't change anything in the above sequence of events.

D.
Please note: I do not use the Private Messaging system! I will not see any PMs that you send to me!!

Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT

Contributor to Beat The GMAT!

Learn more about me

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2228
Joined: 27 Dec 2006
Location: Montreal, Canada
Thanked: 639 times
Followed by:693 members
GMAT Score:780

by Stacey Koprince » Tue May 11, 2010 1:03 pm
I was going to post my responses for Qs 2 and 3, but I'm going to stop here for now, actually. Use what I wrote so far and see whether you can take this any further on your own.

If you still need help, just post again - but do make sure that you articulate what you did figure out versus what is still giving you trouble. It's important to make yourself try to take it as far as you possibly can before you get help from someone else.
Please note: I do not use the Private Messaging system! I will not see any PMs that you send to me!!

Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT

Contributor to Beat The GMAT!

Learn more about me

Legendary Member
Posts: 809
Joined: 24 Mar 2010
Thanked: 50 times
Followed by:4 members

by akhpad » Wed May 19, 2010 9:58 pm
Thanks Stacey; I appreciate it.

Q 1
Which of the following, if true, would most undermine the central premise of the Jacobs hypothesis?

A: LSD does not completely inhibit normal transmission of serotonin.
B: Serotonin is only one of many chemicals that play a role in regulating sleep.
C: Researchers prove conclusively that the level of norepinephrine in the brain is a significant factor in enabling the brain to sleep.
D: Some semi-synthetic hallucinogenic drugs other than LSD do not inhibit serotonin.
E: The first four stages of sleep are as crucial to the process of dreaming as the fifth stage.
OA: D; It is one of the toughest one. Stacey already explained above.

Q 2
Which of the following best represents the author's primary goal in writing the passage?

A: to outline a theory and suggest options for further research
B: to act as an advocate for additional research to help elucidate a particular theory's validity
C: to introduce a theoretical construct that has not yet been sufficiently proven
D: to demonstrate the complexities involved in conducting a certain type of scientific research
E: to articulate a hypothesis and lay out the case for proving it

Explanation:
3rd paragraph: The research thus far is promising but inconclusive; future scientific advances should allow this theory to be tested more rigorously.
OA: C

Q 3
According to the passage, which of the following is true of the drug lysergic acid diethlyamide?

A: Research into the drug is promising but inconclusive.
B: The neuron receptor sites that normally bind serotonin will also bind the drug.
C: The locus ceruleus causes the drug to affect bodily systems more rapidly than normal.
D: The drug stimulates norepinephrine and serotonin.
E: A person who ingests more than 20 micrograms of the drug will have hallucinations.

Explanation:
3rd paragraph: LSD mimics serotonin well enough to be able to bind at most of the neurotransmitter's receptor sites, largely inhibiting normal transmission.
OA: B

Q 4
Which best represents the author's attitude towards the presented theory?
A: passionate but unbiased
B: optimistic and persuasive
C: pessimistic and dismissive
D: hopeful and conciliatory
E: supportive but objective
OA: E; Can someone explain it?

Q 5
According to the passage, serotonin plays a role in managing which body processes?
A: sleep and appetite
B: alertness and mental focus
C: alertness and appetite
D: mood and mental focus
E: sleep and speech

Explanation:
2nd paragraph: "serotonin appears important for managing sleep, mood, and appetite, among other important functions."
OA: A
Last edited by akhpad on Thu May 20, 2010 6:02 pm, edited 2 times in total.

Master | Next Rank: 500 Posts
Posts: 305
Joined: 27 Jul 2009
Thanked: 10 times

by Shawshank » Wed May 19, 2010 10:55 pm
=
Q 4
Which best represents the author's attitude towards the presented theory?
A: passionate but unbiased
B: optimistic and persuasive
C: pessimistic and dismissive
D: hopeful and conciliatory
E: supportive but objective
OA: E; Can someone explain it?
Lets give it a shot.. it would have been better if you would not have posted the OA


A: passionate but unbiased -- No passionate approach. SO can be eliminated.
B: optimistic and persuasive
C: pessimistic and dismissive --- No pessismistic approach is seen in the passage. So can be direclty eliminated.
D: hopeful and conciliatory
E: supportive but objective

Between

B: optimistic and persuasive -- the author can be considered to be "optmiistic" but not presuasive. As mentioned in the last line. future scientific advances should allow this theory to be tested more rigorously. . SO eliminate

D: hopeful and conciliatory --> The last line again says .. The research thus far is promising but inconclusive; future scientific advances should allow this theory to be tested more rigorously. The approach can be hopeful, but then the author does not conciliate anywhere in the passage.

E: supportive but objective --> The author is supportive and objective. Correct
++++++++++++++++++++++++++++++
Shawshank Redemtion -- Hope is still alive ...

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2228
Joined: 27 Dec 2006
Location: Montreal, Canada
Thanked: 639 times
Followed by:693 members
GMAT Score:780

by Stacey Koprince » Thu May 20, 2010 11:02 am
Shawshank, I like how you explain your reasoning. I agree! :)

akhp77, the explanation that you posted for #2 looks like the the official explanation (as opposed to something written in your own words). Does that mean that you think you understand the official explanation? You didn't post a specific question about it.

If you aren't entirely sure, I would encourage you to try to write your own explanation for that one. If you can write your own explanation, then you know you understand it. If you can't, then you know there's still some more work to do!
Please note: I do not use the Private Messaging system! I will not see any PMs that you send to me!!

Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT

Contributor to Beat The GMAT!

Learn more about me

Junior | Next Rank: 30 Posts
Posts: 10
Joined: 21 Jun 2010

by Operation780 » Fri Jul 30, 2010 10:13 am
Q 2
Which of the following best represents the author's primary goal in writing the passage?

A: to outline a theory and suggest options for further research
B: to act as an advocate for additional research to help elucidate a particular theory's validity
C: to introduce a theoretical construct that has not yet been sufficiently proven
D: to demonstrate the complexities involved in conducting a certain type of scientific research
E: to articulate a hypothesis and lay out the case for proving it

Explanation:
3rd paragraph: The research thus far is promising but inconclusive; future scientific advances should allow this theory to be tested more rigorously.
OA: C
I am unable to understand this...IMO B is the answer.
The author first explains the new theory that has not been proven yet. But his main point is that "future scientific advances should allow this theory to be tested more rigorously."..... SHOULD denotes his opinion.

I am of the understanding that when the passage has a Opinion of the author the main idea/primary purpose answer should reflect this opinion and tone of author. Choice B reflets this opinion. Also this ans gets the tone of the author right. The author is somewhat +ve towards the therory.

As opposed choice C has neutral tone and also does not represent author's opinion. Hence i feel Choice B is correct.

Please explain. Also explain whether my understandingi is correct - "I am of the understanding that when the passage has a Opinion of the author the main idea/primary purpose answer should reflect this opinion and tone of author."

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2228
Joined: 27 Dec 2006
Location: Montreal, Canada
Thanked: 639 times
Followed by:693 members
GMAT Score:780

by Stacey Koprince » Fri Jul 30, 2010 1:37 pm
"Should" means something like "might" (but a bit more certain): something will likely be allowed or will happen. When a word like "should" is placed next to another verb ("should allow"), this is a way to talk about the future but not in absolutely sure terms. "This will allow" means you think there's no doubt that this will happen in future. "This should allow" means it will probably happen in future, but you're not saying it definitely will.

If people do more research, then that should allow us to understand more. That is not the same thing as saying that I personally think someone should go do that research. Those are two different concepts.

Someone has a theory that shooting yourself in the head will kill you. If someone undertakes that action, we should be able to test that theory.

Have I told you that I think we should actually conduct that experiment? I hope not. :)

The word "should" does not automatically mean "I think you should do this" or "I think this should be done."

The tone is somewhat positive, yes. This is not a tone question. Be wary of looking for a tone response to a non-tone question. Generally speaking, the correct answer can't contradict the tone, no - but it doesn't actually have to reflect the tone, either. (For example, you wouldn't say "to introduce a theoretical construct with which the author disagrees" because that actually contradicts what the passage says.)
Please note: I do not use the Private Messaging system! I will not see any PMs that you send to me!!

Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT

Contributor to Beat The GMAT!

Learn more about me

Junior | Next Rank: 30 Posts
Posts: 10
Joined: 21 Jun 2010

by Operation780 » Sat Jul 31, 2010 6:30 am
Thank You... Now i understand properly. By using 'should', the author is not advocating. hence B is wrong.

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2228
Joined: 27 Dec 2006
Location: Montreal, Canada
Thanked: 639 times
Followed by:693 members
GMAT Score:780

by Stacey Koprince » Wed Aug 04, 2010 11:48 am
Right - in this case, the author isn't trying to say he thinks something should happen. That's only one way to use should.

I think you should study more. I'm advocating something.
It should rain tomorrow. I'm making a prediction, or I'm repeating something I heard the meteorologist predict. That doesn't mean I want it to rain tomorrow. :)
Please note: I do not use the Private Messaging system! I will not see any PMs that you send to me!!

Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT

Contributor to Beat The GMAT!

Learn more about me

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 2228
Joined: 27 Dec 2006
Location: Montreal, Canada
Thanked: 639 times
Followed by:693 members
GMAT Score:780

by Stacey Koprince » Wed Aug 04, 2010 2:13 pm
Just adding because, in your PM, you asked a couple of additional questions.

Yes, "main idea" and "primary purpose" are generally the same thing. The only time they're not is when the question limits the scope. eg, What is the main idea of the third paragraph?

This article talks about how to find the main point:
https://www.beatthegmat.com/mba/2010/07/ ... rc-passage

I don't have an article yet that talks about how to answer and study these types of questions specifically. I'll add the idea to my list!
Please note: I do not use the Private Messaging system! I will not see any PMs that you send to me!!

Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT

Contributor to Beat The GMAT!

Learn more about me

Senior | Next Rank: 100 Posts
Posts: 62
Joined: 06 May 2008
Thanked: 4 times

by rashmi.kaushal » Wed Aug 04, 2010 11:31 pm
For Q3 Why not Option E ?