It is currently 19 Nov 2017, 09:51

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Scientific advances in the latter half of the twentieth

Author Message
TAGS:

### Hide Tags

Intern
Joined: 05 May 2014
Posts: 11

Kudos [?]: 6 [0], given: 11

Location: United States
Concentration: General Management, Human Resources
GMAT Date: 05-30-2014
GPA: 3.92

### Show Tags

06 May 2014, 18:21
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.
"norepinephrine was required to enable the brain to remain asleep"
question 3 anyone pls tell me why option c is wrong , but from above sentence we can conclude that absence of norepinephrine = asleep , this shows that "c" is correct...

Kudos [?]: 6 [0], given: 11

Intern
Joined: 27 May 2014
Posts: 7

Kudos [?]: 1 [0], given: 9

### Show Tags

27 May 2014, 01:01
Got all right and it took aroun 5-6minutes.

And it's a bit late but if this is helpful to any future students:
In Q 1, A is not right because the sentence (The research thus far is promising but inconclusive; future scientific advances should allow this theory to be tested more rigorously) that people are referring to actually means the whole research and not the research of the drug only.
In Q3, B is wrong beause the question is what would MOST hinder, not what would hinder. The right answer (D) would be the one that hinders the theory most.

Kudos [?]: 1 [0], given: 9

Intern
Joined: 25 May 2014
Posts: 22

Kudos [?]: 7 [0], given: 13

GPA: 3.55

### Show Tags

09 Jun 2014, 05:12
1
This post was
BOOKMARKED
Explanation for #3:

"(D) Some semi-synthetic hallucinogenic drugs other than LSD do not inhibit serotonin."

It may seem Out of Scope at first -- why would we bring in some other drug in the "argument." Tricky as it is, the answer choice actually implies that there are other hallucinogenic drugs other than LSD that still perform their main function--make one hallucinate--despite its inability to inhibit serotonin (unlike LSD).

Hence, if it is true that there are other drugs that make people hallucinate without inhibiting serotonin, then the whole argument of the author collapses since his underlying premise is that the inhibition of serotonin is a necessary condition.

Kudos [?]: 7 [0], given: 13

Manager
Joined: 04 Jan 2014
Posts: 121

Kudos [?]: 14 [0], given: 24

### Show Tags

11 Jun 2014, 06:08
Can anyone explain this phrase?

"LSD mimics serotonin well enough to be able to bind at most of the neurotransmitter’s receptor sites"

Is LSD binding neurotransmitter or...?

Kudos [?]: 14 [0], given: 24

Intern
Joined: 25 May 2014
Posts: 22

Kudos [?]: 7 [0], given: 13

GPA: 3.55

### Show Tags

11 Jun 2014, 07:33
pretzel wrote:
Can anyone explain this phrase?

"LSD mimics serotonin well enough to be able to bind at most of the neurotransmitter’s receptor sites"

Is LSD binding neurotransmitter or...?

In other words, the function of LSD is to act as a "fake" serotonin thereby blocking the so-called "receptor sites." Because of this, the "real" serotonin neurotransmitters are prevented from going to their receptor sites and consequently preventing them from functioning normally.

Kudos [?]: 7 [0], given: 13

Chat Moderator
Joined: 19 Apr 2013
Posts: 687

Kudos [?]: 171 [0], given: 537

Concentration: Strategy, Healthcare
Schools: Sloan '18 (A)
GMAT 1: 730 Q48 V41
GPA: 4

### Show Tags

18 Mar 2015, 10:19
Difficult passage. It must be from manhattan cats.
_________________

If my post was helpful, press Kudos. If not, then just press Kudos !!!

Kudos [?]: 171 [0], given: 537

Intern
Joined: 19 Aug 2014
Posts: 6

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

GMAT 1: 640 Q48 V29

### Show Tags

03 Aug 2015, 10:28
Scientific advances in the twentieth century have allowed researchers to study the chemical activities taking place in the sleeping human brain. In the 1970s, researcher Barry Jacobs drew on these advances to propose that a shared neurochemical basis in the neurotransmitters serotonin and norepinephrine accounts for the observable similarities between dreams and hallucinations. To test Jacobs’ theory, researchers attempted to elucidate the role of serotonin and norepinephrine in the normal sleep cycle and the effect of hallucinogenic drugs on these neurotransmitters.
Serotonin appears important for managing sleep, mood, and appetite, among other functions, while norepinephrine facilitates alertness and mental focus. Both neurotransmitters are discharged in high quantities only during waking states. At the onset of sleep, the neurons that release these neurotransmitters become less active, allowing the brain to enter the three non-rapid eye movement (non-REM) stages of sleep. The non-REM stages typically are not associated with normal dreaming, though parasomnias, such as sleepwalking and confusional arousals, are most common during stage 3. When the brain is ready to enter the fourth stage, REM, which is strongly 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; 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 coeruleus, a cluster of neurons containing norepinephrine, to greatly accelerate activity. If the drug stimulates norepinephrine, thereby precluding sleep, and inhibits serotonin, creating 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.

Q1. Which of the following, if true, would most undermine the central premise of the Jacobs hypothesis?
1. LSD does not cause as much long-term neurological damage as previously thought.
2. Serotonin and norepinephrine are found to rise and fall in tandem.
3. Researchers prove conclusively that the level of norepinephrine in the brain is a significant factor in enabling the brain to sleep.
4. Some semi-synthetic hallucinogenic drugs other than LSD do not inhibit serotonin.
5. The first three stages of sleep are as crucial to the process of dreaming as the fourth stage.

Q2. The author discusses the Locus coeruleus in order to
1. demonstrate that lysergic acid diethylamide causes hallucinations
2. confirm that Jacobs’ hypothesis was valid
3. illustrate how lysergic acid diethylamide induces dreaming
4. explain the mechanism by which a hallucinogenic drug affects a certain neurotransmitter
5. establish that norepinephrine is necessary in order to stimulate activity in the Locus coeruleus

In Q1 I was able to eliminate the options 1, 2,3 & 5. Although the right answer is option 4, I am unable to understand the line of reasoning.
In Q2, I am confused between Options 3 and 4. The context appears to be the same in both the options, but the correct answer is 4. please explain.

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

Non-Human User
Joined: 01 Oct 2013
Posts: 10132

Kudos [?]: 270 [0], given: 0

### Show Tags

16 Apr 2016, 14:22
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

Kudos [?]: 270 [0], given: 0

Intern
Joined: 20 Aug 2015
Posts: 13

Kudos [?]: 6 [0], given: 4

GMAT 1: 710 Q49 V37

### Show Tags

29 Apr 2016, 07:20
siddhans wrote:
Why is A wrong in 1?

The last line of the para says this:- The research thus far is promising but inconclusive; future scientific advances should allow this theory to be tested more rigorously.

I know my answer may not matter now to you, still I am happy to reply.
The passage does not intend to say that the research that seems promising was done on the drug rather the research was for the entire process.

Kudos [?]: 6 [0], given: 4

Verbal Forum Moderator
Joined: 05 Nov 2012
Posts: 529

Kudos [?]: 641 [0], given: 606

Concentration: Technology, Other

### Show Tags

29 Aug 2016, 08:26
Top Contributor
8.40 mins
Q2:
P1: Hypothesis is introduced.
P3: Author asks for future research to test the validity of theory. "future scientific advances should allow this theory to be tested more rigorously."
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

Q3:
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.
....
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.
.......
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.”

D: Some semi-synthetic hallucinogenic drugs other than LSD do not inhibit serotonin. //There are some medicine exception to J's hypothesis.
_________________

--------------------------------------------------------
Regards

Kudos [?]: 641 [0], given: 606

Verbal Forum Moderator
Status: Greatness begins beyond your comfort zone
Joined: 08 Dec 2013
Posts: 1595

Kudos [?]: 1003 [0], given: 80

Location: India
Concentration: General Management, Strategy
GPA: 3.2
WE: Information Technology (Consulting)

### Show Tags

05 Sep 2016, 10:38
Took 9 mins 30 seconds , including 3 mins 40 seconds to read .
Was in a fix in question 2 between option B and C

1 .Paragraph three is about the effects of and research results on lysergic acid diethlyamide, or LSD.
(A) The passage describes research into Jacob's theory as "promising but inconclusive," but does not make this statement about the drug LSD itself.
(B) CORRECT. The second sentence of the third paragraph says that "LSD mimics serotonin well enough to... bind at most of [serotonin's] receptor sites."
(C) The passage says that the drug causes the locus ceruleus to accelerate activity, the opposite of the causation suggested by this choice – that the locus ceruleus affects the body’s response to the drug.
(D) The passage states that the drug stimulates norepinephrine but inhibits serotonin.
(E) The passage says that "at doses higher than 20 micrograms, it can have a hallucinogenic effect." This means that some people may have hallucinations, but it
does not mean that everyone will, as this answer choice suggests.

2. We are asked to find the purpose of the passage. The first paragraph of the passage introduces a theory that seeks to show a link between dreams and
hallucinations based upon two chemicals. The second paragraph elaborates on the role of the two chemicals in dreams and the third paragraph does the
same for hallucinations. The third paragraph also concludes by noting that the theory remains unproven and would benefit from further testing.
(A) While the passage does outline a theory it does not suggest options for further research; it merely notes that further research would be beneficial.
(B) The author does not act as an advocate, or try to convince the audience of the need for additional research; instead, the author merely notes that further research
would be beneficial.
(C) CORRECT. A "theoretical construct" is equivalent to a theory; the author does introduce a theory that is "inconclusive," or not sufficiently proven.
(D) While the first sentence does imply that research associated with the brain is complex, the rest of the passage does not focus on this topic or attempt to demonstrate the specific complexities involved.
(E) While the passage does articulate a hypothesis, it only presents current research; it does not "lay out the case for proving it." In fact, the last sentence says
the hypothesis is "inconclusive."

3. We are asked to "undermine the central premise" of the presented hypothesis, which is summarized in the second sentence of the first paragraph. Jacobs proposed that dreams and hallucinations function via a similar brain mechanism involving the levels of two chemicals, serotonin and norepinephrine. Jacobs tried to prove this by demonstrating that the levels of
these two chemicals fluctuate in a similar fashion while both dreaming (natural state) and hallucinating (via ingestion of a hallucinatory drug).
(A) In sentence 2, paragraph 3, we are told that LSD binds "at most of the neurotransmitter's receptor sites" (italics added), indicating that we (and Jacobs)
already know that LSD does not completely inhibit serotonin transmission. This has already been taken into account, therefore, and does not undermine Jacobs' theory.
(B) The theory in question does not require serotonin to be the only chemical, or one of only a few chemicals, involved in regulating sleep. It merely proposes that two of
of the chemicals involved with sleep also function similarly when the brain is hallucinating. This choice is out of scope.
(C) This could undermine Jacobs' theory under certain circumstances, but it could also bolster the theory. Jacobs believed that the drop in norepinephrine levels
enabled the brain to sleep. This choice merely says the "levels" are significant; it does not quantify these levels, so we do not know whether this choice supports or
(D) CORRECT. If other hallucinogens (i.e., drugs that cause hallucinations) are able to produce hallucinations without inhibiting serotonin, then the central premise of
Jacobs' hypothesis--that dreams and hallucinations function via a similar brain mechanism involving the levels of serotonin and norepinephrine--would not hold.
(E) This choice says these stages are "crucial" to the overall process of dreaming (which we can already infer from the passage - we have to fall asleep before we
dream), but it does not say anything else. Perhaps if we were told that dreaming occurs during the first four stages, when levels of the two chemicals are higher, we
might conclude that this weakens the hypothesis; the information is too vague as presented, however, to conclude anything.

4. "Except" questions require us to test the five answer choices to determine the "odd one out." It is beneficial to use the True / False technique: label each
answer choice with a T or an F and look for the odd one out (which, in this case, we should expect to be an F).
(A) CORRECT. False. The second sentence of the second paragraph says of the chemicals that "Both are discharged in high quantities only during waking states."
Later sentences tell us that the chemical levels drop during non-REM sleep, not that they disappear completely.
(B) True. The first sentence of the third paragraph says that "at doses higher than 20 micrograms, [LSD] can have a hallucinogenic effect." This is equivalent to the
statement that the dosage will cause hallucinations in some people (otherwise, we could not say that it "can have" a hallucinogenic effect).
(C) True. Sentence four in paragraph two tells us that REM (rapid eye movement sleep) "is associated with dreaming."
(D) True. The third sentence of paragraph three says that the neurons containing norepinephrine "greatly accelerate activity" when LSD is in someone's system.
Sentence one of paragraph two tells us that "neurons release norepinephrine" - so if this neuronal activity is increased, then the rate at which norepinephrine is released
must also increase.
(E) True. The last sentence of the second paragraph says that Jacobs hypothesized that "the absence of serotonin was necessary to allow dreaming to occur."
_________________

When everything seems to be going against you, remember that the airplane takes off against the wind, not with it. - Henry Ford
The Moment You Think About Giving Up, Think Of The Reason Why You Held On So Long
+1 Kudos if you find this post helpful

Kudos [?]: 1003 [0], given: 80

CR Forum Moderator
Status: The best is yet to come.....
Joined: 10 Mar 2013
Posts: 471

Kudos [?]: 198 [0], given: 191

### Show Tags

31 Oct 2016, 22:59
The passage says LSD ................... bind .......the neurotransmitter’s receptor sites, whereas option B says the neuron receptor sites ........ bind serotonin will also bind the drug. Isn't it reverse? Moreover, how can we infer that receptor sites also bind drug?

I also don't understand why not it E.
The passage says 'at doses higher than 20 micrograms, it can have a hallucinogenic effect' which is in line of choice E.
_________________

Hasan Mahmud

Kudos [?]: 198 [0], given: 191

Intern
Joined: 07 Dec 2016
Posts: 1

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

### Show Tags

12 Dec 2016, 12:53
siddhans wrote:
Why is A wrong in 1?

The last line of the para says this:- The research thus far is promising but inconclusive; future scientific advances should allow this theory to be tested more rigorously.

he used the word promising which means second choice is better , which says he actually supports advocates the research being done

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

Manager
Joined: 24 Jan 2017
Posts: 165

Kudos [?]: 77 [0], given: 106

GMAT 1: 640 Q50 V25
GMAT 2: 710 Q50 V35
GPA: 3.48

### Show Tags

25 Apr 2017, 07:43
mohitmohansahu wrote:
Scientific advances in the twentieth century have allowed researchers to study the chemical activities taking place in the sleeping human brain. In the 1970s, researcher Barry Jacobs drew on these advances to propose that a shared neurochemical basis in the neurotransmitters serotonin and norepinephrine accounts for the observable similarities between dreams and hallucinations. To test Jacobs’ theory, researchers attempted to elucidate the role of serotonin and norepinephrine in the normal sleep cycle and the effect of hallucinogenic drugs on these neurotransmitters.
Serotonin appears important for managing sleep, mood, and appetite, among other functions, while norepinephrine facilitates alertness and mental focus. Both neurotransmitters are discharged in high quantities only during waking states. At the onset of sleep, the neurons that release these neurotransmitters become less active, allowing the brain to enter the three non-rapid eye movement (non-REM) stages of sleep. The non-REM stages typically are not associated with normal dreaming, though parasomnias, such as sleepwalking and confusional arousals, are most common during stage 3. When the brain is ready to enter the fourth stage, REM, which is strongly 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; 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 coeruleus, a cluster of neurons containing norepinephrine, to greatly accelerate activity. If the drug stimulates norepinephrine, thereby precluding sleep, and inhibits serotonin, creating 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.

Q1. Which of the following, if true, would most undermine the central premise of the Jacobs hypothesis?
1. LSD does not cause as much long-term neurological damage as previously thought.
2. Serotonin and norepinephrine are found to rise and fall in tandem.
3. Researchers prove conclusively that the level of norepinephrine in the brain is a significant factor in enabling the brain to sleep.
4. Some semi-synthetic hallucinogenic drugs other than LSD do not inhibit serotonin.
5. The first three stages of sleep are as crucial to the process of dreaming as the fourth stage.

Q2. The author discusses the Locus coeruleus in order to
1. demonstrate that lysergic acid diethylamide causes hallucinations
2. confirm that Jacobs’ hypothesis was valid
3. illustrate how lysergic acid diethylamide induces dreaming
4. explain the mechanism by which a hallucinogenic drug affects a certain neurotransmitter
5. establish that norepinephrine is necessary in order to stimulate activity in the Locus coeruleus

In Q1 I was able to eliminate the options 1, 2,3 & 5. Although the right answer is option 4, I am unable to understand the line of reasoning.
In Q2, I am confused between Options 3 and 4. The context appears to be the same in both the options, but the correct answer is 4. please explain.

Hi, I got Q2 correct but was confused at Q1 too.
In Q2, I guess you know how to eliminate options 1, 2, and 5. The following is the reason why I think Option 3 is wrong:

In addition, the drug causes the Locus coeruleus, a cluster of neurons containing norepinephrine, to greatly accelerate activity. If the drug stimulates norepinephrine, thereby precluding sleep, and inhibits serotonin, creating a necessary condition for dreaming, then the resulting hallucinations could merely be “dreaming while awake.”

The drug has 2 activities: stimulating norepine to preclude sleep, and inhibiting serotonin to create dreaming. "Locus coeruleus" is related to stimulating norepine (underlined words), and has nothing to do with inhibiting serotonin (bold lines). That is the reason why Option 4, not Op3, is correct

Kudos [?]: 77 [0], given: 106

SC Moderator
Joined: 13 Apr 2015
Posts: 1505

Kudos [?]: 1172 [0], given: 890

Location: India
Concentration: Strategy, General Management
WE: Information Technology (Consulting)

### Show Tags

16 Jun 2017, 07:22
Explanation for Q5:

The second half of paragraph two discusses the stages of sleep, including stage 4.

(A) While it might be reasonable to assume that the four stages generally occur in order, the passage does not provide any information to infer that the fourth stage occurs only after passing through the first three.

(B) The passage states that parasomnias are “most common during stage 3”; the passage provides no information about whether parasomnias occur during stage 4.

(C) CORRECT. The fourth sentence of paragraph two says that the non-REM stages are not associated with normal dreaming. The fifth sentence then says that “the fourth stage, REM…is strongly associated with dreaming.”

(D) The passage does say that certain neurotransmitter levels “drop virtually to zero” during the fourth stage. The passage does not indicate, however, that the levels “fluctuate” (move up and down) during that stage.

(E) The passage says that the levels of the two neurotransmitters drop “when the brain is ready to enter the fourth stage.” This means the levels drop before the brain enters the fourth stage, not as a result of entering it.

Kudos [?]: 1172 [0], given: 890

Manager
Joined: 27 Jun 2015
Posts: 50

Kudos [?]: 9 [0], given: 48

WE: Information Technology (Computer Software)

### Show Tags

17 Jun 2017, 00:51
Can anyone plz explain how can we infer ans C in Q5? Where is it remotely referred as Normal dreaming in the fourth stage?

Kudos [?]: 9 [0], given: 48

Senior Manager
Joined: 27 May 2012
Posts: 420

Kudos [?]: 88 [0], given: 484

### Show Tags

17 Jun 2017, 07:23
Vyshak wrote:
Explanation for Q5:

The second half of paragraph two discusses the stages of sleep, including stage 4.

(A) While it might be reasonable to assume that the four stages generally occur in order, the passage does not provide any information to infer that the fourth stage occurs only after passing through the first three.

(B) The passage states that parasomnias are “most common during stage 3”; the passage provides no information about whether parasomnias occur during stage 4.

(C) CORRECT. The fourth sentence of paragraph two says that the non-REM stages are not associated with normal dreaming. The fifth sentence then says that “the fourth stage, REM…is strongly associated with dreaming.”

(D) The passage does say that certain neurotransmitter levels “drop virtually to zero” during the fourth stage. The passage does not indicate, however, that the levels “fluctuate” (move up and down) during that stage.

(E) The passage says that the levels of the two neurotransmitters drop “when the brain is ready to enter the fourth stage.” This means the levels drop before the brain enters the fourth stage, not as a result of entering it.

Dear Vyshak,

Thank you for your contribution. However I have one concern:

Below is paragraph 2, with regards to question 5 can you please tell me :

Vyshak wrote:
The second half of paragraph two discusses the stages of sleep, including stage 4.
where exactly in paragraph 2 is the fourth stage mentioned.

Vyshak wrote:
The fourth sentence of paragraph two says that the non-REM stages are not associated with normal dreaming. The fifth sentence then says that “the fourth stage, REM…is strongly associated with dreaming.”

Again I am not able to find where "the fourth stage, REM…is strongly associated with dreaming" is mentioned

Please note para 2 says FIFTH stage is associated with dreaming NOT fourth stage.
" .... the fifth stage, REM, which is associated with dreaming....," is mentioned.

Maybe I missing something or maybe I am under hallucination. Your help would be greatly appreciated.

Paragraph 2 :

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.
_________________

- Stne

Kudos [?]: 88 [0], given: 484

Manager
Joined: 03 May 2017
Posts: 98

Kudos [?]: 16 [0], given: 13

### Show Tags

17 Jun 2017, 17:36
stne wrote:
Vyshak wrote:
Explanation for Q5:

The second half of paragraph two discusses the stages of sleep, including stage 4.

(A) While it might be reasonable to assume that the four stages generally occur in order, the passage does not provide any information to infer that the fourth stage occurs only after passing through the first three.

(B) The passage states that parasomnias are “most common during stage 3”; the passage provides no information about whether parasomnias occur during stage 4.

(C) CORRECT. The fourth sentence of paragraph two says that the non-REM stages are not associated with normal dreaming. The fifth sentence then says that “the fourth stage, REM…is strongly associated with dreaming.”

(D) The passage does say that certain neurotransmitter levels “drop virtually to zero” during the fourth stage. The passage does not indicate, however, that the levels “fluctuate” (move up and down) during that stage.

(E) The passage says that the levels of the two neurotransmitters drop “when the brain is ready to enter the fourth stage.” This means the levels drop before the brain enters the fourth stage, not as a result of entering it.

Dear Vyshak,

Thank you for your contribution. However I have one concern:

Below is paragraph 2, with regards to question 5 can you please tell me :

Vyshak wrote:
The second half of paragraph two discusses the stages of sleep, including stage 4.
where exactly in paragraph 2 is the fourth stage mentioned.

Vyshak wrote:
The fourth sentence of paragraph two says that the non-REM stages are not associated with normal dreaming. The fifth sentence then says that “the fourth stage, REM…is strongly associated with dreaming.”

Again I am not able to find where "the fourth stage, REM…is strongly associated with dreaming" is mentioned

Please note para 2 says FIFTH stage is associated with dreaming NOT fourth stage.
" .... the fifth stage, REM, which is associated with dreaming....," is mentioned.

Maybe I missing something or maybe I am under hallucination. Your help would be greatly appreciated.

Paragraph 2 :

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.

Hi,

I have the same issue regarding question 5. Maybe I am missing something or the paragraph was altered. Anyhow, I would not worry too much, as far as you know that something is amiss. The real GMAT RCs are usually clearer.

Kudos [?]: 16 [0], given: 13

Re: Scientific advances in the latter half of the twentieth   [#permalink] 17 Jun 2017, 17:36

Go to page   Previous    1   2   [ 38 posts ]

Display posts from previous: Sort by

# Scientific advances in the latter half of the twentieth

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne 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®.