It is currently 16 Jan 2018, 09:40

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Scientist long believed that two nerve cluster in the human hypothalam

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

1 KUDOS received
Verbal Forum Moderator
avatar
Joined: 05 Nov 2012
Posts: 529

Kudos [?]: 698 [1], given: 606

Concentration: Technology, Other
GMAT ToolKit User Premium Member Reviews Badge
Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 16 Aug 2015, 08:06
1
This post received
KUDOS
3
This post was
BOOKMARKED
Question 1
00:00
A
B
C
D
E

Question Stats:

72% (01:55) correct 28% (01:49) wrong based on 705

HideShow timer Statistics

Question 2
00:00
A
B
C
D
E

Question Stats:

89% (00:23) correct 11% (00:21) wrong based on 702

HideShow timer Statistics

Question 3
00:00
A
B
C
D
E

Question Stats:

69% (00:55) correct 31% (01:22) wrong based on 691

HideShow timer Statistics

Scientist long believed that two nerve cluster in the human hypothalamus, called suprachiasmatic nuclei (SCNs), were what controlled our circadian rhythms. Those rhythms are the biological cycles that recur approximately every 24 hours in synchronization with the cycle of sunlight and darkness caused by Earth’s rotation. Studies have demonstrated that in some animals, the SCNs control daily fluctuations in blood pressure, body temperature, activity level, and alertness, as well as the nighttime release of the sleep-promoting agent melatonin. Furthermore, cells in the human retina dedicated to transmitting information about light level to the SCNs have recently been discovered.

Four critical genes governing circadian cycles have been found to be active in every tissue, however, not just the SCNs, of flies, mice, and humans. In addition, when laboratory rats that usually ate at will were fed only once a day, peak activity of a clock gene in their livers shifted by 12 hours, whereas the same clock gene in the SCNs remained synchronized with light cycles. While scientists do not dispute the role of the SCNs in controlling core functions such as the regulation of body temperature and blood pressure, scientists now believe that circadian clocks in other organs and tissues may respond to external cues other than light–-including temperature changes--that recur regularly 24 hours.
The primary purpose of the passage is to
A) challenge recent findings that appear to contradict earlier findings
B) present two sides of an ongoing scientific debate
C) report answers to several questions that have long puzzled researchers
D) discuss evidence that ;has caused a longstanding belief to be revise
E) attempt to explain a commonly misunderstood biological phenomenon


[Reveal] Spoiler:
D


The passage mentions each of the following as a function regulated by SCNs in same animals EXCEPT
A) activity level
B) blood pressure
C) alertness
D) vision
E) temperature

[Reveal] Spoiler:
D


The author of the passage would probably agree with which of the following statement about the SCNs ?
A) The SCNs are found in other organs and tissues of the body besides the hypothalamus.
B) The SCNs play a critical but not exclusive role in regulating circadian rhythms.
C) The SCNs control clock genes in a number of tissues and organs throughout the body.
D) The SCNs are a less significant factor in regulating blood pressure than scientists once believed.
E) The SCNs are less strongly affected by changes in light levels than are by other external cues.

[Reveal] Spoiler:
B

[Reveal] Spoiler: Question #1 OA
[Reveal] Spoiler: Question #2 OA
[Reveal] Spoiler: Question #3 OA

_________________

--------------------------------------------------------
Regards :)


Last edited by mikemcgarry on 19 Feb 2017, 14:24, edited 1 time in total.
corrected misprints in the passage text

Kudos [?]: 698 [1], given: 606

Expert Post
3 KUDOS received
Magoosh GMAT Instructor
User avatar
G
Joined: 28 Dec 2011
Posts: 4634

Kudos [?]: 9260 [3], given: 116

Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 17 Aug 2015, 10:56
3
This post received
KUDOS
Expert's post
JarvisR wrote:
Scientist long believed that two nerve cluster in the human hypothalamus, called suprachiasmatic nuclei (SCNs), were what controlled our circadian rhythms. Those rhythms are the biological cycles that recur approximately every 24 hours in synchronization with the cycle of sunlight and darkness caused by Earth’s rotation. Studies have demonstrated that in some animals, the SCNs control daily fluctuations in blood pressure, body temperature, activity level, and alertness, as well as the nighttime release of the sleep-promoting agent melatonin. Furthermore , cells in the human retina dedicated to transmitting information about light level to the SCNs have recently been discovered.

Four critical genes governing circadian cycles have been found to be active in every tissue, however, not that the SCNs, of flies, mice, and humans. In addition, when laboratory rats that usually ate at will were fed only once a day, peak activity of a clock gene in their livers shifted by 12 hours, whereas the same clock gene in the SCNs remained synchronized with light cycles. While scientists do not dispute the role of the SCNs in controlling core functions such as the regulation of body temperature and blood pressure, scientists now believe that circadian clocks in other organs and tissues may respond to external cues other than light – including temperature changes – that recur regularly 24 hours.
The primary purpose of the passage is to
A) challenge recent findings that appear to contradict earlier findings
B) present two sides of an ongoing scientific debate
C) report answers to several questions that have long puzzled researchers
D) discuss evidence that ;has caused a longstanding belief to be revise
E) attempt to explain a commonly misunderstood biological phenomenon

[Reveal] Spoiler:
D


The passage mentions each of the following as a function regulated by SCNs in same animals EXCEPT
A) activity level
B) blood pressure
C) alertness
D) vision
E) temperature
[Reveal] Spoiler:
D


The author of the passage would probably agree with which of the following statement about the SCNs ?
A) The SCNs are found in other organs and tissues of the body besides the hypothalamus.
B) The SCNs play a critical but not exclusive role in regulating circadian rhythms.
C) The SCNs control clock genes in a number of tissues and organs throughout the body.
D) The SCNs are a less significant factor in regulating blood pressure than scientists once believed.
E) The SCNs are less strongly affected by changes in light levels than are by other external cues.
[Reveal] Spoiler:
B


Dear JarvisR,
I'm happy to respond. :-) This of course is the 3rd RC passage in the OG2016, and the questions are RC #8-10.

The primary purpose of the passage is to
A) challenge recent findings that appear to contradict earlier findings
B) present two sides of an ongoing scientific debate
C) report answers to several questions that have long puzzled researchers
D) discuss evidence that has caused a longstanding belief to be revise
E) attempt to explain a commonly misunderstood biological phenomenon

In Par 1, he talks about the role of the SCN in regulating circadian rhythms. In Par. 2, he cites new evidence that is not entirely compatible with the SCN running everything. The first paragraph really sets the stage of what the author wants to say. The second paragraph is really the author's main point, the juicy point he want to make--- the first paragraph just sets the stage so we have context for the second paragraph. The "SCN runs the whole thing" theory was called "long believed," so it is a longstanding theory that the new evidence calls into question, causing scientist to revise the longstanding theory. This is what (D) says.

The passage mentions each of the following as a function regulated by SCNs in same animals EXCEPT
A) activity level
B) blood pressure
C) alertness
D) vision
E) temperature

The choices (A), (B), (C), and (E) are all mentioned, in the second half of the first paragraph, as functions that the SCN controls. By contrast, vision is tricky. The SCN doesn't "control" vision. Instead, vision provides the crucial data, information about natural light, that allows the SCN to do its job. The SCN depends on vision, it doesn't control it. OA = (D).

The author of the passage would probably agree with which of the following statement about the SCNs ?
A) The SCNs are found in other organs and tissues of the body besides the hypothalamus.

No, nonsense. The regulation of circadian rhythms occurs elsewhere in the body, but there is no SCN outside the hypothalamus.

B) The SCNs play a critical but not exclusive role in regulating circadian rhythms.
A good balanced assessment. The SCN is important, but is no longer believed to be "the only show in town." This is promising.

C) The SCNs control clock genes in a number of tissues and organs throughout the body.
There's zero evidence for this. The SCN is discussed, and then later, gene clocks with a similar role are discuss, but no connection is made back to the SCN.

D) The SCNs are a less significant factor in regulating blood pressure than scientists once believed.
The second paragraph says: "While scientist do not dispute the role of the SCNs in controlling core functions such as ... blood pressure." This choice directly contradicts this quote.

E) The SCNs are less strongly affected by changes in light levels than are by other external cues.
No. Confuses different things. The SCNs respond to light. The gene clocks & circadian clocks in other parts of the body respond to other external cues.

OA = (B)

Here's a blog you may find useful:
http://magoosh.com/gmat/2012/gmat-rc-el ... g-answers/

Does all this make sense? Please let me know if you have any further questions about any of these.

Mike :-)
_________________

Mike McGarry
Magoosh Test Prep

Image

Image

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Kudos [?]: 9260 [3], given: 116

Intern
Intern
avatar
Joined: 14 Nov 2011
Posts: 39

Kudos [?]: 8 [0], given: 245

Location: Kenya
Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 03 Mar 2016, 11:29
Super easy passage. Got all correct in less than 5 minutes. Love what you are reading, make judicious notes and POE for the answer options. Hope that works in the real exam too!

Kudos [?]: 8 [0], given: 245

Manager
Manager
User avatar
B
Status: In the realms of Chaos & Night
Joined: 13 Sep 2015
Posts: 171

Kudos [?]: 105 [0], given: 95

Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 14 Dec 2016, 00:34
5:24 on the timer.
All correct.
_________________

Good luck
=========================================================================================
"If a street performer makes you stop walking, you owe him a buck"
"If this post helps you on your GMAT journey, drop a +1 Kudo "


"Thursdays with Ron - Consolidated Verbal Master List - Updated"

Kudos [?]: 105 [0], given: 95

Intern
Intern
avatar
Joined: 25 Jan 2017
Posts: 5

Kudos [?]: 1 [0], given: 3

Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 19 Feb 2017, 01:56
Hi, I am finding it difficult to understand the passage starting from "Four Critical genes" till the end. So, unable to answer Q1 and Q3. Please support

Kudos [?]: 1 [0], given: 3

Expert Post
1 KUDOS received
Magoosh GMAT Instructor
User avatar
G
Joined: 28 Dec 2011
Posts: 4634

Kudos [?]: 9260 [1], given: 116

Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 19 Feb 2017, 14:31
1
This post received
KUDOS
Expert's post
priyanshu14 wrote:
Hi, I am finding it difficult to understand the passage starting from "Four Critical genes" till the end. So, unable to answer Q1 and Q3. Please support

Dear priyanshu14

I'm happy to respond. :-)

Part of the problem was a single word misprint that made the first sentence incomprehensible. Here's what appeared in the first post of this thread:
Four critical genes governing circadian cycles have been found to be active in every tissue, however, not that the SCNs, of flies, mice, and humans.
That sentence made no sense, so I check in the OG: here's what it should be:
Four critical genes governing circadian cycles have been found to be active in every tissue, however, not just the SCNs, of flies, mice, and humans.
I made the change in the passage above. I don't know whether this helps.

Apart from that, my friend, I am going to say that your question is really a non-question. All you say is that you don't understand. This is a question that provide almost no information. An excellent question would make clear: what do you understand? What questions do you have about the passage? What do you think about the things about which you feel uncertain? Say as much as you can about this passage. See this post:
Asking Excellent Questions
You see, asking excellent question is one of the habits of excellence. You cannot achieve excellence on the GMAT unless you are willing to put in the effort to be excellent in each aspect of your studying.

I am going to challenge you: write the high-quality question you can about this second paragraph, and I will answer your question.

Does all this make sense?
Mike :-)
_________________

Mike McGarry
Magoosh Test Prep

Image

Image

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Kudos [?]: 9260 [1], given: 116

Intern
Intern
avatar
B
Joined: 20 Jan 2016
Posts: 25

Kudos [?]: [0], given: 2

GMAT 1: 600 Q49 V23
GMAT 2: 660 Q50 V30
Reviews Badge
Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 30 Mar 2017, 05:18
5:47 Min..All correct..

Kudos [?]: [0], given: 2

Director
Director
avatar
G
Joined: 02 Sep 2016
Posts: 784

Kudos [?]: 24 [0], given: 275

Premium Member CAT Tests
Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 29 Jun 2017, 02:10
Passage notes:
Passage 1: Scientists (long believed): 2 nerve clusters (SCNs) controlled rhythms (cycles-24 hours)
- Studies suggest something about animals : SCNs control BP, temp., activity, alertness, and melatonin.

- Furthermore (more info. on the same line): cells in retina discovered

Passage 2: 4 genes governing cycles are found in every tissue.
- However (some contrast)
-In addition- Experiment explained

Scientists (now believe): C. Clocks MAY respond to external cues other than light.

412. D
413. D
414. A



Thanks
_________________

Help me make my explanation better by providing a logical feedback.

If you liked the post, HIT KUDOS !!

Don't quit.............Do it.


Last edited by Shiv2016 on 29 Sep 2017, 08:47, edited 1 time in total.

Kudos [?]: 24 [0], given: 275

Manager
Manager
avatar
B
Joined: 20 Aug 2015
Posts: 65

Kudos [?]: 10 [0], given: 149

GMAT 1: 710 Q50 V36
GMAT ToolKit User
Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 15 Jul 2017, 10:54
4:54 sec.

Ans:
1. Scientists believe SCN controlled circadian rhythms. But later new discoveries have led to believe that other genes also regulate these cycles.
So answer is D) discuss evidence that has caused a longstanding belief to be revise

2. Passage mentions everything except vision. Answer D

3. Four critical genes governing circadian cycles have been discovered. Answer is B which says that the SCNs do not play an exclusive role in regulating circadian rhythms.

Kudos [?]: 10 [0], given: 149

Manager
Manager
avatar
S
Joined: 17 Mar 2014
Posts: 157

Kudos [?]: 54 [0], given: 361

GMAT ToolKit User CAT Tests
Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 09 Oct 2017, 18:22
mikemcgarry wrote:
JarvisR wrote:
Scientist long believed that two nerve cluster in the human hypothalamus, called suprachiasmatic nuclei (SCNs), were what controlled our circadian rhythms. Those rhythms are the biological cycles that recur approximately every 24 hours in synchronization with the cycle of sunlight and darkness caused by Earth’s rotation. Studies have demonstrated that in some animals, the SCNs control daily fluctuations in blood pressure, body temperature, activity level, and alertness, as well as the nighttime release of the sleep-promoting agent melatonin. Furthermore , cells in the human retina dedicated to transmitting information about light level to the SCNs have recently been discovered.

Four critical genes governing circadian cycles have been found to be active in every tissue, however, not that the SCNs, of flies, mice, and humans. In addition, when laboratory rats that usually ate at will were fed only once a day, peak activity of a clock gene in their livers shifted by 12 hours, whereas the same clock gene in the SCNs remained synchronized with light cycles. While scientists do not dispute the role of the SCNs in controlling core functions such as the regulation of body temperature and blood pressure, scientists now believe that circadian clocks in other organs and tissues may respond to external cues other than light – including temperature changes – that recur regularly 24 hours.
The primary purpose of the passage is to
A) challenge recent findings that appear to contradict earlier findings
B) present two sides of an ongoing scientific debate
C) report answers to several questions that have long puzzled researchers
D) discuss evidence that ;has caused a longstanding belief to be revise
E) attempt to explain a commonly misunderstood biological phenomenon

[Reveal] Spoiler:
D


The passage mentions each of the following as a function regulated by SCNs in same animals EXCEPT
A) activity level
B) blood pressure
C) alertness
D) vision
E) temperature
[Reveal] Spoiler:
D


The author of the passage would probably agree with which of the following statement about the SCNs ?
A) The SCNs are found in other organs and tissues of the body besides the hypothalamus.
B) The SCNs play a critical but not exclusive role in regulating circadian rhythms.
C) The SCNs control clock genes in a number of tissues and organs throughout the body.
D) The SCNs are a less significant factor in regulating blood pressure than scientists once believed.
E) The SCNs are less strongly affected by changes in light levels than are by other external cues.
[Reveal] Spoiler:
B


Dear JarvisR,
I'm happy to respond. :-) This of course is the 3rd RC passage in the OG2016, and the questions are RC #8-10.

The primary purpose of the passage is to
A) challenge recent findings that appear to contradict earlier findings
B) present two sides of an ongoing scientific debate
C) report answers to several questions that have long puzzled researchers
D) discuss evidence that has caused a longstanding belief to be revise
E) attempt to explain a commonly misunderstood biological phenomenon

In Par 1, he talks about the role of the SCN in regulating circadian rhythms. In Par. 2, he cites new evidence that is not entirely compatible with the SCN running everything. The first paragraph really sets the stage of what the author wants to say. The second paragraph is really the author's main point, the juicy point he want to make--- the first paragraph just sets the stage so we have context for the second paragraph. The "SCN runs the whole thing" theory was called "long believed," so it is a longstanding theory that the new evidence calls into question, causing scientist to revise the longstanding theory. This is what (D) says.

The passage mentions each of the following as a function regulated by SCNs in same animals EXCEPT
A) activity level
B) blood pressure
C) alertness
D) vision
E) temperature

The choices (A), (B), (C), and (E) are all mentioned, in the second half of the first paragraph, as functions that the SCN controls. By contrast, vision is tricky. The SCN doesn't "control" vision. Instead, vision provides the crucial data, information about natural light, that allows the SCN to do its job. The SCN depends on vision, it doesn't control it. OA = (D).

The author of the passage would probably agree with which of the following statement about the SCNs ?
A) The SCNs are found in other organs and tissues of the body besides the hypothalamus.

No, nonsense. The regulation of circadian rhythms occurs elsewhere in the body, but there is no SCN outside the hypothalamus.

B) The SCNs play a critical but not exclusive role in regulating circadian rhythms.
A good balanced assessment. The SCN is important, but is no longer believed to be "the only show in town." This is promising.

C) The SCNs control clock genes in a number of tissues and organs throughout the body.
There's zero evidence for this. The SCN is discussed, and then later, gene clocks with a similar role are discuss, but no connection is made back to the SCN.

D) The SCNs are a less significant factor in regulating blood pressure than scientists once believed.
The second paragraph says: "While scientist do not dispute the role of the SCNs in controlling core functions such as ... blood pressure." This choice directly contradicts this quote.

E) The SCNs are less strongly affected by changes in light levels than are by other external cues.
No. Confuses different things. The SCNs respond to light. The gene clocks & circadian clocks in other parts of the body respond to other external cues.

OA = (B)

Here's a blog you may find useful:
http://magoosh.com/gmat/2012/gmat-rc-el ... g-answers/

Does all this make sense? Please let me know if you have any further questions about any of these.

Mike :-)


Hi Mike,

in above passage what does following sentence want to convey.

Four critical genes governing circadian cycles
have been found to be active in every tissue,
however, not just the SCNs, of flies, mice, and
humans.

Regards,
Ammu

Kudos [?]: 54 [0], given: 361

Expert Post
Magoosh GMAT Instructor
User avatar
G
Joined: 28 Dec 2011
Posts: 4634

Kudos [?]: 9260 [0], given: 116

Re: Scientist long believed that two nerve cluster in the human hypothalam [#permalink]

Show Tags

New post 10 Oct 2017, 08:54
ammuseeru wrote:
Hi Mike,

in above passage what does following sentence want to convey.

Four critical genes governing circadian cycles
have been found to be active in every tissue,
however, not just the SCNs, of flies, mice, and
humans.

Regards,
Ammu


I'm happy to respond. :-)

So, the passage lets us know that the "suprachiasmatic nuclei (SCN)" is the place that runs the circadian cycles (that is, the 24-hour cycles of sleeping & waking). Naively, we would expect everything about circadian rhythms to be run from there. Then, this sentences surprises us.

Four critical genes governing circadian cycles have been found to be active in every tissue, however, not just the SCNs, of flies, mice, and humans.

Four of the genes that play crucial role in governing sleep/wake cycles are not just in the SCN, where we'd expect--instead, they're everywhere throughout the body!

My friend, if this sentence was a challenge to you, you need to practice reading. You need to read Scientific American every week for practice. See:
How to Improve Your GMAT Verbal Score

Does all this make sense?
Mike :-)
_________________

Mike McGarry
Magoosh Test Prep

Image

Image

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Kudos [?]: 9260 [0], given: 116

Re: Scientist long believed that two nerve cluster in the human hypothalam   [#permalink] 10 Oct 2017, 08:54
Display posts from previous: Sort by

Scientist long believed that two nerve cluster in the human hypothalam

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.