Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Mar 2709:30 AM PDT
-10:30 AM PDT
Preparing for the GMAT? Avoid these 5 major mistakes that can lower your score and hurt your MBA dreams. In this expert panel discussion, 4 top GMAT coaches - GMAT Ninja, Jeff Miller from TTP, Rida Shafiq from eGMAT, and Chris Gentry from Manhattan Prep- Mar 27
10:00 AM PDT
-11:00 AM PDT
What happens after getting an MBA? Is it worth the investment? To find out, I interviewed 10 GMAT Club professionals who have completed their MBAs and built careers in consulting, finance, tech, and entrepreneurship. Their answers might surprise you! 
Mar 1910:00 AM EDT
-11:59 PM EDT
Get a massive $250 off the TTP OnDemand GMAT course by using the coupon code FLASH25 at checkout. If you prefer learning through engaging video lessons, TTP OnDemand GMAT is exactly what you need.- Mar 26
10:00 AM PDT
-11:00 AM PDT
Confused about how to get the most from your GMAT mock tests? In this video, learn the perfect strategy to analyze GMAT mocks effectively and boost your score. We break down the common mistakes GMAT aspirants make when using mock tests 
Mar 2911:30 AM EDT
-12:30 PM EDT
Learn how Keshav, a Chartered Accountant, scored an impressive 705 on GMAT in just 30 days with GMATWhiz's expert guidance. In this video, he shares preparation tips and strategies that worked for him, including the mock, time management, and more.
Mar 3005:30 AM PDT
-07:30 AM PDT
We know Strengthen and Weaken questions account for more than 50% of the CR questions on the GMAT. With CR becoming even more important on GMAT Focus, it's time you strengthen your weaknesses with an approach that improves your solving time and accuracy!
Mar 3011:00 AM IST
-01:00 PM IST
Attend this session to evaluate your current skill level, learn process skills, and solve through tough Arithmetic questions.
Mar 3110:00 AM EDT
-11:59 PM EDT
The Target Test Prep team has recently introduced TTP OnDemand GMAT, a 400-hour live masterclass video course created by Scott Woodbury-Stewart, founder and CEO of Target Test Prep.
Updated on: 06 Apr 2020, 21:27
Originally posted by surat on 17 Feb 2004, 05:10.
Last edited by Sajjad1994 on 06 Apr 2020, 21:27, edited 14 times in total.
Last edited by Sajjad1994 on 06 Apr 2020, 21:27, edited 14 times in total.
Updated
Kudos
Bookmarks
Question 1
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
65%
(hard)
Question Stats:
55% (03:18) correct
45%
(03:25) wrong
based on 5015
sessions
History
Date
Time
Result
Not Attempted Yet
Question 2
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
64% (01:33) correct 36%
(01:59) wrong
based on 5846
sessions
History
Date
Time
Result
Not Attempted Yet
Question 3
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
87% (00:47) correct 13%
(01:02) wrong
based on 5676
sessions
History
Date
Time
Result
Not Attempted Yet
Question 4
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
76% (01:01) correct 24%
(00:58) wrong
based on 5600
sessions
History
Date
Time
Result
Not Attempted Yet
Question 5
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
76% (00:54) correct 24%
(01:14) wrong
based on 5568
sessions
History
Date
Time
Result
Not Attempted Yet
Question 6
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
59% (01:12) correct 41%
(01:18) wrong
based on 5350
sessions
History
Date
Time
Result
Not Attempted Yet
Quote:
Part of New RC Series- Please check this link for more questions
Caffeine, the stimulant in coffee, has been called “the most widely used psychoactive substance on Earth.” Snyder, Daly, and Bruns have recently proposed that caffeine affects behavior by countering the activity in the human brain of a naturally occurring chemical called adenosine. Adenosine normally depresses neuron firing in many areas of the brain. It apparently does this by inhibiting the release of neurotransmitters, chemicals that carry nerve impulses from one neuron to the next.
Like many other agents that affect neuron firing, adenosine must first bind to specific receptors on neuronal membranes. There are at least two classes of these receptors, which have been designated A1 and A2. Snyder et al. propose that caffeine, which is structurally similar to adenosine, is able to bind to both types of receptors, which prevents adenosine from attaching there and allows the neurons to fire more readily than they otherwise would.
For many years, caffeine’s effects have been attributed to its inhibition of the production of phosphodiesterase, an enzyme that breaks down the chemical called cyclic AMP. A number of neurotransmitters exert their effects by first increasing cyclic AMP concentrations in target neurons. Therefore, prolonged periods at the elevated concentrations, as might be brought about by a phosphodiesterase inhibitor, could lead to a greater amount of neuron firing and, consequently, to behavioral stimulation. But Snyder et al. point out that the caffeine concentrations needed to inhibit the production of phosphodiesterase in the brain are much higher than those that produce stimulation. Moreover, other compounds that block phosphodiesterase’s activity are not stimulants.
To buttress their case that caffeine acts instead by preventing adenosine binding, Snyder et al. compared the stimulatory effects of a series of caffeine derivatives with their ability to dislodge adenosine from its receptors in the brains of mice. “In general,” they reported, “the ability of the compounds to compete at the receptors correlates with their ability to stimulate locomotion in the mouse; i.e., the higher their capacity to bind at the receptors, the higher their ability to stimulate locomotion.” Theophylline, a close structural relative of caffeine and the major stimulant in tea, was one of the most effective compounds in both regards.
There were some apparent exceptions to the general correlation observed between adenosine receptor binding and stimulation. One of these was a compound called 3-isobutyl-1-methylxanthine (IBMX), which bound very well but actually depressed mouse locomotion. Snyder et al. suggest that this is not a major stumbling block to their hypothesis. The problem is that the compound has mixed effects in the brain, a not unusual occurrence with psychoactive drugs. Even caffeine, which is generally known only for its stimulatory effects, displays this property, depressing mouse locomotion at very low concentrations and stimulating it at higher ones.
Like many other agents that affect neuron firing, adenosine must first bind to specific receptors on neuronal membranes. There are at least two classes of these receptors, which have been designated A1 and A2. Snyder et al. propose that caffeine, which is structurally similar to adenosine, is able to bind to both types of receptors, which prevents adenosine from attaching there and allows the neurons to fire more readily than they otherwise would.
For many years, caffeine’s effects have been attributed to its inhibition of the production of phosphodiesterase, an enzyme that breaks down the chemical called cyclic AMP. A number of neurotransmitters exert their effects by first increasing cyclic AMP concentrations in target neurons. Therefore, prolonged periods at the elevated concentrations, as might be brought about by a phosphodiesterase inhibitor, could lead to a greater amount of neuron firing and, consequently, to behavioral stimulation. But Snyder et al. point out that the caffeine concentrations needed to inhibit the production of phosphodiesterase in the brain are much higher than those that produce stimulation. Moreover, other compounds that block phosphodiesterase’s activity are not stimulants.
To buttress their case that caffeine acts instead by preventing adenosine binding, Snyder et al. compared the stimulatory effects of a series of caffeine derivatives with their ability to dislodge adenosine from its receptors in the brains of mice. “In general,” they reported, “the ability of the compounds to compete at the receptors correlates with their ability to stimulate locomotion in the mouse; i.e., the higher their capacity to bind at the receptors, the higher their ability to stimulate locomotion.” Theophylline, a close structural relative of caffeine and the major stimulant in tea, was one of the most effective compounds in both regards.
There were some apparent exceptions to the general correlation observed between adenosine receptor binding and stimulation. One of these was a compound called 3-isobutyl-1-methylxanthine (IBMX), which bound very well but actually depressed mouse locomotion. Snyder et al. suggest that this is not a major stumbling block to their hypothesis. The problem is that the compound has mixed effects in the brain, a not unusual occurrence with psychoactive drugs. Even caffeine, which is generally known only for its stimulatory effects, displays this property, depressing mouse locomotion at very low concentrations and stimulating it at higher ones.
D
71. A. The passage discusses a current investigation, not one planned for the future.
B. The passage examines two explanations, but the earlier theory is discussed only to expose its weakness and the diff erences between the explanations are not reconciled. Most of the passage is devoted to the more recent hypothesis.
C. Only two theories are presented in the passage.
D. Correct. Th e recent hypothesis provides an alternative to an earlier one and is supported by evidence and arguments.
E. Lines 32–37 do pose such a challenge to the earlier theory; however, the challenge is a small part of the whole passage. Similarly, in the final paragraph, an exception to the more recent theory is introduced, only to be dismissed as an unimportant concern.
The correct answer is D.
B. The passage examines two explanations, but the earlier theory is discussed only to expose its weakness and the diff erences between the explanations are not reconciled. Most of the passage is devoted to the more recent hypothesis.
C. Only two theories are presented in the passage.
D. Correct. Th e recent hypothesis provides an alternative to an earlier one and is supported by evidence and arguments.
E. Lines 32–37 do pose such a challenge to the earlier theory; however, the challenge is a small part of the whole passage. Similarly, in the final paragraph, an exception to the more recent theory is introduced, only to be dismissed as an unimportant concern.
The correct answer is D.
1. The primary purpose of the passage is to
(A) discuss a plan for investigation of a phenomenon that is not yet fully understood
(B) present two explanations of a phenomenon and reconcile the differences between them
(C) summarize two theories and suggest a third theory that overcomes the problems encountered in the first two
(D) describe an alternative hypothesis and provide evidence and arguments that support it
(E) challenge the validity of a theory by exposing the inconsistencies and contradictions in it
D
72. A. The passage does not suggest that adenosine stimulates behavior.
B. While the final paragraph reveals that caffeine displays mixed eff ects, the passage does not state that adenosine has a stimulatory effect.
C. Increasing cyclic AMP concentrations is part of the earlier theory, not that of Snyder et al.
D. Correct. Lines 17–21 explain that caffeine binds to the receptors, releasing neurotransmitters, whereas adenosine hinders that release.
E. Inhibiting the production of phosphodiesterase is discussed in the earlier theory, not in the work of Snyder et al.
The correct answer is D.
B. While the final paragraph reveals that caffeine displays mixed eff ects, the passage does not state that adenosine has a stimulatory effect.
C. Increasing cyclic AMP concentrations is part of the earlier theory, not that of Snyder et al.
D. Correct. Lines 17–21 explain that caffeine binds to the receptors, releasing neurotransmitters, whereas adenosine hinders that release.
E. Inhibiting the production of phosphodiesterase is discussed in the earlier theory, not in the work of Snyder et al.
The correct answer is D.
(A) stimulates behavior in the mouse and in humans, whereas adenosine stimulates behavior in humans only
(B) has mixed effects in the brain, whereas adenosine has only a stimulatory effect
(C) increases cyclic AMP concentrations in target neurons, whereas adenosine decreases such concentrations
(D) permits release of neurotransmitters when it is bound to adenosine receptors, whereas adenosine inhibits such release
(E) inhibits both neuron firing and the production of phosphodiesterase when there is a sufficient concentration in the brain, whereas adenosine inhibits only neuron firing
A
73. A. Correct. The results of one experiment can be explained by mixed eff ects in the brain, which Snyder et al. say may occur with psychoactive drugs.
B. This response refers back to the earlier theory, not to Snyder et al.’s response concerning IBMX experiment results.
C. Caffeine is only included within the broad category of psychoactive drugs.
D. This effect is attributed to one compound,IBMX, not to all psychoactive drugs.
E. This ability is not discussed in the passage.
The correct answer is A.
B. This response refers back to the earlier theory, not to Snyder et al.’s response concerning IBMX experiment results.
C. Caffeine is only included within the broad category of psychoactive drugs.
D. This effect is attributed to one compound,IBMX, not to all psychoactive drugs.
E. This ability is not discussed in the passage.
The correct answer is A.
(A) mixed effects in the brain
(B) inhibitory effects on enzymes in the brain
(C) close structural relationships with caffeine
(D) depressive effects on mouse locomotion
(E) the ability to dislodge caffeine from receptors in the brain
E
74. A. Lines 54–55 state that IBMX binds to receptors.
B. Lines 17–19 state that caff eine binds to receptors.
C. Lines 13–14 state that adenosine binds to receptors.
D. Lines 46–50 state that theophylline binds to receptors.
E. Correct. The passage includes no evidence that phosphodiesterase binds to receptors.
The correct answer is E.
B. Lines 17–19 state that caff eine binds to receptors.
C. Lines 13–14 state that adenosine binds to receptors.
D. Lines 46–50 state that theophylline binds to receptors.
E. Correct. The passage includes no evidence that phosphodiesterase binds to receptors.
The correct answer is E.
(A) IBMX
(B) caffeine
(C) adenosine
(D) theophylline
(E) phosphodiesterase
B
75. A. Phosphodiesterase is discussed in an entirely diff erent context in lines 22–25.
B. Correct. Lines 17–19 suggest that caffeine’s structural similarity to adenosine may be responsible for its ability to bind to A1 and A2 receptors.
C. Caff eine acts on neurotransmitters; it is not structurally similar to them.
D. Caffeine’s ability to stimulate behavior results from, rather than causes, this process.
E. The passage does not discuss the natural occurrence of these compounds.
The correct answer is B.
B. Correct. Lines 17–19 suggest that caffeine’s structural similarity to adenosine may be responsible for its ability to bind to A1 and A2 receptors.
C. Caff eine acts on neurotransmitters; it is not structurally similar to them.
D. Caffeine’s ability to stimulate behavior results from, rather than causes, this process.
E. The passage does not discuss the natural occurrence of these compounds.
The correct answer is B.
(A) The chemical relationship between caffeine and phosphodiesterase
(B) The structural relationship between caffeine and adenosine
(C) The structural similarity between caffeine and neurotransmitters
(D) The ability of caffeine to stimulate behavior
(E) The natural occurrence of caffeine and adenosine in the brain
B
76. A. The quotation explains results of an experiment, not assumptions about a theory.
B. Correct. The quotation summarizes the experiment with mice and reports a major finding in support of the hypothesis.
C. The quotation generalizes on the basis of the experiment; it does not limit the finding to mice.
D. Specific, not general, correlations were made between the ability to bind to receptors and to stimulate locomotion.
E. The passage includes no such objections; therefore no refutations are needed.
The correct answer is B.
B. Correct. The quotation summarizes the experiment with mice and reports a major finding in support of the hypothesis.
C. The quotation generalizes on the basis of the experiment; it does not limit the finding to mice.
D. Specific, not general, correlations were made between the ability to bind to receptors and to stimulate locomotion.
E. The passage includes no such objections; therefore no refutations are needed.
The correct answer is B.
(A) reveal some of the assumptions underlying their theory
(B) summarize a major finding of their experiments
(C) point out that their experiments were limited to the mouse
(D) indicate that their experiments resulted only in general correlations
(E) refute the objections made by supporters of the older theory
30 Apr 2020, 14:05
Kudos
Bookmarks
This post is a response to those by guarav2m and willacethis above. Now, let me preface my post by saying that I am a native speaker of American English, so I cannot know how hard such a passage may be to tackle if I were a second-language learner of English. With that said, neither I nor most native speakers I know would find this passage easy to navigate (read as something that I would choose to peruse and enjoy on my own). Yes, there is a bunch of jargon, and yes, the passage is lengthy, with sentence after sentence about scientific-sounding chemicals and processes.
To overcome the language barrier, one of my students employed a strategy of reading everything that looked technical as its leading letter instead. So, for instance, a word such as adenosine would simply be A. In this manner, he could comb through the passage pretty efficiently and know where to look to find the information to a question asking about A.
As for my own approach, I take nothing more than mental notes as I go. I pay attention to the authorial presence or bent regarding the information presented, and I also look to follow what I call the transition trail from line to line or paragraph to paragraph. For example, if you see a line that starts with nevertheless, you understand, without going any further, that the information that is about to come is going to follow in a despite [whatever you just read] or even so vein. I also look for emotionally charged words or strong language, such as must (from the beginning of paragraph two in this passage), so that I can follow the tenor of the passage even without taking in all the information on offer. Finally, when it comes to detail-based, according-to-the-passage questions, I match keywords from the question stem to what I can locate in the passage. I refer to the passage a lot when I answer RC questions. My timing is still fine across any given set, and, most importantly, my accuracy is high. I do not overburden my mind with details, since I know GMAT™ questions are nuanced anyway, to the point that relying on memory alone will often lead to incorrect answers on more difficult passages. One or two words in the answer choices might be all that separates those answers from what the passage actually says, and that can make all the difference.
I hope that helps at least a little. One more thing about timing: If you know your timing across other types of Verbal questions comes in under 1:48 or so on average, then you might be able to take a bit more time reading through passages and processing the question stem and answer choices. Just stick to the above, and, with practice, you will grow more confident as your results improve.
Good luck with your studies.
- Andrew
To overcome the language barrier, one of my students employed a strategy of reading everything that looked technical as its leading letter instead. So, for instance, a word such as adenosine would simply be A. In this manner, he could comb through the passage pretty efficiently and know where to look to find the information to a question asking about A.
As for my own approach, I take nothing more than mental notes as I go. I pay attention to the authorial presence or bent regarding the information presented, and I also look to follow what I call the transition trail from line to line or paragraph to paragraph. For example, if you see a line that starts with nevertheless, you understand, without going any further, that the information that is about to come is going to follow in a despite [whatever you just read] or even so vein. I also look for emotionally charged words or strong language, such as must (from the beginning of paragraph two in this passage), so that I can follow the tenor of the passage even without taking in all the information on offer. Finally, when it comes to detail-based, according-to-the-passage questions, I match keywords from the question stem to what I can locate in the passage. I refer to the passage a lot when I answer RC questions. My timing is still fine across any given set, and, most importantly, my accuracy is high. I do not overburden my mind with details, since I know GMAT™ questions are nuanced anyway, to the point that relying on memory alone will often lead to incorrect answers on more difficult passages. One or two words in the answer choices might be all that separates those answers from what the passage actually says, and that can make all the difference.
I hope that helps at least a little. One more thing about timing: If you know your timing across other types of Verbal questions comes in under 1:48 or so on average, then you might be able to take a bit more time reading through passages and processing the question stem and answer choices. Just stick to the above, and, with practice, you will grow more confident as your results improve.
Good luck with your studies.
- Andrew
12 Jul 2017, 20:55
Kudos
Bookmarks
This passage took me 20 minutes to read. 
Here is my understanding of the passage.
#1. S.D.B. came up with a hypothesis that caffeine affects behavior by doing the opposite of what adenosine (ade) does.
#2. S.D.B. further explain how that works. Because caffeine is structurally similar to ade, it can prevent ade from attaching A1&A2 and allows more neuron firing.
#3. S.D.B. refute the previous view that caffeine affects behavior by stop producing phosphodiesterase(pho). It will need more caffeine concentrations to do that.
#4. S.D.B. strengthen their hypothesis by citing an experiment. They conclude that the higher the compounds’ capacity to bind at the receptors, the higher the compounds’ ability to stimulate behavior. (Theophylline <Theo> is such a compound.)
#5. S.D.B. argue that although there are some compounds don’t show that kind of correlation mentioned in #4, their hypothesis is still valid.
Here is my understanding of the passage. #1. S.D.B. came up with a hypothesis that caffeine affects behavior by doing the opposite of what adenosine (ade) does.
#2. S.D.B. further explain how that works. Because caffeine is structurally similar to ade, it can prevent ade from attaching A1&A2 and allows more neuron firing.
#3. S.D.B. refute the previous view that caffeine affects behavior by stop producing phosphodiesterase(pho). It will need more caffeine concentrations to do that.
#4. S.D.B. strengthen their hypothesis by citing an experiment. They conclude that the higher the compounds’ capacity to bind at the receptors, the higher the compounds’ ability to stimulate behavior. (Theophylline <Theo> is such a compound.)
#5. S.D.B. argue that although there are some compounds don’t show that kind of correlation mentioned in #4, their hypothesis is still valid.
.
