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Tiger beetles are such fast runners that they can capture [#permalink]
 21 Dec 2012, 06:57
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Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack. Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop. Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other? A. When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and runs away without its usual intermittent stopping. B. In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline. C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause. D. If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. E. When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier. OA Though the same stimulus is available with different answer choices, I found this one to be a tough one. Explanations will be appreciated.
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Marcab wrote: Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack. Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop. Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other? A. When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and runs away without its usual intermittent stopping. B. In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline. C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause. D. If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. E. When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier. OA Though the same stimulus is available with different answer choices, I found this one to be a tough one. Explanations will be appreciated. I will select B. "the beetles usually respond immediately to changes in the insect's direction" in the choice undermines that beetles go blind and stop. Since it says that beetles respond immediately, hence they cannot go blind, otherwise they could not respond immediately. "pause equally frequently whether the chase is up or down an incline" in the choice supports the other hypothesis that beetles pause to take rest.
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First part seems correct but second doesn't. If the beetle goes up and down the incline, stopping at equal intervals in each case then "taking rest" might not be the reason; it takes much more energy to run up the incline than to run down the incline.
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Tiger Beetles pause for moment while chasing their prey for probable reasons: 1. They cannot maintain their pace. (Stamina problem  ) 2. They cannot view the prey when prey changes the direction. (Eye sight problem ) Now we have to chose one option that validates one reason and invalidates the other. Looking at the options: A. When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and runs away without its usual intermittent stopping: Incorrect. Does not validate or invalidate any of the reason above.B. In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline: Correct. The first part of the sentence (highlighted in Orange) invalidate Reason 2 and the second part of the sentence (highlighted in green) validates Reason 1. C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause: Incorrect. Validates Reason 1 but does not touch upon reason 2.D. If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit: Incorrect. Does not validate or invalidate any of the reason above.E. When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier: Incorrect. Does not validate or invalidate any of the reason above.
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Hii Vineetk. One thing I would like to mention here is that since the beetle took equal intervals while running up the incline and down the incline, then you can't speculate anything about stamina. Running up the incline will make you take pauses more quickly.
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Marcab wrote: First part seems correct but second doesn't.
If the beetle goes up and down the incline, stopping at equal intervals in each case then "taking rest" might not be the reason; it takes much more energy to run up the incline than to run down the incline. do not focus on whether the beetle runs up or down, the main point here is that the beetle takes frequent stops which suggests that it gets tired and takes frequent pauses. This is how it supports the hypothesis. We need not look at very minute details, i guess.
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you cannot neglect the fact that the "beetle pauses equally frequently while runing up or down". Thats wrong. You have to focus on each and every aspect of the stimulus. Anyways answer is not B.
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Marcab wrote: you cannot neglect the fact that the "beetle pauses equally frequently while runing up or down". Thats wrong. You have to focus on each and every aspect of the stimulus.
Anyways answer is not B. then can you please post the OA with explanation...
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Let the others pour their explanation also. I will post the OA after getting explanations.
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This ones a toughie, lets break it down Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack. Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop. Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other? 2 hypotheses - A---beetle cannot maintain pace and must pause for rest ;B--Beetle has speed related eye sight issues hence has to stop
so we have to prove A right AND B-wrong OR A-wrong AND B-right
Wrong answers will Strengthen both / weaken both/ just (strength/weaken) ONLY ONE/ DO nothing to BOTHA. When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and
runs away without its usual intermittent stopping-- THIS choice does nothing for B as the beetle doesn't stop but turns and we don't know if the prey was moved at a great speed to cause rapid changes in visual field BUT it undermines A B. In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline. This undermines B AND strengthens A as the beetles cannot maintain their high speed up and down the incline and need to rest before they continue C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause. DOES NOTHING AND Could slightly undermine AD. If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.Supports A marginally ie end pursuit=stop and rest E. When an o bstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop
immediately, but they never respond by running around the barrier.-- support B and does nothing for A never respond by running around the barrier--Has no bearing on quick change of pace or visual field. IMO B
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HERE IS ANOTHER VERSION OF THE QUESTION [color=#000000] (answer choices differ)[/color] So the OA also differs Tiger beetles are such fast runners that they can capture virtually any non flying insect . However, when running towards an insect , a tiger beetle will intermittently stop and then, a moment later, resume its attack. Perhaps the beetles cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running, tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop. Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypothesis and undermine the other? A. When a prey insect is moved directly towards a beetle that has been chasing it, the beetle immediately stops and runs away without its ususal intermittent stopping. B. In pursuing a swerving insect, a beetle alters its course while running and it pauses become more frequent as the chase progresses. C. In pursuing a moving insect , a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down the incline. D. If , when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. E. The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.SOURCE-- OG 12 diagnostic test (OA-B)
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Marcab wrote: Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack. Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop. Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other? A. When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and runs away without its usual intermittent stopping. B. In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline. C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause. D. If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. E. When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier. OA Though the same stimulus is available with different answer choices, I found this one to be a tough one. Explanations will be appreciated. I will go with C. Hypothesis 1 states rest for resuming the attack , but increase in speed negates it. Hypothesis is still valid.
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C does weaken the first hypothesis that beetles get tired and need rest , how does is strengthen hypothesis 2?
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Marcab wrote: Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack. Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go blind and stop. Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other? A. When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and runs away without its usual intermittent stopping. B. In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline. C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause. D. If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit. E. When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier. OA Though the same stimulus is available with different answer choices, I found this one to be a tough one. Explanations will be appreciated. Unfortunately I find no clear cut answer to the question. Hypothesis 1: Tiger beetles need to constantly rest for a moment while pursuing a prey Hypothesis 2: The rapidly changing visual information make the tiger beetles momentarily blind and force them to pause frequently while pursuing a prey. Choice A: Hypothesis 1 is neither undermined nor supported. While turning and running away they do not make the usual stops. It is reasonable to assume that they are running at least at the same pace as they were while pursuing the prey as it is now seems a matter of survival. They may not be expected to make pauses even though they may need rest because as I said they are sensing danger. So we can eliminate choice A. Choice B: Hypothesis 1 is undermined because they pause equally frequently whether the chase is up or down an incline. So it doesn't seem to be the question of getting tired and needing the rest. However hypothesis 2 also seem to be undermined because, when a prey is changing its direction, the visual information changes the most and hence according to hypothesis 2 they should go blind but according to choice B, they immediately respond to change in the direction of the prey. So we can eliminate choice B Choice C: Nothing can be concluded about both the hypotheses. Choice D: Totally irrelevant Choice E: The beetles stop immediately when a barrier is introduced probably because it goes momentarily blind. But we expect that even normally if something doesn't go blind. So not a definitive support for hypothesis 2. Nothing can be concluded about hypothesis 1.
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SravnaTestPrep wrote: Marcab wrote: Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running
toward an insect, the beetles intermittently stop, and then, a moment later, resume their attack. Perhaps they
cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while
running tiger beetles are unable to process the resulting rapidly changing visual information, and so quickly go
blind and stop. Which of the following, if discovered in experiments using artificially moved prey
insects, would support one of the two hypotheses and undermine the other?
A. When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately turns and
runs away without its usual intermittent stopping.
B. In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and
pause equally frequently whether the chase is up or down an incline.
C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary
begins to flee, the beetle increases its speed after its next pause.
D. If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
E. When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop
immediately, but they never respond by running around the barrier.
OAThough the same stimulus is available with different answer choices, I found this one to be a tough one. Explanations will be appreciated. Unfortunately I find no clear cut answer to the question. Hypothesis 1: Tiger beetles need to constantly rest for a moment while pursuing a prey Hypothesis 2: The rapidly changing visual information make the tiger beetles momentarily blind and force them to pause frequently while pursuing a prey. Choice A: Hypothesis 1 is neither undermined nor supported. While turning and running away they do not make the usual stops. It is reasonable to assume that they are running at least at the same pace as they were while pursuing the prey as it is now seems a matter of survival. They may not be expected to make pauses even though they may need rest because as I said they are sensing danger. So we can eliminate choice A. Choice B: Hypothesis 1 is undermined because they pause equally frequently whether the chase is up or down an incline. So it doesn't seem to be the question of getting tired and needing the rest. However hypothesis 2 also seem to be undermined because, when a prey is changing its direction, the visual information changes the most and hence according to hypothesis 2 they should go blind but according to choice B, they immediately respond to change in the direction of the prey. So we can eliminate choice B Choice C: Nothing can be concluded about both the hypotheses. Choice D: Totally irrelevant Choice E: The beetles stop immediately when a barrier is introduced probably because it goes momentarily blind. But we expect that even normally if something doesn't go blind. So not a definitive support for hypothesis 2. Nothing can be concluded about hypothesis 1. well , even I am not convinced by the OA and this a Gmatprep question so official answer cannot be a suspect. the OFFICIAL explanation given for ruling out B -- 'In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline' is that in this experiment neither vision nor tiredness appear to be problematic,the beetle could be stopping for either reason; this information neither weakens or strengthens either hypothesis PLEASE NOTE-- the question in CR diagnostic of OG12 has 2 DIFFERENT answer choices and the order of answer choices differs OA is B (the question is quoted in one of the post above) this question under discussion (highlighted above) is from gmatprep software and has a different OA
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The introduction of another question was not at all required. This will only helped the confusion that will arise while posting the explanations. Since the question from the diagnostic was pretty easy, so I urge everyone no to discuss here in this thread. Henceforth the discussion will be only on the topic question. Now my question is why do you guys feel that C does nothing? If it says that the beetle takes equal intervals while running up the incline and down the incline, then for sure it undermines the hypothesis that the beetle pauses to take rest. I will explain how- Consider that you are running up the hill and you take 1 stop per minute. Now consider that you are running down the hill, will the stops/min be higher, lower or equal? They will be lower because they are spending less energy. Thus the first part of C undermines one hypothesis. Now further explanation is required. And yeah B is wrong.
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Marcab wrote: The introduction of another question was not at all required.
This will only helped the confusion that will arise while posting the explanations.
Since the question from the diagnostic was pretty easy, so I urge everyone no to discuss here in this thread. Henceforth the discussion will be only on the topic question.
Now my question is why do you guys feel that C does nothing? If it says that the beetle takes equal intervals while running up the incline and down the incline, then for sure it undermines the hypothesis that the beetle pauses to take rest.
I will explain how-
Consider that you are running up the hill and you take 1 stop per minute. Now consider that you are running down the hill, will the stops/min be higher, lower or equal?
They will be lower because they are spending less energy.
Thus the first part of C undermines one hypothesis. Now further explanation is required.
And yeah B is wrong. Marcab, Running up and down an incline is only part of choice B . We cannot assume it for choice C.
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See, thats what I was talking about, mixed B and C. Thanks Sri for pointing that out. Actually what I was trying to say was that since the beetle takes equal time interval for rests then the clear cut factor, in IMO, is that the beetle has some capacity to run; it can't run without stopping. So it undermines the other hypothesis that the beetles stops when an insect chnages its direction quickly.
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C. The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause. But consider this. If fixed time interval between pauses means they do not get tired at all, one could definitely make a even less stringent assumption that they need rest but a momentary rest is enough to regain their energy, however long they run?
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Last edited by SravnaTestPrep on 23 Dec 2012, 07:08, edited 1 time in total.
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Sorry marcab great question. But according to the mgmat forum the question has this answers Quote: A When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping.
B In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.
C In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline.
D If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
E The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops. OA here is C and in your question is B. So the definitive answer should be B (my answer too) Correct me if i'm wrong 
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