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Tiger beetles

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Tiger beetles

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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.

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I am sorry that I forgot the add the specific thing I want to everyone to discuss. Can experts please discuss the each convoluted options.
OA C

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The hypetheses as stated are:
1.There is an equal interval of pauses --for rest
2.To catch the quickly changing visual images

Now the question says that one of the option undermines one hypothesis and supports the other.Lets evaluate the options.In short the correct option should strengthen one hypothesis and weaken the other.

A.Beetle doesn't stop--No efefct. Beetle stops according to both the hypothesis

B.Beatles respond to changes in insect direction--Now this doesn't support the hypotheses because one of them is for rest and the other is for usual.This clearly pertains to insect movement ans so is not relevant.

C.Beetles maintain fixed intervals between pauses --and the beetle increases its speed based on insects fleeing-- so this mean that it probably facilitates better visualization thats why they stop..

D.Out of scope.We are concerned with the hypotheses and stops

E.Nothing in this option is relevant to the strengthening or weakening of the hypothesis.It discusses sudden stop while the argument is concerned about pauses and its relevance to stated hypothesis.

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I was leaning slightly towards B actually. If the beetle is responding immediately to the insects change of direction means it is certainly not going blind during pursuit as it can visually follow the insect's movements. This debunks the "going blind" theory. Whereas they pause frequently during the chase irrespective of the inclination because they cannot maintain their pace.....

I don't see how C debunks the going blind theory though it partially supports the "cannot maintain pace theory".

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Cthulu wrote:
I was leaning slightly towards B actually. If the beetle is responding immediately to the insects change of direction means it is certainly not going blind during pursuit as it can visually follow the insect's movements. This debunks the "going blind" theory. Whereas they pause frequently during the chase irrespective of the inclination because they cannot maintain their pace.....

I don't see how C debunks the going blind theory though it partially supports the "cannot maintain pace theory".
See option B
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


The second hypothesis is about the the rests or equal pauses that beetles take because they loose the visuals of the fast moving target.Now what is implied by your statement is that it is not going blind..we have to prove that these rests are not for chasing the beetle and that 'not being blind' or beetle having No sight will have no impact on the conclusion.We need to weaken hypothesis.

Now Pausing frequently with fixed interval also doesnt helps debunk the first hypothesis.Its stated whether its an uphill or downhill they maintain same equal intervals of pauses.Now During uphill they definitely should have paused for larger interval of time.Please notice the words in statement to--Up or down incline

Hope it helps!!
Smile

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Actually yes, B debunks both theories, : If the beetle were blind it would not change direction when the insect is moving around.Also, since the frequency of rest is the same whether going uphill or downhill means the reason for not stopping is not "tiredness"...since it is not supporting (however mildly) either of the options B cannot be correct. I still feel C is not a strong option but is the best of what is available.

Thanks.

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