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# Networks of blood vessels in bats' wings serve only to

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Manager
Joined: 14 Sep 2006
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Schools: Olin Business School - Washington University
Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 20:20
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95% (hard)

Question Stats:

41% (02:25) correct 59% (01:33) wrong based on 1860 sessions

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Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.
[Reveal] Spoiler: OA
Manager
Joined: 13 Sep 2006
Posts: 212
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 20:30
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E..

Had difficulty w/ this one..not sure if i'm right..

what is the difficulty level?
VP
Joined: 21 Aug 2006
Posts: 1016
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 20:37
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A says that Sandactylus used its network of blood vessels. Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Based on this, I would say answer is A.
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VP
Joined: 25 Jun 2006
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Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 20:45
E for me.
Director
Joined: 10 Oct 2005
Posts: 526
Location: US
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 20:55
This is a OG problem i will go with A
Senior Manager
Joined: 11 Jul 2006
Posts: 380
Location: TX
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 21:16
diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

I think its A

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.
It assumes that veins are there only for some purpose other than supplying blood. Negate it the argument falls apart. It provides a nuch clearer and a much broader assumption.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

This statement presupposes the assumption that Sandactylus flapps it wings and flapping might generate heat for Sandactylus and viens are there to cool them. So what do we negate here ? Do they flap their wings ? Do they generate heat if the flap ? Do they use their viens to cool their wings ? Negate each one , one by one and it doesn't do much harm to the argument as A.

Beat me up if don't make much sense....
VP
Joined: 21 Mar 2006
Posts: 1127
Location: Bangalore
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 21:21
Between A and E, I go for E.
I'm confused here Both A and E pass the negation test. I just liked E better . A is a little extreme
Current Student
Joined: 29 Jan 2005
Posts: 5218
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 22:48
ivymba wrote:
diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

I think its A

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.
It assumes that veins are there only for some purpose other than supplying blood. Negate it the argument falls apart. It provides a nuch clearer and a much broader assumption.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

This statement presupposes the assumption that Sandactylus flapps it wings and flapping might generate heat for Sandactylus and viens are there to cool them. So what do we negate here ? Do they flap their wings ? Do they generate heat if the flap ? Do they use their viens to cool their wings ? Negate each one , one by one and it doesn't do much harm to the argument as A.

Beat me up if don't make much sense....

I`m with (B) on this one. "creatures" is the key term used a basis of comparison here.
Senior Manager
Joined: 14 Jul 2006
Posts: 326
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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25 Sep 2006, 22:55
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I am up for (A) too.
(E) says heat generated in flapping its wings(we havent yet established if sandalyctuses flapped their wings).
(B) is of the type
if A then B
therefore,if B then A(which is wrong)
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Manager
Joined: 14 Sep 2006
Posts: 198
Schools: Olin Business School - Washington University
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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26 Sep 2006, 01:26
OA is A...thanks for playing!
Director
Joined: 17 Jul 2006
Posts: 706
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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26 Sep 2006, 10:04
I was close between A and B.

Finally chose A.
CEO
Joined: 21 Jan 2007
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Location: New York City
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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29 Dec 2007, 05:34
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sangarelli wrote:
I am up for (A) too.
(E) says heat generated in flapping its wings(we havent yet established if sandalyctuses flapped their wings).
(B) is of the type
if A then B
therefore,if B then A(which is wrong)

most helpful to eliminate between E and A
VP
Joined: 22 Nov 2007
Posts: 1079
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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30 Dec 2007, 09:48
diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

the argument says that the heat which is needed by networks is generated only by flapping wings, so if the dinosaurs would not have flapped their wings, the networks would be of no use

A. is coherent with the above
B. we do not know for sure if the dinosaurs flapped their wings
C. out of scope
D. not interesting for us
E. see B
Director
Joined: 29 Aug 2005
Posts: 859
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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13 Dec 2008, 05:38
diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

Great question. I now realise that it should indeed be A.

E is wrong:
E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings. IMO, there is nothing to suggest that heat is dispersed only by blood vessels. It says that blood vessels are there only to disperse heat, but this does not suggest the reserve is true.
Anyone disagrees?
Director
Joined: 01 Aug 2008
Posts: 732
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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16 Dec 2008, 08:07
between A and B I pick A (even the OA is also A so it was easy to pick )

option B is too open .... no limits (all flying creatures) ...these kind of statements usually are wrong.
Manager
Joined: 25 Jul 2012
Posts: 75
Location: United States
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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08 Mar 2013, 10:51
Actual OG13 #84 has different question and answer stems. Here you go:

Networks of blood vessels in bats’ wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists’ recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

In the passage, the author develops the argument by

(A) forming the hypothesis that best explains several apparently conflicting pieces of evidence
(B) reinterpreting evidence that had been used to support an earlier theory
(C) using an analogy with a known phenomenon to draw a conclusion about an unknown phenomenon
(D) speculating about how structures observed in present-day creatures might have developed from similar structures in creatures now extinct
(E) pointing out differences in the physiological demands that flight makes on large, as opposed to small, creatures

OA:C
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Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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08 Mar 2013, 23:00
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diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

Responding to a pm:

This is not an easy question - especially if you are trying to explain the answer.
So first let's try to understand how the argument is structured. I will use variables to make it easier:

Networks of blood vessels in wings - A
heat generated in flight by flapping wings - B

Given Argument:
Bats have A. Bats have B. A's only job is to get rid of B.

What is the assumption? That A must have had a purpose in Dinos too (getting rid of B). You cannot have A without having a job for it. Just because Dinos had A, we are concluding that they must have had B too. We are assuming that A must have had a purpose. This is option (A) and is the answer.

Are we assuming that we cannot get rid of B without A? No. (This is what option (E) says)
When would this be the assumption?
If the argument were a little different: Dinos had B. Hence, Dinos had A too.
In this argument, the assumption would have been that we cannot get rid of B without A.
But given the original argument, this is not the assumption. Hence, answer is not (E).
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Manager
Status: struggling with GMAT
Joined: 06 Dec 2012
Posts: 213
Concentration: Accounting
GMAT Date: 04-06-2013
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Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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09 Mar 2013, 03:18
i was confused between A & B then select b.....whats the problem with b?
Director
Joined: 05 Sep 2010
Posts: 833
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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09 Mar 2013, 04:05
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To mun
i can explain this to u like this though its difficult to parse in words
try and negate B : not All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.
that means out of 100 creatures ,lets say, 95 falls into this category and 5 do not .so with this information u cannot be sure as into which category does this particular species fall( it might be in 95 category in that case the conclusion holds or it might be into 5 category and in that case the conclusion will fall apart ) and hence negating B is not making the destroying the conclusion
does it make sense ?
Manager
Status: struggling with GMAT
Joined: 06 Dec 2012
Posts: 213
Concentration: Accounting
GMAT Date: 04-06-2013
GPA: 3.65
Re: Networks of blood vessels in bats' wings serve only to [#permalink]

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09 Mar 2013, 04:23
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To mun
i can explain this to u like this though its difficult to parse in words
try and negate B : not All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.
that means out of 100 creatures ,lets say, 95 falls into this category and 5 do not .so with this information u cannot be sure as into which category does this particular species fall( it might be in 95 category in that case the conclusion holds or it might be into 5 category and in that case the conclusion will fall apart ) and hence negating B is not making the destroying the conclusion
does it make sense ?

thanks for your explanation.Now i have got it
Re: Networks of blood vessels in bats' wings serve only to   [#permalink] 09 Mar 2013, 04:23

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