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

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

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30 Aug 2017, 11:43
4
gmatexam439 wrote:
GMATNinja abhimahna GMATNinjaTwo

Please explain why "E" is wrong and why "A" is correct? Also, please give the correct negation of each option.

Regards

Hi gmatexam439 ,

Here I go :

The passage says

1) Vessels serve ONLY to disperse heat.
2) Heat is generated ONLY while flapping wings.

=> I flap my wings, heat is generated and now it MUST disperse out of my vessels.

Then it concludes, since dinosaurs had these vessels therefore they used to flew.

Come on! This is non sense. Having some body part doesn't mean we are going to use it, right? What if they had those features but they never used it?

Hence, my pre thinking assumption is If THEY have a body feature, they have to use it anyhow.

Statement A is doing the same. Let's negate it.

They have had networks even if they don't use it. Ohh WOW, my conclusion is broken. How dare author say they used to fly? Call him, I wanna talk to him.

Moving on to option E.

(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.

We are already told that heat generated is dispersed ONLY by vessels. So, saying the same thing in different manner won't do any benefit. E can never be the answer.

Let's negate it.

Heat generated could be dispersed by other things too. Come on!! I am trying to break my premise. I cannot do so. (Look at the implication I drew after writing my two premises above.)

Hence, E is 100% wrong.

Does that make sense?
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Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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31 Aug 2017, 23:18
Someone please explain Why B and D are wrong confused here
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Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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02 Sep 2017, 00:51
1
haardiksharma wrote:
Someone please explain Why B and D are wrong confused here

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

It doesn't matter whether all creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings. The author is simply arguing that the discovery "provides evidence for the hypothesis that Sandactylus flew by flapping its wings." For example, not EVERYONE who has a fancy car has a lot of money. However, having a fancy sports car can still be evidence that someone has a lot of money.

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

If choice (D) were not true, we would have: "If Sandactylus flew by flapping its wings, then paleontologists might be able to find some evidence that it did so." The author argues that the discovery provides evidence for the hypothesis that Sandactylus flew by flapping its wings. This argument does not require that, if Sandactylus did in fact fly by flapping its wings, paleontologists would DEFINITELY find evidence that it did so. (D) is not a required assumption.

I hope this helps!
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Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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02 Apr 2018, 06:24
Quote:
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) Not 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 not 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 not 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.

Hi mikemcgarry, GMATNinjaTwo, GMATNinja, MagooshExpert Carolyn, sayantanc2,VeritasPrepKarishma
it took me many hours to review this question.

First, i have no idea where is my reasoning 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.

E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat.
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.

second
if negate E,
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.
then negative (E) means there are other ways to disperse the heat generated by flapping.
so whether sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

BUT E is incorrect.

I think i must be wrong, but i have no idea where.

mostly, Assumption questions cost me lots of time and energy and i barely get right choice.

Have a nice day
>_~
GMAT Club Verbal Expert
Joined: 20 Nov 2016
Posts: 264
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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02 Apr 2018, 07:59
zoezhuyan wrote:
Quote:
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) Not 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 not 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 not 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.

Hi mikemcgarry, GMATNinjaTwo, GMATNinja, MagooshExpert Carolyn, sayantanc2,VeritasPrepKarishma
it took me many hours to review this question.

First, i have no idea where is my reasoning 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.

E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat.
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.

second
if negate E,
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.
then negative (E) means there are other ways to disperse the heat generated by flapping.
so whether sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

BUT E is incorrect.

I think i must be wrong, but i have no idea where.

mostly, Assumption questions cost me lots of time and energy and i barely get right choice.

Have a nice day
>_~

zoezhuyan, stay tuned for a full QOTD explanation for this question later this month! In the meantime, we'll let the other experts and users weigh in
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Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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02 Apr 2018, 09:24
zoezhuyan wrote:
Quote:
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) Not 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 not 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 not 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.

Hi mikemcgarry, GMATNinjaTwo, GMATNinja, MagooshExpert Carolyn, sayantanc2,VeritasPrepKarishma
it took me many hours to review this question.

First, i have no idea where is my reasoning 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.

E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat.
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.

second
if negate E,
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.
then negative (E) means there are other ways to disperse the heat generated by flapping.
so whether sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

BUT E is incorrect.

I think i must be wrong, but i have no idea where.

mostly, Assumption questions cost me lots of time and energy and i barely get right choice.

Have a nice day
>_~

Not sure if you have seen my previous post which discusses exactly why (E) is not the answer. Let me give it again here:

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, we are assuming that presence of B implies presence of A to get rid of B. The assumption is that we cannot get rid of B without A.
But given the original argument, this is not the assumption. Hence, answer is not (E).

Does this help?
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Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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02 Apr 2018, 23:22
VeritasPrepKarishma wrote:
zoezhuyan wrote:
Quote:
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) Not 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 not 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 not 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.

Hi mikemcgarry, GMATNinjaTwo, GMATNinja, MagooshExpert Carolyn, sayantanc2,VeritasPrepKarishma
it took me many hours to review this question.

First, i have no idea where is my reasoning 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.

E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat.
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.

second
if negate E,
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.
then negative (E) means there are other ways to disperse the heat generated by flapping.
so whether sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

BUT E is incorrect.

I think i must be wrong, but i have no idea where.

mostly, Assumption questions cost me lots of time and energy and i barely get right choice.

Have a nice day
>_~

Not sure if you have seen my previous post which discusses exactly why (E) is not the answer. Let me give it again here:

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, we are assuming that presence of B implies presence of A to get rid of B. The assumption is that we cannot get rid of B without A.
But given the original argument, this is not the assumption. Hence, answer is not (E).

Does this help?

Hi Karishma VeritasPrepKarishma
Frankly, I did read your explanation, and my interpretation is that , based on the discovery, the paleontologists conclude the hypothesis that Sandactylus flew by flapping, in other words, paleontologists fist got the discovery, then conclude a hypothesis from the discovery,
per your explanation, you point out a reverse logic that paleontologists first suppose Sandactylus did have heat generated from flapping if E is assumption, did i miss something or misunderstand?

When i reviewed this question yesteday, i tried to analyse E by myself, then new question came up,

Assumption is defined --an unstated evidence, without assumption, the author won't believe the conclusion is true.

E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat, Am I right?
then, i think if Sandactylus has blood vessel, then they can dispersed the heat, right?
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.

I am not sure where is incorrect.

If i use negative skill, then i think E break the argument.
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.

then negative (E) means there are other ways to disperse the heat generated by flapping.
so whether sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

Would you please point out the errors of my reasoning

Have a nice day
>_~
Senior Manager
Joined: 17 Sep 2016
Posts: 255
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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04 Apr 2018, 00:29
zoezhuyan wrote:
Hi Karishma VeritasPrepKarishma
Frankly, I did read your explanation, and my interpretation is that , based on the discovery, the paleontologists conclude the hypothesis that Sandactylus flew by flapping, in other words, paleontologists fist got the discovery, then conclude a hypothesis from the discovery,
per your explanation, you point out a reverse logic that paleontologists first suppose Sandactylus did have heat generated from flapping if E is assumption, did i miss something or misunderstand?

When i reviewed this question yesteday, i tried to analyse E by myself, then new question came up,

Assumption is defined --an unstated evidence, without assumption, the author won't believe the conclusion is true.

E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat, Am I right?

then, i think if Sandactylus has blood vessel, then they can dispersed the heat, right?
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.
I am not sure where is incorrect.

If i use negative skill, then i think E break the argument.
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.

then negative (E) means there are other ways to disperse the heat generated by flapping.
so the discovery that sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

Would you please point out the errors of my reasoning

Have a nice day
>_~

Hi mikemcgarry, GMATNinjaTwo, GMATNinja, MagooshExpert Carolyn, @sayantanc2,@VeritasPrepKarishma
i think i got one of my reasoning problems , but new question came up , genuinely need you help to confirm.

here is my incorrect reasoning
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.-- is incorrect.

(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.

zoezhuyan wrote:
E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat, Am I right?

up to there, i hold my reasoning

zoezhuyan wrote:
then, i think if Sandactylus has blood vessel, then they can dispersed the heat, right?
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.

here, i think my reasoning --because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.-- is incorrect.
i reviewed the following
mikemcgarry wrote:
These are the words "necessary" and "sufficient." One way to say it is as follows:
"A is necessary for B." Here we know that if A doesn't happen, then B would not happen. If A does happen, then it may or may not be true that B can happen.

mikemcgarry wrote:
The word "sufficient" summaries the opposite relationship.
"A is sufficient for B." This means that if A happens, we know that B must be true; in other words, A is a guarantee for B. If A doesn't happen, then B may or may not be true.

so i think E is a necesary assumption, in other words, blood vessel is necessary assumption to dispersed heated generated by flapping
if sandactylus has blood vessels, it maybe dispered heated generated by flapping, maybe not.

So my rasoning is incorrect.

Wait a minute,a new problem,
according the stimulus, 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.
Can i then get that Sandaytlus can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings, not just by gliding ?

Further confused between assumption, necessary assumption.
Is necessary assumption a branch of assumption?
An assumption is unstated something that the author must believe to be true in order to draw a certain conclusion
Does it mean if the assumption happens, it can lead to the conclusion?
A is necessary for B, if A doesn't happen, then B would not happen.
necessary assumption is a branch of assumption?

i am still confused the following:
Quote:
I am not sure where is incorrect.

If i use negative skill, then i think E break the argument.
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.

then negative (E) means there are other ways to disperse the heat generated by flapping.
so the discovery that sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

Have a nice day
>_~
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8400
Location: Pune, India
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

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04 Apr 2018, 04:08
zoezhuyan wrote:
Hi Karishma VeritasPrepKarishma
Frankly, I did read your explanation, and my interpretation is that , based on the discovery, the paleontologists conclude the hypothesis that Sandactylus flew by flapping, in other words, paleontologists fist got the discovery, then conclude a hypothesis from the discovery,
per your explanation, you point out a reverse logic that paleontologists first suppose Sandactylus did have heat generated from flapping if E is assumption, did i miss something or misunderstand?

When i reviewed this question yesteday, i tried to analyse E by myself, then new question came up,

Assumption is defined --an unstated evidence, without assumption, the author won't believe the conclusion is true.

E is bit complex, i simplify E,
flapping generats heat, and the heat CANNOT be dispersed without blood vessels.
in other word, no blood vessel , no dispersed heat, Am I right?
then, i think if Sandactylus has blood vessel, then they can dispersed the heat, right?
it meants blood vessel is necessary to dispersed heat generated by Sandactylus in flapping.
because Sandactylus has blood vessel, so it can disperse heat generated in flapping, then provide the evidence that sandactylus flew by flapping its wings,not just by gliding.

I am not sure where is incorrect.

If i use negative skill, then i think E break the argument.
(E) Heat generated by Sandactylus in flapping its wings in flight could not COULD have been dispersed by anything other than the blood vessels in its wings.

then negative (E) means there are other ways to disperse the heat generated by flapping.
so whether sandactylus has blood vessels does not provide evidence for the hypothesis,
Does it weaken ?
I think it does weaken.

Would you please point out the errors of my reasoning

Have a nice day
>_~

We are on the same page - they did first discover blood vessels in wings. This discovery led to hypothesis - "they must be flying by flapping wings".
Think why? Just because they know that bats have blood vessels and the only purpose of those is to disperse heat generated by flapping wings in flight.
So they assumed that blood vessels in wings must have a purpose. They also assumed that the purpose must be the same as that in bats.

Did they have to assume that heat generated could not have been dispersed by any other way? No. That would have been your assumption had they found out that heat is generated by flapping and then tried to conclude that they MUST have had blood vessels. Here the assumption is that there is no other way to disperse heat.

By negating (E), you are discussing what happens when you KNOW that they generate heat by flapping wings. But we don't know that so it is irrelevant. Don't get lost in it.

See what happens when you negate (A) - Blood vessels may not have had a purpose. Then the whole conclusion falls apart.

_________________

Karishma
Veritas Prep GMAT Instructor

GMAT self-study has never been more personalized or more fun. Try ORION Free!

Re: Networks of blood vessels in bats' wings serve only to disperse heat &nbs [#permalink] 04 Apr 2018, 04:08

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