GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 22 Oct 2018, 07:54

Close

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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

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

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Manager
Manager
avatar
Joined: 20 Oct 2004
Posts: 117
Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post Updated on: 27 Sep 2018, 02:44
9
58
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

36% (01:29) correct 64% (01:34) wrong based on 2692 sessions

HideShow timer Statistics

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.


Verbal Question of The Day: Day 269: Critical Reasoning


Subscribe to GMAT Question of the Day: E-mail | RSS
For All QOTD Questions Click Here


The Official Guide for GMAT Review, 11th Edition, 2005

Practice Question
Question No.: CR 89
Page: 493


Similar Question : LINK 1 LINK 2

Originally posted by kdhong on 05 Dec 2005, 21:19.
Last edited by Bunuel on 27 Sep 2018, 02:44, edited 9 times in total.
Renamed the topic and edited the question.
Most Helpful Expert Reply
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8406
Location: Pune, India
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 08 Mar 2013, 23:00
18
13
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.
Dinos had A too. Hence, Dinos had B too.

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).
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

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

GMAT Club Verbal Expert
User avatar
P
Status: GMAT and GRE tutor
Joined: 13 Aug 2009
Posts: 2043
Location: United States
GMAT 1: 780 Q51 V46
GMAT 2: 800 Q51 V51
GRE 1: Q170 V170
Re: QOTD: Networks of blood vessels in bats' wings serve only to disperse  [#permalink]

Show Tags

New post 03 May 2018, 19:15
4
4
Let's start by nailing down the conclusion. Is the conclusion that "Sandactylus flew by flapping its wings, not just by gliding."? Not quite... that is the hypothesis. The author's conclusion is that the "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."

So the author is not simply trying to conclude that Sandactylus flew by flapping its wings (or that Sandactylus DEFINITELY flew by flapping its wings). Instead, the author is trying to make the case that the recent discovery provides evidence for the hypothesis stated above.

Now that the distinction between the hypothesis and the conclusion is clear, let's review the author's argument:

  • Bats have networks of blood vessels in their wings, and those blood vessels disperse heat generated in flight.
  • "This heat is generated only because bats flap their wings." - This implies that if the bats did NOT flap their wings, then they would not generate the heat and thus would not need the blood vessels in their wings to disperse that heat.
  • Paleontologists' have recently discovered that Sandactylus had similar networks of blood vessels in their wings.
  • According to the author, that discovery provides evidence for the hypothesis (that "Sandactylus flew by flapping its wings, not just by gliding"). Does the hypothesis imply that Sandactylus never used gliding during flight? No. It simply says that gliding was not the ONLY method. So, if the hypothesis is correct, Sandactylus certainly could have used some gliding, but it MUST have used wing-flapping too.

Now that we understand the argument, we need an assumption on which that argument depends:

Quote:
(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.

Bats only need the blood vessel networks because they flap their wings. If we assume that Sandactylus actually used the networks, then we'd have reason to believe that those networks were used only for heat dispersion, not for any other purpose.

But what if the networks were not used at all? Just because an animal has a feature that CAN be used for some purpose, does that necessarily mean that the animal actually uses that feature? If the networks in Sandactylus actually served no purpose, then we would have no reason to suspect that they flapped their wings. Thus, (A) is a required assumption.

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. Eliminate (B).

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

We don't care about the effectiveness of wing-flapping vs. gliding. We are only concerned with whether networks of blood vessels in the wings are evidence of wing-flapping. (C) is irrelevant and can be eliminated.

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

What other evidence paleontologists may or may not find is irrelevant. We KNOW that paleontologists have recently discovered "that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings." According to the author, that discovery alone provides evidence for the hypothesis.

Also, remember that we don't actually care whether Sandactylus flew by flapping its wings. The author is not trying to prove that this is true. The author is simply arguing that the blood vessel networks are evidence that Sandactylus flew by flapping its wings. (D) is not a required assumption and can be eliminated.

Quote:
(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.

Sandactylus may have had several mechanisms for heat dispersion. As long as the networks of blood vessels in their wings comprised one of those mechanisms, the author's argument would hold. Eliminate (E).

(A) is the best answer.
_________________

GMAT Club Verbal Expert | GMAT/GRE tutor @ www.gmatninja.com (Now hiring!) | Instagram | Food blog | Notoriously bad at PMs

Beginners' guides to GMAT verbal
Reading Comprehension | Critical Reasoning | Sentence Correction

YouTube LIVE verbal webinars
Series 1: Fundamentals of SC & CR | Series 2: Developing a Winning GMAT Mindset

SC & CR Questions of the Day (QOTDs), featuring expert explanations
All QOTDs | Subscribe via email | RSS

Need an expert reply?
Hit the request verbal experts' reply button -- and please be specific about your question. Feel free to tag @GMATNinja in your post. Priority is always given to official GMAT questions.

Sentence Correction articles & resources
How to go from great (760) to incredible (780) on GMAT SC | That "-ing" Word Probably Isn't a Verb | That "-ed" Word Might Not Be a Verb, Either | No-BS Guide to GMAT Idioms | "Being" is not the enemy | WTF is "that" doing in my sentence?

Reading Comprehension, Critical Reasoning, and other articles & resources
All GMAT Ninja articles on GMAT Club | Using LSAT for GMAT CR & RC |7 reasons why your actual GMAT scores don't match your practice test scores | How to get 4 additional "fake" GMAT Prep tests for $29.99 | Time management on verbal

Most Helpful Community Reply
Manager
Manager
avatar
Joined: 11 Aug 2005
Posts: 80
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 16 Dec 2005, 05:09
7
2
i will try to explain.

let network of blood cells = x
heat dispersion = y
Sandactylus = z

its given that x can "only" do y. but its not given that y cannot be done any other way in a creature. its also given that z has x. and the conclusion is that in z, x does y.

it assumes that in z, y cannot be done any other way than x. and thus assumes that in z , x exists with a purpose and it is given that x has only one purpose that is y

hence A

hope i made some sense :-)
_________________

------------------------------

only if i could choose....

General Discussion
Director
Director
User avatar
Joined: 21 Aug 2006
Posts: 943
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 25 Sep 2006, 20:37
1
1
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.
_________________

The path is long, but self-surrender makes it short;
the way is difficult, but perfect trust makes it easy.

Senior Manager
Senior Manager
User avatar
Joined: 14 Jul 2006
Posts: 305
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 25 Sep 2006, 22:55
3
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)
_________________

A well-balanced person is one who has a drink in each of his hands.

Manager
Manager
avatar
Joined: 27 Jul 2012
Posts: 113
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 05 Jul 2014, 04:58
7
2
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 Sandactytus.
the network of blood vessels serve only to disperse heat generated in flight.
so it has a certain function and usage.
negation of this option will break the argument apart

(B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings. we can infer from the argument that those creatures that their wings have networks of blood vessels in the skin of their wings fly by flapping their wings not vice versa.

(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. they've already found some evidence.. network of blood vessels.

(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 have a premise:Networks of blood vessels in bats’ wings serve only to disperse heat generated in flight. ---> there might be other ways that bats disperse heat generated in flight. however, the usage of Networks of blood vessels in bats' wings is only to disperse heat generated in flight------- so, E is incorrect
Intern
Intern
avatar
Joined: 06 Jun 2011
Posts: 22
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 26 Oct 2014, 10:44
I may be tempted to reject A on the grounds that it's just a conditional statement leading to a statement that confirms the event never occurred. A bit of SC logic : If < simple past> , past perfect construction is used for an event that never occurred.

The conclusion is that the finding ' provides evidence for the hypothesis...'. Does A provides evidence of the hypothesis? Probably not.
Does E provide evidence for the hypothesis? Sure, it does.

May be a bit of over-thinking but it would be good to know the source of this question ( not from OG for sure).
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8406
Location: Pune, India
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 26 Oct 2014, 19:35
kishgau wrote:
I may be tempted to reject A on the grounds that it's just a conditional statement leading to a statement that confirms the event never occurred. A bit of SC logic : If < simple past> , past perfect construction is used for an event that never occurred.

The conclusion is that the finding ' provides evidence for the hypothesis...'. Does A provides evidence of the hypothesis? Probably not.
Does E provide evidence for the hypothesis? Sure, it does.

May be a bit of over-thinking but it would be good to know the source of this question ( not from OG for sure).


This is question number 89 from OG 11. The question and solution are official and perfect. Expect to see such questions on the actual exam.

And the option (A) does give you a hypothetical event but that hypothetical event is - if these networks were of no use, they would not have had the network. It is just another way of saying that the networks were useful. 'Networks were of no use' is hypothetical.
In verbal, rules will not help you. Things change depending on context.

The argument assumes that the network of blood vessels was not present just like that - it had a purpose. It was present means it was needed to disperse heat and hence the dinos flapped their wings.
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

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

Intern
Intern
User avatar
Joined: 17 Oct 2014
Posts: 29
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 28 Oct 2014, 07:52
(A) is definitely right here. The premise of the argument is that the only purpose of blood vessels in bat wings is to disperse heat from flapping. The conclusion is that the flying dinosaur most likely flapped, since it has similar blood vessels. Therefore, the assumption is that the blood vessels served a purpose, any purpose, at all. If they served no purpose (the negation of choice (A)), then the argument about flapping has no basis.

For choice (B), the distractor, it's important to remember that the negation of "All" is "Not all." Even if not all flappers have these blood vessel networks, that tells us little or nothing about animals that do, including both bats and Sandactylus.

Hope this helps!
Current Student
User avatar
B
Joined: 04 Jul 2014
Posts: 299
Location: India
GMAT 1: 640 Q47 V31
GMAT 2: 640 Q44 V34
GMAT 3: 710 Q49 V37
GPA: 3.58
WE: Analyst (Accounting)
Reviews Badge
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 26 Nov 2014, 21:19
3
A indeed is the correct answer. I was stuck between A and E for long. Great question!!! Hope this explanation helps!

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.

F1: Blood vessels in bat ONLY dispersed heat generated in flight
F2: In bats, heat generation was ONLY because bats flapped wings
F3: S glides
F4: There is a view that S could fly flapping its wings too. This view is not proved yet.
C: Since S has a network of blood vessels similar to that of Bats, S flew flapping its wings

GAP: Since in Bats the vessels only served for dispersing heat, in S too they must serve the same purpose


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. Addresses gap

B. All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings. Over generalisation. Questionable too. If all creatures must have this feature then why compare only with the Bat today when scientists have been compared this earlier since they were having a view that S flew?

C. Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide. effectiveness not at all a part of the discussion. OUT

D. If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so. So this evidence is not good enough? Irrelevant

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. who said they flapped their wings? None knows that yet. Scope shift. Out
_________________

Cheers!!

JA
If you like my post, let me know. Give me a kudos! :)

Retired Moderator
User avatar
P
Status: The best is yet to come.....
Joined: 10 Mar 2013
Posts: 508
GMAT ToolKit User
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 01 Feb 2015, 05:45
VeritasPrepKarishma 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.


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.
Dinos had A too. Hence, Dinos had B too.

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).



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.

What if A must have had a purpose in Dinos too other than B?

_________________

Hasan Mahmud

Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8406
Location: Pune, India
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 01 Feb 2015, 22:51
Mahmud6 wrote:
VeritasPrepKarishma 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.


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.
Dinos had A too. Hence, Dinos had B too.

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).



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.

What if A must have had a purpose in Dinos too other than B?


Option (A) states that "A must have had a purpose" - that is the assumption. Without this assumption, the conclusion makes no sense. If A could exist without a purpose, then we cannot say that Dinos had B too. Another assumption would be that A's purpose can only be to get rid of B.
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

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

Verbal Forum Moderator
avatar
Joined: 15 Apr 2013
Posts: 184
Location: India
Concentration: General Management, Marketing
GMAT Date: 11-23-2015
GPA: 3.6
WE: Science (Other)
GMAT ToolKit User Premium Member Reviews Badge
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 06 Feb 2015, 23:14
karishma

Could you please explain why negation did not worked out for B here?

Many thanks
Vikas

Posted from my mobile device
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8406
Location: Pune, India
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 09 Feb 2015, 00:10
vikasbansal227 wrote:
karishma

Could you please explain why negation did not worked out for B here?

Many thanks
Vikas

Posted from my mobile device


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.
Dinos had A too. Hence, Dinos had B too.

The assumption is that if someone has A, he has B too.

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

It says, all creatures that have B, have A too. This is not our assumption.

If we negate it, we get that there are some who have B but not A. It doesn't kill our conclusion. In our conclusion, we are concerned about people who have A, whether they have B or not. We are not concerned about people who have B, whether they have A or not.
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

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

Director
Director
User avatar
B
Joined: 17 Dec 2012
Posts: 629
Location: India
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 04 Jun 2017, 19:44
chshashankreddy 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 Sandactytus.

(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 wingsin 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 findsome 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.
:
Fact: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. winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings.

Missing Information:Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactytus. i.e., the network of blood vessels had a purpose

Conclusion: This provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding

The right choice needs to fill a gap. Choice A does that and hence is the missing information.

So we see that the missing information starts from the fact shown in bold and leads to the conclusion.
_________________

Srinivasan Vaidyaraman
Sravna Holistic Solutions
http://www.sravnatestprep.com

Holistic and Systematic Approach

Retired Moderator
User avatar
P
Status: The best is yet to come.....
Joined: 10 Mar 2013
Posts: 508
GMAT ToolKit User
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 16 Aug 2017, 21:44
VeritasPrepKarishma 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.


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.
Dinos had A too. Hence, Dinos had B too.

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).


In case of A, I am not clear how can we assume that the function of networks of blood vessels in Bat's wings is SAME as the function of networks of blood vessels in Dino's wings! It may happen that networks of blood vessels in Bat's wings are used for only to disperse heat generated in flight, whereas networks of blood vessels in Bat's wings are used for only to circulate blood or anything else.

Would you please help me to get out of it?
_________________

Hasan Mahmud

Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8406
Location: Pune, India
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 18 Aug 2017, 03:56
Mahmud6 wrote:
VeritasPrepKarishma 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.


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.
Dinos had A too. Hence, Dinos had B too.

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).


In case of A, I am not clear how can we assume that the function of networks of blood vessels in Bat's wings is SAME as the function of networks of blood vessels in Dino's wings! It may happen that networks of blood vessels in Bat's wings are used for only to disperse heat generated in flight, whereas networks of blood vessels in Bat's wings are used for only to circulate blood or anything else.

Would you please help me to get out of it?


I understand what you are saying. Here is something to consider: Even if you feel that it is an assumption, do you suggest another option as the answer? If yes, which one and why?
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

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

Manager
Manager
avatar
S
Joined: 17 Aug 2012
Posts: 135
Location: India
Concentration: General Management, Strategy
Schools: Copenhagen, ESMT"19
GPA: 3.75
WE: Consulting (Energy and Utilities)
GMAT ToolKit User
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 29 Aug 2017, 10:49
1
If we negate (E) - Heat generated by Sandactylus in flaping its wings in flight could have been dispersed by things other than the blood vessels in its wings. It does not invalidate our conclusion. However, if we negate (A), it reads Sandactylus would have had networks of blood vessels in the skin of its wings if these networks were of no
use of to Sandactylus . If the vessels were "of no use" to Sandactylus, this directly undermines the evidence on which the entire conclusion is based which is Network of blood vessels in bats' wings serve only to disperse heat generated in flight.
BSchool Forum Moderator
User avatar
D
Joined: 28 Mar 2017
Posts: 1167
Location: India
GMAT 1: 730 Q49 V41
GPA: 4
Re: Networks of blood vessels in bats' wings serve only to disperse heat  [#permalink]

Show Tags

New post 30 Aug 2017, 11:19
GMAT Club Bot
Re: Networks of blood vessels in bats' wings serve only to disperse heat &nbs [#permalink] 30 Aug 2017, 11:19

Go to page    1   2    Next  [ 29 posts ] 

Display posts from previous: Sort by

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

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


cron
Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.