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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.
Similar Question : LINK 1 LINK 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 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.
Similar Question : LINK 1 LINK 2
diegmat
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).
This question and a very similar subsequent official question are discussed here: https://youtu.be/ZQnhC4d5ODU
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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:
Now that we understand the argument, we need an assumption on which that argument depends:
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.
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.
(A) is the best answer.
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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:
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:
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:
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:
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:
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.
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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
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
General Discussion
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
(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
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).
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).
kishgau
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.
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(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!
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!
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
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
VeritasPrepKarishma
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?
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Hasan Mahmud
Mahmud6
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.
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karishma
Could you please explain why negation did not worked out for B here?
Many thanks
Vikas
Posted from my mobile device
Could you please explain why negation did not worked out for B here?
Many thanks
Vikas
Posted from my mobile device
vikasbansal227
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.
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chshashankreddy
:
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.
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Srinivasan Vaidyaraman
VeritasPrepKarishma
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?
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Hasan Mahmud
Mahmud6
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?
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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.
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.
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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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Someone please explain Why B and D are wrong confused here 
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