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Raman109
Understanding the argument - ­
Paleontologist: Scientists have used evidence about bone structure to infer that carnivorous dinosaurs like Trynnasauraus rex had genomes - sets of genetic information in their DNA - much smaller than those of most modern mammals. - background info. 
Modern birds have genomes about the same size as those of human dinosaurs, from which they evolved. - Fact. 
Therefore, the hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false. - Conclusion. 

As the size of the genome of birds and carnivorous dinosaurs like Trynnasauraus rex (could not fly) is the same, we can't say that birds have smaller genomes as an evolutionary adaptation to conserve energy for flight. 

Which of the following, if true, most strengthen the argument?

Option Elimination - 

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species. - strengthens the conclusion that small bird genomes were not an evolutionary adaptation to conserve energy for flight.

B. Flying mammals such as bats have genomes about the same size as modern bird genomes. - out of scope. 

C. Species with small genomes typically use energy much more efficienly than do closely related species with larger genomes. - but in birds, there is no change in genomes with respect to carnivorous dinosaurs like Trynnasauraus rex. Out of scope. 

D. Many animal species that lived in the period as Tyrannosaurus rex but were not ancestors of modern birds also had relatively small genomes. - out of scope. 

E. At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have. - out of scope. 
­Raman109 I chose option D because it shows that there are many animal species that did not have flying capabilities but still had small genomes, that is why I had a confusion among options A and D. I got your point justifying A nevertheless how is option D out of scope?­ plus how am I to completely eliminate this option
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­ameya.satyawadi

It seems like option D is not connected to the conclusion. It has no relationship/effect on the argument that small genomes were not an evolutionary adaptation. 

Option A strenghtens the argument. If we take another look, the flying animals with small genomes evolved from their flightless ancestors, who did not need small genomes to conserve energy to fly-- since they did not fly. So the modern flying animals did not adopt the small genomes out of evolutionary necessity either. ­
ameya.satyawadi
Raman109
Understanding the argument - ­
Paleontologist: Scientists have used evidence about bone structure to infer that carnivorous dinosaurs like Trynnasauraus rex had genomes - sets of genetic information in their DNA - much smaller than those of most modern mammals. - background info. 
Modern birds have genomes about the same size as those of human dinosaurs, from which they evolved. - Fact. 
Therefore, the hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false. - Conclusion. 

As the size of the genome of birds and carnivorous dinosaurs like Trynnasauraus rex (could not fly) is the same, we can't say that birds have smaller genomes as an evolutionary adaptation to conserve energy for flight. 

Which of the following, if true, most strengthen the argument?

Option Elimination - 

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species. - strengthens the conclusion that small bird genomes were not an evolutionary adaptation to conserve energy for flight.

B. Flying mammals such as bats have genomes about the same size as modern bird genomes. - out of scope. 

C. Species with small genomes typically use energy much more efficienly than do closely related species with larger genomes. - but in birds, there is no change in genomes with respect to carnivorous dinosaurs like Trynnasauraus rex. Out of scope. 

D. Many animal species that lived in the period as Tyrannosaurus rex but were not ancestors of modern birds also had relatively small genomes. - out of scope. 

E. At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have. - out of scope. 
­Raman109 I chose option D because it shows that there are many animal species that did not have flying capabilities but still had small genomes, that is why I had a confusion among options A and D. I got your point justifying A nevertheless how is option D out of scope?­ plus how am I to completely eliminate this option
­
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don't really understand this question. Human dinosaurs --- what is this in the question?
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Human dinosaurs " are the recent flightless ancestors from which birds evolved.
MartyMurray KarishmaB
Can you please help on this question ?

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Basically we need to prove that the small genomes in birds are not an evolutionary adaptation to conserve energy during flight.
It was small in case of their recent ancestors and that's why it is also small in them ( birds).
Option A states that this feature of small genome is present amongst other flying animals too ( other than birds ) and also in case of their flightless ancestors .
Since this same thing can be seen amongst other flying animals too ,
the conclusion gets strengthened that the evolutionary adaptation is not what is causing the small genomes. Small genomes are present in the birds because they were present amongst their ancestors . They ( the birds) simply inherited it just the way other flying animals did from their flightless ancestors.
MartyMurray Sir / KarishmaB maa'm , request you to check my reasoning.

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sayan640
MartyMurray Sir / KarishmaB maa'm , request you to check my reasoning.
­This part doesn't capture what choice (A) says:
Quote:
Option A states that this feature of small genome is present amongst other flying animals too ( other than birds ) and also in case of their flightless ancestors .
Since this same thing can be seen amongst other flying animals too
The choice (A) says the following:

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

Notice that choice (A) does not say species other than birds have "this feature of small genome." Quite the contrary, it says that their genomes are "no smaller" than those of their ancestors. In other words, they may be quite large.

So, the point is that other flying animals do not have genomes that are smaller than those of flightless ancestors even thought they fly. This information indicates that animals that evolve to fly don't tend to evolve smaller genomes. That information indicates that birds have small genomes just because their ancestors did.
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Thank you marty !! 
MartyMurray
sayan640
MartyMurray Sir / KarishmaB maa'm , request you to check my reasoning.
­This part doesn't capture what choice (A) says:
Quote:
Option A states that this feature of small genome is present amongst other flying animals too ( other than birds ) and also in case of their flightless ancestors .
Since this same thing can be seen amongst other flying animals too
The choice (A) says the following:

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

Notice that choice (A) does not say species other than birds have "this feature of small genome." Quite the contrary, it says that their genomes are "no smaller" than those of their ancestors. In other words, they may be quite large.

So, the point is that other flying animals do not have genomes that are smaller than those of flightless ancestors even thought they fly. This information indicates that animals that evolve to fly don't tend to evolve smaller genomes. That information indicates that birds have small genomes just because their ancestors did.
­
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Hypothesis: Genome sizes shrank to develop the ability to fly (by developing the ability to conserving energy).
Author says hypothesis is not true. We have to strengthen the author's statement.
So we need to show that Small genomes are not required for / Not related to flying ability OR genome sizes did not shrink while the species developed ability to fly.

A) Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

Genome size of Flying species greater than or equal to flightless species. Which supports the main conclusion that small genomes are not required for / Not related to flying. Genome sizes have remained constant or increased during the development of ability to fly in the species.

B) Flying mammals such as bats have genomes about the same size as modern bird genomes.
Doesn’t tell anything about the logic/conclusion.

C) Species with small genomes typically use energy much more efficiently than do closely related species with larger genomes.
Small genomes are co-related to energy conservation. Weakness the argument.

D) Many animal species that lived in the same period as Tyrannosaurus rex but were not ancestors of modern birds also had relatively small genomes.
Out of scope
. Not linked to modern birds.

E) At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have.
Weakens the argument. Flying species had smaller genomes than those of flightless species.­
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I deleted the previous response because I wasn't able to solve the question applying the process and I found out why. Here is my corrected interpretation.

The conclusion is that the hypothesis that small genomes in birds were an evolutionary adaptation (ATTACKED REASON) to conserve energy for flights is wrong (SUPPORTING EVIDENCE) because the small genomes of birds were only due to their ancestors, the T-Rex. So the conclusion is not questioning the genome size but why it is this small in birds. The conclusion is tricky because it plays on one’s visual interpretation of the information. It uses a prehistoric large animal, such as a dinosaur, to lead the reader down the wrong path by equating genome sizes. And if one doesn't know what genome sizes are, one might actually think that if it is small in a dinosaur and it is almost the same size in a bird, it must be huge in a bird. However, genome size refers to the amount of DNA contained in a genome. It's not a physical size, something I didn't know, and I feel that outside knowledge is needed to actually understand that this is not a physical size comparison in birds and dinosaurs – but maybe it's just me. Here, an example is presented to explain why a hypothesis is incorrect. We are asked to strengthen the conclusion of the researcher. So what is the researcher assuming? He is assuming that if it the case in birds, it will be the case in all flying animals that originated from non-flying ancestors. To do that, we will need to present information that the small genomes in birds are not an evolutionary adaptation for flight but are due to the ancestors. So we need a similar case that will make us believe more in the conclusion of the researcher. Choice A does that. It's not proving that the small genomes are not an evolutionary adaptation but it presents a similar case with a similar outcome where the genomes of the animals, even if they are now able to fly, didn't change in size compared to their non-flying ancestor species.
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keywords to consider ''adaptation and energy for flights'

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species. - x species could not fly however their offspring could (and they have small genomes) - but has not evolved. Hence A is correct.­
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Premise 1: Scientists have inferred that carnivorous dinosaurs like Tyrannosaurus rex had smaller genomes compared to modern mammals.
Premise 2: Modern birds, which evolved from carnivorous dinosaurs, also have small genomes.
Conclusion: Since dinosaurs already had small genomes, the hypothesis that small genomes in birds evolved as an adaptation to conserve energy for flight is probably false.
Shadow Answer: To strengthen the argument, we need evidence that small genomes were not unique to birds or flight but were already present in the dinosaurs that predated birds.
(A) Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

This option suggests that flying animals (other than birds) typically do not have smaller genomes than their flightless ancestors. This strengthens the argument by showing that small genomes are not necessarily tied to flight, weakening the idea that small genomes evolved in birds specifically for flight energy conservation. Hold on
(B) Flying mammals such as bats have genomes about the same size as modern bird genomes.

This option points out that flying mammals like bats have genomes of similar size to modern birds. While this provides some context, it does not directly strengthen the argument about dinosaurs and the evolutionary function of genome size in birds. The size of genomes in bats does not affect the argument about whether small genomes in birds evolved specifically for flight. Eliminate
(C) Species with small genomes typically use energy much more efficiently than do closely related species with larger genomes.

This option suggests that small genomes lead to more efficient energy use, which could actually support the idea that small genomes in birds were an adaptation for flight (to conserve energy). This would weaken the argument rather than strengthen it. Eliminate
(D) Many animal species that lived in the period as Tyrannosaurus rex but were not ancestors of modern birds, also had relatively small genomes.

This option states that small genomes were common in various species during the same period as Tyrannosaurus rex, not just in those that evolved into birds. But the argument is about whether birds evolved relatively small genomes to conserve energy or just retained small genomes from their ancestors. Eliminate
(E) At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have.

This option suggests that some flightless species that evolved from dinosaurs had larger genomes than modern birds. While this is interesting, it does not directly address the relationship between genome size and flight. It focuses on genome size differences between species, but it does not show that small genomes were not related to flight. ­Eliminate Correct Answer:

(A) Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.
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Hi MartyMurray KarishmaB

I have a doubt because of Option C. If in the arguement it is mentioned that 'Modern birds have genomes about the same size as those of carnivorous dinosaurs, from which they evolved.' then why can't we take Option C as strengthener considering that both Car. Dinosaur and Birds had small genomes and were using energy very much efficiently so Birds didn't evolve to small genomes to conserve energy.

Kindly can you help ?

Thanks !
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Raman109
Paleontologist: Scientists have used evidence about bone structure to infer that carnivorous dinosaurs like Trynnasauraus rex had genomes - sets of genetic information in their DNA - much smaller than those of most modern mammals. Modern birds have genomes about the same size as those of carnivorous dinosaurs, from which they evolved. Therefore, the hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false.

Which of the following, if true, most strengthen the argument?

A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.
B. Flying mammals such as bats have genomes about the same size as modern bird genomes.
C. Species with small genomes typically use energy much more efficienly than do closely related species with larger genomes.
D. Many animal species that lived in the period as Tyrannosaurus rex but were not ancestors of modern birds, also had relatively small genomes.
E. At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have. ­

Premises:

C dinosaurs like T rex (no flight) had much smaller genomes than those of most modern mammals.
Modern birds have genomes about the same size as those of C dinosaurs, from which they evolved.

Conclusion: Hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false.

The author says that birds evolved from C dinos and they have the same small genomes as those of C dinos. So looks like they have inherited small genomes were C dinos. These small genomes are not an adaptation in birds to conserve energy for flight.

We need to strengthen this so we are looking for something that tells us - yes, birds just inherited the small genomes. They did not evolve to have small genomes to conserve energy for flight. So look for this - "Flight has nothing to do with small genomes".


A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.

Flying animal genomes are no smaller than those of their non flying ancestors. So it looks like birds and animals don't evolve to have small genomes to conserve energy for flight. It they were evolving to have small genomes, then the genomes of flying animals would be expected to be smaller than those of their non flying ancestors. Hence this is further evidence supporting the author's conclusion. Correct.

B. Flying mammals such as bats have genomes about the same size as modern bird genomes.

Flying mammals genomes are same as modern bird genomes. Both fly. Both have same size genomes. No comparison between non flying animals and flying animals/birds.

C. Species with small genomes typically use energy much more efficienly than do closely related species with larger genomes.

Nothing related to flight given here. Do birds evolve to have smaller genomes to conserve energy for flight? Doesn't say. Note that even if it was given that it helps in flight, this would strengthen the hypothesis, not the author's argument. It would weaken the author's argument. We are looking for "Flight has nothing to do with small genomes". This option says that small genomes use less energy (so actually may be useful during flight). Hence it would go the opposite way.
Typical GMAT trap!

D. Many animal species that lived in the period as Tyrannosaurus rex but were not ancestors of modern birds, also had relatively small genomes.

Just says that small genomes were common at that time. No connection to flight.

E. At least some flightless species that evolved from carnivorous dinosaurs and were ancestors to modern bird species had much larger genomes than modern birds have. ­

Again, it somewhat weakens our argument. We are looking for "Flight has nothing to do with small genomes". But this says that there are some bird ancestors with much larger genomes. Then it could be possible that birds evolved to have smaller genomes to conserve energy for flight. Goes against what we are looking for.

Answer (A)


Some discussions on strengthen questions:
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https://youtu.be/uPdDYbYpXuI
https://youtu.be/9o3y4Hz16es
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