Re: Paleontologist: Scientists have used evidence about bone structure to
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12 May 2024, 07:38
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.
The conclusion of the argument is the following:
the hypothesis that small genomes in birds were an evolutionary adaptation functioning to conserve energy for flight is probably false
The reasoning of the argument is basically the following. Birds evolved from dinosaurs that had small genomes. So, it's probable that the reason birds have small genomes is not that they evolved small genomes to conserve energy but simply that they evolved from ancestors that had small genomes and thus ended up with small genomes.
Which of the following, if true, most strengthen the argument?
This is a Strengthen question, and the correct answer will somehow help to support or confirm the conclusion.
A. Species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species.
This choice is interesting.
If species of flying animals other than birds typically have genomes no smaller than those of their most recent flightless ancestor species, then what we see is that, when animals have evolved from being flightless to flying, their genomes haven't become smaller.
While that information doesn't prove that birds didn't evolve relatively small genomes to conserve energy for flight, it helps to support that conclusion.
After all, if these other animals didn't evolve smaller genomes as they evolved to flying, then it could be that relatively small genomes aren't very helpful for flying.
Therefore, maybe birds didn't evolve small genomes to help with flying. In that case, it's quite possible that birds' genomes are relatively small just because their ancestors' genomes were relatively small.
So, this choice helps to confirm that the conclusion of the argument is correct.
Keep.
B. Flying mammals such as bats have genomes about the same size as modern bird genomes.
This choice weakens the support for the conclusion.
After all, if flying mammals such as bats have genomes about the same size as modern bird genomes, then we have other examples of flying animals with relatively small genomes. The fact that other flying animals also have relatively small genomes tends to indicate that flying animals evolve to have small genomes for some purpose that they all share, which could be to conserve energy for flight.
By supporting the conclusion that flying animals evolve to have small genomes to conserve energy for flight, this choice weakens rather than strengthens the case for the conclusion of the argument.
Eliminate.
C. Species with small genomes typically use energy much more efficienly than do closely related species with larger genomes.
If anything, this choice weakens the support for the conclusion.
After all, if this choice is true, then it make sense that birds would have evolved relatively small genomes to conserve energy for flight.
Of course, by indicating that that makes sense, this choice weighs against the conciusion of the argument.
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 information about other animal species doesn't indicate whether birds evolved relatively small genomes to conserve energy or just retained small genomes from their ancestors.
After all, these other animals have no clear relationship with birds. They just happened to have small genomes.
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.
If anything, this choice slightly weakens the argument.
After all, if this choice is true, then flightless ancestors of some birds had larger genomes than those birds have.
That information indicates that some birds evolved to have genomes that are smaller than their flightless ancestors had, which in turn tends to indicate that those birds have relatively small genomes because they fly, and thus benefit from conserving energy, whereas their ancestors didn't fly.
That train of logic goes against the conclusion of the argument.
Eliminate.
Correct answer: A