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The discrepancy is that even though the GM salmon bred with the wild one, the offsprings should have some genes present which could identify them. But no trace was found. So there could be a very few reasons for that- one is that GM modified genes had very less chances of survival inn environment or the genes were recessive and could not reflect in the offsprings. A is one option which is a possiblity. B says that natural predators avoid GM salmon but as they tested earlier genetic testing found genes in the wild salmon so atleast one mutation was confirmed.
C is not related to the passage as after the spawn all GM salmon were removed. D is also on the similar lines.
If a few salmon escaped there is no proof that they mutated or not. So E is also wrong.
Bunuel
A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
E. Fewer than ten adult GM salmon escaped before the facility was closed.

 


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I was considering both options A and C. My pre-thinking was that the GM gene might reduce the salmon’s shelf-life or survival, or maybe the salmon simply didn’t stay in that river long enough to be found in later samples. I ultimately chose option A because it offers a more solid explanation.

While choice C is possible, the phrase “more likely to escape” doesn’t necessarily mean the salmon would escape. And if any had remained, the researchers should have detected them, given the large sample size.
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After three years, no traces of GM genes found in wild salmon

A. Because of the lower survival rates, overtime the GM salmons might have vanished from the ecosystem. Correct

B.
This weakens the outcome. If this was true, there would be more GM salmons than wild ones. Eliminate

C.
This does not explain why GM traces were present in the first study and vanished after three years. Eliminate

D.
If they returned after few years, then why there where no traces of GM genes found. Also, it is contradicting to the presence of juvenile wild salmons in the first study. Eliminate

E. No of GM salmons escaped before the first study, does not explain their vanishing after 3 years. Eliminate

Answer: A
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we have to select option which MOST helps to explain the discrepancy, so multiple options may be correct explanation but we need to find the best.

A Correct. since offsprings have significantly lower survival rates, hence it is possible that in 3 years all the offsprings died and no trace of GM genes were found
B: although they tend to avoid but that does not mean there will be no trace at all
C: GM salmon more likely to escape but still not 100% escape so difficult to say that it is the explanation because no trace was found
D: Vague statement as we don't know in how many years they return
E: out of context
Bunuel
A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
E. Fewer than ten adult GM salmon escaped before the facility was closed.

 


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A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
If offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon then after the facility was then shut down and all remaining GM salmon were removed, presence of GM genes in juvenile wild salmon disappeared because of lower survival rates of offsprings.
Correct

B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
If natural predators tend to avoid genetically modified salmon because of differences in their taste, then there should have been traces of GM genes in sampled wild salmon in the follow-up studies.
Incorrect

C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
If genetically modified salmon are more likely to escape into ocean environments than remain in rivers, then interbring with wild salmon in a local river system could not have been possible.
Incorrect

D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
If wild salmon in the river system typically migrate to distant spawning grounds and return only every few years, then also interbreding could have happened and traces of GM genes in offsprings could have been available. The statement does not help to explain the discrepancy between the two studies.
Incorrect

E. Fewer than ten adult GM salmon escaped before the facility was closed.
It hardly matters how many adult GM salmon escaped before the facility was closed, but what matters is how traces of GM genes in wild salmon disappear in follow-up study after traces were observed in initial study after interbreeding.
Incorrect

IMO A
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A phenomenon: Juvenile wild salmon have GM genes as GM salmon escape into a local river system. After that GM salmon were removed,
A Paradox: Three years later we don't find any trace of GM genes, even in those cross-bred juvenile wild salmon. How come?
- Choice (A): make senses. Since the cross-bred are more likely to die, this population will disappear from the local river system
- Choice (B): If anything, this will puzzle us even more BECAUSE the cross-bred are more likely to survive
- Choice (C & D): doesn't help since juvenile's GM genes could still be there
- Choice (E): the number of the original GM salmon doesn't matter since they were all already removed
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A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon. - This gives us an explanation that the hybrids were already present, but they had low survival rates, so in the second study, they might be dead.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.- This gives us higher survival rates, so no
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.-so they escaped? How does this explain the discrepancy
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.- Issue here is not about their returning, but what happened to them
E. Fewer than ten adult GM salmon escaped before the facility was closed- Again why did they t=disappear not how many of them escaped
IMO:A
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A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.-- If they died off then fewer of these genes remained In wild population even if they may have been transferred before dying
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.-- predators are irrelevant
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.--all salmons were sampled doesn't matter river or ocean
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.--doesnt explain why they were absent after 3 years and that they could return
E. Fewer than ten adult GM salmon escaped before the facility was closed.-- so why were there no genes

Ans A
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We need to find something in the options that can explain why the GM genes disappeared from the wild salmon population.


A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
- This explains that hybrid offspring didn’t survive because they naturally died out over time.

B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
- This is opposite to what we are looking for. It supports the higher survival rate, not disappearance.

C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
- Close but it doesn’t explain the disappearance of genes from the river population.

D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
- irrelevant

E. Fewer than ten adult GM salmon escaped before the facility was closed.
- Still genetic testing of juvenile wild salmon confirmed the presence of GM genes. So, this statement is irrelevant.


Answer: A



Bunuel
A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
E. Fewer than ten adult GM salmon escaped before the facility was closed.

 


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Bunuel
A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
E. Fewer than ten adult GM salmon escaped before the facility was closed.

 


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A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
--> Lower survival rates of offspring of genetically modified and wild salmon would explain the reason.

B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
--> This weakens the explanation

C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
--> No data available for this to be verified as a causing factor

D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
--> GM salmons are not referred here

E. Fewer than ten adult GM salmon escaped before the facility was closed.
--> Irrelevant. offsprings could have spread and increased.


Option A
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A) lower survival rate offsprings can only explain why GM genes didn't propogate
B) if this is true it means genetically modified salmon exists in the river and may interbred also
C) if genetically modified escape into oceans, it doesn't means there interbred offsprings will also do so
D) after first spawning season GM genes found in offsprings, which means migrating to distant doesn't explain absence of genes
E) even fewer genetically modified salmon can change the genes of offsprings if they interbred actively


BunuelA research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
E. Fewer than ten adult GM salmon escaped before the facility was closed.

 


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A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
That would explain why the GM genes were present early (in juveniles), but absent later (because those offspring didn't survive to adulthood or reproduce).

B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
If predators avoid GM salmon, those fish would survive better, meaning GM genes would persist, not disappear.

C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
Escaping to the ocean doesn't explain why GM genes were present in juveniles but gone three years later.

D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
That might explain why fish weren't seen for a time, but the study sampled hundreds of wild salmon, enough to detect GM genes if they were still present.

E. Fewer than ten adult GM salmon escaped before the facility was closed.
A small number of GM salmon explains why there were few GM genes to begin with, but doesn't explain why they disappeared after being detected in offspring.

The right answer is A
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Bunuel
A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

GM genes were present in Juvenile wild salmon which signifies the genes can be transferred from parents to off springs. However, in follow-up study no GM genes were found -> Either all salmons with the genes died, or due to some other reason they were wiped out..

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon. - Correct, if Juvenile wild salmon with GM genes won't survive than the salmon won't be able to reproduce and the genes won't be able to survive either.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.- this would have caused the increase in such salmon population.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers. - Water bodies are not relevant, we have not details whether the sample was collected from ocean or rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years. - there will be some trace of GM genes in this case.
E. Fewer than ten adult GM salmon escaped before the facility was closed. - there is no support why there is no trace of the GM genes left.
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A because that is the best of the choices available here, if the GM and wild salmon's offspring had higher survival rates than of that of 2 wild salmon, study would have found some trace atleast of GM genes, which is not the case here. Rest of the options can be eliminated right away as they dont explain the discrepancy in any way.
Bunuel
A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.

Which of the following, if true, most helps to explain the discrepancy between the two studies?

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
E. Fewer than ten adult GM salmon escaped before the facility was closed.

 


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We know that the initial study found GM genes in juvenile wild salmon. Then the facility shut down and all GM fish were removed. After 3 years, a follow-up study found no trace of GM genes in wild salmon.

But why?
Let's look at the options :
A perfectly explains why the genes show up initially but then vanish. If the hybrids have much lower survival in the river, then we can expect that their genes would disappear over time.
B doesn't help with discrepancy because if predators avoid GM salmon then that would actually protect the hybrids.
C doesn't explain anything because removing the parent population doesn't help in understanding the disappearance of hybrids
D doesn't explain why GM genes vanish entirely and how a study sampling from 100s cannot spot even a few cases.
E doesn't explain the complete disappearance. Even if only 10 adults escaped, we can still expect some of their genes to persist.

So the best explanation is A.
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Paradox: GM genes found in juvenile Wild salmon > when all GM salmon removed> no GM genes 3 years later
We need something to explain the complete disappearance of GM genes from the wild salmon.

A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon. - correct. This explains the disappearance of GM genes from the hybrid salmon- if their survival rates were much lower- it is likely over the years that such offsprings decreased - till they completely dwindled.

B. Natural predators tend to avoid genetically modified salmon because of differences in their taste - wrong. This is opposite of what we want. IF predators avoid GM salmon, then they are more likely to survive than Wild salmon and we should find GM genes more, which is not the case.

C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers- wrong. This talks about GM salmon, while our focus is more on Wild salmon and GM genes found in Wild Salmon. This does not resolve the discrepancy.

D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years - wrong. The migration pattern of Wild salmon is irrelevant to solving the paradox here. Even if they migrate to other grounds, they should still carry the GM genes when they return - does not explain the total disappearance of GM genes from Wild Salmon.

E. Fewer than ten adult GM salmon escaped before the facility was closed - wrong. Again, does not resolve the paradox. Fewer than 10 GM could have escaped, but our problem is not how many GM escaped, but why after they escaped and interbed with Wild Salmon, did their genes disappear.


Answer is A
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A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
Relevant as it directly addresses the discrepancy. If the hybrids had low survival, they likely died off before reproducing. This would explain why GM genes vanished in just a few years.

B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
Irrelevant as it has the opposite effect since this would suggest GM salmon survive better, not worse.

C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
Irrelevant as it doesn't address the hybrid offspring survival. It tells us where the GM salmon go not why their genes disappeared from the river’s wild population.

D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
Somewhat relevant but too speculative. If the fish that carried GM genes return only every few years, we might miss them in a 3 year sample. But this assumes that all GM gene carriers were migratory and none return within 3 years.

E. Fewer than ten adult GM salmon escaped before the facility was closed.
Irrelevant as even a small number of escapees could introduce GM genes. It doesnt explain why genes found in juveniles would vanish in 3 years.



A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
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