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Q22 - Last summer, after a number

by LSAT-Chang Thu Sep 15, 2011 4:19 pm

Hellooo, I correctly chose B for this one, but I was very very tempted by E. I didn't know how to eliminate it. Could someone help me understand why E does not explain this paradox? I thought it does because if P. australis cannot survive in large numbers in seawater that does not contain significant quantities of domoic acid, and we know that P. australis population dropped, we know that there is not much domoic acid, so can't we conclude that it's safe to eat anchovies?
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Re: Q22 - Last summer, after a number

by demetri.blaisdell Fri Sep 16, 2011 12:41 pm

Good question. I love to see students going the extra mile and asking questions even when they get the right answer.

The result we need to explain is why it's safe to lift the ban. To do that, we will need to connect the levels of P. australis plankton to the reduction of domoic acid levels in the anchovies. (B) gives us exactly what we need. The anchovies apparently only eat enough P. australis to get poisonous levels of domoic acid when the population is large. Now that the population small, the levels will no longer be toxic.

(A) actually makes it more difficult to explain the result. If there are other types of plankton that cause toxicity, why should we reduce the ban when we only know that P. australis levels are down?

(C) is well out of scope. This background information gets us no closer to explaining why the ban should be lifted.

(D) is also out of scope. Though it connects the populations of the plankton and the anchovies, it tells us nothing about how toxic the fish are.

(E) is the most tempting wrong answer choice. There are two problems here. The most obvious is that it doesn't give us a mechanism by which the anchovies actually take in the domoic acid. In (B) we are told the anchovies eat the P. australis, but here we don't know that. We don't have any evidence that simply by swimming around in water with domoic acid, the fish will absorb or swallow in toxic levels.

The other slightly geekier problem with (E) is a negation issue. We are told: Big P. australis population --> high domoic acid. We can't use that piece of evidence to conclude that if there is a low population there are low levels of domoic acid. There could be another reason why the levels are low (predatory plankton, whales, mercury poisoning, etc).

I hope this helps clear up your confusion. (E) is a great wrong answer choice that brings up some really classic LSAT tricks. Let me know if you have any further questions.

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Re: Q22 - Last summer, after a number of people

by irene122 Tue Sep 20, 2011 4:28 pm

I also hesitate between B and E, but after seeing "along with numberous other compounds" I cross out E--it brings in stuff out of scope.

Could any one help and point out whether I cross out E out of good reason?

Thanks in advance!
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Re: Q22 - Last summer, after a number of people

by demetri.blaisdell Tue Sep 20, 2011 10:23 pm

Be very careful about knocking out the answer choice for that reason. We're only concerned with the domoic acid but if they give us other compounds that's not a reason to rule it out.

Take a look at my explanation and try to think about other ways to knock this out. The best LSAT takers are not satisfied with just one reason to knock an answer choice out. Let me know what you think.

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Re: Q22 - Last summer, after a number

by sumukh09 Fri May 03, 2013 10:35 am

Could another reason for eliminating E be that it says P. australis require "significant" quantities of domoic acid? We don't need significant quantities of domic acid to be in the waters, nor do we know how the amount of domic acid plays any role in the argument.
 
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Re: Q22 - Last summer, after a number

by LsatCrusher822 Wed Aug 10, 2016 2:39 am

I think a better explanation why E is incorrect is that we cannot be sure that there is a drop in domoic acid!

Basically, E) says that P.australis' survival requires significant amounts of domoic acid

P.australis survive --> significant q domoic acid along with numerous other compounds

Just because the there is a "dramatic drop" in P.australias (meaning not many of them actually survives), doesn't mean that domain acid is lacking in the environment!

Now if the answer said that large quantities of domoic acid is sufficient for P.australias, this would be a different story! With a dramatic drop in P.australias' population, we could logically conclude that there is less domoic acid in the ocean.
 
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Re: Q22 - Last summer, after a number

by weid247 Sun May 30, 2021 4:32 am

Because I do it wrong the first time for choosing E, I would like to explain why E is wrong.
p plankton can’t survive in the seawater that does not include enough neurotoxin domoic acid along with other compounds. It is said the domoic acid along with other compounds is necessary. Without domoic acid, P can’t survive. But it is not to say when p can’t survive, it must b true not enough domoic acid. Perhaps domoic acid is still enough, just lack of the alongside compounds. Thus we can’t get the result the neurotoxin domoic acid is dropping to safe and left the ban.