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Re: #15 - Hine’s emerald dragonflies are an endangered speci

PostPosted: Sun Mar 29, 2015 11:00 pm
by Administrator
Complete Question Explanation

Resolve the Paradox. The correct answer choice is (A)

This stimulus presents a surprising situation concerning certain dragonfly larvae. The dragonfly
species lives in wetlands, and can survive only in water. However, in the water they need to survive,
they are the prey of several species, including the red devil crayfish. Despite this fact, it turns out that
the dragonfly populations more often stay healthy in areas also occupied by red devil crayfish than in
areas without red devil crayfish.

This is a Resolve the Paradox question, and our job is to select the answer choice that explains why
the situation described in the stimulus is the case. More to the point, we need to find an answer
choice that causes the surprising situation to occur. In the context of this stimulus, we are looking for
something that causes the dragonfly populations to be healthier in places where the crayfish are also
located than in places lacking the crayfish. So, we are looking for an effect that is positive for the
dragonflies and caused by the presence of the crayfish. Do not spend time trying to think up what the
answer choice will actually say. Just be on the lookout for an answer choice that meets these criteria.

Answer choice (A): This is the correct answer choice because it describes a result that is positive
for the health of the dragonflies and is caused by the presence of the crayfish. These chambers dug
by the crayfish provide the dragonflies with a small body of water that they can use without being
subject to water-dwelling predators.

Answer choice (B): Here, the answer choice focuses on the adult dragonflies, which were not
involved in the surprising situation. Rather, it was the larvae that were eaten by crayfish and other
predators.

Answer choice (C): In this case, the answer choice makes the situation more confusing, since it
removes a potential benefit of the crayfish’s presence. If the crayfish did eat other species that prey
on the larvae, then the crayfish could potentially make the larvae safer, even if only slightly.

Answer choice (D): These other locations in which crayfish can be found but dragonflies are not are
irrelevant to the paradox.

Answer choice (E): This answer choice tells us that the crayfish are not dependent on the dragonflies,
but that does not tell us why the dragonfly populations are more likely to remain healthy when the
crayfish are present.

#15 - Hine’s emerald dragonflies are an endangered species

PostPosted: Wed Sep 30, 2015 11:31 am
by kaeeela6
Hello!

I am completely confused as to why A is the correct answer choice. I understand why the answer I selected (B) is wrong. I also understand why all the other answer choices are wrong too. But how does the red devil crayfish's digging chambers filled with water help the dragonfly larvae? Wouldn't hanging out in chambers dug by RDC subject the dragonfly larvae to predation by RDC? Is this the "best" answer choice simply because all the others are junk?

Thanks for your help!

Re: September 2014 Section 4 Q 15

PostPosted: Wed Sep 30, 2015 4:46 pm
by Robert Carroll
Kaela,

Because the larvae are already subject to predation, it's not inherently a problem that these chambers are dug by the predators. We don't have any reason to think this will make things worse for the larvae. Since the larvae need water, a wetland that dried up would be a threat to their survival, but the chambers provide a water-filled habitat for them, so the predators are actually helpful to the larvae survival in this way. This resolves the paradox.

The correct answer must resolve the paradox, and not merely be "leftover" because the other answers clearly do not resolve the paradox. The correct answer is always positively correct. If you are sure 4 answers do not resolve the paradox, the one left will be right, but this is only one way to get to the answer - the other way, by finding what you are looking for (a resolution to the paradox) rather than eliminating what's not right, will always work.

Robert Carroll

Re: September 2014 Section 4 Q 15

PostPosted: Wed Sep 30, 2015 5:25 pm
by kaeeela6
Thank you Robert! That makes sense.

#15 - Hine's emerald dragonfiles are an endangered species

PostPosted: Mon Jan 14, 2019 7:16 pm
by LetsGetThis180
Paradox Question - The correct answer choice is (A)

While I was taking this test I had some trouble between A and B. I'm having a hard time to realize how answer choice A is correct. I thought B was able to link the two situations more since it helps to explain Red devil crayfish only prey on larvae and explains how the dragonfly populations are more likely to remain healthy in areas where red devil crayfish are still present. I just need more elaboration on why answer A is a better answer choice versus B.

Thanks

Re: #15 - Hine's emerald dragonfiles are an endangered speci

PostPosted: Tue Jan 15, 2019 3:41 pm
by Stephanie Turaj
Hi LetsGetThis180,

Thanks for the question! I moved your post to the thread discussing this topic. Please review the official administrator explanation and the discussion above, and let us know if this helps, or if you still have further questions! :) Thanks!