zoezhuyan
GMATNinja,
gmat1393,
GMATNinjaTwo,
nightblade354dear experts,
I am still confused with B,D,E although I read the whole thread, would you please clarify further and point out what I missed.
I picked up B because
Quote:
(B) If the Arctic warming continues, guillemots’ current predators are likely to succeed in extending their own range farther north.
if B is true, then why guillemots go to farther north, where maybe danger(if more predators) or similar danger (if as many as predators).
B weakens the conclusion by showing that it is less likely for guillemots to extend northward.
as for D,
before the temperature rise, the guillemots are limited southmost,
if the warming continues, the thin ice disappears, then it is likely for guillemots to extend northward to find a proper area.
I still think D strengthens the conclusion by showing warming causes ice disappear and then cause guillemots extend northward.
as for E
Quote:
(E) The fish that guillemots eat are currently preyed on by a wider variety of predators in the southernmost Arctic regions than they are farther north.
if farther north area is less dangerous, why not go there,
E shows another reason -- fewer predator--for guillemots to go northward, instead of warming,
Doesn't E weakens the conclusion that warming cause the extend of range.
GMATNinjaTwo
The author thinks that the rise in temperatures will cause the birds' range to be extended northward along the coast.
Take another look at the exact wording of the conclusion: "if the warming continues,
the guillemots’ range will probably be enlarged by being extended northward along the coast."
The author is primarily arguing that the guillemot's range will be enlarged. He/she then further clarifies exactly
how this will occur: "by extending northward along the coast."
With that in mind, take another look at (D):
Quote:
D) If the Arctic warming continues, much of the thin ice in the southern Arctic will disappear.
From the passage, we know that the guillemots depend on thin ice near the coast, because they feed on the fish that gather there. If this ice disappears, then the guillemots potentially will not be able to feed!
So, if (D) is true, then the guillemots will probably extend northward to find a suitable climate. But will their range be
enlarged, as the author argues?
Not necessarily. Because the southern arctic region will no longer be suitable for guillemots, then moving northward could just
shift the range of the birds to a different location, rather than actually
enlarging their range.
(D) weakens the author's argument, so it is the correct answer.
Quote:
(B) If the Arctic warming continues, guillemots’ current predators are likely to succeed in extending their own range farther north.
The guillemots currently coexist with their predators in the southern arctic region. If both the guillemots and their predators extend northward, there is nothing to suggest that the predators will completely stamp out the guillemots in the north. The guillemots' range will still be enlarged, so the information in (B) does not weaken the author's argument.
Quote:
(E) The fish that guillemots eat are currently preyed on by a wider variety of predators in the southernmost Arctic regions than they are farther north.
The author argues that guillemots will extend northward because rising temperatures will allow them to raise chicks in more northerly areas of the coast.
(E) just tells us that the guillemot's food source may
also have a good shot of thriving farther north. This actually provides additional
support for the argument that "if the warming continues, the guillemots’ range will probably be enlarged by being extended northward along the coast." It doesn't matter that this evidence is different than the evidence supplied in the passage -- it doesn't weaken the author's conclusion, so eliminate (E).
I hope that helps!
Thank you very much for very detailed and understandable explanation. I have one concern regarding (c): Answer (C) says that not
be alive in the south, but not as many quantity as before. This inference implies that range of Guillmots will actually enlarge. So, this answer does not weaken the conclusion. If the answer (C) says, "ALL of the thin ice" will disappear, then I would definitely choose (C). Can you please comment on this opinion?