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Strange OG question

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Strange OG question

by nonameee » Wed Jan 25, 2012 9:58 am
One of the more reliable methods of determining regional climatic conditions in prehistoric periods is to examine plant pollen trapped in glacial ice during ancient times. By comparing such pollen samples with spores taken from modern vegetation, scientists can figure out approximately what the weather was like at the time of pollen deposition. Furthermore, by submitting the prehistoric samples to radiocarbon dating techniques, we can also determine when certain climatic conditions were prevalent in that portion of the globe.

Which one of the following may be inferred from the information in the passage?
(A) The earth has undergone several glacial periods.
(B) Radiocarbon dating can be corroborated by glacial evidence.
(C) Similarities between prehistoric and contemporary climates do not exist.
(D) Pollen deposition is a fairly continuous process.
(E) Certain flora are reliably associated with particular climatic conditions.

OA: E

Can someone please explain what I'm missing here?

The stimulus talks about examining plant pollen. (E) talks about flora. How can (E) be the correct answer????

IMO (B) is the correct answer because this is exactly what the stimulus says:

Furthermore, by submitting the prehistoric samples to radiocarbon dating techniques, we can also determine when certain climatic conditions were prevalent in that portion of the globe.
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by ArunangsuSahu » Wed Jan 25, 2012 10:24 am
This is an INFERENCE Question..
(B)INCORRECT due to "can be"

(E) "reliable associated"...a SURE thing---CORRECT
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by nonameee » Wed Jan 25, 2012 10:25 am
Could you please address the points that I've raised?
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by ArunangsuSahu » Wed Jan 25, 2012 10:41 am
It would have been correct if this was written
"Glacial evidence can be corroborated by Radio Carbon Dating"
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by nonameee » Wed Jan 25, 2012 10:45 am
Why is the order necessary?

Also, in my initial question I questioned the validity of E:

The stimulus talks about examining plant pollen. (E) talks about flora. How can (E) be the correct answer????
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by chris@magoosh » Wed Jan 25, 2012 12:30 pm
Hi Nomanee,


I agree that on the surface this question can seem quite strange. The correct answer (E) ostensibly introduces something not mentioned in the passage - flora.

It looks like the GMAT expects test takers to know that flora refers to any plants/vegetation. (Otherwise there is no way you can make this connection).
Thus when the passage says, "By comparing such pollen samples with spores taken from modern vegetation..." we can substitue flora for vegetation.

Rewriting this sentence we get, "By comparing the pollen samples (from ancient flora) withs spores taken from modern flora...".

As for Answer (B), it reverses the order of 'radiocarbon dating' and 'glacial evidence.' It is the radiocarbon dating that corroborates the glacial evidence.

To say that radiocarbon dating is corroborated by glacial evidence is to imply that the validity of radiocarbon dating is backed up by the glacial evidence.

I hope that helps :)
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by nonameee » Wed Jan 25, 2012 12:43 pm
Chris, thanks a lot for your reply.

I know what flora and vegetation mean :) I just thought that they've substituted flora for pollen. Now I see that they subtstituted that for vegetation (which made it all very confusing). But even in this case, I have some very serious reservations:

To determine regional climatic conditions scientists:
1) take pollen from prehistoric plants
2) compare it to spores from modern vegetation

(E) says that certain flora (= plants, vegetation) is associated with particular conditions. But I still don't see how comparing (1) and (2) infers (E).

It's like I compare lights (a very small aspect of a car) of cars from the beginning of the 20th century to lights of cars from the beginning of the 21st century and conclude that some cars have typical characteristics of a certain era. Isn't that too strong? I would say even absudrly strong?
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by ranjeet75 » Wed Jan 25, 2012 10:31 pm
why (D) "Pollen deposition is a fairly continuous process" is wrong?
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by chris@magoosh » Thu Jan 26, 2012 2:56 pm
Nomanee,

To be honest, I too am unsure how comparing paleo-pollen to modern pollen helps us understand the weather during
the time of the prehistoric pollen. However, the answer - which could probably be provided by a paleobotanist (I just
made that up :) - is not necessary in arriving at the correct answer.

The question is asking us what we can infer from the information stated in the passage. Ignoring for a moment the link between
the pale-pollen and the present pollen, we can still infer that the paleo-pollen must be a reliable indicator of the what the weather
was like at one point. Otherwise, we cannot "figure out what the weather was like at the time of the pollen deposition."

Remember this isn't a weaken/strengthen question. We have to accept the argument as true. And if it is true, we can infer that the
paleo-pollen could reliably be associate with certain weather.

Hope that made sense :).
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by nonameee » Thu Jan 26, 2012 11:57 pm
paleo-pollen must be a reliable indicator of the what the weather
was like at one point. Otherwise, we cannot "figure out what the weather was like at the time of the pollen deposition."
Chris, I totally understand it and agree with it. But my objection wasn't about the reliability of the method! My objection was about the fact that the correct answer doesn't mention the word "pollen"! How in the world can you make a stretch from pollen to flora?
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by praveen_gmat » Fri Jan 27, 2012 1:33 am
Hi Nonameee,

I understand you concern. One thing about inference questions is that, the answer must be true. Not probably true.
In choice B, corroborated means establish. When I read it, I understood that, radio carbon dating can be established by glacial evidence. In fact, it is not the even the reverse. The premise states that samples were submitted to this technique to determine the weather pattern. Also, be aware that weather patters have to be determined(not just in glacial places) - read first line.

Hence B is wrong.

"By comparing such pollen samples with spores taken from modern vegetation"
--> means comparing pollen from one era with modern vegetation(or flora), we can determine the weather.

So, I can infer that vegetation ( or flora) are reliably associated with particular climatic conditions. Don't assume that the flora in answer choice is only referring to prehistoric periods.

Hope I did not confuse you.
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by nonameee » Fri Jan 27, 2012 1:45 am
Thanks for your reply, but they are comparing pollen with spores. The OA doesn't mention either. Based on the stimulus, I could say that pollen or spores are reliably associated with particular climatic conditions. That would be a legitimate claim that would be based on the logic of the stimulus. But to say that flora is associated with climatic conditions? No. I've stated my reasons above.

I believe the question is simply flawed.
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by praveen_gmat » Fri Jan 27, 2012 1:55 am
Yup. You are right in terms of the comparison mentioned in the stimulus.

I too am not sure.

Looks flawed.
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