Monarch butterflies, whose average life span is nine months, migrate : Critical Reasoning (CR)

Technext

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

02 Mar 2009, 21:33

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grumpyoldman wrote:

I picked B as well, and I'll add a few points to Technext's explanation:

This is really an Inference question, which means we have to think about what MUST be true if the monarch butterflies react differently to the grove with the transmitter. The larger theory is really beside the point.

(A) We have no reason to think that reacting to electricity proves the presence of a brain. Pieces of quartz react to electricity. This does not follow.

(B) This logically follows. The only thing different about the grove with the transmitter is the electromagnetic field created by the transmitter, and the monarchs react to it. They could not do that if they were not sensitive to electricity in some way or another. (Note: GMAT questions are supposed to NOT depend on outside knowledge, but this one does depend on you knowing that voltage measures ELECTRICITY, period. It doesn't measure anything else. So a "low voltage transmitter" does have to be transmitting an electromagnetic field.

(C) If the monarch butterflies respond to low voltage electricity, this DOES in fact prove that "butterflies" can respond to low voltage electricity. Monarch butterflies are butterflies, and if even one butterfly does something, then (logically) butterflies as a group "can" do that thing. But choice (C) says the electricity AFFECTS butterflies, and the facts do not show that it AFFECTS monarchs; only that they can sense it.

(D) (E) Obviously, finding out that they react to electrical fields in this limited experiment is not enough to show that they find their way all the way back using the earth's field, nor to show that they communicate intergenerationally that way. Personally, I think we can assume that "monarchs" are monarch butterflies, but it doesn't matter -- these choices are out anyway.

This has nothing to do with the GMAT, but -- how in the world do we know that the great-great-grandchildren return to the same trees? That sounds like someone had to put a lot of very tiny tags on a lot of butterflies, AND had to watch where they laid their eggs, AND tag the caterpillars, AND watch them hatch and tag them again before they flew away...

Thanks a lot for your explanation sir!

(C) If the monarch butterflies respond to low voltage electricity, this DOES in fact prove that "butterflies" can respond to low voltage electricity. Monarch butterflies are butterflies, and if even one butterfly does something, then (logically) butterflies as a group "can" do that thing. ---> Can we really assume this sir?

(D) (E) ".....Personally, I think we can assume that "monarchs" are monarch butterflies, but it doesn't matter....." ---> Though I have read the word Personally, can we really assume this sir? For ex., if the passage discusses about some entity (having some compound name as in this passage) and the option just states part of the compound name. Do you advise us to ignore such things?

This has nothing to do with the GMAT, but -- how in the world do we know that the great-great-grandchildren return to the same trees? That sounds like someone had to put a lot of very tiny tags on a lot of butterflies, AND had to watch where they laid their eggs, AND tag the caterpillars, AND watch them hatch and tag them again before they flew away... ---> Totally agree.

Regards,
Technext

grumpyoldman

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

04 Mar 2009, 09:22

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About (C): I'm not assuming anything; just following the logical meaning of the words. "Can" just means "is possible". If peanuts cause allergic reactions in some people, then it is correct to say that peanuts "can" cause allergic reactions in "people", even though for most people they do not. Similarly, if electric fields did "affect" at least some monarch butterflies, then it is correct to say that electric fields "can" affect butterflies -- because monarch butterflies ARE butterflies. This remains true even if the fields do not affect all monarchs, and even if they do not affect any other species of butterflies.

About "monarchs": This is English grammar, not logic. We are able to refer back to a subclass of a noun by using the modifier only, once we have identified the subclass with both the modifier and the noun. For instance, I could start writing about "heavyweight boxers", and then refer to them as "heavyweights" for the rest of the passage. I suspect, however, that real GMAT questions might NOT use this particular grammatical structure (as this question did).

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

05 Mar 2009, 02:40

grumpyoldman wrote:

About (C): I'm not assuming anything; just following the logical meaning of the words. "Can" just means "is possible". If peanuts cause allergic reactions in some people, then it is correct to say that peanuts "can" cause allergic reactions in "people", even though for most people they do not. Similarly, if electric fields did "affect" at least some monarch butterflies, then it is correct to say that electric fields "can" affect butterflies -- because monarch butterflies ARE butterflies. This remains true even if the fields do not affect all monarchs, and even if they do not affect any other species of butterflies.

I was really not aware that we can frame sentences this way. It's really good information. Thanks a lot sir!

grumpyoldman wrote:

About "monarchs": This is English grammar, not logic. We are able to refer back to a subclass of a noun by using the modifier only, once we have identified the subclass with both the modifier and the noun. For instance, I could start writing about "heavyweight boxers", and then refer to them as "heavyweights" for the rest of the passage. I suspect, however, that real GMAT questions might NOT use this particular grammatical structure (as this question did).

By the way, I shouldn’t have asked this question in the first place. Though, I read the options carefully, I somehow missed that the subclass was already identified by the modifier in the passage. :shock:

Sorry for bothering you.

Regards,
Technext

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

14 Jan 2010, 07:48

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I went for D thinking that is the plausible choice among all,but after reading the other posts I realized that I missed the obvious errors :-(

choice C talks about butterflies but not about monarch butterfilies, so it is irrelevant
choice D and E says nothing about butterfiles it specifes only about monarchs so it is irrelevant ( I fell for this trap)
though choice A talks about monarch butterfliers it is neither talks about electormagnetic field nor electricity so it is out of context

so only choice B is relevant ( how easy it is to expalin after seeing the answer choice :-)

)

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

14 Jan 2010, 09:34

Powerscore CR bible says, there is a specific standard of attempting these fill-the-blank type questions. Go with the general flow of the argument, make sure the elements are duly noted and associated with each other properly, the required statement will either end up as a premise or a will be a conclusion statement.

My answer was indeed B. Btw, Low Voltage is associated with electricity only, voltage term itself should suggest that it is electricity.

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

04 Jun 2012, 09:50

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shikhar wrote:

Which of the following best completes the passage below?
Monarch butterflies, whose average life span is nine months, migrate from the midwestern United States to selected forests outside Mexico City. It takes at least three generations of monarchs to make the journey, so the great-great-grandchildren who finally arrive in the Mexican forests have never been there before. Yet they return to the same trees their forebears left. Scientists theorize that monarchs, like homing pigeons, map their routes according to the earth’s electromagnetic fields. As a first step in testing this theory, lepidopterists plan to install a low-voltage transmitter inside one grove of “butterfly trees” in the Mexican forests. If the butterflies are either especially attracted to the grove with the transmitter or especially repelled by it, lepidopterists will have evidence that______
(A) monarch butterflies have brains, however minuscule
(B) monarch butterflies are sensitive to electricity
(C) low-voltage electricity can affect butterflies, whether positively or adversely ===
(D) monarchs map their routes according to the earth’s electromagnetic fields
(E) monarchs communicate in intergenerationally via electromagnetic fields

The wording of the answer choice for (B) is not the best, but it is the best answer choice here. It's really that the butterflies' route is sensitive to electricity, not so much that butterflies physically themselves are sensitive to electricity.

(D) says the butterflies route according to earth's electromagnetic fields. Well, that is the argument originally hypothesized, we are trying to find the assumption.
So as an assumption, we are using a volt transmitter to simulate the electromagnetic fields (an assumption linking the earth's electromagnetic fields and a volt transmitter).

If we are testing with a volt transmitter, this is not evidence that routes are based on the earth's electromagnetic fields. Keyword here is "earth" - the butterflies may be sensitive to some magnetic fields and we may have evidence for that...but making the stretch to the conclusion that we are talking about the "earth's" electromagnetic field is not supported.

(D) simply restates the argument. But because of the example used and the lack of a link between transmitter and earth's electromagnetic fields, we can only say that butterflies (at least their route) are sensitive to electricity (assumed to be linked to these volt transmitters). Thus (B) is the better answer.

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

05 Jun 2012, 01:15

shikhar wrote:

Monarch butterflies, whose average life span is nine months, migrate from the midwestern United States to selected forests outside Mexico City. It takes at least three generations of monarchs to make the journey, so the great-great-grandchildren who finally arrive in the Mexican forests have never been there before. Yet they return to the same trees their forebears left. Scientists theorize that monarchs, like homing pigeons, map their routes according to the earth’s electromagnetic fields. As a first step in testing this theory, lepidopterists plan to install a low-voltage transmitter inside one grove of “butterfly trees” in the Mexican forests. If the butterflies are either especially attracted to the grove with the transmitter or especially repelled by it, lepidopterists will have evidence that______

(B) monarch butterflies are sensitive to electricity
(D) monarchs map their routes according to the earth’s electromagnetic fields

The correct answer should be B. Choice D is too far to reach. The lepidopterists only set up the transmitter into one grove of "butterfly trees", not the Earth' electromagnetic field (EEF). The center word is EEF. There is no bridge between the transmitter and the EEF, so this is the ambiguous assumption if we choose D. Choice B is more correct because we do not need that bridge to reach the conclusion.

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

07 Jun 2012, 01:10

(A) monarch butterflies have brains, however minuscule - Irrelevant information - Incorrect
(B) monarch butterflies are sensitive to electricity - Since they are sensitive to electricity, the butterflies are able to find their way. - Correct
(C) low-voltage electricity can affect butterflies, whether positively or adversely - What kind of affect is uncertain and how does this affect help butterflies find their way - Incorrect
(D) monarchs map their routes according to the earth’s electromagnetic fields - Already mentioned in the premise - Incorrect
(E) monarchs communicate in intergenerationally via electromagnetic fields - This option goes too far to link the communication mechanism in butterflies - Incorrect

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

26 Feb 2013, 03:27

shikhar wrote:

Which of the following best completes the passage below?
Monarch butterflies, whose average life span is nine months, migrate from the midwestern United States to selected forests outside Mexico City. It takes at least three generations of monarchs to make the journey, so the great-great-grandchildren who finally arrive in the Mexican forests have never been there before. Yet they return to the same trees their forebears left. Scientists theorize that monarchs, like homing pigeons, map their routes according to the earth’s electromagnetic fields. As a first step in testing this theory, lepidopterists plan to install a low-voltage transmitter inside one grove of “butterfly trees” in the Mexican forests. If the butterflies are either especially attracted to the grove with the transmitter or especially repelled by it, lepidopterists will have evidence that______
(A) monarch butterflies have brains, however minuscule
(B) monarch butterflies are sensitive to electricity
(C) low-voltage electricity can affect butterflies, whether positively or adversely ===
(D) monarchs map their routes according to the earth’s electromagnetic fields
(E) monarchs communicate in intergenerationally via electromagnetic fields

A. Brains not tackled anywhere in the passage
B. this is just right, no jumpy conclusions
C. The issue is sensitivity. If they are repelled we cannot tell just yet that they are adversely affected by it.. It could be just like a smelly cheese they wanted to get away from but has no adverse effects...
D. The passage says this is just the first step to test the theory. Hence, this cannot be concluded just yet.
E. finding routes and not communicating with each other is the issue

Answer: B

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

28 Jul 2014, 10:50

How is the solution B ? Why not D ? Nowhere in the stem is the sensitivity to electricity mentioned

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

28 Jul 2014, 11:03

himanshujovi wrote:

How is the solution B ? Why not D ? Nowhere in the stem is the sensitivity to electricity mentioned

D: just states what's in the passage. "Monarchs, like homing pigeons, map their routes according to the earth’s electromagnetic fields"- This already present as theory stated by the scientists.

The electromagnetic field will have electric current. So if they prove that Monarch Butterfly either attracted or repelled by the electricity produced by transmitters then they are sensitive to electricity.

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

28 Jul 2014, 19:40

Just think about what we're proving: if the butterflies are attracted or repelled by the low-voltage transmitter, the only thing that we can actually conclude is that they are sensitive to electricity. We have no conclusive evidence as to whether the scientist's theory is accurate; this just somewhat supports the hypothesis. So the strongest answer is B.

B

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

29 Jan 2020, 22:23

Monarch butterflies, whose average life span is nine months, migrate from the midwestern United States to selected forests outside Mexico City. It takes at least three generations of monarchs to make the journey, so the great-great-grandchildren who finally arrive in the Mexican forests have never been there before. Yet they return to the same trees their forebears left. Scientists theorize that monarchs, like homing pigeons, map their routes according to the earth’s electromagnetic fields. As a first step in testing this theory, lepidopterists plan to install a low-voltage transmitter inside one grove of “butterfly trees” in the Mexican forests. If the butterflies are either especially attracted to the grove with the transmitter or especially repelled by it, lepidopterists will have evidence that______

(A) monarch butterflies have brains, however minuscule
The whole argument is around butterflies following the electric magnetic field.

(B) monarch butterflies are sensitive to electricity
Keyword monarch butterflies is right here. And yes it proves that they are sensitive to electricity.

(C) low-voltage electricity can affect butterflies, whether positively or adversely]
Low-voltage electricity is correct but this is defining all the butterflies and we are specifically talking about monarch butterflies.

(D) monarchs map their routes according to the earth’s electromagnetic fields
Wrong. This has not been proven. This was the first step towards it and not the conclusion.

(E) monarchs communicate in intergenerationally via electromagnetic fields
Wrong. Nothing about communicating or anything.

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

02 Jul 2021, 00:52

(A) monarch butterflies have brains, however minuscule
We are not in apositionn to determine whether it was due to brain or some other sensory organs

(B) monarch butterflies are sensitive to electricity
This is the only conclusion from the premise provided

(C) low-voltage electricity can affect butterflies, whether positively or adversely
This answer was part of the initial short listing however it usees strong language in addition it affects positively and negativelt chipping in adversely and not positively alone

(D) monarchs map their routes according to the earth’s electromagnetic fields
This is a far fetched which we cannot jump in layman words we need more info to determine the same

(E) monarchs communicate in intergenerationally via electromagnetic fields'
Same reasoning ad D
Hence IMO B

B

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

13 Jul 2022, 05:05

Were we supposed to draw the correct conclusion? Or we were supposed to finish the sentence? Although D is not a logical conclusion,it most certainly is how that sentence would end. So, how wrong knew is in choosing D?

Posted from my mobile device

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

20 Aug 2023, 03:36

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Re: Monarch butterflies, whose average life span is nine months, migrate [#permalink]

20 Aug 2023, 03:36

GMAT Critical Reasoning (CR) Questions

Monarch butterflies, whose average life span is nine months, migrate