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Although an insecticide may initially prove effective in

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Although an insecticide may initially prove effective in [#permalink] New post 23 Nov 2012, 12:56
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Although an insecticide may initially prove effective in reducing malaria-causing mosquito populations, the surviving
mosquitoes, genetically endowed to withstand the insecticide, thrive on the reduced competition from other
mosquitoes and pass on their genetically based resistance to their offspring. Mosquito populations then become
less and less susceptible to the insecticides. Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Which of the following, if true, would most help support the researchers’ proposal?

A. Younger mosquitoes are also essential to the life cycle of the malaria parasite.
B. The older mosquitoes have completed their breeding activity.
C. The proposed approach to controlling mosquito populations is likely to require more frequent applications of pesticides.
D. Malaria is only transmitted to humans by mosquito bites.
E. The older mosquitoes are not as susceptible to insecticides as younger mosquitoes.

Pls provide explanations... OA
[Reveal] Spoiler:
after deliberations

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Re: Although an insecticide may initially prove effective [#permalink] New post 28 Nov 2012, 19:24
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gmatbull wrote:
Although an insecticide may initially prove effective in reducing malaria-causing mosquito populations, the surviving
mosquitoes, genetically endowed to withstand the insecticide, thrive on the reduced competition from other
mosquitoes and pass on their genetically based resistance to their offspring. Mosquito populations then become
less and less susceptible to the insecticides. Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Which of the following, if true, would most help support the researchers’ proposal?

A. Younger mosquitoes are also essential to the life cycle of the malaria parasite.
B. The older mosquitoes have completed their breeding activity.
C. The proposed approach to controlling mosquito populations is likely to require more frequent applications of pesticides.
D. Malaria is only transmitted to humans by mosquito bites.
E. The older mosquitoes are not as susceptible to insecticides as younger mosquitoes.

Pls provide explanations... OA
[Reveal] Spoiler:
after deliberations


Responding to a pm:

Definitely a tough one.

The problem is that you need to read the stimulus at least twice just to understand it. The scene is something like this:

Say there are lots of mosquitoes and you spray insecticide to control malaria. Now what happens when quite a few mosquitoes die? The leftover ones are immune to insecticide and have little competition so they breed uncontrollably. Next time when you spray, the mosquito population doesn't get affected since they are mostly immune.
The solution proposed is this: Older mosquitoes are essential to maintaining the life cycle of the malaria parasite. Target only them instead of the entire mosquito population. There is still competition but an essential part of maintaining the life cycle of malaria parasites is missing.

(B) strengthens the 'there is still competition' part of the argument. If older mosquitoes have already bred, this will ensure a thriving mosquito population which means enough competition so that the insecticide immune mosquitoes do not take over.
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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 04:29
gmatbull wrote:
Although an insecticide may initially prove effective in reducing malaria-causing mosquito populations, the surviving
mosquitoes, genetically endowed to withstand the insecticide, thrive on the reduced competition from other
mosquitoes and pass on their genetically based resistance to their offspring. Mosquito populations then become
less and less susceptible to the insecticides. Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Which of the following, if true, would most help support the researchers’ proposal?

A. Younger mosquitoes are also essential to the life cycle of the malaria parasite.
B. The older mosquitoes have completed their breeding activity.
C. The proposed approach to controlling mosquito populations is likely to require more frequent applications of pesticides.
D. Malaria is only transmitted to humans by mosquito bites.
E. The older mosquitoes are not as susceptible to insecticides as younger mosquitoes.

Pls provide explanations... OA
[Reveal] Spoiler:
after deliberations


IMO E

I just have doubt on B...
Is this weakener/strengthener ???
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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 05:39
"presence of older mosquitoes—those ten or more days old—is essential to maintaining the life cycle of the malaria parasite"-------- part of the premise. we have to strengthen the fact that:-

researchers have proposed addressing the problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.
Lets scan the options contenders B and E,

option B states that "B. The older mosquitoes have completed their breeding activity.".......If they have completed their breeding cycle, then there is no use of targeting old mosquitoes.

E. The older mosquitoes are not as susceptible to insecticides as younger mosquitoes.--------Though this is a repetition of the premise but there is no other option close to it.

If the old mosquitoes are not susceptible to insecticide than they need to be targeted for elimination and it is already stated in the premise that these older mosquitoes are needed to thrive the life cycle.

Hence i feel that E is the best option which strengthens and B is somewhat weakening the argument.
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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 11:11
this was completely over my head. Had to go though the argument and answer choice 3-4 times to understand what is actually required to strengthen and which answer choice will do the trick.

After all the torture I will pick B.

Will love to see how others comprehend and explain.

@gmatbull : Kudos to you for such lovely question that push our limit.
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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 11:37
Vineetk wrote:
this was completely over my head. Had to go though the argument and answer choice 3-4 times to understand what is actually required to strengthen and which answer choice will do the trick.

After all the torture I will pick B.

Will love to see how others comprehend and explain.

@gmatbull : Kudos to you for such lovely question that push our limit.


B the virus transmits through the mosquito population through breeding... just a guess
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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 12:04
I think it's E.

This is a strengthen question, so we need to back up the conclusion. Because older mosquitoes are essential to maintaining the life-cycle of the parasite researchers need to target ONLY these old mosquitos.

If as E implies that younger mosquitos are more susceptible (than are older ones) to the (already present methods for figthing mosquitos) insecticides, then targeting the older mosq. population may have a positive outcome. That's not definitive, but good enough to show it supports the conclusion.

@shanmugamgsn: If added as a premise, B has no bearing on the conclusion. It weakens it indirectly, since our plan to kill ONLY the old mosquitos will fail.
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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 18:48
I think it's E... Could u pls tell the ans
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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 20:56
Very tough one indeed. IMHO, the answer should be E. It would make sense to research a new method for killing mosquitoes that have survived being sprayed with insecticides at a young age. On the real GMAT, I would just pick E and move on. Will not be too worried if I get this wrong. IMHO, B is wrong. If the mosquitoes have already bred, then they would have already passed on their strong genes to the offsprings hence targeting only the older mosquitoes will have very limited use.

Answer should be E.

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Re: Although an insecticide may initially prove effective [#permalink] New post 24 Nov 2012, 20:57
gmatbull wrote:
Although an insecticide may initially prove effective in reducing malaria-causing mosquito populations, the surviving
mosquitoes, genetically endowed to withstand the insecticide, thrive on the reduced competition from other
mosquitoes and pass on their genetically based resistance to their offspring. Mosquito populations then become
less and less susceptible to the insecticides. Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Which of the following, if true, would most help support the researchers’ proposal?

A. Younger mosquitoes are also essential to the life cycle of the malaria parasite.
B. The older mosquitoes have completed their breeding activity.
C. The proposed approach to controlling mosquito populations is likely to require more frequent applications of pesticides.
D. Malaria is only transmitted to humans by mosquito bites.
E. The older mosquitoes are not as susceptible to insecticides as younger mosquitoes.

Pls provide explanations... OA
[Reveal] Spoiler:
after deliberations

Option A, and D are clearly irrelevant. Only contenders that affect the proposal are B,C and E.
Now B, if anything, weakens the proposal. if breeding activity is completed that means older mosquitoes have passed on the resistance. Eliminate B.
C and E remains. We can also check that from passage it is clear that older mosquitores have better resistance to insecticide. and if choice E says the same thing- it means it is just restating the premise cleverly so that it will be picked. Eliminate E.
Choice C remains. Now notice, older mosquitoes are 10 or more days old. If new approach requires frequent application of pesticides that would mean mosquitoes will not get chance to get older or basically presence of old mosquitoes will be highly unlikely, thus success of researchers' plan is ensured.

Ans C it is!
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 01:52
No doubt the question is a tough one even with the splits:
B(2); C(1); and E(5). I also went with E, but that was not to be...

Thanks everyone for your contributions, OA is however,
[Reveal] Spoiler:
B
.

By focusing on
[Reveal] Spoiler:
B
, how would researchers achieve their aim?
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 03:15
Haha... Would never have gone with B any day.....
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 03:37
@Vineetk & Cpanagio,
what are your explanations for choosing B?
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 04:45
gmatbull wrote:
@Vineetk & Cpanagio,
what are your explanations for choosing B?


I went with B because of below highlighted statement provided in the argument:

Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Maintenance of life cycle (reproduction) is an important activity that's why older mosquito comes in picture. The pesticide will target the older mosquito (after reproduction) but not on young ones so that young ones become 10 or more days old and reproduce and life cycle can continue. At the same time, older mosquito can be killed by this pesticide, controlling the population.
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 05:45
Vineetk wrote:
gmatbull wrote:
@Vineetk & Cpanagio,
what are your explanations for choosing B?


I went with B because of below highlighted statement provided in the argument:

Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Maintenance of life cycle (reproduction) is an important activity that's why older mosquito comes in picture. The pesticide will target the older mosquito (after reproduction) but not on young ones so that young ones become 10 or more days old and reproduce and life cycle can continue. At the same time, older mosquito can be killed by this pesticide, controlling the population.

Supposing the old mosquitoes are eliminated after passing the resistant genes to the younger ones, does it make any sense?

My expectation is that u target the old ones (before breeding starts). That way, u prevent them from passing the stubborn genes
to their young ones. Otherwise, anytime u eliminate the old ones, the younger ones (in possession of the adamant genes) transfer
the genes and the vicious cycle continues...

E, on the other hand, says the adult mosquitoes are less susceptible than their younger ones. So, it becomes easier to eliminate the
re-production cycle. Also, we are guaranteed that the agent (or mechanism) for transfer of the genes-adult mosquitoes- are easily
killed, leaving only the younger but ones who grow old and also become less vulnerable to the insecticide. Malaria is thus easier to control.

Am sorry, OE not available, but What do u think Vineetk?
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 06:10
Expert's post
gmatbull wrote:
No doubt the question is a tough one even with the splits:
B(2); C(1); and E(5). I also went with E, but that was not to be...

Thanks everyone for your contributions, OA is however,
[Reveal] Spoiler:
B
.

By focusing on
[Reveal] Spoiler:
B
, how would researchers achieve their aim?


If I somehow come to know that I shall be facing such questions on real test, then I will surely not be taking test within a year.
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 06:14
gmatbull wrote:
Vineetk wrote:
gmatbull wrote:
@Vineetk & Cpanagio,
what are your explanations for choosing B?


I went with B because of below highlighted statement provided in the argument:

Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Maintenance of life cycle (reproduction) is an important activity that's why older mosquito comes in picture. The pesticide will target the older mosquito (after reproduction) but not on young ones so that young ones become 10 or more days old and reproduce and life cycle can continue. At the same time, older mosquito can be killed by this pesticide, controlling the population.

Supposing the old mosquitoes are eliminated after passing the resistant genes to the younger ones, does it make any sense?

My expectation is that u target the old ones (before breeding starts). That way, u prevent them from passing the stubborn genes
to their young ones. Otherwise, anytime u eliminate the old ones, the younger ones (in possession of the adamant genes) transfer
the genes and the vicious cycle continues...

E, on the other hand, says the adult mosquitoes are less susceptible than their younger ones. So, it becomes easier to eliminate the
re-production cycle. Also, we are guaranteed that the agent (or mechanism) for transfer of the genes-adult mosquitoes- are easily
killed, leaving only the younger but ones who grow old and also become less vulnerable to the insecticide. Malaria is thus easier to control.

Am sorry, OE not available, but What do u think Vineetk?


Below is my inference :
In B- If we eliminate older ones before breeding, younger ones will not be produced and existing ones will also die when they become old before breeding. Thus, the mosquito population will eventually end or disappear. Life cycle will no longer continue.

In E- If old mosquito are less susceptible then danger to younger ones are more and the objective of killing only old mosquito is not achieved.

Correct me if I inferred wrongly.
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 13:41
@ Vineetk,

For B, yes, that's precisely how I feel it should have been worded.

E: older mosquitoes are LESS susceptible to insecticide THAN the younger ones. The older ones are more difficult to
kill with the insecticide.

If Older ones transfer immunity genes to younger ones, and are more difficult to eliminate, then any such plan that
will eliminate the older ones will assure the researchers that malaria will be curtailed.

This is my opinion....
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 14:19
I chose answer B.

Reasoning:

The goal is to support the goal of targeting older mosquitos in order to reduce the problem of genetic resistance to pesticides.

Answer B would support this goal - if the older mosquitos being targeted have already completed the breeding process, they will not pass along their resistance as they will not produce any additional offspring, and resistance is passed on genetically.
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Re: Although an insecticide may initially prove effective [#permalink] New post 25 Nov 2012, 18:42
I seriously doubt the OA reason since B states that old mosquitoes have completed their breeding cycle that means they wont breed anymore and they have passed on their resistance. Either the option is out of scope or an interpretation.

Hey gmat bull can u pls provide the OE and source.
Re: Although an insecticide may initially prove effective   [#permalink] 25 Nov 2012, 18:42
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