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Lyme disease is caused by a bacterium transmitted to - evaluate arg

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Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally deer ticks pick up the bacterium while in the larval stage from feeding on infected whitefooted mice. However, certain other species on which the larvae feed do not harbor the bacterium. Therefore, if the population of these other species were increased, the number of ticks acquiring the bacterium and hence the number of people contracting Lyme disease—would likely decline.

Which of the following it would be most useful to ascertain in evaluating the argument?

A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white footed mice.

B. Whether the size of the deer tick population is currently limited by the availability of animals for ticks ‘s larval stage to feed on

C. Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white footed mice.

D.Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.

E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmits to humans.


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Please help with your explanations, it was a tough one for me.

Thanks!
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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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AndersonBound wrote:
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

(A) Whether populations of the other species on which deer tick larvae feed are found only in the areas also inhabited by white-footed mice.
(B) Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on.
(C) Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice.
(D) Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.
(E) Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans.

[Had a really hard time understand the approach of the question and how to eliminate choices. Could only eliminate one answer choice. Any help / insight on how one could reach the actual answer????]


Good question.

B IMO

Say the size of deer tick is limited by availability of animals, ie, if there were more animals to feed upon, their would be more deer ticks, but because there is less food, population of deer ticks is limited. Then when uninfected food (animals) increases, uninfected deer tick population will increase.

However, if the deer tick already has sufficient food (infected or uninfected) there is no guarantee that the tick will feed on the extra uninfected animals. So no guarantee that extra uninfected animals will increase uninfected tick population.

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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

Conclusion: If the population of the other species increased, the number of ticks acquiring the bacterium would decline.

Premises: The other species do not harbor the bacterium. The ticks generally acquire the bacterium while feeding in the larval stages.

Assumption: That the ticks will feed on the the other species if given the opportunity to do so.

Prediction: The correct answer will address the assumption and strengthen or weaken the conclusion. It will show whether the ticks actually will feed on the other species.

To understand the answer choices more easily, rephrase them without the word whether.

(A) The populations of the other species on which deer tick larvae feed are found only in the areas also inhabited by white-footed mice. Doesn't help us determine whether the ticks will feed on the other species.
(B) The size of the deer tick population is not currently limited by the availability of animals for the tick's larval stage to feed on. In other words, the ticks have plenty of food; the number of ticks is not being held back by the amount of food available. Thus, more food will NOT lead to more ticks. Implication: Any larvae that eat the uninfected food will not increase the total population of ticks but will instead DECREASE the number of ticks getting infected, STRENGTHENING the conclusion that the number of infected ticks will decrease. CORRECT.
(C) The infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice. Outside the scope. The argument is not about how the population can be controlled but about whether the population would increase.
(D) The deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed. Tempting, but incorrect. The argument states that the way the ticks generally get infected is by feeding in the larval stages. This is a premise of the argument and cannot be disputed. Any answer choice that discusses other ways the ticks can get infected is irrelevant. Even if ticks can get infected as adults, this is not the way ticks generally get infected, so who cares? A word of advice: an answer choice that attacks a premise will not be correct. The correct answer will address the assumption, which in this case is that the ticks will feed on the other species.
(E) Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans. Out of scope. The argument isn't about other bacteria.

Hope this helps!

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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

(A) Whether populations of the other species on which deer tick larvae feed are found only in the areas also inhabited by white-footed mice.
(B) Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on.
(C) Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice.
(D) Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.
(E) Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans.

Last edited by broall on 27 May 2017, 01:04, edited 3 times in total.
Merged topic. Please search before posting question.

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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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This question is a tricky one. Let us begin by first understanding what the question is asking.

"Which of the following would it be most important to ascertain in evaluating the argument?"
In other words, the answer to which of the following questions would be the most useful in determining whether or not the author's argument is logical.

In order to answer this question, we must first understand the author's logic.

The argument can be simplified as follows:

[*]Lyme disease is transferred to humans by infected deer ticks.
[*]When deer ticks are in the larval stage, they feed on two species:
[*][*]1. White-footed mice; and
[*][*]2. Other species.

[*]White footed mice carry Lyme disease, and larvae who feed on infected mice also become infected.

[*]Other species do not carry Lyme disease, and so larvae who feed on other species do not become infected.

[*]Therefore, increasing the population of 'Other species' will lead to a decrease in the number of infected larvae.

Because this is an evaluate the argument type question, we know that there is probably something wrong with this argument. In this case, the author is making an assumption. Understanding what this assumption is will help us to evaluate which of the answer choices is best, because the best answer choice will address this assumption directly.

So, what is the author's assumption? In this question, the author actually states his/her assumption in the conclusion. The structure of the author's conclusion is A leads to B leads to C, where B is the assumption.
A: Increase population size of other species.
B: (Assumption) "more of the larvae would be feeding on the uninfected hosts"
C: The number of newly infected deer ticks will decrease.

Are we absolutely certain that by introducing new hosts, the larvae will prefer to feed on this host as opposed to the white-footed mice? No, we are not certain. So, when we examine the answer choices, we will look for an answer choice that makes this assumption (B) a fact. (A common mistake on this problem is searching for an answer to the author's final point (C). This would be the case if we were looking to weaken the argument. However, this is not our goal. Our goal is to determine whether or not we do in fact have an argument.)

The answers:
A: Irrelevant. Whether or not the 'Other Species' is found only in the same areas in which white-footed mice are found does not help us address the assumption. If they are found only in the same are, it is still likely that the larvae may feed on the new host, but it is just as likely that they may not begin feeding on the new host. Furthermore, even if the 'Other species' is found in places other than those in which white-footed mice are found, this would not inhibit the larvae from feeding on the new hosts, because they may still be present in the areas inhabited by the white-footed mice.

B. If the population size is currently limited by the number of available hosts to feed on, then introducing a new host would remove this limitation, and the larvae would in fact begin feeding on the 'Other species.'
Furthermore, if the population size is not currently limited by the number of available hosts to feed on, then there is no limitation to be removed, and the larvae would not begin feeding on the 'Other specie,' because they have no incentive to.
In other words, the answer to this question, whether it be yes or no, directly addresses the author's assumption, which, in turn, will help us in evaluating the author's logic. This is the correct answer.

C. This answer may seem correct at first. However, it will only appear to be so if we are assuming the same thing as the author (that the population size is currently limited by the number of available hosts and that introducing a new host will cause the larvae to feed on the new host.
Only if we accept this assumption to be true would we be concerned about what steps should be taken next to control the infected deer tick population. However, since the question deals with evaluating the author's argument (and the validity of the author's assumption), this answer choice is irrelevant, because it does not address the author's assumption (in fact, it maintains it), and as a result does not help is in evaluating the author's argument.

D. This answer choice is similar to answer 'c'. It maintains the author's assumption rather than addressing it.
Remember: The author is assuming that the introduction of a new species will cause deer ticks to feed on this new species.
Because this answer choice assumes that the current population size is currently limited by the number of 'Other species' available to feed on, it does not help us in evaluating the validity of the original assumption.

E. This answer choice is out of the scope of the author's argument. The author is concerned about a reduction in the spread of Lyme disease. Other diseases are irrelevant to this argument.

In summary, when we are given an evaluation question, we must first understand the author's line of reasoning and then search for a flaw in this line of reasoning. The best answer choice will directly address this flaw.

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Good questions!

The larva of the tick "generally pick up the bacteria" from feeding on white footed mice--here, 'infected' and 'acquiring the bacteria' are synonyms.

So, if we have 1000 ticks feeding on the white-footed mice, we'll see infection. Some percentage of the mice will have the bacteria, and some percentage of the ticks feeding on those mice will acquire the bug. These percentages are a constant. So if 1000 ticks feeding on white-footed mice produce n infected ticks, then 500 will produce 1/2 n and 2000 will produce 2n. In other words, the plan is trying to reduce the number of infected ticks be reducing the number of ticks feeding on white-footed mice.

Since in the first case I described, introducing a non-carrier species for ticks to feed on would reduce the number of ticks drinking infected blood, but in the second case it would not, (B) is a central determinant to the success or failure of the plan. I hope that helps!
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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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In GMAT if any answer choice is asking you to bend backwards then probably its wrong - there will be herculean amount of thinking in 2 mins. That's not the technique used to crack.

D means many things hypothetically -
1) The infected number is going to first decrease and then at later point increase linearly causing the final number of infected ticks to remain the same
2) The infected number is going to decrease. Later time when the adults get infected the number is going to rise exponentially.
Basically D depends on lady luck and can take either sides. So D is not the answer. The most important thing is D is a shift in the focus of the argument.

nikhilkatira wrote:
nusmavrik wrote:
Food is the bone of contention between the ticks and the third species. We need to evaluate whether the method can limit the population of deer ticks. I hope you got B easily.

D is a scope shift. We are not here to ascertain the ultimate fate of the adolescent deer ticks. The argument here is to evaluate whether the method can limit the population of deer ticks based on the food they eat.

nikhilkatira wrote:
Agree that Option B is correct, but why is Option D incorrect ?


thanks for the explanation, but I am still getting little confused...please help me where am i getting wrong ?

The last sentence of the argument says"If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline. "

So as per option D, what if ticks acquire bacterium after they become adults ?
The overall number will increase...

nusmavrik what am I missing ?

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jjhko wrote:
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally deer ticks pick up the bacterium while in the larval stage from feeding on infected whitefooted mice. However, certain other species on which the larvae feed do not harbor the bacterium. Therefore, if the population of these other species were increased, the number of ticks acquiring the bacterium and hence the number of people contracting Lyme disease—would likely decline.

Which of the following it would be most useful to ascertain in evaluating the argument?

A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white footed mice.

B. Whether the size of the deer population is currently limited by the availability of animals for ticks ‘s larval stage to feed on

C. Whether the infected deer population could be controlled by increasing the number of animals that prey on white footed mice.

D.Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.

E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmits to humans.


Please help with your explanations, it was a tough one for me.

Thanks!


I think OA is B

Read B as

Whether the size of the deer <b>ticks</b> population is currently limited by the availability of animals for ticks ‘s larval stage to feed on

Argument says in order to control lyme disease, increase the number of species that larva feeds on. So larva has multiple options to feed on i.e. feeding on deer sticks, grasshopper, ants etc (grasshopper & ants are just my examples for understanding purposes). As larva has multiple options to feed on, larva is spread across multiple options and less larva feeds on deer ticks..so reduction in lyme disease.

B is asking the question size of population is currently limited by the availability of animals for ticks ‘s larval stage to feed on?
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This is a cause-effect question. For the same effect, if there is an alternate cause, then this will help evaluate the argument.

The conclusion of the argument says that people contracting Lymn desease would decline by increasing number of other species as this would ensure decline in infected deer ticks.

But, if there deer ticks get infection from infected deers then people contracting Lymn desease may not decline.

Hence, D should be the answer.

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B..i think
:arrow:
if the population of deer tick increases with addition of new species to feed, possibility of the disease increase further. The white mice population is not reduced anyway.

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AndersonBound wrote:
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

(A) Whether populations of the other species on which deer tick larvae feed are found only in the areas also inhabited by white-footed mice. ....in the argument it is stated that "If the population of these species increased, more of the larvae would be feeding on uninfected hosts" ...it means that tehy are feeding on infected mice bcoz there is not enough unifected host...
(B) Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on....we r not concerned abt population
(C) Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice.......it cannot be inferrrd fom argument
(D) Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed. ...correct ...bocz if adult ticks can pick the bacteria from dear..then number of infected ticks will not decline.
(E) Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans....out of scope

[Had a really hard time understand the approach of the question and how to eliminate choices. Could only eliminate one answer choice. Any help / insight on how one could reach the actual answer????]


IMO D....OA plz

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Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally deer ticks pick up the bacterium while in the larval stage from feeding on infected whitefooted mice. However, certain other species on which the larvae feed do not harbor the bacterium. Therefore, if the population of these other species were increased, the number of ticks acquiring the bacterium would likely decline.

Which of the following it would be most useful to ascertain in evaluating the argument?

(A) Whether populations of the other species on which deer tick larvae feed are found only in the areas also inhabited by white-footed mice.

(B) Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on.

(C) Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice.

(D) Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.

(E) Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans.

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AndersonBound wrote:
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

(A) Whether populations of the other species on which deer tick larvae feed are found only in the areas also inhabited by white-footed mice.
(B) Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on.
(C) Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice.
(D) Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.
(E) Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans.

[Had a really hard time understand the approach of the question and how to eliminate choices. Could only eliminate one answer choice. Any help / insight on how one could reach the actual answer????]

It 's B because the conclusion is about the dependence of deer stick population on the population of the animals for the tick's larval stage to feed on.

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AndersonBound wrote:
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

(B) Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on.
The difficulty here is that the conclusion is about the NUMBER of ticks acquiring the bacterium, not their proportion.

Imagine if some factor limits us to, say, 1000 ticks per acre. Maybe they are limited by water or by predators. In any event, if those 1000 ticks feed on 1000 white-footed mice, we have a 1000 infected ticks. On the other hand, if those ticks have a fifty/fifty shot of picking one of 1000 white-footed mice, or one of 1000 black-footed mice, then we'll have 500 infected ticks--substantially fewer, confirming the hypothesis.

Now imagine that food is the limiting factor of ticks. We imagine each mouse can have one tick; in other words, we have a 1000 ticks because we have a 1000 white-footed mice. Now, we add 1000 black-footed mice, and suddenly there is food available 2000 ticks. We'll have a larger proportion that are uninfected, but the number that feed on white-footed mice remains unchanged at 1000.
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Here's the connection -

Lyme disease----caused by deer ticks---deer ticks acquire it by feeding on bacterium which is in the larval stage----this bacterium uses mice as the host spreading infection

Now to decrease the offset of this disease, the argument states that we will introduce only those species that cannot serve as host carriers for the bacterium. This would lead to the bacterium feeding on inert hosts and therefore lead to a decrease in the number of lyme disease victims

B clearly states the correct evaluation of the argument by pointing out that this would be an effective way only if the host carrier plays a key role in its spread (i.e. the disease can only spread through the host-carrier concept)

Hope it helps

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jjoon1979 wrote:
OA is B!

This question is from the prep, but I still don't understand why OA is B..
Take a look at my explanation a few posts back, and let me know if I can clear up any specific issues about it.
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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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New post 24 Jul 2010, 11:51
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OA is B.
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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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New post 28 Jul 2010, 00:16
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rashminet84 wrote:
AndersonBound wrote:
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these species increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

(A) Whether populations of the other species on which deer tick larvae feed are found only in the areas also inhabited by white-footed mice.
(B) Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on.
(C) Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice.
(D) Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.
(E) Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans.

[Had a really hard time understand the approach of the question and how to eliminate choices. Could only eliminate one answer choice. Any help / insight on how one could reach the actual answer????]


Good question.

B IMO

Say the size of deer tick is limited by availability of animals, ie, if there were more animals to feed upon, their would be more deer ticks, but because there is less food, population of deer ticks is limited. Then when uninfected food (animals) increases, uninfected deer tick population will increase.

However, if the deer tick already has sufficient food (infected or uninfected) there is no guarantee that the tick will feed on the extra uninfected animals. So no guarantee that extra uninfected animals will increase uninfected tick population.



Agree with B
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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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New post 08 Apr 2014, 05:16
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Please add the OA. I think that someone said that it is B. Also, the correct version of the question is at the following URL http://www.manhattangmat.com/forums/rc- ... t7861.html.

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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg [#permalink]

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New post 24 Nov 2014, 14:45
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Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

So the answer choice we are looking for must strengthen or weaken the argument. The answer choice must show why or why not it will decrease the number of ticks with the bacterium.

A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white-footed mice
The answer to this question is irrelevant.

B. Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on.
The conclusion states

Number of uninfected animals goes up = Number of ticks with the bacterium will go down.

If the availability of animals to feed on limits the deer tick population then this will greatly affect the decline of ticks acquiring the bacterium.



C. Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice.
We do not care about controlling the population. The conclusion only cares about the number of ticks acquiring the bacterium by the increase of other species for the larvae to feed on.

D. Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed.
We're only concerned with the larvae feeding on uninfected hosts.

E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans.
We only care about the bacterium that can cause lyme disease.

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Re: Lyme disease is caused by a bacterium transmitted to - evaluate arg   [#permalink] 24 Nov 2014, 14:45

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