Entomologist: Beginning around 2006, many honeybee colonies

Question

Entomologist: Beginning around 2006, many honeybee colonies started dying mysteriously, a condition known as colony collapse disorder. Bee autopsies revealed a virus called IAPV in almost all colonies with symptoms of colony collapse disorder, but in only one apparently healthy colony. Thus, IAPV must be the cause of the disorder.

In order to assess the strength of the entomologist's argument, it would be most helpful to know which of the following?

(A) Whether the apparently healthy colony infected with IAPV was also infected with any other viruses
(B) By what means IAPV has been spreading between honeybee colonies since 2006
(C) To what extent symptoms associated with colony collapse disorder make honeybee colonies more susceptible to infection by IAPV
(D) Whether scientists are able to detect IAPV in honeybee colonies with symptoms of colony collapse disorder without conducting bee autopsies
(E) Which symptoms of colony collapse disorder were observed among the colonies in which IAPV was detected

gmatophobia · Accepted Answer

This is an evaluate type of question. The conclusion of the argument is "  IAPV must be the cause of the disorder  "

Inference : In concluding that IAPV is the cause of the disorder, the Entomologist must have assumed that no other factors were at play, including the fact that a colony with 'colony collapse disorder' is not more susceptible to contract the virus, i.e. there was no reverse causality.

Answer choice elimination

(A) Whether the apparently healthy colony infected with IAPV was also infected with any other viruses

We have to find an option that on one extreme supports the conclusion that IAPV was responsible for 'colony collapse disorder' and on the other extreme weakens the conclusion. This option does neither. Knowing whether other viruses were present in the healthy colony doesn't help us conclude anything substantial. Even if other viruses were present in the healthy colony, we have no information if such viruses were presented in all other colonies in which IAPV was detected. Hence, we can neither substantiate nor rule out the possibility that the colony collapse disorder was caused by IAPV virus. We can eliminate this option.

(B) By what means IAPV has been spreading between honeybee colonies since 2006

This option is out of scope. We are trying to evaluate a statement that will help strengthen the conclusion. The rate of spread of the virus cannot guarantee that the disorder was caused by the virus. It is a good possibility that the virus, regardless of how soon it spreads, is not harmful to the bees. Hence, the presence of the virus and the occurrence of colony collapse disorder can be merely be a correlation and not causation. The information provided by this option doesn't provide much ground to support or reject the conclusion.

Hence, we can rule out this option.

(C) To what extent symptoms associated with colony collapse disorder make honeybee colonies more susceptible to infection by IAPV

This is a good one.

Let's assume that colony collapse disorder makes honeybee colonies more susceptible to infection by IAPV → In this case, we cannot conclude that "IAPV must be the cause of the disorder", maybe something else was responsible for colony collapse disorder. In fact, the disorder caused the bees to contract the IAPV virus. Hence, in this extreme, the possibility weakens the conclusion.

On the other hand, if colony collapse disorder does not make honeybee colonies more susceptible to infection by IAPV → We can conclude that probably, the IAPV virus must have caused the disorder. In this extreme, the possibility strengthens the conclusion.

We can keep this option.

(D) Whether scientists are able to detect IAPV in honeybee colonies with symptoms of colony collapse disorder without conducting bee autopsies

Again, out of scope. How the viruses are detected is not the point of contention here. Hence, we can rule out this option.

(E) Which symptoms of colony collapse disorder were observed among the colonies in which IAPV was detected

Do we really care about which symptoms were observed? The conclusion as mentioned in the last line of the argument is " IAPV must be the cause of the disorder.  ". Whether the bee colonies in which IAPV was detected display none, one, or all symptoms of colony collapse disorder doesn't help us evaluate the conclusion. 
Hence, we can eliminate this option.

Option C

Goldenfuture · Answer

I reached by elimination b/w A & C and then made a mistake.

A - talks about an alternative explanation. Now why A fails is even if other viruses were present in the healthy colony, we have no information if such viruses were presented in all other colonies in which IAPV was detected. So this does not help with the alternative cause once. It could be IAPV caused both - colony disorder and another one- so it still can be the cause of disorder - this made me believe answer should be C

C - is a causation test

SwethaReddyL · Answer

GMATNinja  /  KarishmaB  - could you please explain this

KarishmaB · Answer

Almost all CCD colonies had IAPV and only one apparently healthy one had it. So the author is concluding that IAPV is the cause of CCD.

How do we evaluate whether A is the cause of B? What further data will help us?
We could find out whether B could be the cause of A instead. If not, then it is more likely that A is the cause of B.
We could find out whether C could be the cause of B. If not, then it is more likely that A is the cause of B.
etc.

(A) Whether the apparently healthy colony infected with IAPV was also infected with any other viruses

Irrelevant what caused CCD. Inspecting the healthy colony for other viruses does not tell us why the failed colonies failed. We could have inspected the CCD colonies to see if there are any other viruses present which could be the cause instead.

(B) By what means IAPV has been spreading between honeybee colonies since 2006

Mode of spread doesn't tell us whether IAPV causes CCD.

(C) To what extent symptoms associated with colony collapse disorder make honeybee colonies more susceptible to infection by IAPV

Exactly. This is questioning whether B causes A. Instead of IAPV causing CCD, what if CCD leads to IAPV? What if a colony that has collapsed is much more susceptible to IAPV? That could explain why CCD colonies have IAPV too even though IAPV may not be causing CCD. 
  
(D) Whether scientists are able to detect IAPV in honeybee colonies with symptoms of colony collapse disorder without conducting bee autopsies

Irrelevant. How IAPV can be detected doesn't matter.

(E) Which symptoms of colony collapse disorder were observed among the colonies in which IAPV was detected

We know that CCD colonies had IAPV. Which symptoms of CCD were observed and which were not doesn't matter.

Answer (C)

MartyMurray · Answer

Entomologist: Beginning around 2006, many honeybee colonies started dying mysteriously, a condition known as colony collapse disorder. Bee autopsies revealed a virus called IAPV in almost all colonies with symptoms of colony collapse disorder, but in only one apparently healthy colony. Thus, IAPV must be the cause of the disorder.

Conclusion of the argument:

IAPV must be the cause of the disorder  (colony collapse disorder)

Support for the conclusion:

Bee autopsies revealed a virus called IAPV in almost all colonies with symptoms of colony collapse disorder, but in only one apparently healthy colony.

We see that the reasoning of the argument is the following: Since, generally, IAPV was found in colonies experiencing the disorder and not in colonies not experiencing it, IAPV must be the cause of the disorder.

So, basically, the author has seen a correlation between the presence of IAPV and the occurrence of the disorder and decided that the first is the cause of the second.

In order to assess the strength of the entomologist's argument, it would be most helpful to know which of the following?

This is an Evaluate question. So, the correct answer will be the choice such that different answers to the question it poses will weaken or strengthen the support for the conclusion.

(A) Whether the apparently healthy colony infected with IAPV was also infected with any other viruses

This choice could sound important because it could appear to bring up a confounding variable, "other viruses."

However, since we have no reason to believe that "other viruses" would be what caused the healthy colony to be healthy even though it was infected by IAPV, the information mentioned by this choice is not helpful.

If this choice posed the question of whether the colonies experiencing the disorder were infected with other viruses, then it might be correct. So, it's key to notice that it doesn't do that and instead brings up something that doesn't make any clear difference.

Eliminate.

(B) By what means IAPV has been spreading between honeybee colonies since 2006

Information on how IAPV has been spreading does not indicate whether IAPV causes colony collapse disorder.

After all, regardless of how it spreads, it still may or may not cause the disorder.

Eliminate.

(C) To what extent symptoms associated with colony collapse disorder make honeybee colonies more susceptible to infection by IAPV

This choice is interesting.

The reasoning of the argument is that a correlation between the presence of IAPV and symptoms of colony collapse disorder indicates that IAPV causes colony collapse disorder. At the same time, what if symptoms associated with colony collapse disorder make honeybee colonies more susceptible to infection by IAPV?

If the answer to that question is that, yes, symptoms associated with colony collapse disorder DO make honeybee colonies more susceptible to infection by IAPV, that information weakens the case for the conclusion. After all, in that case, it could be that, in reality, the cause and effect are the reverse of what the author has concluded they are, meaning that colony collapse disorder causes infection with IAPV rather than that IAPV causes colony collapse disorder.

On the other hand, if the answer to the question is that symptoms associated with colony collapse disorder DO NOT make honeybee colonies more susceptible to infection by IAPV, then that information strengthens the case for the conclusion. After all, in that case, we know that the cause and effect are not reversed, meaning that an alternative explanation has been eliminated, and so there's more reason to believe that the explanation that IAPV causes colony collapse disorder is correct.

So, different answers to the question posed by this choice weaken and strengthen the argument, meaning that it would be helpful to know what this choice brings up.

Keep.

(D) Whether scientists are able to detect IAPV in honeybee colonies with symptoms of colony collapse disorder without conducting bee autopsies

This information would not help with evaluating the support for the conclusion.

After all, it doesn't really matter whether scientists conduct autopsies to detect IAPV. Either it's present or it isn't, and the fact that they have detected its presence in colonies experiencing the disorder supports the conclusion regardless of whether they can detect it without conducting autopsies.

Now, if conducting autopsies could somehow cause colony collapse disorder, this information might be helpful. At the same time, since we have no reason to believe that conducting autopsies causes colony collapse disorder, this information makes no difference.

Eliminate.

(E) Which symptoms of colony collapse disorder were observed among the colonies in which IAPV was detected

This choice could be tempting because we could get the impression that it's bringing up the question of whether the colonies in which IAPV was detected had many or significant symptoms of colony collapse disorder.

It's not really doing that though. It's just asking "which" symptoms were observed, and which symptoms were observed doesn't really matter.

What matters is that symptoms were present when the virus was present and were not when the virus was not.

Eliminate.

Correct answer:   C

Entomologist: Beginning around 2006, many honeybee colonies

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Entomologist: Beginning around 2006, many honeybee colonies

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