Almost all microbe species live together in dense, interdependent comm

Question

Almost all microbe species live together in dense, interdependent communities, supporting the environment for each other, and regulating the population balances for their different species through a complex system of chemical signals. For this reason, it is currently impossible to cultivate any one such species in isolation. Thus, microbiologists lack complete knowledge of most microbe species.
Which one of the following, if assumed, enables the argument’s conclusion to be properly drawn?

A. It is currently impossible for microbiologists to reproduce the complex systems of chemical signals with which microbe communities regulate the population balances for their different species.
B. If it is currently impossible to reproduce the environmental supports and chemical signals in dense, interdependent communities of microbe species, then it is also impossible to cultivate any microbe species from such a community in isolation.
C. No microbiologist can have complete knowledge of any species of organism unless that microbiologist can cultivate that species in isolation.
D. At least some microbiologists lack complete knowledge of any microbe species that live together in dense, interdependent communities.
E. No microbe species that normally lives together with other microbe species in dense, interdependent communities can survive outside such a community.

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IEsailor · Answer

The last two sentence provide the main conclusion of the argument. Hence in answer choice look for assumptions based on them.
1.) Assumption does not help conclusion completely
2.) Out of scope or false
 3.) Fits the conclusion in the last two sentences  
4.) Even if true, does not help the conclusion
5.) False

vjsharma25 · Answer

My doubt about C is that,Do a microbiologists needs to experiment it PERSONALLY to have the complete knowledge about any species of organism.Means can't some other microbiologist(s) do the research and publish the result to others to gain the knowledge?
Option E says "No microbiologists can have the complete knowledge of any species of organism  unless that microbiologist  can cultivate that species in isolation".
Why B is OOS or false. OOS is the easiest reason I have seen to avoid an option. No personal offence to you IEsailor.

KapTeacherEli · Answer

Looks like you've got a good point!

The author provides a great deal of evidence about how and why individual species of microbe can't be isolated. His conclusion, based on that evidence, is that microbiologists don't fully understand those microbes. The glaring hole in the argument is the assumption that biologists can only understand things that they isolate. This leads us to (C) as the closest answer.

(B) is the right answer to the wrong question type. The first two sentences of evidence can be pieced together to logically infer that (B) must be true. However, this is an Assumption question, not an Inference question. Assumptions are unstated facts that are necessary for the conclusion to follow from the evidence. If they are true, the author's conclusion is properly drawn, but if they are proven false then the author's conclusion is undermined despite his facts being otherwise correct. (B)  must  be true as a consequence of his data, and (B) does not tie into his conclusion at all; for these two reasons, we can rule it out.

However, you're correct that we've made an error. The proper assumption is that no microbiologist can understand a microbe unless some microbiologists can isolate the bug. Indeed, it doesn't have to be the same one doing the isolating and the understanding. We've made a typo, and if you'll shoot me a PM with the source of the problem and a page number or problem ID number, I'll make sure it get's added to the errata sheet ASAP!

vjsharma25 · Answer

Though I have also opted C first,but because of the reason explained above I didn't choose it and went for option B. I think now its clear that B can't be the answer and C also has some problem with it

But OA is C only.

KapTeacherEli · Answer

vj, thanks for the PM. I actually have to backtrack--this problem doesn't have a mistake. However, what we do have here is an illustration of why LSAT problems aren't necessarily the best practice for the GMAT!

One of the major subjects tested by the LSAT is the difference between a 'sufficient' assumption and a 'necessary' assumption. Here is an example:

If a house is far from the city and either small or poorly constructed, it will be cheap. Clearly, my house was inexpensive

Necessary assumption: my house is far from the city. This must be true for my logic to be sound: if my house is close to the city, then my premises don't connect to my final conclusion and my argument is nonsense. However that assumption isn't enough in and of itself! My house also needs to be either small or cheaply built for us to be certain.

Sufficient assumption: My house is far from the city and small. This doesn't have to be true--my house could be far from the city and poorly built. But if it  is  true, then that is sufficient to prove my conclusion accurate 100% of the time.

The GMAT rarely distinguishes between these two, but the LSAT often tests both ways--and what we have here is a question of the latter. The prompt asks us what "enables the conclusion to be properly drawn," or in other words, which answer choice  guarantees  that the evidence logically leads to the conclusion. If (C) is true, then the conclusion is true--so it's the unambiguous right answer.

marcsciandra · Answer

i chose c too cause it easily was tied to the conclusion, which is the last sentence. negate that conclusion and the arguments falls apart.

karun0109 · Answer

C links isolation and complete knowledge

kraizada84 · Answer

only C goes the best................!!!!

spartacus1412 · Answer

negate statment C and the conclusion will no longer stand...hence , C is the assumption

macjas · Answer

Cause and Effect

Which one makes fore sense:

1. It is currently impossible to cultivate any one such species in isolation. Therefore microbiologists lack complete knowledge of most microbe species.

2. Microbiologists lack complete knowledge of most microbe species thus it is currently impossible to cultivate any one such species in isolation.

I think 1. is better because claiming that microbiologists lack complete knowledge of most microbe species. is out of scope for the passage; while 2. is more in line with the passage.

C is a good explanation for 2.

dexerash · Answer

Option C seems to be correct here which states the assumption.

chesstitans · Answer

Using POE, C is left even though test takers hardly comprehend the idea of "complete knowledge".
E is wrong because the passage states that it is impossible to cultivate any one of "almost species".

VerbalBot · Answer

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Almost all microbe species live together in dense, interdependent comm

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Almost all microbe species live together in dense, interdependent comm

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