Hi folks,

I’m afraid the correct answer for this one is choice E and not choice D.

Although the turtle has been toothless for more than 150 million years, in some contemporary turtle species the moderately sharp and jagged edges of their horny jaws function for teeth.

Per the context of the sentence, it is not difficult to understand that here turtle’s “horny jaws” are NOT compared to “teeth”. The horny jaws actually play the role/function of teeth. Hence, this sentence presents function of horny jaws.

PoE:

A. their horny jaws function for teeth: Incorrect.
1. Plural pronoun “their” does not agree in number with singular “turtle”.
2. Use of “for” is incorrect.

B. its horny jaws function for teeth: Incorrect. Use of “for” is unidiomatic.

C. its horny jaws function as do teeth: Incorrect. Notice that “as” is followed by a clause here, presenting comparison. This is not correct because the sentence does not compare the horny jaws with teeth.

D the horny jaws function as teeth do: Incorrect. Same as choice C.

E the horny jaws function as teeth: Correct. When “as” is used to present role/function of something/someone, it is followed by a noun entity. Here “as” is correctly followed by noun entity “teeth”. Hence, this is the correct answer.

P.S: To be able to get rid of the confusion of when to use “as” and when to use “like”, read the article by clicking on the following link:
as-vs-like-correct-and-incorrect-usages-133950.html

Also. At e-gmat, we have 4 dedicated “In-depth” concepts for this topic with many exercise questions. In fact, “Usage of Like” features in our free concepts level – Level 1 Preview Concepts. Just log in to e-gmat.com, register for FREE and learn the concept.

Hope this helps.
Thanks.
Shraddha
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I believe the correct idiom is function as... so a,b, and c are out
Between D&E, D changes the meaning to say that the jaws perform the same functions as teeth do (the jaws chew), whereas E retains the original meaning that the jaws act as teeth -> so E

A uses their to refer to singular turtle. Wrong

B uses for. wrong

Among C, D & E, I feel do is unnecessary when the word function already encapsulates the idea that HJ performs functions similar to teeth

E is my pick.

found this


"some contemporary turtle species", is an adverbial modifier so cannot be the main subject of the sentence


http://www.manhattangmat.com/forums/gma ... t1321.html

Hey All,

Seems like there's still confusion on this one, so I thought I'd weigh in. There are two important splits to deal with here. The first is pronoun (singular/plural and pronoun/versus no pronoun) and the second is idiomatic.

"Although the turtle has been toothless for more than 150 million years" has no bearing on the rest of the sentence. The next clause begins with a new subject "some contemporary turtle species" (which is not an adverbial modifier, by the way), which is the most logical antecedents for any pronoun. Species is plural, so we would need "their", or else to remove the pronoun altogether. This is better, because there would be definite confusion between the two possible antecedents (turtle, species) anyway. From there, we need the right idiom, which is "x functions as y". There's no need for the verb "do", because that's obvious (i.e. I can say "The Tacoma Narrows Bridge ended up functioning as a real-life physics experiment", and don't need to say "The Tacoma Narrows Bridge Ended up functioning as a real-life physics experiment does".

This gets us to answer choice E.

Hope that helps!

Thanks for the explanation . Tommy, however ben ku ( MGMAT instructor) has mentioned that as adverbial modifier and there not the main subject.

http://www.manhattangmat.com/forums/gma ... t1321.html

would you mind explaining some adverbial modifiers to differentiate from above ?

Aha,

I understand now! It is indeed a modifier, though of the prepositional phrase variety (adverbial in that the verb "function" is being modified). You'll want to avoid referring to nouns in such phrases. For example:

I ran for two hours on the beach yesterday, because ITS sand was so soft.

Even though the "ITS" clearly refers to beach, there's no need to use a possessive pronoun here ("on the beach" is another prepositional/adverbial modifier). Better just to say:

I ran for two hours on the beach yesterday, because THE sand was so soft.

Hope that's clearer! Thanks for the follow-up!

Let us remember that the subject of the main sentence is not - some contemporary turtle species – but the moderately sharp and jagged edges.

Secondly, there is a rule that when you compare nouns you use like rather than as. If you are comparing the edges to teeth, then we have to say - the horny jaws function like teeth. -

On the contrary as is used normally while comparing actions, and therefore verbs, and therefore clauses containing verbs.

This is the problem in E. Here we are comparing sharp and jagged edges with teeth. Hence we have to say that the moderately sharp and jagged edges of the horny jaws function like teeth.

Now you may see why that the moderately sharp and jagged edges of the horny jaws function as teeth do is right as in D because as is rightly followed by teeth do which is a clause

IMO, whatever the OA, after eliminating A, B and C for too obvious reasons, between D and E, my vote will be for D
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The correct idiom is 'function AS.' Eliminate (A) and (B).

(C) is incorrect because 'its' (a pronoun referring to the singular case) incorrectly refers to plural 'turtle species.'

(E) omits the verb 'function.' Because of the preposition 'AS', we are comparing verbs. The sentence should read "their horny jaws function as teeth function.' In standard English, you do not repeat the verb, but instead replace it with the 'do.'

Therefore, (D) is the answer.
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Hi Egmat,

Is species singular or plural?

Regards
Srinath

Hi Srinath,

The word "species" is the singular as well as the plural. It can be used as both.

Thanks.
Shraddha
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Hi Shraddha,
I think that here we are comparing the moderately sharp and jagged edges(say,X) of the horny jaws(say,Y) function as teeth do. X of Y-then X is the subject I guess.So here the sharp and jagged edges work as the teeth do.(Not comparing the horny jaws with teeth)

Then would you please elaborate why D is wrong ?

Much help appreciated.
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Hi Debayan,

Even if we say that the sharp and jagged edged of the horny jaws and not the horny jaws act as teeth, the main flaw in choice D is that per that choice "sharp and jagged edges" are compared to "teeth". The intent of the question is not to show comparison. The intent of the sentence is to show function. When we need to show function using "as", we must put just the noun after "as" and not the clause. The moment we put a clause after "as", it presents compariosn and not the function.

In choice D, "as" is followed by a clause "teeth do" and hence presents comparison. Choice E corrects that error by placing just noun after "as" to present the function correctly.

Hope this helps.
Thanks.
Shraddha
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Almost convinced Thanks Shardhha..!

But...still a little doubt left-don't you think that here we are comparing the functions (of teeth and that of sharp and jagged edges of the horny jaws) ?

P.S: Is it because of the fact that as the presence of teeth is virtual in this case so we're not doing the comparison of functions actually...?

Really appreciate your reply as always!
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Hi Debayan,

Let's take a very basic example here:

I work as a GMAT expert with e-gmat.

Here, I am not compared to a GMAT expert. I am a GMAT expert. I function in the capacity of a GMAT expert.

In the very same way, the official sentence does not compare the "sharp abd jagged edges" with "teeth". It says that these "sharp and jagged edges" functions as "teeth". These edges themselves are the teeth in turtle. There is no question of any comparison here.

Hope this helps.
Thanks.
Shraddha
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I understand why its E with regards to the idiom 'function as' - makes sense
What about the 'their' vs 'its' split - tortoises usually have the pronoun 'its' - which is correct in B. Would like some clarity on the doubts below:
Although the turtle has been toothless for more than 150 million years, in some contemporary turtle species the moderately sharp and jagged edges of their horny jaws function for teeth.

a) their horny jaws function for teeth
b) its horny jaws function for teeth - correct in terms of pronoun
e) the horny jaws function as teeth - doesnt the 'the' word seem out of place/ without antecedent? The sentence now says "in some contemporary turtle species the moderately sharp and jagged edges of the horny jaws function as teeth (the horny jaws doesn't seem as clear).

Madhavi1990

The subject of the sentence is the "turtle" and the turtle species are introduced just as an example. Hence, the pronoun should be singular i.e. 'its' or 'the' and not 'their' which is plural.

The correct idiom is 'X functions as Y.' Eliminate A and B.

In C and D, the inclusion of 'do' changes the meaning:

The jaws function as teeth. (This means that the jaws substitute for teeth. In other words, the jaws and teeth play the same role: both are used to eat. This is the intended meaning of the sentence.)
The jaws function as teeth do. (This means that the jaws and teeth operate the same way. This is not the intended meaning of the sentence. The jaws and teeth work differently.)

Eliminate C and D. The correct answer is E.
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GMATNinja - Could you please explain all the answer choices for the above question?
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+ 1 E

Although the turtle has been toothless for more than 150 million years, in some contemporary turtle species the moderately sharp and jagged edges of their horny jaws function for teeth.


(A) their horny jaws function for teeth

Their is wrong. S-V agreement

(B) its horny jaws function for teeth

Function for teeth is wrong and not idiomatic

(C) its horny jaws function as do teeth

As teeth does

(D) the horny jaws function as teeth do

As teeth does

(E) the horny jaws function as teeth

Correct