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Sub 505 Level|   Parallelism|      
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AndrewN
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In laboratory rats, a low dose of aspirin usually suffices t 07 Mar 2021, 05:07
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mSKR
To reject D,
one reason mentioned above : a substance to promote is wrong.

Can I also reject D because it is ambiguous in meaning:

a low dose of aspirin usually suffices to block production of thromboxane which is a substance to promote blood clotting, but does not seriously interfere
Ambiguous meaning : but doesn't can be implied in parallel with suffices xx|| doesn't interfere because which xx could be interpreted additional information for thromboxane.
Intended meaning : thromboxane <verb> but doesn't <verb>

This reasoning can help to reject some wrong options in other questions. Please share your opinions .
AndrewN AjiteshArun :please: :please:

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In laboratory rats, a low dose of aspirin usually suffices to block production of thromboxane, which is a substance that promotes blood clotting, but not seriously interfering with the production of prostacyclin, which prevents clotting.

(A) which is a substance that promotes blood clotting, but not seriously interfering
(C) a substance that promotes blood clotting, but does not seriously interfere
(D) which is a substance to promote blood clotting, but does not seriously interfere
Hello, mSKR. I do not think a strong case can be made for ambiguity of meaning in the way you have outlined. The comma before but effectively ropes off the which clause so that the reader understands the main clause is going to continue:

a low dose of aspirin suffices to block production of thromboxane... but does not seriously interfere with the production of prostacyclin

Without the comma in question, the non-essential information about thromboxane would seem to continue instead:

thromboxane, which is a substance to promote blood clotting but does not seriously interfere...

I hope that clarifies your concerns.

- Andrew
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In laboratory rats, a low dose of aspirin usually suffices t 02 May 2022, 10:18
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rishabhmishra
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In laboratory rats, a low dose of aspirin usually suffices to block production of thromboxane, which is a substance that promotes blood clotting, but not seriously interfering with the production of prostacyclin, which prevents clotting.

(A) which is a substance that promotes blood clotting, but not seriously interfering
(B) a substance that promotes blood clotting, but not seriously interfering
(C) a substance that promotes blood clotting, but does not seriously interfere
(D) which is a substance to promote blood clotting, but does not seriously interfere
(E) which is a substance that promotes blood clotting, but not a serious interference


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Can someone explain C and D
Hey can anybody tell me that without which such as in option B and C, a substance doesn't create ambiguity that this substance refer to aspirin or thromboxane or prostacyclin because structure like this can modify any noun at any place in this sentence please explain.


"Which" and "substance" both function as noun modifiers here, so if there were ambiguity about what "substance" were referring to, you'd have the same ambiguity for "which."

And context makes it pretty clear that both must be describing "thromboxane." If we don't know what thromboxane does, it's not going to be terribly meaningful that aspirin blocks it, right? And "thromboxane" also happens to be the closest noun to the modifier. Certainly not a rule, but if a noun modifier is right next to a noun it could logically describe, it isn't wrong.

I hope that clears things up!
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In laboratory rats, a low dose of aspirin usually suffices t 02 May 2022, 13:29
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"Which" and "substance" both function as noun modifiers here, so if there were ambiguity about what "substance" were referring to, you'd have the same ambiguity for "which."

And context makes it pretty clear that both must be describing "thromboxane." If we don't know what thromboxane does, it's not going to be terribly meaningful that aspirin blocks it, right? And "thromboxane" also happens to be the closest noun to the modifier. Certainly not a rule, but if a noun modifier is right next to a noun it could logically describe, it isn't wrong.

I hope that clears things up!

Thanks for your reply GMATNinja sir, if my understanding of noun modifiers is correct usage of 'which' won't have the ambiguity issue posed by 'substance' (a flexible noun modifier) because 'which' is constrained by touch rule while flexible noun modifier 'substance' can modify farther away noun. 'Substance' can modify thermoboxane or aspirin (though illogical, it still can, thus creating ambiguity)
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In laboratory rats, a low dose of aspirin usually suffices t 07 May 2022, 05:27
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Dhwanii
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"Which" and "substance" both function as noun modifiers here, so if there were ambiguity about what "substance" were referring to, you'd have the same ambiguity for "which."

And context makes it pretty clear that both must be describing "thromboxane." If we don't know what thromboxane does, it's not going to be terribly meaningful that aspirin blocks it, right? And "thromboxane" also happens to be the closest noun to the modifier. Certainly not a rule, but if a noun modifier is right next to a noun it could logically describe, it isn't wrong.

I hope that clears things up!

Thanks for your reply GMATNinja sir, if my understanding of noun modifiers is correct usage of 'which' won't have the ambiguity issue posed by 'substance' (a flexible noun modifier) because 'which' is constrained by touch rule while flexible noun modifier 'substance' can modify farther away noun. 'Substance' can modify thermoboxane or aspirin (though illogical, it still can, thus creating ambiguity)
The "touch rule" isn't actually a rule, and there are plenty of exceptions to it. (For more on that, check out "Usage #4" in this article.)

So, no, I wouldn't say that the "which" is somehow less ambiguous. Tying "substance" back to "aspirin" would be just as much of a stretch as tying "which" back to "aspirin," so that isn't a significant decision point in this case.
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In laboratory rats, a low dose of aspirin usually suffices t 30 Dec 2022, 08:12
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Hi Experts,

I realize that the use of the comma between "clotting" and "but" is discussed on this form, but I am still a bit confused.

In Choice C: "a substance that promotes blood clotting, but does not seriously interfere with the production of prostacyclin..."

To me, if you are using ",but" shouldn't there be an "it" to refer to "a substance"? Why is the comma absolutely necessary before "but"? It seems to read fine without it: "a substance that promotes blood clotting but does not seriously interfere with the production of prostacyclin..."

Thank you!
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In laboratory rats, a low dose of aspirin usually suffices t 30 Dec 2022, 19:51
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woohoo921

The "but" part belongs to the main clause: "A low dose of aspirin suffices to block the production of T, but does not interfere with the production of P."

If we wanted "but does not interfere" to continue the modifier for T ("a substance that promotes X but does not interfere with Y"), we'd want to leave the comma out to make that intention clear. As it is, the presence of a comma after "clotting" in all 5 choices is a strong indicator that the author does NOT intend the following portion to be read as part of the modifier.
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In laboratory rats, a low dose of aspirin usually suffices t 02 Jan 2024, 21:00
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