A common genetic mutation that lowers levels of the enzyme

Question

A common genetic mutation that lowers levels of the enzyme cathepsin C severely reduces a person’s ability to ward off periodontitis, or gum disease. The enzyme triggers immunological reactions that destroy diseased cells and eliminate infections
in the mouth. But researchers are developing ways to restore the enzyme to normal levels. Once that happens, we will be able to eliminate periodontitis.

Which one of the following is an assumption on which the argument depends?

(A) Restoring cathepsin C to normal levels is the only way to eliminate periodontitis.

(B) Genetic mutation is the only cause of lowered levels of cathepsin C.

(C) Researchers will soon succeed in finding means of restoring cathepsin C to normal levels.

(D) Persons who do not have the genetic mutation that lowers levels of cathepsin C do not get gum disease.

(E) A person whose cathepsin C level has been restored to normal will not suffer from periodontitis.

Source: LSAT

GMATNinja · Accepted Answer

The conclusion comes from the last two sentences: "Once {researchers develop ways to restore the enzyme cathepsin C to normal levels}, we will be able to eliminate periodontitis." Why will we be able to eliminate periodontitis?

A common genetic mutation  lowers  levels of the enzyme cathepsin C,  reducing  a person’s ability to ward off periodontitis, or gum disease. 
 The enzyme cathepsin C "triggers immunological reactions that destroy diseased cells and eliminate infections in the mouth." Thus, we can infer that destroying diseased cells and eliminating infections in the mouth helps ward off periodontitis, or gum disease. 
 If we can restore the enzyme to normal levels, then we can counteract the effect of that common genetic mutation.

Will this allow us to eliminate periodontitis? Only if one of the following is assumed:

According to the argument, restoring cathepsin C to normal levels is  sufficient  for eliminating periodontitis, but that does not mean it is  necessary . Perhaps other ways for eliminating periodontitis could also be developed. Eliminate choice (A).

If we have a way to restore the enzyme, it doesn't matter what causes lowered levels of the enzyme. Perhaps there are several other causes of lowered levels of cathepsin C. Regardless, according to the author, if we can restore the enzyme to normal levels, then we can eliminate periodontitis. Eliminate (B).

The author does not talk about  when  researchers will be able to restore the enzyme to normal levels. The author simply states that "once that happens", we will be able to eliminate periodontitis. It doesn't matter how long it takes researchers to develop those ways, so choice (C) can be eliminated.

As described for choice (B), there could be other factors leading to lowered levels of cathepsin C. Thus, even people who do not have the genetic mutation could have lowered levels of the enzyme. This would not disrupt the author's argument, which is that if we can restore the enzyme to normal levels, then we can eliminate periodontitis. Eliminate (D).

What if there are other causes of periodontitis besides lowered levels of the enzyme? If that is the case, then restoring the enzyme to normal levels might not be sufficient for eliminating periodontitis. Thus, the author's argument depends on this assumption, and choice (E) is the correct answer.

dvnielng · Answer

not a fan of the explanations given. what are you doing in D and E, youer not negating it. youre contradicting yourself in your explanation "hus, even people who do not have the genetic mutation could have lowered levels of the enzyme. This would not disrupt the author's argument, which is that if we can restore the enzyme to normal levels, then we can eliminate periodontitis. Eliminate (D)."

rhythminme2008 · Answer

I think this is a very tough one to get right, and to explain the thought process for getting the right answer.

I totally see how D & E can be confused as the right answer. The difference is as subtle as a hair strand. Here are my 2 cents:

Remember this line: “ But researchers are developing ways to restore the enzyme to normal levels.“ —> the author took the effort to emphasize that researchers are trying to restore the enzyme to normal levels, and NOT FIXING THE GENETIC MUTATION in order to achieve the conclusion, whereby periodontitis is eliminated. The author is giving away the implicit assumption that there ARE OTHER WAYS to lower the enzyme levels, not just via the genetic mutation.

If you read Answer (D) carefully, which is tricky due to the double negatives, it is saying that there IS NO OTHER WAY to get periodontitis. If people who do NOT get the genetic mutation that lowers the enzyme levels do NOT get gum disease, then it means that the genetic mutation IS THE ONLY WAY to get periodontitis. Right? This directly contrasts the implicit assumption that the author gave away in the question stem.

This is how I was able to eliminate (D) and went with (E). (E) is the perfect link between the author’s premise (lower enzyme levels, not necessarily genetic mutation causing lower enzyme levels, is the reason for periodontitis) and the conclusion (correcting the cause, which means restoring the enzyme levels, will lead to the elimination of the disease).

Hope this helps.

honey1 · Answer

A common genetic mutation that lowers levels of the enzyme cathepsin C severely reduces a person???s ability to ward off periodontitis, or gum disease. The enzyme triggers immunological reactions that destroy diseased cells and eliminate infections
in the mouth. But researchers are developing ways to restore the enzyme to normal levels. Once that happens, we will be able to eliminate periodontitis.

Which one of the following is an assumption on which the argument depends?

(A) Restoring cathepsin C to normal levels is the only way to eliminate periodontitis.

(B) Genetic mutation is the only cause of lowered levels of cathepsin C.

(C) Researchers will soon succeed in finding means of restoring cathepsin C to normal levels.

(D) Persons who do not have the genetic mutation that lowers levels of cathepsin C do not get gum disease.

(E) A person whose cathepsin C level has been restored to normal will not suffer from periodontitis
can you plz help me with this question
In option c if we remove word SOON then can it be our answer. 
The word ONCE THAT HAPPENS says that IF we develop ways to restore enzyme then we will be able to ward off periodontitis without much surety or says it with conformity that we WILL able to restore enzymes 
I eliminated option D as wrong negation. Is it correct? 
if lowers levels of the enzyme then reduces a person???s ability to ward off periodontitis
if NOT lowers levels of the enzyme then NOT reduces a person???s ability to ward off periodontitis

AndrewN · Answer

Hello,  honey1 . We have discussed in previous question threads how the negation technique, if you prefer to use it, should be used sparingly. Keep it simple. For the most part, that means adding or removing a  not . In choice (C), yes,  soon  is a problem. The passage provides no such indication. And yes,  once that happens  is more like a conditional  if , like my saying that  when pigs fly, I will start living underwater .

Choice (D) is too extreme, akin to saying that  only  people with the genetic mutation in question get gum disease. But there might be other people who suffer from periodontitis, such as those who do not brush their teeth frequently enough to ward off infections. The passage simply does not discuss this group of people. (You should know by now that such exclusion does not mean such a group cannot exist.)

If you remove the  not  from (E), then the entire argument falls apart. If a person with  restored -to-normal levels of cathepsin C can suffer from periodontitis, then how can the argument assert that because  researchers are developing ways to  restore  the enzyme to normal levels... we will be able to eliminate periodontitis ? That would make no sense at all.

I prefer to think of assumption questions as a search for a missing link. How can the passage go from X to Z without one of the five answers serving as Y? What makes this question less difficult than some we have examined is that assertive or extreme language—here,  only ,  will soon ,  do not —often creates an easier target to argue against in an answer choice. And yes, our missing link here incorporates a bold  will not  in  will not suffer from periodontitis . But is that not synonymous with the conclusion that mentions the ability  to eliminate periodontitis ? If the shoe fits...

I hope that helps. Good luck with your studies.

- Andrew

ricardorr04 · Answer

I thought this was a pretty easy question despite being classified as 700. Can someone confirm the level of this question?

Using negation and understanding the reasoning behind the argument you can easily eliminate all answer choices until E, which fits parameters of the reasoning and argument.

lostminer · Answer

Hello  MartyTargetTestPrep  Can you please help here. In TTP CR Assumption chapter, you said " The correct answer type in Assumption will be - If the the argument says there is a way to success then answer choice will be " it is the only way and there will be no other path to success" ".

I felt this question is of similar type and applied your strategy. I was down to A & E, however, as I remembered your strategy, I went with A.

Can you please explain where I went wrong ? and why A is not the right answer in line with what I have learned from TTP Course. ?

MartyTargetTestPrep · Answer

Hi lostminer.

In answering a CR question, we have to be careful to notice exactly what's going on in the particular question rather than simply seek to apply a pattern without fully analyzing and understanding the question.

In TTP, multiple types of correct answers are discussed with regards to plans, and to get this question correct, we have to notice that type of correct answer you mentioned does not apply here.

The conclusion of this argument is the following:

Once that happens, we will be able to eliminate periodontitis.

Notice that the author does not have to assume what you mentioned, "it is the only way and there will be no other path to success." After all, even if there IS another path to success, this plan could work as well. So, (A) is not the correct answer since, even if (A) is not true and restoring cathepsin C to normal levels is NOT the only way to eliminate periodontitis, the plan could still work.

On the other hand, the author does have to assume (E) because, if a person whose cathepsin C level has been restored to normal WILL suffer from periodontitis, then the plan likely will not have the result of eliminating periodontitis.

unraveled · Answer

A common genetic mutation that lowers levels of the enzyme cathepsin C severely reduces a person’s ability to ward off periodontitis, or gum disease. The enzyme triggers immunological reactions that destroy diseased cells and eliminate infections
in the mouth. But researchers are developing ways to restore the enzyme to normal levels. Once that happens, we will be able to eliminate periodontitis.

Which one of the following is an assumption on which the argument depends?

Two assumption that I could think of:
1. The researchers' developed enzymes would also trigger immunological reactions that destroy diseased cells and eliminate infections.
2. Once these enzymes are restored in a patients the patient's disease would be eliminated without a possibility of recurrence.

(A) Restoring cathepsin C to normal levels is the  only way  to eliminate periodontitis.

(B) Genetic mutation is the  only cause  of lowered levels of cathepsin C.

(C) Researchers  will soon succeed  in finding means of restoring cathepsin C to normal levels.

(D) Persons  who do not have  the genetic mutation that lowers levels of cathepsin C  do not get gum disease . - WRONG. A----> B. But not necessarily Not A ----> Not B. We don't know anything about the unknown.

(E) A person whose cathepsin C level has been restored to normal will not suffer from periodontitis. - CORRECT. 2nd point as suggested above.

A,B and C all are irrelevant.

Answer E.

RiyaJ0032 · Answer

MartyMurray , could you please help eliminating D?

If this option is negated, if people still get gum disease despite enzyme levels not being lowered (due to genetic mutation)

then even if someone restores the enzyme levels to normal

there is no guarantee one won't get the disease

hence won't we assume that normal levels of enzyme won't lead to gum disease for the conclusion to work

Please if some expert could comment

Thank you so much!

egmat 
 DmitryFarber 
 KarishmaB 
 GMATNinja

egmat · Answer

RiyaJ0032  Good question – you've applied the negation test correctly, but there's a subtle scope issue that's causing the confusion. Let me help you see why  (D)  can be eliminated.

The Key Distinction: Different Populations 
 
The argument is that  once the researchers' plan is successful , periodontitis will be eliminated.

Now, what is the objective of the researchers' plan? To restore the enzyme to normal levels.

So, the argument's conclusion is specifically about people  whose low cathepsin C is caused by the genetic mutation . When we restore their enzyme levels, we're addressing  their specific cause  of periodontitis.

Option  (D)  talks about people who  never had the mutation at all  – a completely different group. Here's why that matters:

Why Your Negation Doesn't Break the Argument:

When you negate  (D) : "People with normal cathepsin C (no mutation)  do  get gum disease"

This could be true because they get gum disease from  other causes  – poor hygiene, smoking, other health conditions, etc. Their gum disease has nothing to do with cathepsin C levels.

But the argument's conclusion only considers people who get periodontitis specifically  because of low  cathepsin C from the mutation. When we restore their enzyme, we fix their specific problem.

The people who do not have the genetic mutation (that D talks about) are completely out of scope. So even if they do get gum disease for different reasons, it doesn't affect whether we can eliminate periodontitis in the mutation group- the main argument.

Why (E) is correct:

Option  (E)  directly addresses the conclusion population: "A person whose cathepsin C level has been  restored  to normal will not suffer from periodontitis."

Negate this: "A person with  restored  cathepsin C  will  suffer from periodontitis" → This directly contradicts the conclusion that we'll "eliminate periodontitis" through restoration.

The Strategic Lesson:

In assumption questions, it's very important to understand the premise, evidence and conclusion clearly enough. Always, draw a logical chain between these and clearly write it out.

You should practice some assumption CR questions  here . You can do a guided quiz that will help you understand the approach for these questions with the detailed explanations - just select  Assumption Questions  under  Critical Reasoning  and choose the difficulty as per your ability levels.

RiyaJ0032 · Answer

Hello  egmat !
Appreciate the detailed explanation!

just wanted to confirm if I get this right

basically, D is saying that there can be people that can get gum disease, despite having normal levels of enzyme

But our group is people who get gum disease due to lowered levels of enzyme and since this group is not addressed in D rather in E, we eliminate D and go for E

Can you help me confirm if this is what you mean

Thank you!

egmat · Answer

RiyaJ0032 yes, you are correct in your understanding now

A1Batr0ss · Answer

Option E directly addresses the assumption of passage

A common genetic mutation that lowers levels of the enzyme

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GMAT Critical Reasoning (CR) Questions

A common genetic mutation that lowers levels of the enzyme

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615 to 715 in 15 Days (Ria's Strategies)

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