Damaged nerves in the spinal cord do not regenerate themselves natural

Question

Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord. Antibodies that deactivate those inhibitors have now been developed. Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.

Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above?

Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above?

(A) Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.

(B) Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors.

(C) Nerves in the brain are similar to nerves in the spinal cord in their inability to regenerate themselves naturally.

(D) Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants.

(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.

Source  :  Paper Test (Test Code 48)

mikemcgarry · Accepted Answer

Dear imawolf , My lupine friend, I am happy to respond.

This is a brilliant question. I don't know the source. Here's the prompt & question: Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord. Antibodies that deactivate those inhibitors have now been developed. Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future. Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above? Here's (A), the OA: (A) Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth . That's a very complicated sentence. If you don't understand the term " by-product ," you need to look that up and understand it thoroughly. First, there are " substances inhibiting nerve growth " in the human body. Call these SING for short--an acronym. The argument proposes using " antibodies " to " deactivate " the SING, to render them completely ineffective and non-functioning. We may wonder whether " inhibiting nerve growth " is all the SING do or whether they have any other jobs. Well, (A) tells us quite definitively that " Prevention of the regeneration of damaged nerves is merely a by-product of " SING. In other words, the SING have other jobs in the human body, their "main jobs," and " inhibiting nerve growth " is simply some that happens in addition to everything else they do. Each SING has a "main job" first, and " inhibiting nerve growth " is an extra that also happens--a by-product. This piece of information presents a HUGE problem for the argument. We want to encourage nerve regrowth, but if we us antibodies to render the SING ineffective, then that will stop everything the SING do--it will stop all their "main jobs," as well as removing the blog to nerve regrowth. Now, we don't know what those main jobs are, but the human body is truly miraculously designed. Three billion years of evolution have come together in producing a complex system so brilliantly interconnect and interrelated that it truly boggles our mind. Each body is a miracle packed full of a million miracles. Human beings walk around every day with no idea that their bodies are astonishing miracles beyond all reckoning. If a substance in the body has a "main job," chances are very good that this "main job" is absolutely essential for the life and health of the body. Stopping this "main job" would have lead to dysfunction, illness, and perhaps even instant death! Thus, shutting off the SING and their "main job" would produce devastating effects. Those side-effects are far too severe and dangerous, so this kind of treatment does not look promising after all. Does all this make sense? Mike

Sovjet · Answer

Our conclusion in this paragraph is "nerve repair will be a standard medical procedure in the forseeable future". We can imagine two instances were this would not be the case:

1) "Nerve repair" does not work - and there is therefore no reason to conduct the procedure.
2) "Nerve repair" will damage the body to such a degree, that the procedure will never be conducted (because of its byproduct), regardless of whether or not it regenerates nerves in the spinal cord.

Answer (A): This states that the  main  purpose of this inhibitor isn't to prevent regeneration of nerves, but something else entirely. Thus, we can conjecture that the main purpose is far more important than its secondary purpose of preventing regenration. Therefore, by turning off the inhibitor, we are possibly/probably causing collateral damage to the body.

(B) This esentially states that using other nerve-growth stimulants  may  have the same effect as injecting the antibodies. However, the effect would be the same, and therefore does not weaken the argument.
(C) This potentially strengthens (but certainly doesn't weaken) the argument that nerve repair will be a standard medical procedure in the future, as we can conjecture that the procedure might be possible on nerves found in both the brain and the spinal cord.
(D) The paragraph clearly states that those methods do not work on the spinal cord because of that inhibitor. This doesn't add any new information.
(E) This just tells you that the procedure is time-consuming/expensive. It doesn't negate the conclusion that we will be performing this procedure. (For example, chemotherapy is both a long and expensive treatment, but is still used in combatting cancer because of its effectiveness)

jainu · Answer

I think it should be A, because
conclusion: Nerve repair would be a standard procedure
OptionA: Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth. 
This implies that there are many fiunctions of this substance apart from inhibitiion....So every time there is a procedure doctors should take care that other functions should not get affected and hence doctors cannot do the same thing for every patient evrytime. It will depend from patient to patient.

alexpiers · Answer

Definitely, A.

(B) Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors. Not valid. This means that growth stimulants are antibodies. I don`t like the word "certain".
(C) Nerves in the brain are similar to nerves in the spinal cord in their inability to regenerate themselves naturally. - Not valid. We don`t care about nerves in the brain, we are talking about nerves in the cord
(D) Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants. Not valid. It doesnt`t correct to talk about other locations - there could be another types of nerves.
(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies. So what??? Ok, let it be... We are talking about possibility, but not time period. So, irrelevant.

Actually, B, a bit confusing. It looks like a correct variant. But it is not.

pqhai · Answer

I chose B and got this question wrong. 
However, after review I think the answer is straight A.

Premise 1: Damaged nerves do not regenerate themselves naturally.
Premise 2: The reason is the presence of nerve-growth inhibitors. 
Premise 3: Antibodies that deactivate those inhibitors have been developed.
Conclusion: Nerve repair will be a standard medical procedure in the foreseeable future.

Assumption: nerve-growth inhibitors are main factors that prevent damaged nerves' regeneration.

To weaken this assumption, we have to demonstrate those inhibitors are not the main factors, in fact, they are just  by-products of the main function  in the human body of the substances inhibiting nerve growth. So does that make any sense to attack the by-products. Nope!.

B is incorrect. Please see the first sentence: "Damaged nerves in the spinal cord do not regenerate themselves naturally,  nor even under the spur of nerve-growth stimulants ". It clearly says nerve-growth stimulants do not help to regenerate damaged nerves.

anish123ster · Answer

My take is A

Reason

A)  If the prevention of nerve growth is just a by-product, it may disrupt other functions of the body when the anti-bodies were introduced to the body. 
Thereby it would cast doubt over the possibility that nerve growth would become a standard procedure. Because this anti-bodies may have other unfavorable side effects.

B) Does not cast any doubt over the claim, because it would mean that there are more ways to encourage nerve growth beside the anti-bodies. Hence it supports the claim, that it will be a standard medical procedure.

C) Does not cast any doubt because the claim was that it will be a standard medical procedure. So this choice is suggesting that even the brain cells can be benefited from the anti-bodies would only increase demands of this procedure.

D) It supports the claim, because it means besides the anti-bodies, there is other means to make nerve repair be a standard medical procedure.

E) Since the question did not state that the anti-bodies are very limited, nor does it state any reason for it to be. This choice does not cast any doubt to the claim that it will be a standard medical procedure.

OA please..

LogicGuru1 · Answer

Answer is A

Explaination :-
 
Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord. Antibodies that deactivate those inhibitors have now been developed. Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.

Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above?

(A) Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.
Some substance in your body has has some main function but it is also inhibiting nerve growth. Lets say that substance is vital such as insulin. Insulin is required for ATP metabolism, glucose and lipid transformations. Now no matter how many antibodies you give, insulin will be produced in your body, the moment even one molecule of glucose or fat enters your body. Now you can't avoid eating. You will die. So no doctor will carry such procedure. Another case. ASSUME serotonin an enzyme in brain that keeps you happy and prevent you from committing suicide is the inhibitor of nerve damage. You can suppress serotonin by chemically changing the brain chemistry by using medicines, but then the chances of your being forever depressed or killing yourself is high. So the procedure will not be standard but rare. hence A is right.
 
 (B) Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors.
we are not talking about those certain growth stimulant , we are talking about a particular antibody.

(C) Nerves in the brain are similar to nerves in the spinal cord in their ability to regenerate themselves naturally.
It is a medical fact. But it is not relevant. All it is saying that brain cells also cannot regenerate naturally. In fact by using the same antibody we might actually regenerate them too.

(D) Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants.
Another fact. But we are concerned only about Spinal cord's nerves and Antibodies.

(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.
And a steady supply of antibody is quite easy to supply. Once the antibody is in market keep buying it. Whats the problem in that.

imawolf · Answer

mikemcgarry   GMATNinja   GMATNinja two  carcass  Could you kindly explain the logic behind answer choice A?

DwightSchrute · Answer

My question here is B says the certain nerve growth stimulants have a similar chemical structure to those of the antibodies, we know that nerve growth stimulants did not work and the reason was they could not do so because of the presence of the inhibitors. So if the Nerve Growth Stimulants could not deactivate the inhibitors, it tells us the antibodies also will not be able to do so. Antibodies are developed, argument doesn't provide any evidence if they work or not.

I understand the reasoning of A as well and I am not doubting it, but can someone help point out the flaw in my reasoning for answer choice B

I was stuck between A and B and I disregarded A because we don't know what is the main function of the inhibitors and stopping it particularly for how long will have an adverse effect? It could also be temporary without having an adverse effect and could finally help in nerve growth.

KarishmaB · Answer

Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. 
It is because of the presence of nerve-growth inhibitors in the spinal cord. 
Antibodies that deactivate those inhibitors have now been developed.

Conclusion: Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.

Spinal cord has some growth inhibitors. They prevent regrowth of nerves. Antibodies that deactivate these inhibitors have been developed. We are concluding that nerve repair will become a standard procedure now.

We need to cast doubt that it will become a standard procedure now.

What if the antibodies that deactivate the inhibitors harm us in other worse ways? What if the growth inhibitors play some other crucial role in our bodies and deactivating them is harmful to us? 
Then, nerve repair may not become standard procedure.

The only relevant options are (A) and (B).

(A) Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.

Correct. Inhibitors have a main function (they play some other role in our body). Inhibition of regeneration is just a by-product. If we deactivate these inhibitors, their main function will stop. It may impact our body in a much worse way. Hence, it casts doubt on the conclusion that it will become standard procedure.

(B) Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors.

Similar chemical structure does not mean "same". A small difference could be all that is needed to make antibodies work. So the fact that stimulants do not work does not imply that antibodies will not work either. Besides we are given that antibodies do deactivate those inhibitors. So we know that the antibodies work.

Answer (A)

Mavisdu1017 · Answer

Hello expert,
Could you help on B? 
B says nerve-growth stimulants have similar chemical structures to those of the antibodies—>means they should have similar effect. And passage says nerve-growth stimulants can’t actuate damaged nerves, so the antibodies should have the same effect which can’t actuate damaged nerves, so nerve repair is not promising—>weaken the conclusion.
I wonder where I am wrong? Thanks in advance.

MartyTargetTestPrep · Answer

Hi Mavisdu1017.

Notice that "nerve growth stimulants" by definition stimulate nerve growth. So, regardless of that fact that the nerve growth stimulants have chemical structures similar to those of the antibodies, their effects must be different.

An analogous example is that of glucose, a sugar, and benzene, a volatile and toxic liquid. The chemical structures of molecules of the two are quite similar, but the effects of the two substances on the human body are very different.

Raman109 · Answer

This is a combination of cause-effect and assumption

Presence of the nerve-growth inhibitors is the cause behind damaged nerves not regenerating themselves (effect). Now we have the antibodies developed, we can use the antibodies to remove the cause and possibly no cause no effect. The assumption in making the conclusion that"nerve repair will be a standard medical procedure" is that if you switch off the inhibitor button, there are no alternate effects. Option A challenges this assumption by highlighting that if we switch off the inhibitors button there can be significant issues, thus making us believe less in the conclusion that "standard medical procedure". Option B says certain and not all. More importantly, as Karishma pointed out, similar doesn't mean the same. Even one difference can make a difference. Option E says it would require steady supplies - there is nothing in the argument that says supplies can be a challenge. This is at best out of scope - the argument scope is limited to that "nerve repair will be a standard medical procedure" how - using the antibodies that deactivate those inhibitors.

gurugmat · Answer

Option A is the correct answer. Imagine a substance in the body that prevents nerve growth but also plays a crucial role in another vital function, like regulating immune responses. If the main function of these inhibitors is critical to other bodily functions, deactivating them could have serious side effects. For instance, if these inhibitors are essential for immune system regulation, removing them could compromise the immune system. This casts doubt on the prediction because it suggests that deactivating these inhibitors might not be feasible or safe, making widespread nerve repair unlikely.

gurugmat · Answer

Option B is incorrect because it focuses on the chemical similarity between nerve-growth stimulants and antibodies, which is not relevant to the main argument about the effectiveness of antibodies in deactivating inhibitors. The prediction about nerve repair becoming a standard procedure depends on the antibodies’ ability to remove the inhibitors, and option B does not cast serious doubt on this ability.

pappal · Answer

The gist of the argument lies in  "the standard medical procedure"  --any procedure that merely inhibits any natural substance whose part time job is non-beneficial, while main job would be beneficial
(though not mentioned in the argument anywhere) cannot be regarded as described in bold above.
Thought process in this manner somehow results in negation of the argument, since no other options stand nearer to weaken the conclusion.
so no other choice but A.

agrasan · Answer

Hi  KarishmaB   MartyMurray

(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.

I was tuck between (A) and (E), is (E) wrong because we simply don't know from the argument whether  "steady supply"  will really be a challenge for the antibodies to be a    standard  medical procedure  ? So it will be an unwarranted assumption to make (E) correct?

Please let me know if my reasoning is wrong.

guddo · Answer

Your reasoning is basically right.

(E) says you would need a  steady supply  of antibodies for a long time. But the conclusion is “will be a  standard  procedure,” and lots of standard treatments require ongoing dosing or repeated supply (insulin, antibiotics courses, dialysis, etc.). So (E) does not show an obstacle that would stop it from becoming standard; it only adds a requirement.

To make (E) a serious doubt, it would need an extra step like “a steady supply is not feasible or would be prohibitively expensive.” The option does not say that, so treating “steady supply” as a blocker would be an  unwarranted leap .

That is why (A) is stronger: it suggests deactivating inhibitors could disrupt an important main function, which directly raises safety risk and could prevent the procedure from ever becoming standard.

KarishmaB · Answer

Yes, the argument doesn't say that there is any problem in providing that steady supply of antibodies. Perhaps some medicine taken orally everyday will provide that steady supply - we don't know. Until and unless we know that steady supply is an issue, we cannot say that it weakens the possibility of the solution working.

Think about it this way -
Claim: Process A is likely to be successful.

X: Process A needs continuous power supply.

Does it mean our process A will not be successful? No. We may have continuous power supply. Until and unless it is mentioned that we do not have continuous power supply, it is not a shortcoming of process A.

Damaged nerves in the spinal cord do not regenerate themselves natural

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Damaged nerves in the spinal cord do not regenerate themselves natural

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