Telomerase is an enzyme that is produced only in cells that are active

stuck b/w C and D... not even sure either is right, but the exceptions seem to be independent, so presence of telomerase in bone marrow is no indication of bone marrow cancer (C)

as far as D, I think it is too broad...

<phew> Close one b/w B and C, and I got it right C.

A) Not necessarily. We only dicussed Telomerase, other enzymes that fit the bill may exist, but are not discussed here.
B) The question mentions that Telomerase is only produced in cells that are actively dividing, but it does not mention that it is produced in all cells that are actively dividing. It may not be present in some of the cells.
C) True.
D) Not mentioned.
E) Not mentioned.

A. Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing. Could be true or could not be true. Stimulus states that telomerase is generally absent from body tissue. Furthermore, it's a exaggeration: "Generally" <> "only".
B. In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing. This is another exaggeration; nowhere in the necessary condition say cells must "rapidly" divide.
C. The presence of telomerase in bone marrow is no indication of bone marrow cancer. OK - Since bone marrow and cancer are exceptions, this must be inferred.
D. Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue. This is another exaggeration; nowhere in the necessary condition say cells must "rapidly" divide.
E. The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue Could be true/could not be true.

IMO C

Telomerase is an enzyme that is produced only in cells that are actively dividing. For this reason it is generally absent from body tissues in adults. Bone marrow is an exception to this rule, however, since even in adults, bone marrow cells continually divide to replace old blood cells. Cancers are another exception, because their cells are rapidly dividing.

The information provided most strongly supports which of the following?

A. Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing
Cannot be inferred as the passage doesn't say that Telomerase is the only enzyme

B. In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing.
We are talking about actively dividing and not rapidly dividing.

C. The presence of telomerase in bone marrow is no indication of bone marrow cancer.
That can be inferred as presence of telomerase indicates that bone marrow tissues are actively dividing - Correct

D. Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue.
Cannot be inferred - We are not talking about the rapid growth of cancer

E. The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue
Cannot be inferred as level of telomerase is not compared. The presence or absence is discussed.

Telomerase is an enzyme that is produced only in cells that are actively dividing. For this reason it is generally absent from body tissues in adults. Bone marrow is an exception to this rule, however, since even in adults, bone marrow cells continually divide to replace old blood cells. Cancers are another exception, because their cells are rapidly dividing.

The information provided most strongly supports which of the following?

A. Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing. can't be supported - we don't have information on other enzymes
B. In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing. can't be supported - telomerase is produced in dividing cells but that doesn't mean it is present in every tissue that has dividing cells
C. The presence of telomerase in bone marrow is no indication of bone marrow cancer. Telomerase is present in actively dividing cells. In adults, bone marrow cells and cancer cells actively divide. Since the cells may be normal bone marrow or cancerous, the presence of telomerase in these cells does not necessarily indicate bone marrow cancer.
D. Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue. can't be supported - no evidence of the relative cell division rates
E. The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue can't be supported - we only know that it is present sometimes in both, but not to what extent

This question has been giving many people a lot of trouble, and the truth is that the reason there are so many doubts is that the question has issues, as some of the wording does not quite clearly state what the question's creator felt that it states. So let's define what the issues are.

First let's define what they are not. Answer choices A, D and E, are fine. Each of them says something that clearly cannot be inferred from what the prompt says.

A does not have to be true. There could be all manner of differences between cancerous cells and cells that are not actively dividing.

D cannot be inferred, as what the prompt say about bone marrow does not clearly indicate anything about the rate at which bone marrow cancer grows.

E cannot be inferred as the prompt does not indirectly or directly support any conclusions about relative levels of telomerase production. It merely provides a binary set of situations, cells in which telomerase is produced and cells in which telomerase is not produced.

Ok so, with A, D, and E out, we are left with the two problematic answer choices.

First let's talk about B, "In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing."

Since C is the OA, the creator of this question clearly felt that B cannot be inferred from the prompt, and here is the logic underlying that stance.

For all we know, while the prompt says that telomerase is only produced by cells that are dividing, it is possible that not all cells that are dividing produce telomerase. That cells that are dividing may not produce telomerase seems possible, and this logic means that B cannot be inferred.

However, there are aspects of the wording of the prompt that could be taken to indicate that actually all dividing cells produce telomerase.

The prompt says, "Bone marrow is an exception to this rule, however, since even in adults, bone marrow cells continually divide to replace old blood cells." The prompt also says, "Cancers are another exception, because their cells are rapidly dividing."

The implication that one could take from those statements is that SINCE BONE MARROW CELLS AND CANCER CELLS DIVIDE, THEY ARE EXCEPTIONS. The prompt does not say that since they divide they CAN BE exceptions. It say that since they divide they ARE exceptions, which can be taken to mean "SINCE THEY DIVIDE, THEY PRODUCE TELOMERASE."

That somewhat reasonable interpretation of the meanings of the sentences in the prompt could in turn be taken as implying that CELLS THAT DIVIDE PRODUCE TELOMERASE, which supports B.

I believe that that analysis partially explains why B is being chosen by so many people.

Now let's look at C, "The presence of telomerase in bone marrow is no indication of bone marrow cancer."

The issue in C is similar to the issue in B, actually.

Just as B does not say CAN BE AN EXCEPTION, C does not say, IS NOT NECESSARILY AN INDICATION.

C says that telomerase in bone marrow is NO indication of cancer. That's an extreme statement, as telomerase in bone marrow could be coming from cancerous cells. I realize that I am playing with subtle differences, but I think that if C were worded even "The presence of telomerase in bone marrow is NOT AN indication of bone marrow cancer," C would be slightly clearer.

So if the wording in the prompt regarding the bone marrow and cancer exceptions were just slightly clearer, and if a couple of words in C were changed in order to increase clarity, this question would perhaps go from 700 level to 600 level.

MartyMurray

I rejected E mainly because Telomerase may be present in higher amount in bone marrow(non cancerous) instead of cancerous cell. Is this justification apt??

Yes, that justification works perfectly.

Also, telomerase may be present in non cancerous tissue in children in amounts higher than those found in cancerous tissue.

HI marty Murray , GMATNinja ,

Below is one meaning that i understood from the prompt. Pl check whether my understanding is correct.

T is produced only in actively dividing cells.... Ok...Hence it is not produced in adult tissue which are not dividing ----Fair enough

Bone marrow and cancer cells divide rapidly but they are exception too.....How can they be exception even after dividing???


They must not be producing T.....

If we go with above understanding then all options apart from B looks wrong..... B can also be eliminated as rapidly and actively may not be similar.

What say??? Where am I going wrong??

Understanding the argument -
Telomerase is an enzyme that is produced only in cells that are actively dividing. Fact
For this reason it is generally absent from body tissues in adults. Fact
Bone marrow is an exception to this rule, however, since even in adults, bone marrow cells continually divide to replace old blood cells. "however" shares a contrast. Fact.
Cancers are another exception, because their cells are rapidly dividing. - Fact.

Option Elimination -

(A) Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing. "only" is a bit hyperbolic. Wrong.

(B) In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing. - the presence of "telomerase" is in no way shown as a minimum condition for "cells that are actively dividing." Distortion.

(C) The presence of telomerase in bone marrow is no indication of bone marrow cancer. - ok. It's normal to have "telomerase" in the bone marrow.

(D) Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue. - This comparison is not mentioned in the argument. Distortion. Wrong.

(E) The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue. This comparison is not mentioned in the argument. Distortion. Wrong.

­Premises:

Telomerase is an enzyme that is produced only in cells that are actively dividing. For this reason, it is generally absent from body tissues in adults. 

Bone marrow is an exception to this rule, however, since even in adults, bone marrow cells continually divide to replace old blood cells. 

Cancers are another exception, because their cells are rapidly dividing.

Let’s look for a conclusion/inference - something that must be true as per the premises.

(A)    Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing.



Not necessary. There could be other such enzymes too.



(B)    In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing.



Not necessary. Telomerase is produced only in cells that are actively dividing. It does not mean that it is produced in all cells that are actively dividing. There could be some cells which are actively dividing but which do not produce Telomerase. 
 
(C)    The presence of telomerase in bone marrow is no indication of bone marrow cancer.

Correct. Bone marrow would normally have Telomerase since cells are actively dividing in it. Its presence does not indicate cancer.



(D)    Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue.



No such information available in the argument.



(E)    The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue.

No such information available in the argument.


Answer (C)

Discussion on Inference Questions: https://youtu.be/PMnU9ULdSfs
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