Telomerase is an enzyme that is produced only in cells that are actively dividing.
Key fact

For this reason it is generally absent from body tissues in adults.
Result of that fact. Because adults have grown up - they don't need to get any more new cells

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

Cancers are another exception, because their cells are rapidly dividing.
Here is another exception to the rule

The information provided most strongly supports which of the following?
So we have a fact, and 2 places where it doesn't work. What can this be applied to?

A. Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing. Key word that immediatly worries me is 'only'. We have no evidence that T is the 'only' enzyme in cancer cells
B. In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing. We have no evidence for this. It sort of makes sense, but no definite evidence for it
C. The presence of telomerase in bone marrow is no indication of bone marrow cancer. This looks good. If a certain enzyme is present in non cancerous bone marrow, then it can't be evidence of cancer.
D. Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue. This is not mentioned anywhere, nor can it be implied. Where is there any mention of speed?
E. The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue Again, not mentioned. No implication if it grows faster or slower in any particular conditions

Hope that helps.

James

<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.
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Hi James,
I've a doubt here.
In inference type of questions we pick the must be true options. However, in option C, can we infer "The presence of telomerase in bone marrow is no indication of bone marrow cancer," on solid grounds? , because telomerase can be present in cancer cells ,and so it may be present in bone marrow cancer cells as well.
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Don't understand why D does not work... The argument says that "cancer cells are rapidly dividing".. If cancer is placed on bone marrow, which cells are also dividing, speed of cancer should be enhanced - no? It is like a boat which goes along the river flow, in my mind.. mejia401 plumber250 VeritasPrepKarishma can anyone help please? Thanks in advance!

Thanks a lot! Tough question..

the argument tells us "Telomerase is in: (i) kids cells that are actively dividing, (ii) kids & adults cancer cells, and (iii) kids and adults bone marrow"

For those confused between B and C.

B = "rapidly" does not = "actively". for all we know the cells that are dividing actively are dividing once a year, which is actually really slowly
C = telomerase is in bone marrow, and not because of cancer. this is correct, see above point (iii)

Thanks James.

I was able to eleminate all but C.However, was not sure why C is correct

Option "E" is talking about "Levels"...
No information given about the same..
Hope my understanding is clear

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.
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Hi,

a. Premise 1- Telomerase Enzyme –present in actively dividing cells.
b. Premise 2- It is absent from body tissues in adults.
c. 2 exceptions- Bone Marrow cells –continually divide.
d. Cancer cells- rapidly divide.
e. However the cells are dividing(continually or rapidly) the enzyme will be produced.
f. Both the cells(cancer and bone marrow) are different from each other , C is the correct answer.