GWD 02-21

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?

1. Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing.
2. In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing.
3. The presence of telomerase in bone marrow is no indication of bone marrow cancer.
4. Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue.
5. The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue.

思路不是很清晰,感觉答案处于意料.大家讨论讨论

telomerase 是一种只在 active dividing 的细胞里存在的酶，所以成人身体里一般没有酶存在。

但是呢，有2个例外：1,成人身体里的骨髓里的细胞仍然在继续分解，有酶存在    

                   2，癌症也是例外，原因是：分解速度快，也有酶存在

选c

C is the answer

A typical conculsion question.

why B is incorrect?