Q31: TTGWD2-Q21:

shirley8707

Q31: TTGWD2-Q21:

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.

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

C.      The presence of telomerase in bone marrow is no indication of bone marrow cancer.

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

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

这里除非有一个隐含假设，癌症不能与正常细胞共存，怎么推出

hansomecd

不存在这个隐含假设

因为题目中给出了2个exception,所以当病症出现时,无法确定就一定是cancer

C指出,telomerase出现不能indicate 就是患有cancer,因为bone marrow本身就在dividing

笨笨可可

不懂，能解释一下吗？

对于原文的解释，我也是不懂。。字面不了解

xlele11

T是一种酶，只在活跃分裂的细胞中生产，因此基本不出现在人体的组织中。骨髓是一个例外，骨髓细胞分裂而替代了老的血细胞。癌细胞是另外一个例外，因为它们的细胞分裂迅速。

C,T的出现不能指示出骨髓癌，(因为骨髓细胞本身也是分裂的，支持了原文的论述)

fiona_hq

UP

wendygoon

第一次选了E 后来回头看C觉得很对呀
弱弱的补充一个错误选项E 错在 因为BONE MARROW是个例外 而它BELONG TO NONCANCEROUS TISSUE

wtylys

那B错在哪里，说是not rapidly dividing 不就是说not active dividing吗？哪位大大解释一下啊。。。

seachina

无关选项。题干只说成人中基本没有，并没有提及什么儿童，儿童怎么样，谁也不清楚呀。

琛angela

E为什么不对呢？

killmcgill

琛angela 发表于 2012-8-19 10:33
E为什么不对呢？

E: Bone marrow也可能造成T跟cancerous tissue一样高