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标题: TT GWD 2-21 [打印本页]

作者: dot_deng 时间: 2006-11-8 07:51
标题: TT GWD 2-21
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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?

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

Answer:C?

我怎么觉得改选E啊

作者: christy42728 时间: 2007-11-20 21:45

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

1）T这种酶只在分裂活跃的细胞中出现-〉因此T在成年人的组织中经常缺失

2）例外a Bone marrow 例外b cancer ，这两个在成年人的组织中分裂的也很快

能讲讲解题思路吗。题目中的this role是什么？是 The cells in adults are not actively divided 吗？如果是这样，那么题目中说的T和bone marrow 和 bone marrow cancer好像没啥关系呀。而且1，2连立貌似还是和c相反的，即t在Bone marrow 和bone marrow cancer中都应该出现，因为他们分裂的快？

真灰心~老也不开窍，麻烦大家了

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