TT GWD9-25

foreverhour

Q25 to Q27:

      Researchers studying how genes

       control animal behavior have had

       to deal with many uncertainties.  In

Line       the first place, most behaviors are

  (5)      governed by more than one gene,

and until recently geneticists had no

method for identifying the multiple

genes involved.  In addition, even

when a single gene is found to control

 (10)      a behavior, researchers in different

fields do not necessarily agree that it is

a “behavioral gene.”  Neuroscientists,

whose interest in genetic research is to

understand the nervous system (which

 (15)      generates behavior), define the term

broadly.  But ethologists—specialists

in animal behavior—are interested

in evolution, so they define the term

narrowly.  They insist that mutations in

 (20)      a behavioral gene must alter a specific

       normal behavior and not merely make

       the organism ill, so that the genetically

induced behavioral change will provide

variation that natural selection can act

 (25)      upon, possibly leading to the evolution

of a new species.  For example, in the

fruit fly, researchers have identified

the gene Shaker, mutations in which

cause flies to shake violently under

 (30)      anesthesia.  Since shaking is not

healthy, ethologists do not consider

Shaker a behavioral gene.  In con-

       trast, ethologists do consider the gene

period (per), which controls the fruit

 (35)
                       fly’s circadian (24-hour) rhythm, a

behavioral gene because files with

mutated per genes are healthy; they

simply have different rhythms.

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Q25:

The passage suggests that neuroscientists would most likely consider Shaker to be which of the following?

             

1. An example of a behavioral gene
2. One of multiple genes that control a single behavior
3. A gene that, when mutated, causes an alteration in a specific normal behavior without making the organism ill
4. A gene of interest to ethologists but of no interest to neuroscientists
5. A poor source of information about the nervous system

Answer: A

why A? What't wrong with E?Thanks!

DeliciaAn

题干只是用了most likely.就是说，按照逻辑关系来看，哪个更像是neuroscientists的对于Shaker的观点。根据全文，我们并没有办法找到很明确的neuroscientists对于Shaker的看法。所以只能是从逻辑入手。
Neuroscientists, whose interest in genetic research is to understand the nervous system (which generates behavior), define the term broadly. But ethologists ― specialists in animal behavior― are interested in evolution, so they define the term narrowly.
就是内容上说一个是broadly,一个是narrowly.我们并不能够确定他们两个是完全含义上的对立，还是说一个事物的两个方面。只能够确定的是，是一种对立的关系。
Since shaking is not
healthy, ethologists do not consider
Shaker a behavioral gene.
这样看来，对ethologists进行取非的观点，就有可能是neuroscientists的观点了（注意，我说的是有可能，因为吧，如果有个选项这样写了，只能说这两种人的观念是完全对立的，而不是一个事物的两个方面。所以只能是有可能。）再看其他的选项，没有更合适的了。所以就选这个了。

注意:GMAT我们要排除错的，而不是去选择正确的。