Question

    People who grow up left-handed have a different, more flexible brain structure than those born to take life by the right hand, say researchers at the University of California, Los Angeles.

The reason is that right-handers have genes that force their brains into a slightly more one-sided structure, according to the research. Left-handers appear to be missing those genes.

"There really is a difference in brains that results in a more symmetric (对称的) brain in left-handers, where the two sides are more equal," said Daniel Geschwind, who led the research team.

In the effort to understand how the brain shapes the mind, researchers have been trying to document the way genes and environment affect intelligence and mental abilities. They found that right-and left-handedness is determined by genetics. If a person has the gene for right-handedness, that person will be right-handed. People who do not have that gene, however, can be either left- or right-handed. There is no specific gene for left-handedness.

Right-handers typically have a larger left brain, where their language abilities are concentrated. Conversely, left-handers have more balanced brains. The language abilities of left-handers more often, are concentrated on the right side.

The UCLA researchers conducted brain scans on 72 pairs of male identical (同卵双生的) twins between 75 and 85 years old. They noticed that if identical twins carry the gene for hand preference, both must be right-handed. If they lack the gene, one twin can develop right-handed while the other can develop left- handed.

The researchers found that the brains of identical right-handed twins were very similar in size and structure. But when a left-hander was part of the twin set, the brains were different. The conclusion, researchers said, is that the absence of the gene for hand preference allows the brain to develop differently as the individual grows up.

1.What is the finding of the researchers of UCLA?

A.Left-handers have more balanced brains. B.Right-handers have more flexible brains.

C.Left-handers' brains are more one- sided. D.Right-handers' brains are more symmetric.

2.Which element determines a person's hand preference?

A.Environment. B.Intelligence.

C.Habit. D.Gene.

3.What can be said about identical twins?

A.They always have similar brain structure.

B.They never carry the gene for hand preference.

C.They have different genes for hand preference.

D.They can have different hand preference.

4.What did the UCLA team research on?

A.People's genetic makeup. B.People's hand preference.

C.People's brain sizes. D.People's communicative skills.

Answer

1.A

2.D

3.D

4.B

【解析】

这是一篇说明文。文章讲述了一项研究，研究发现左右手习惯是由基因决定的，如果一个人有惯用右手的基因，那他就是惯用右手的；然而，没有这种基因的人可以是惯用左手的，也可以是惯用右手的，总之，左撇子没有特定的基因，手偏好基因的缺失使得大脑在个体成长过程中会有不同的发展。

1.细节理解题。由第三段的“"There really is a difference in brains that results in a more symmetric (对称的) brain in left-handers, where the two sides are more equal," said Daniel Geschwind, who led the research team.”可知，加州大学研究小组负责人Daniel Geschwind发现，大脑的差异确实会导致左撇子的大脑更加对称，两边更加平等，所以左撇子有更平衡的大脑。故选A项。

2.细节理解题。由第四段的句子“They found that right-and left-handedness is determined by genetics.”可知，研究人员发现左右手习惯是由基因决定的。故选D项。

3.推理判断题。由“They noticed that if identical twins carry the gene for hand preference, both must be right-handed. If they lack the gene, one twin can develop right-handed while the other can develop left-handed.”可知，研究人员注意到，如果同卵双胞胎携带用手偏好的同种基因，那么他们都必须是右手的；如果他们缺乏这种基因，一个双胞胎可以发展成右手，而另一个可以发展成左手。从这里可以推断出，双胞胎可以携带同样的（右手）基因，若不携带（右手）基因时，他们可以有不同的用手偏好，排除BC两项，D项切题；由最后一段的“The researchers found that the brains of identical right-handed twins were very similar in size and structure. But when a left-hander was part of the twin set, the brains were different.”可知，研究人员发现，同卵右手双胞胎的大脑在大小和结构上非常相似，但当一个左撇子是双胞胎的一部分时，大脑就不同了，说明双胞胎不总是拥有相似的大脑结构，排除A项。故选D项。

4.推理判断题。由第一段的“People who grow up left-handed have a different, more flexible brain structure than those born to take life by the right hand, say researchers at the University of California, Los Angeles.”（加州大学洛杉矶分校的研究人员说，左撇子长大后的大脑结构与那些天生以右手为生的人不同，更灵活。），第四段的“They found that right-and left-handedness is determined by genetics.”（他们发现左右手习惯是由基因决定的。）和最后一段的“The conclusion, researchers said, is that the absence of the gene for hand preference allows the brain to develop differently as the individual grows up.”（研究人员说，结论是，手偏好基因的缺失使得大脑在个体成长过程中有不同的发展。），可知加州大学洛杉矶分校的研究团队研究人们用手的偏好。故选B项。