11.A recent finding has showed that blue-eyed people have already been living in Europe for at least 7,000years.
A man who lived on the Iberian Peninsula before Europeans became farmers probably had blue eyes but dark hair and skin,according to scientists who have arranged his DNA in order.This surprising combination of eye,hair and skin coloring may not have been unusual during his lifetime,but it is no longer seen among modem Europeans,reported by the journal Nature.
The man,a Neolithic hunter-gatherer known to scientists as La BranaⅠ,is of great interest to scientists because he offers a brief introduction to what was in Europeans'DNA before agriculture spread through the continent.Experts have theorized that certain genetic feature spread quickly among humans after they adopted the farming lifestyle.La BranaⅠshows that at least some of their predictions were correct.
The man's skeleton,along with that of a male companion,was discovered in 2006in a cave in what is now northeastern Spain.The site,known as La Brana-Arintero,sits about 5,000feet above sea level,and the cave provided a cold,refrigerator-like environment that preserved his DNA.
In the lab,scientists were able to remove enough DNA from a single tooth to reconstruct La BranaⅠ's entire genome (基因組).They compared it to the DNA of other ancient Europeans(including Otzi,the 5,300-year-old mummy found in an Alpine glacier) and determined that he was a closer match with hunter-gatherers than with farmers.
When it came to genes that would influence La BranaⅠ's appearance,the researchers found that their 7,000-year-old subject had versions of two skin pigment(色素) genes that are either very rare or nonexistent among Europeans today.Then they looked at other places in the genome that influence pigmentation(色素沉著)and found a mix of ancient and modern gene variants(變種).Taken together,La BranaⅠ's DNA"is likely to have resulted in dark skin pigmentation and dark or brown hair,"they wrote.
However,his DNA indicates that his eyes were most likely blue,the scientists found.This suggests that gene variants for light-colored eyes and skin did not spread together,they wrote,adding that La BranaⅠ's combination"of dark skin and non-brown eyes is unique and no longer present in contemporary European populations."Today,a blue-eyed person would typically have fair skin.To get some idea of whether La BranaⅠ's coloring was unusual for his day,the researchers will try to arrange in order the DNA of his companion,who has been named La BranaⅡ.
32.Scientists have carried out the research into La BranaⅠbecause they wanted to know
C.
A.today's Europeans'DNA
B.the ancient agriculture in Europe.
C.European hunter-gatherers'DNA.
D.the correctness of some of their predictions
33.La BranaⅠ's skeleton was best preserved mainly because ofB.
A.the height of the cave
B.the cold condition in the cave
C.the location of the cave
D.the wet condition in the cave
34.Which of the following statements is TRUE?B
A.La BranaⅠ's gene variants spread together.
B.La BranaⅠ's DNA influences his appearance.
C.Today's blue-eyed person may typically have rough rather than fair skin.
D.La BranaⅠ's gene is completely different from the contemporary Europeans'.
35.The last paragraph suggests thatC.
A.La BranaⅡhas the same genome with La BranaⅠ.
B.Blue-eyed people were common in Europe 7,000years ago.
C.It's not certain that La Brana's appearance was common at that time.
D.BranaⅠ's combination of dark skin and non-brown is popular in contemporary Europeans.
分析 本文屬于說明文閱讀,作者通過這篇文章主要向我們介紹了最近關于 La BranaⅠ的調查,事實證明這個群體的基因已經(jīng)存在了七千多年,但是這個基因并沒有廣泛存在,藍眼睛的人在歐洲依然很少.
解答 32.C 細節(jié)理解題,根據(jù)第三段The man,a Neolithic hunter-gatherer known to scientists as La BranaⅠ,is of great interest to scientists because he offers a brief introduction to what was in Europeans'DNA before agriculture spread through the continent.可知科學家們研究 La BranaⅠ是因為他們想知道歐洲獵人的DNA,故選C.
33.B 細節(jié)理解題題,根據(jù)第四段The site,known as La Brana-Arintero,sits about 5,000feet above sea level,and the cave provided a cold,refrigerator-like environment that preserved his DNA.可知La BranaⅠ的骨架保存最好的主要原因是因為洞里的寒冷條件,故選B.
34.B 推理判斷題,根據(jù)第六段Taken together,La BranaⅠ's DNA"is likely to have resulted in dark skin pigmentation and dark or brown hair,"they wrote.可知La BranaⅠ的基因可能導致黑皮膚色素沉著,以及黑色或棕色的頭發(fā),因此可推斷出它能影響人們的外表,故選B.
35.C 推理判斷題,根據(jù)最后一段This suggests that gene variants for light-colored eyes and skin did not spread together,they wrote,adding that La BranaⅠ's combination"of dark skin and non-brown eyes is unique and no longer present in contemporary European populations."Today,a blue-eyed person would typically have fair skin.可知La Brana的外表并不是常見的,故選C.
點評 考查學生的細節(jié)理解和推理判斷能力.做細節(jié)理解題時一定要找到文章中的原句,和題干進行比較,再做出正確選擇.在做推理判斷題時不要以個人的主觀想象代替文章的事實,要根據(jù)文章事實進行合乎邏輯的推理判斷.