5.Expensive perfumes (香水) come in tiny bottles,but many hide a whale-sized secret.
To perfect a particular smell,perfume-makers often use an ingredient that comes from sperm whales,called ambergris.But using ambergris,which helps a perfume last longer,is strongly opposed by many people who think it is wrong to kill whales just so we can smell sweet.Joerg Bohlmann is neither a perfumer nor a whale expert.He's a plant biologist at the University of British Columbia in Canada.But his discovery of a new plant gene (基因) might push whales out of the perfume business.
The gene comes from fir trees,found throughout North America and commonly used as Christmas trees.The trees produce a chemical that can be used in perfume in place of ambergris--but with a catch.
"There's a problem that many people wouldn't consider.In the tree,the chemical is mixed with many others.That makes separation a challenge,"Bohlmann says."It's like trying to isolate sugar from a biscuit."
This is where science becomes useful.When Bohlmann learned that fir trees produce the ambergris-like chemical,he decided to use his gene know-how to find the instructions for how to make the ambergris-substitute.
Bohlmann found that gene and took it out of the tree cells.Then he did something that might sound strange to someone who doesn't work in genetics:Bohlmann put the gene from the tree into yeast (酵母) cells.
Yeast may sound familiar because it's used to make things like bread,wine and beer.Biologists like to work with yeast because it easily adopts new genes and changes its features and behaviour.When Bohlmann put the fir tree gene into the yeast,the yeast started making the same chemical that had been produced by the tree.
Perfumers pay big money for ambergris because it is a fixative,which means it holds a smell in place on a person's body.
"Cheap perfumes smell good in the first hour or so and then everything is gone,"explains Bohlmann."But expensive perfumes are much more stable.Their smell lasts much longer,for hours or even a day after you apply them."
The new chemical,made from the tree genes,can be used as a fixative,too.And using yeast to make it is far cheaper than acquiring ambergris.
Bohlmann admits he never thought he'd get into the perfume business.But now,he says,producers have been calling to find out how to use his technology in new perfumes.
41.It can be inferred from the passage that if a perfume contains ambergris,D
A.its user probably supports whale hunting
B.its smell will last for about an hour
C.there will be a whale symbol on the bottle
D.it is probably very expensive
42.The underlined expression"with a catch"in Paragraph 3meansB
A.being difficult to hold B.having a hidden problem
C.needing further testing D.being too similar
43.According to the passage,why are yeast cells often used in genetic research?A
A.They can take on the characteristics of other genes.
B.They can reproduce much faster than other cells.
C.They share some of the qualities of plant genes.
D.They're much cheaper to use than ambergris.
44.What can we learn about Joerg Bohlmann from the passage?D
A.He is opposed to whale hunting.
B.He made his discovery during Christmas.
C.He has worked in the perfume industry for many years.
D.He has previously done genetic research.
45.What is the best title for the passage?C
A.The Christmas tree's secret
B.The sweet smell of success
C.Whale-free perfume
D.Save the whale.
分析 本文是一篇科普說明文.介紹了一種使香水香味持久的物質(zhì)--龍涎香,因這一物質(zhì)來自于鯨,所以遭到人們的反對.科學(xué)家們發(fā)現(xiàn)一些樹中的化學(xué)物質(zhì)可以用來取代它,他們利用酵母菌成功制造出了這些化學(xué)物質(zhì).
解答 41-45 DBADC
41 D 推理判斷題.根據(jù)第二段第二句中"But using ambergris,which helps a perfume last longer…"以及倒數(shù)第三段中"But expensive perfumes are much more stable."可知,含有龍涎香的香水價(jià)格昂貴,故D項(xiàng)正確;根據(jù)倒數(shù)第三段中"Their smell lasts much longer,for hours or even a day after you apply them."可知,B項(xiàng)錯(cuò)誤;根據(jù)第二段第二句中"is strongly opposed by many people who think it is wrong to kill whales…"可知,A項(xiàng)錯(cuò)誤;C項(xiàng)文中未提及相關(guān)信息.
42 B 詞義猜測題.根據(jù)第四段中"There's a problem that many people wouldn't consider."可知,該詞組意為"有隱含的問題",故B項(xiàng)正確.
43 A 細(xì)節(jié)理解題.根據(jù)第七段第二句中"it easily adopts new genes and changes its features and behaviour."可知,由于酵母菌容易吸收其他基因,并將目的基因成功表達(dá)出來,故常被用于基因工程研究中,故A項(xiàng)正確.
44 D 推理判斷題.根據(jù)第二段最后一句"But his discovery of a new plant gene (基因)…the perfume business."及第三段表達(dá)的語境可知,Joery Bohlmann已經(jīng)意識到,這些樹中某些基因所產(chǎn)生的化學(xué)物質(zhì)可以被用于香水中以代替龍涎香,但是這些化學(xué)物質(zhì)和其他物質(zhì)混合在一起,難以分離,故可以斷定,Joerg Bohlmann曾經(jīng)做過基因研究,故D項(xiàng)正確.
45 C 標(biāo)題概括題.根據(jù)文章第一段"Expensive perfumes (香水) come in tiny bottles,but many hide a whalesized secret."及文章最后一句中"producers have been calling to find out how to use his technology in new perfumes."可知,本文主要介紹了在香水中使用的龍涎香,這種價(jià)格昂貴的物質(zhì),最終被樹中的某種化學(xué)物質(zhì)成功取代.故C項(xiàng)為最佳標(biāo)題.
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