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 本文是一篇科普说明文.介绍了一种使香水香味持久的物质--龙涎香,因这一物质来自于鲸,所以遭到人们的反对.科学家们发现一些树中的化学物质可以用来取代它,他们利用酵母菌成功制造出了这些化学物质.
解答 41-45 DBADC
41 D 推理判断题.根据第二段第二句中"But using ambergris,which helps a perfume last longer…"以及倒数第三段中"But expensive perfumes are much more stable."可知,含有龙涎香的香水价格昂贵,故D项正确;根据倒数第三段中"Their smell lasts much longer,for hours or even a day after you apply them."可知,B项错误;根据第二段第二句中"is strongly opposed by many people who think it is wrong to kill whales…"可知,A项错误;C项文中未提及相关信息.
42 B 词义猜测题.根据第四段中"There's a problem that many people wouldn't consider."可知,该词组意为"有隐含的问题",故B项正确.
43 A 细节理解题.根据第七段第二句中"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,并将目的基因成功表达出来,故常被用于基因工程研究中,故A项正确.
44 D 推理判断题.根据第二段最后一句"But his discovery of a new plant gene (基因)…the perfume business."及第三段表达的语境可知,Joery Bohlmann已经意识到,这些树中某些基因所产生的化学物质可以被用于香水中以代替龙涎香,但是这些化学物质和其他物质混合在一起,难以分离,故可以断定,Joerg Bohlmann曾经做过基因研究,故D项正确.
45 C 标题概括题.根据文章第一段"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,本文主要介绍了在香水中使用的龙涎香,这种价格昂贵的物质,最终被树中的某种化学物质成功取代.故C项为最佳标题.
点评 做阅读理解时要快速的浏览全文,把握文章主旨大意,带着问题回到原文,寻找细节或概括相应的答案,最后要理清作者写作思路.