问题 单项选择题

(五)

美国北卡罗来纳大学的研究人员在黄鼠身上鉴别并绘制出了启动动物冬眠的两个基因,这两个基因控制合成对于冬眠至关重要的酶。
据当地媒体报道,该校马修·安德鲁博士等人在黄鼠体内找到了一种基因控制合成胰腺甘油三酯酶。这种酶能分解以脂肪酸形式储存在体内的甘油三酯,然后将之转化成作为黄鼠冬眠时能量来源的脂肪。另一种基因则控制丙酮酸盐脱氢酶、激活酶和同功酶的合成,这些在饥饿时候被激发的酶能帮助保持体内的葡萄糖储备,在冬眠开始时或即将开始前,两个基因都在黄鼠的心脏中得到了表达。
研究人员还发现,这些基因与在非冬眠动物身上找到的对等基因几乎是一致的,但它们在冬眠与非冬眠动物身上的表达不一样。胰腺甘油三酯酶仅在非冬眠哺乳动物的胰腺中得到表达,却同时出现在黄鼠的胰腺和心脏中。
科学家若能鉴别出哪些是在冬眠这类极端状态下负责保护器官、降低血糖消耗和保持肌肉性能的酶,将能开发出延长移植用人体器官“保质期”的新方法,还可研制出诱导宇航员在长期太空旅行过程中安全进入冬眠状态的方法。

本文第二段主要说明的是( )

A.黄鼠冬眠的能量来源于两个基因控制合成的酶

B.两个基因在黄鼠心脏中的表达

C.冬眠的原因

D.马修·安德鲁博士的研究取得成功

答案

参考答案:A

阅读理解

Motorists used to listening to the radio or their favorite tunes on CDs may have a new way to entertain themselves, after engineers in Japan developed a musical road surface.

The Hokkaido Industrial Research Institute has built a number of “melody roads”, which use cars as tuning forks to play music as they travel.

The concept works by using grooves(凹槽). They are cut at very specific intervals(间隔) in the road surface. The melody road uses the spaces between to create different notes(音符).

Depending on how far apart the grooves are, a car moving over them will produce a series of high or low notes, and designers are able to create a distinct tune.

Patent documents for the design describe it as notches “formed in a road surface so as to play a melody without producing simple sound or rhythm and reproduce melody-like tones”.

There are three musical roads in central and northern Japan---one of which plays the tune of a Japanese pop song. Reports say the system was invented by Shizuo Shinoda. He scraped some markings into a road with a bulldozer(推土机) before driving over them and found that they helped to produce all kinds of tones.

The optimal speed for melody road is 44 kph, but people say it is not always easy to get the intended sound.

“You need to keep the car windows closed to hear well,” wrote one Japanese blogger. “Driving too fast will sound like playing fast forward, while driving around 12 mph (20 kph) has a slow-motion effect, making you almost car-sick.”

59. According to the passage, to create different notes, melody roads use ______.

A. cars    B. grooves    C. spaces between internals    D. bulldozers

60. We can learn from the passage that the highness of notes is dependent on ______.

A. how far the grooves are                B. how big the grooves are

C. the number of the grooves              D. the speed of the car

61. The underlined word “optimal” in the passage might mean ______.

A. fastest      B. possible      C. best     D. suitable

62. In order to hear the music well, you have to ______.

A. drive very fast                       B. drive slowly

C. open the window wide                D. keep the window closed  

单项选择题