问题 填空题

在探索生命起源的研究中,美国学者米勒设计了如图所示的实验装置,请回答下列问题:

(1)把水加入500毫升烧瓶中,抽真空后,从左侧活栓泵入的混合气体中绝不会含下列______

A.甲烷    B.氧气    C.氨气    D.氢气

(2)再把500毫升烧瓶中的水煮沸,是水蒸气驱动混合气体沿玻璃管流入5升烧瓶.此时钨电极连续放电,模拟的是下列______

A.宇宙射线              B.地球喷发出的热

C.大气圈的闪电          D.地球岩石产生的放射线

(3)混合气体在5升烧瓶中反应7天,经冷凝器冷却后,产物沉积在U形管中,对U形管内混合物分析发现,生成的有机小分子物质主要是______,U形管相当于______.

(4)该实验表明______.

答案

化学起源学说认为:原始地球的温度很高,地面环境与现在完全不同:天空中赤日炎炎、电闪雷鸣,地面上火山喷发、熔岩横流;从火山中喷出的气体,水蒸气、氨气、甲烷等构成了原始的大气层,与现在的大气成分明显不同的是原始大气中没有游离的氧;原始大气在高温、紫外线以及雷电等自然条件的长期作用下,形成了许多简单的有机物,随着地球温度的逐渐降低,原始大气中的水蒸气凝结成雨降落到地面上,这些有机物随着雨水进入湖泊和河流,最终汇集到原始的海洋中.原始的海洋就像一盆稀薄的热汤,其中所含的有机物,不断的相互作用,形成复杂的有机物,经过及其漫长的岁月,逐渐形成了原始生命.可见生命起源于原始海洋.

(1)(2)装置里的气体相当于原始大气,有水蒸气、氨气、甲烷等,与现在大气成分的主要区别是无氧气.正负极接通进行火花放电是模拟自然界的闪电.这主要是为该实验提供了条件.

(3)U形管处为取样活塞,若取样鉴定,可检验到其中含有氨基酸等有机小分子物质,共生成20种有机物,其中11种氨基酸中有4种(即甘氨酸、丙氨酸、天冬氨酸和谷氨酸)是生物的蛋白质所含有的.此装置是模拟原始地球条件下的原始海洋.

(4)米勒的实验试图向人们证实,在生命起源的化学进化过程中,生命起源的第一步,即从无机物形成有机物,在原始地球的条件下是完全可能实现的.

故答案为:(1)B     (2)C      (3)氨基酸;    原始海洋

(4)在生命起源过程中,从无机物小分子合成生成有机小分子物质是完全可能的

完形填空

Ⅲ、完形填空(每小题1.5分,满分30分)

It was the last day of the final examination in a large eastern university. On the steps of one building, a group of engineering seniors gathered, discussing the exam due to begin in a few  36 . On their faces was confidence(自信). This was their last exam—then on to   37 and jobs.

Some talked of jobs they already had; others talked of jobs they   38  get. With the certainty of four years of college, they felt ready and able to take  39   of the world.

The coming exam, they knew, would be a(n)   40   task. The professor had said they could bring   41  books or notes they wanted, requesting only that they did not   42  each other during the test.^

43  they entered the classroom. The professor passed out the papers. And smiles   44  on the students’ faces as they noted there were only five essay-type questions.

Three hours had passed   45  the professor began to collect the papers. The students no longer looked confident. On their faces was a frightened expression. Papers in hand, no one spoke as the professor faced the class.

He looked at the   46  faces before him, and then asked, “How many completed all five questions?”   47  a hand was raised.

“How many answered four?” Still no hands.

“Three? Two?” The students moved restlessly in their seats.

“One, then? Certainly somebody finished   48  .” But the class remained silent.

The professor put down the papers. “That is exactly what I   49 ,” He said. “I just want to impress upon you that   50   you have completed four years of engineering, there are still many things about the   51  you don’t know. These questions you couldn’t answer are relatively  52  in everyday practice.” Then smiling, he added, “You will all  53  this course, but remember—even though you are now college graduates, your education has just   54 .”

They years have   55  the name of his professor, but not the lesson he taught.

36. A. seconds           B. minutes             C. hours                D. days

37. A. interview            B. discussion      C. education          D. graduation

38. A. would                 B. must                 C. had to           D. used to

39. A. hold                   B. control                 C. charge           D. place

40. A. interesting           B. necessary           C. easy                  D. unusual

41. A. no                  B. either                C. any                   D. all

42. A. listen to                 B. look at                 C. refer to                D. talk to

43. A. Nervously           B. Joyfully            C. Quickly             D. Curiously

44. A. appeared             B. changed            C. froze                 D. stopped

45. A. then                   B. as                        C. before           D. after

46. A. pleased           B. worried             C. surprised       D. moved

47. A. Not                   B. Once                 C. Only                 D. Even

48. A. all                     B. none                 C. one                   D. it

49. A. wondered            B. enjoyed             C. hated                D. expected

50. A. right now            B. as though          C. now that            D. even though

51. A. exam                  B. subject                 C. question            D. college

52. A. valuable                 B. difficult            C. common            D. strange

53. A. pass                    B. fail                   C. take                  D. start

54. A. begun                 B. completed     C. failed                D. succeeded

55. A. forgot                 B. remembered      C. strengthened      D. Weakened

单项选择题