问题 问答题 简答题

何谓革兰氏染色法?影响革兰氏染色法着色稳定性的因素有哪些?请以枯草芽孢杆菌为例予以说明。

答案

参考答案:此法由丹麦医生C.Gram于1884年创立的一种重要的细菌鉴别染色法而得名。其主要步骤:结晶紫初染,碘液媒染,乙醇脱色和沙黄复染。菌体最后呈蓝紫色者为G+菌,呈红色者为G-菌。研究表明,枯草芽孢杆菌是G+菌。但是,如果培养时间过长或者已死亡,部分菌体自溶,涂片厚薄,尤其脱色时间过长等,都会影响其着色稳定性,使G+菌误染为G-菌。

单项选择题
完形填空

第二节完形填空(共20小题;每小题1分,满分20分)

阅读下面短文,掌握其大意,从每题所给的A、B、C、D四个选项中选出最佳答案,并在答题卡上将该项涂黑。

Mark liked talking. I had to  36 him that talking in class was not acceptable. 37  impressed me was that he responded with such sincerity. “Thank you for correcting me, Sister!” I didn’t know what to make of it at 38  , but soon I got used to 39  it many times a day.

One morning my  40   was growing thin when Mark talked once again. I said, “If you say one more word, I’ll tape your mouth  41  !”

It wasn’t ten seconds  42  when one boy shouted, “Mark is talking again.” I had to keep my  43  . I took out some tape from my desk and covered it 44  Mark’s mouth. Later as I walked back to remove the tape, his first words were “Thank you for correcting me, Sister.”

One afternoon, the students got noisy and started to call each other 45 .

I had to do 46 . I asked each student to prepare 34 small pieces of paper, saying they should write the name of a classmate on each piece and, under that, say something 47  about the person. Then I collected the slips of paper and gave them  48  later. Everyone smiled. Their classmates had  49  such nice things about them!

Nobody ever mentioned the paper again. I never knew if they discussed them after class, but it didn’t matter. The students were  50  with themselves.

Several years later, after I had returned  51  a vacation, my parents met me at the airport. On our way back, my father  52  his throat, as he usually did before saying something  53 .

“The Eklunds called yesterday,” he began. “Really?” I said. “I haven’t heard from them in years. I 54  how Mark is.” Dad responded quietly. “Mark was killed in Vietnam,” he said. “The funeral is tomorrow .”

At the funeral Mark’s father came up and took some slips of paper from his wallet to show me. I knew the slips were the ones on which Mark’s classmates had listed all the nice things about him.

“Thank you so much,” Mark’s mother said. “  55 you can see, Mark treasured those pieces of paper.”

36.A. order             B. remind           C. mind             D. suggest

37. A. Which              B. That                   C. What             D. How

38. A. first                B. last             C. once             D. next

39. A. speaking          B. taking           C. talking            D. hearing

40. A. patience           B. strength                C. energy          D. power

41. A. close              B. shut            C. open           D. opened

42. A. before            B. after           C. later           D. that

43 A. rule                B. words         C. compromise    D. word

44. A. through           B. in             C. across          D. cross

45. A. name               B. names          C. curses          D. swear

46. A. something               B. everything      C. nothing          D. anything

47. A. terrible          B. nice             C. kind                   D. mean

48. A. in                B. up             C. back            D. away

49. A. asked             B. spoken          C. told            D. said

50. A. glad                    B. sad               C. unhappy         D. happy

51. A. from             B. on                C. during          D. at

52. A. cleared           B. cleaned           C. wet             D. dried

53. A. necessary         B. important        C. difficult          D. sad

54. A. doubt           B. believe          C. wonder         D. want

55. A. Because                 B. Though         C. When            D. As