试题与答案

精子内的顶体由溶酶体特化而来。精卵识别后,顶体膜与精子细胞膜融合,释放溶酶体酶使卵子

题型:单项选择题

题目:

精子内的顶体由溶酶体特化而来。精卵识别后,顶体膜与精子细胞膜融合,释放溶酶体酶使卵子外层形成孔洞,以利于精卵融合形成受精卵。下列叙述正确的是()

A.顶体内储存的溶酶体酶是在精子的溶酶体中合成的

B.精子游向卵子所需的能量来自线粒体和细胞质基质

C.顶体膜和精子细胞膜融合体现生物膜的选择透过性

D.受精卵中的遗传物质一半来自父方另一半来自母方

答案:

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参考答案:D

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题型:完形填空

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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,然后选出最佳选项,并在答题卡上将该项涂黑。

We may look at the world around us, but somehow we manage not to see it until whatever we've become used to suddenly disappears.  36 , for example, the neatly-dressed woman I 37  to see -- or look at -- on my way to work each morning.

For three years, no matter  38 the weather was like, she was always waiting at the bus stop around 8:00 am. On   39   days, she wore heavy clothes and a pair of woolen gloves. Summertime  40   out neat, belted cotton dresses and a hat pulled low over her sunglasses.  41   , she was an ordinary working woman. Of course, I  42   all this only after she was seen no more. It was then that I realized how  43  I expected to see her each morning. You might say I   44   her.

“Did she have an accident? Something  45 ?” I thought to myself about her  46  .  Now that she was gone, I felt I had  47  her. I began to realize that part of our  48   life probably includes such chance meetings with familiar 49 : the milkman you see at dawn, the woman who  50   walks her dog along the street every morning, the twin brothers you see at the library. Such people are   51   markers in our lives. They add weight to our  52   of place and belonging.

Think about it.   53   , while walking to work, we mark where we are by  54  a certain building, why should we not mark where we are when we pass a familiar, though  55  , person?

36. A. Make          B. Take         C. Give      D. Have

37. A. happened       B. wanted       C. used      D. tried

38. A. what           B. how         C. which     D. when

39. A. sunny          B. rainy         C. cloudy    D. snowy

40. A. took           B. brought       C. carried    D. turned

41. A. Clearly         B. Particularly    C. Luckily   D. Especially

42. A. believed        B. expressed     C. remembered  D. wondered

43. A. long            B. often          C. soon     D. much

44. A. respected       B. missed        C. praised      D. admired

45. A. better          B. worse        C. more         D. less

46. A. disappearance   B. appearance   C. misfortune      D. fortune

47. A. forgotten       B. lost          C. known         D. hurt

48. A. happy          B. enjoyable      C. frequent      D. daily

49. A. friends         B. strangers      C. tourists     D. guests

50. A. regularly        B. actually        C. hardly     D. probably

51. A. common        B. pleasant      C. important      D. faithful

52. A. choice          B. knowledge    C. decision      D. sense

53. A. Because         B. If            C. Although     D. However

54. A. keeping         B. changing     C. passing       D. mentioning

55. A. unnamed        B.unforgettable  C. unbelievable   D. unreal

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