第二节:听下面5段对话或独白,选出最佳选项。每段对话或独白读两遍。

听第6段材料,回答第6 -- 8题

6. What will Mary do tomorrow afternoon first?

A. See a doctor.   B. Meet a friend.  C. Go to a ball

7. Where will the dancing party be held?

A. In the students’ club  B. In a school hall.     C. On the playground.

8. When will Mary and her friend probably go to the party?

A. At about 5 p.m.  B. At about 7 p.m.    C. At about 4 p.m.

听第7段材料,回答第9 -- 11题

9. What kind of music does Mr. Zhang like?

A. Classical music. B. Jazz.   C. Both A and B.

10. Why does Mr. Zhang dislike going to the theater?

A. Tickets for plays are too expensive.

B. It is too noisy.

C. His English is not very good.

11. What can we learn from the conversation?

A. Mr. Zhang likes shopping in London.

B. Mr. Zhang likes cheap food.

C. Mr. Zhang likes Italian food.

听第8段材料,回答第12 -- 14题

12. How much more will they pay for their telephone calls this month than last month?

A. More than 3 pounds.    B. Less than 3 pounds.    C. 10 pounds.

13. Who do you think Jack is?

A. Their son.  B. One of their friends.     C. The man’s secretary.

14. Why did Jack make so many telephone calls to London?

A. Because his uncle is in London.

B. Because his girlfriend is in London.

C. Because his grandfather is in London.

听第9段材料,回答第15 -- 17题

15. Where are the man and his friends probably?

A. In a bar.     B. In a hotel.  C. At his house.

16. When does the conversation take place?

A. In the morning.  B. In the afternoon.     C. In the evening.

17. What do you think of the man from the conversation?

A. He is cross  B. He is unfriendly.     C. He is easy going.

听第10段材料,回答第18 -- 20题

18. Where does the announcement take place?

A. At a baseball stadium. B. At a department store. C. At an amusement park.

19. What is the boy wearing?

A. A solid white baseball cap.    B. Black and white pants.

C. A blue and white sweatshirt.

20. Where is the boy now?

A. At the information desk.   B. In the sporting goods section.

C. At the cashier where you pay for goods.

37.(10分)微核由染色体的断片或整条染色体形成,是真核细胞中的一种异常结构,呈圆形或椭圆形,游离于主核之外。微核往往由于细胞受辐射或化学药物的作用而产生,“微核检测”可用于了解化学物质的遗传毒性。

某中学研究性学习小组的同学为了了解厨房油烟能否诱导微核,采集了某家庭40天中厨房抽油烟机内积累的油烟冷凝物,用二甲基亚砜溶解后再用蒸馏水稀释,配制了一系列浓度的油烟冷凝物溶液,各取等量加入烧杯A、B、C、D中;另取等量二甲基亚砜和蒸馏水加入烧杯E,取等量蒸馏水加入烧杯F。之后,将6个大小和生长状况相同、幼根已培养至1 cm的洋葱,分别置于上述6种溶液中培养24h,然后再将洋葱转移到蒸馏水中继续培养24h。24h后从每个洋葱上随机取4条根尖并按常规方法制作临时装片,在显微镜下观察每个装片上的1000个根尖细胞,计算其中出现微核的细胞数目(微核的千分率),结果如下表所示。

        项  目
组  别
项目1
细胞微核率(‰)
项目2
A
50μg/ mL
12.54
13.50
11.72
13.00
 
B
100μg/ mL
15.92
15.00
14.85
14.91
 
C
200μg/ mL
18.68
16.22
17.00
18.00
 
D
300μg/ mL
20.00
20.20
20.00
18. 69
 
E
二甲基亚砜加蒸馏水
3.77
3.85
4.00
3.87
 
F
蒸馏水
3.43
3.60
3.64
4.00
 

请分析回答:

(1)为什么将洋葱根尖在上述各种溶液中培养24 h?              。镜检的细胞应该位于根尖      区而且处在细胞分裂     期。 

(2)研究性学习小组的同学在取得洋葱根尖后,按“常规方法”制作装片,这种常规方法的操作步骤可简略表示为                           。

(3)表中的项目2应该是              。

(4)对A-D组而言,E组和F组中,哪一组是对照组?       。将E组和F组进行比较,能说明                             。

(5)该实验可得出什么结论?                           。

 0  339792  339800  339806  339810  339816  339818  339822  339828  339830  339836  339842  339846  339848  339852  339858  339860  339866  339870  339872  339876  339878  339882  339884  339886  339887  339888  339890  339891  339892  339894  339896  339900  339902  339906  339908  339912  339918  339920  339926  339930  339932  339936  339942  339948  339950  339956  339960  339962  339968  339972  339978  339986  447090 

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