0  438075  438083  438089  438093  438099  438101  438105  438111  438113  438119  438125  438129  438131  438135  438141  438143  438149  438153  438155  438159  438161  438165  438167  438169  438170  438171  438173  438174  438175  438177  438179  438183  438185  438189  438191  438195  438201  438203  438209  438213  438215  438219  438225  438231  438233  438239  438243  438245  438251  438255  438261  438269  447090 

第二节(共15小题; 每小题1.5分,满分22.5分)

请听下面5段对话或独白,选出最佳选项。

请听第6段材料,回答第6至8题。

6. Who is the woman speaking to?

 A. Her husband.                 B. A policeman.        C. A fire-fighter.

7. What’s the woman asking for?

 A. Advice on safety.           B. Money.             C. Help.

8. What has happened to the woman’s house?

 A. It’s been burnt down.         

B. It’s been broken into.

  C. It’s been damaged.

请听第7段材料,回答第9至11题。

9. What does the woman want to know?

 A. The best way to go to New York.

 B. The quickest way to go to New York.

 C. The cheapest way to go to New York.

10. How much does it cost the woman to go to New York by bus?

A. $5.                      B. $15.              C. $50.

11. What do we know from the conversation?

A. The woman will go to New York by bus.

B. It will take the woman five hours to go to New York by bus.

C. The woman won’t go to New York by bus.

请听第8段材料,回答第12至14题。

12. When will the ballet performances be on?

A. This week.                  B. Next week.          C. Next month.

13. When will the man attend the performance?

A. On Sunday evening.        

B. On Thursday evening.

C. On Friday evening.

14. How much does the man pay for the tickets?

A. $20.                      B. $10.             C. $40. 

请听第9段材料,回答第15至17题。

15. What’s the probable relationship between the two speakers?

A. Good friends.               B. Strangers.            C. Classmates.

16. What can we know about the woman from the conversation?

A. She won a cup in last week’s tennis competition.

B. She is a science expert. 

C. She works at St Jude’s Training College.

17. How long has the man been in the science department?

A. Half a year.               B. More than a year.        C. Two years.

请听第10段材料,回答第18至20题。

18. How often do people in the Historical Society meet?

A. Every week.               

B. Every other week.    

C. Every three weeks.

19. What is the main purpose of the Historical Society?

A. To find out what they can learn from history. 

B. To study the people in history.

C. To learn about what happened in the past.

20. What do the Historical Society plan to do this year?

A. Study the history of the town.   

B. Visit historic houses in the college. 

C. Visit more historic places.

试题详情

第一节(共5小题;每小题1.5分,满分7.5分)

请听下面5段对话, 选出最佳选项。

1. Where does the conversation most probably take place?

 A. In a park.                    B. In a zoo.            C. In a pet store.

2. What does the woman mean?

 A. Things here are very cheap.  

B. Things here are not cheap. 

 C. She doesn’t know whether things here are cheap or not.

3. Where are the two speakers going to plant the tree?

 A. By the front door.            

B. At the back of the garage.

 C. At the end of the garden.

4. Where does the conversation take place?

 A. In a shop.                    B. In a hotel.          C. In a restaurant.

5. What do we learn from the conversation?

 A. The man went to New Zealand during Christmas.

 B. The man visited New Zealand during the summer holiday.

 C. The man’s parents live in New Zealand.

试题详情

3、时间的控制:做好质壁分离的实验后,不久就要做质壁分离复原实验。避免使质壁分离的细胞长时间处于较高浓度的外界溶液中,细胞过度失水而导致死亡。从而观察不到质壁分离复原的现象。

试题详情

2、试剂:选用0.3g/ml 蔗糖糖溶液。浓度过高,细胞质壁分离速度虽然很快,但不久就会将细胞杀死,细胞不能进行质壁分离复原;若浓度过低,则不能引起细胞质壁分离或速度太慢。

另外,8% 食盐溶液、5%的硝酸钾溶液、一定浓度的尿素、甘油……也可使用,但后面三者在引起质壁分离后可自动复原。

试题详情

1、选材:选取紫色洋葱鳞片叶外表皮。其细胞液为紫色,在显微镜下与无色透明的细胞壁容易区分,观察到的质壁分离和复原效果明显。

另外,取新鲜水绵、黑藻叶、南瓜表皮也可以做这个实验。

试题详情

2、动物细胞能发生渗透作用但不会发生质壁分离。

 例题:下面是一组用新鲜洋葱表皮进行的实验处理和结果,请分析回答:

实验分组
处理方法
实验结果
第1组
①将材料置于30%蔗糖溶液中
①发生质壁分离
②然后将材料移至蒸馏水中
②发生质壁分离复原
第2组
③将材料置于60%蔗糖溶液中
③迅速发生质壁分离
④然后将材料移至蒸馏水中
④质壁分离不能复原
第3组
⑤将材料置于7%的尿素溶液中
⑤开始发生质壁分离,然后逐渐自动复原
第4组
⑥将材料放入100℃热水中3min后取出,重复第1组实验
⑥不发生质壁分离

(1)洋葱表皮细胞在第1、2、3组实验中均发生了质壁分离现象,其内部结构基础和外在条件分别是 。

(2)比较第1和第2组实验结果的差异,说明              。

(3)比较第1和第3组实验结果,出现实验结果差异性的原因是              。

 (4)比较第1和第4组实验结果,出现实验结果差异性的原因是              。

答案:(1)内部结构基础是有原生质层和原生质层内外两个溶液体系的存在;外在条件是原生质层内外两个溶液体系存在浓度差

 (2)高浓度溶液加快质壁分离现象的出现,但由于引起细胞过度失水,导致细胞死亡,使质壁分离复原不能发生

 (3)尿素是可能被细胞主动吸收的小分子物质,随着尿素分子不断的进入细胞内部,当细胞内外浓度趋于一致时,质壁分离就会自动复原

 (4)高温致使细胞死亡,死亡的细胞原生质层失去选择透过性,不能发生质壁分离

注意问题

试题详情

1、细胞发生质壁分离后,细胞壁与细胞膜之间的空隙充满的是0.3mg/mL蔗糖溶液。

试题详情

2.方法步骤:

 应用:1、可以用于测定细胞液的浓度 2、可以用于判断细胞的死活

 注意问题:

试题详情

1.原理:成熟(有明显液泡)的植物细胞能够与外界溶液组成一个渗透系统,通过渗透作用的方式吸水或失水。

试题详情

4、结论: 细胞外溶液浓度 > 细胞内溶液浓度,细胞失水 质壁分离

 细胞外溶液浓度 < 细胞内溶液浓度,细胞吸水 质壁分离复原

 植物细胞质壁分离和复原

试题详情


同步练习册答案