8.等位基因的分离发生于

A．有丝分裂后期　　　　　　　　　 B．减数第二次分裂后期　　　

C．减数第一次分裂后期　　　　　　 D．受精卵发育过程中

7．某DNA片段的碱基组成中，若A占32.8%，则C和T之和应占　　　

A．50%　　　　　　 B．17.2%　 　 C．67.2%　 　 D．65.6%

6. 关于DNA双螺旋结构的主要特点中，错误的是　　　　　　　　　　

A．两条链是按反向平行方式盘旋成双螺旋结构的

B．脱氧核糖和磷酸是交替连接，排列在外侧的

C．腺嘌呤和尿嘧啶、鸟嘌呤和胞嘧啶配对排列在内侧

D．碱基和碱基之间靠氢键相连，复制时氢键断开

5.从下列物质的结构层次看，由简单到复杂的顺序是　　　　

A．脱氧核苷酸→基因→染色体→DNA　 B．脱氧核苷酸→基因→DNA→染色体

C．基因→脱氧核苷酸→染色体→DNA　 D．基因→DNA→脱氧核苷酸→染色体

4.孟德尔的豌豆杂交实验中，将纯种的黄色圆粒(YYRR)与纯种的绿色皱粒(yyrr)豌豆杂

交，F₂代种子为480粒，从理论上推测，基因型为YyRR的个体数大约是

A.60粒　　　　　　 B.30粒　　　　 C.120粒　　　　　 D.240粒

3．在被子植物的一生中，对维持染色体数目恒定和促进植物遗传物质的重新组合起关键作用的环节是

A．受精作用和种子萌发　　　　　　 B．开花和传粉　　 　

C．减数分裂和受精作用　　　　　　 D．精子和卵细胞的形成

2．在减数第二次分裂过程中，主要的变化是　　　　　　　　　　　　　　　

A．DNA复制　　　　　　　　　　　 B．同源染色体复制

C．同源染色体联会　　　　　　　　 D．着丝点一分为二

1. 下列各组中不属于相对性状的是　　　　　　　　　　　　　　　　　　　　　

A.水稻的早熟和晚熟　　　　　 　　B.豌豆的紫花和红花

C.绵羊的长毛和细毛　　　　　　　 D.小麦的抗病和不抗病

5．参考词汇：1)模仿affect (v.)2)港台腔Hong Kong or Taiwanese slang and accents　 3) 普通话standard Mandarin Chinese

What's cool may not be correct

Nowadays some hosts and hostesses of mainland are fond of affecting Hong Kong or Taiwanese speech. Though it’s cool, I don’t think it is a good trend.

　 To millions of Chinese, Hong Kong and Taiwanese speech has come to mean being cool. So these programmes are very popular among the viewers. Thus the radio and TV stations can get much profit from the adverstisements.

But we must admit that hosts and hostesses have a responsibility to spread advanced culture and national virtue and to safeguard the country's interests. Many teenagers can’t tell good from bad, they will follow this way of speaking Chinese. And this is against our government’s aim to promote standard Mandarin Chinese.

Masters of ceremony should always use standard Mandarin Chinese and should stop affecting Hong Kong or Taiwanese slang and accents.

范文(二十三)

假设你是李平，你的美国笔友Nancy听说中国的“2005超级女声”很火爆，便想知道冠军得主的更多情况，现在你给她写一封信，把冠军得主李宇春的基本情况告知她，内容要点如下：

“2005超级女声”(2005 Super Girl)总决赛(contest finals)冠军得主李宇春一共获得了350余万张手机短信(text messages)投票。她出生于成都，今年21岁，生日为3月10日，身高174cm，体重50kg，爱好唱歌，跳舞和睡觉。喜欢的颜色是黑色和蓝色。她在中学时期就很活跃，曾举办过个人演唱会，现就读于四川音乐学院(Sichuan Conservatory of Music)。她有可能要成为一名著名的歌手。

Dear Nancy,

　I'm very glad to have received your letter. You want to know some information about the winner of the 2005 Super Girl. Now here it goes. Her name is Li Yuchun. Born on Mar 10, she is now 21 years old. She is very tall, with the height of 174cm, but is only 50kg in weight. She comes from ChenDu, SiChuan Province, and is now studying at Sichuan Conservatory of Music. She is fond of singing, dancing and sleeping. And her favorite colors are black and blue. Being a middle school student, she was very active. She once held a music concert of her own in her mother school. At the 2005 Super Girl contest finals, she got more than 3.5 million votes through mobile phone text messages, and thus got the first place. It is said that she is sure to become a pop star.

It is all that I know about her. Well, it’s too late, I have to stop here. Looking forward to hearing from you!　　　　　　　　　　　　　　　　　 Yours truly,

Li Ping

3．短文标题与开头已为你写好，不计入总词数；　　 4．词数：120左右。