问题 填空题

孟德尔用黄粒豌豆与绿粒豌豆杂交,所得的杂交第一代全部是黄色豌豆.据此回答下列问题:

(1)豌豆粒色这一相对性状中,显性性状是______,隐性性状是______.

(2)如用R、r表示控制豌豆粒色这一相对性状,那么杂交第一代植株体细胞的基因组成是______;杂交第一代在形成生殖细胞时,能产生______种卵细胞,它们的基因组成是______.

(3)用杂交第一代植株进行自花授粉,其后代的基因组成有______种,它们分别是______,后代表现出来的性状有______种,分别是______.从理论上推测,所结的种子中,______籽粒的数量更多些.

答案

(1)、黄粒豌豆与绿粒豌豆杂交,所得的杂交第一代全部是黄色豌豆,最起码绿色豌豆体细胞的内有控制绿色的基因存在,控制绿色的基因就会传给第一代,如果绿色为显性,则杂交后的第一代中有控制绿色基因的个体就会表现为绿色,而题目中说所得的杂交第一代全部是黄色豌豆,所以绿粒不能是显性的,而是隐性的.黄粒为显性.

(2)、由第一题可知黄粒为显性,绿粒为阴性,则黄粒的体细胞中的基因是RR或Rr,绿粒是Rr,因为孟德尔用黄粒豌豆与绿粒豌豆杂交,所得的杂交第一代全部是黄色豌豆,如果黄粒的基因是Rr,绿粒是rr,则杂交后的第一代中就有可能出现基因型为rr的个体,rr控制的是绿粒.故亲代的黄粒体细胞中的基因只能是RR,绿粒是rr,则它们杂交的第一代的基因型是Rr,在形成生殖细胞时成对的基因Rr要进行分离,形成R或r的两种生殖细胞.

(3)、基因分解如图可知:用杂交第一代植株进行自花授粉,其后代的基因组成有三种:RR、Rr、rr.后代的性状有两种:黄粒和绿粒.理论上讲黄粒多,约是75%.

故答案为;

(1)、黄粒、绿粒

(2)、Rr、两种、R或r、

(3)、三、RR、Rr、rr,两,黄粒、绿粒,黄粒

单项选择题 A1/A2型题
写作题

读写任务:阅读下面的短文,然后按照要求写一篇150词左右的英语短文。

     Beijing is set to lift its12-year-old ban on fireworks for the traditional Spring Festival holidays, probably

starting from next Chinese Lunar New Year in January 2006.

     Zhou Jidong, director of the Legislative Affairs Office of the Beijing municipal government (市政府),

told a press conference last Thursday that his office has completed the draft (草案) regulations on firework

safety supervision.

     Under the draft regulations, setting off fireworks will be allowed in the capital city's eight downtown

districts from the Eve of the Lunar New Year to Lantern Festival 15 days later. When the draft regulations

were posted on the municipal government's website for suggestions, local residents gave a total of 969 pieces

of advice, with 70 per cent in favour of lifting the ban. Related surveys suggest local people who want to

light fireworks during Spring Festival range from 50.4 per cent to 86.3 per cent.

     In fact, the voice of opposition and criticism has never ended since the municipal government introduced

the ban in 1993, considering pollution, noise, fire worries and personal injuries caused by letting off fireworks.

     Opponents accused the government of introducing the ban only for the sake of facilitating its management

role while disregarding the will of the people. Worse, they say, the ban threatened to break down the age-old

traditions of celebrating Spring Festival among Chinese people.

     Partly due to this endless objection, about 106 out of a total 282 Chinese cities that had followed Beijing's

lead in banning fireworks have already dropped the ban.

[写作内容]

     1. 概括短文的内容要点,该部分的字数大约30词左右;

     2. 就“should the ban be lifted这个主题发表你的看法,至少包含以下的内容要点,该部分的字数

         大约120词左右;

         1)解禁的利弊;

         2)你的看法如何;

         3)你有什么建议?

[写作要求]

     你可以使用实例或其他论述方法支持你的论点,也可以参照阅读材料的内容,但不要抄袭阅读材料

中的句子。

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