问题 单项选择题

天然的玫瑰没有蓝色花,这是由于缺少控制蓝色色素合成的基因B,而开蓝色花的矮牵牛中存在序列已知的基因B。现用基因工程技术培育蓝玫瑰,下列操作正确的是()。

A.提取矮牵牛蓝色花的mRNA,经逆转录获得互补的DNA,再扩增基因B

B.利用限制性核酸内切酶从开蓝色花矮牵牛的基因文库中获取基因B

C.利用DNA聚合酶将基因B与质粒连接后导入玫瑰细胞

D.将基因B直接导入大肠杆菌,然后感染并转入玫瑰细胞

答案

参考答案:A

单项选择题
阅读理解

San Francisco, a leader in urban recycling, is preparing to turn dog waste into energy.

Norcal Waste System Inc., the city’s largest garbage company, plans to test collection carts(回收车)and collection bags in a city-center park which is popular with dog walkers.

A city study found that almost 4 percent of all the garbage picked up at San Francisco homes was from animal waste, Norcal Waste spokesman Robert Reid said. San Francisco has about 120,000 dogs.

“The city asked us to start a program to recycle dog waste in order to cut back adding more waste in landfills(废渣埋填池) “,Reid said.

Dog waste will be poured into a methane digester(沼气池),and the methane it gives off will be collected and burned to make electricity or to heat homes.

“Dogs and cats in the United States produce about 10 million tons of waste a year,” Will Brinton, an environmental scientist said.

“As much as we love them, our pets leave a lot of fertilizer behind them in yards and on the street but that can be a major source of contamination of groundwater,” Brinton said.

European cities such as Zurich, Frankfurt, Munich and Vienna are starting biology programs to turn waste into gas ,he said.

San Francisco runs a great program to recycle bottles, cars, paper and other rubbish and now two-thirds of its garbage needn’t be carried to landfills .The city’s goal is a 75 percent drop by 2010 and zero new waste in landfills by 2020.

小题1:San Francisco will plan to use dog waste for making __________.

A.fertilizer

B.gas

C.electricity

D.methane小题2:What does the underlined word “ contamination” mean?

A.Increase

B.Reduction

C.Flow

D.Pollution小题3:What can we infer from the passage?

A.San Francisco is short of electricity

B.San Francisco has done a lot of in rubbish recycling.

C.Fewer people will keep dogs as pets in San Francisco

D.There will be no rubbish by 2010 in San Francisco小题4:The passage is mainly about_______.

A.San Francisco ‘s new policy for pet keepers

B.San Francisco ‘s new plan for recycling

C.how to keep a city clean

D.how to deal with rubbish