问题 填空题

美国《科学》周刊刊登了该杂志评出的2000年十大科学成就,人类基因组草图绘制名列榜首。

     1990年,被誉为生命科学“登月计划”的国际人类基因组计划启动,主要由美、日、德、法、英等国科学家共同参与。1999年9月,中国作为唯一发展中国家加入了这一研究计划,负责测定人类基因组全部序列的1%。在2000年6月26日科学家成功绘制出人类基因组“工作框架图”之后,2001年2月12日,六国科学家又联合宣布,他们又绘制出更加准确、清晰、完整的人类基因图谱。基因测序结果表明:人类大约包含3万到4万个基因。这一重大成果标志着生命科学又向纵深迈进了一步,其重要性不亚于人类登上月球的“阿波罗计划”。

     研究人员曾经预测人类约有14万个基因。但科学家这次研究确定了人类基因约为3万~4万个,只有酵母菌的4倍,果蝇的2倍,比线虫也仅多1万个基因,数量少得惊人。研究表明,人类蛋白质有61%与果蝇同源,43%与线虫同源,46%与酵母菌同源。人类17号染色体上的全部基因几乎都可以在老鼠11号染色体上找到,85%~95%的人类基因构成都与老鼠的基因构成相似。但人类基因的机能却远比其他动物复杂,人类基因是以命令人体制造特定蛋白质而行使其功能的,每个基因都可制造出十多种不同的蛋白质,简单生物便不能做到这一点。同时人类基因组编码的蛋白质活性也比其他生物强。

(1)“人类基因组计划”需要测定人类的24条染色体的基因和碱基顺序,为什么不是测定23条染色体?___________________________________________。

(2)“人类蛋白质有61%与果蝇同源,43%与线虫同源,46%与酵母菌同源”这一事实可以从_________水平说明生物之间存在__________关系。

答案

(1)是22条染色体和X、Y两条性染色体。因为X、Y染色体具有不相同的基因,所以一共要测24条染色体。

(2)分子 亲缘(或远或近的)

多项选择题
阅读理解

阅读理解。

     There are two methods by which hydrogen (氢) can be used to power cars. The first way is

to use hydrogen to drive the engine, in much the same way as many cars use gas. The second

method is to use the reaction of hydrogen with oxygen in a battery, making the car a kind of

electric one.

     The dream of producing hydrogen in the car while driving along by electrolyzing (电解)water

is a long way off, so we are still at the period of batteries and filling the tank with hydrogen gas.

This is the difficulty for potential car users and producers. There are only sixteen hydrogen filling

stations in Los Angeles and none in 99% of other cities worldwide.

     Indeed, some of the big name automobile producers have pulled out of the race to put the first

practical hydrogen car on the streets. Ford and GM have announced that they are pulling out in

America and so has Renault in France.

     However, the Japanese companies are pressing on. In fact, Honda introduced its first hydrogen

fuel cell car in 1999. They are now producing second generation hydrogen car known as the

FCX Clarity. Guess where they are available for sale? In only one city because of its filling stations.

     Honda thinks that they could go into full-scale production of the FCX Clarity by 2020 if the

world is prepared for them by then.

     Then there are hydrogen-powered buses in several European cities including Amsterdam,

Barcelona, Hamburg, London, Luxembourg and Madrid. Lotus, the makers of London taxis,

have announced that they propose to manufacture hydrogen-powered taxis in time for the London

Olympics.

     So, the hydrogen vehicle is out there and the numbers will be growing fairly soon. The buses

go back to their bus station, where an electrolyzing machine changes water into fuel for them to

fill up on and the same will be the case for many of London's taxis.

Unfortunately, getting fuel is not the only difficulty for the average motorist, a number of these

vehicles cost about $300,000 each.

1.According to the text, hydrogen-powered buses _____.

A. can easily be filled up with gas.

B. are likely to sell well in the future.

C. are mainly used in the United States

D. won't be used in the London Olympics

2. What does the underlined word "them" in paragraph 5 refer to?_____.

A. Japanese companies

B. Hydrogen buses

C. The FCX Clarity

D. Filling stations

3. Where are hydrogen cars currently available for sale?_____.

A. In Barcelona

B. In Hamburg

C. In London

D. In Los Angeles

4. We can learn from the text that ______.

A. there are sixty hydrogen filling stations all over the world

B. hydrogen vehicles fueled by water will be very expensive

C. Honda will mass-produce the FCX Clarity by 2012

D. Honda produced its first hydrogen car in 1989