问题 单项选择题

据新华社台北2004年9月30日报道:由于滥用抗生素导致细菌抗药性增强,一种无药可治的超强细菌“全抗药性鲍氏不动杆菌”(简称PDRAB菌)在台湾出现并蔓延,人类感染后的死亡率高达60%。下列对此现象的解释,正确的是( )

A.基因突变和染色体变异是PDRAB菌不断变异的主要原因
B.PDRAB菌的超强抗药性是该细菌逐代对各种抗生素识别能力提高的结果
C.由于滥用抗生素导致PDRAB菌产生抗药性基因突变
D.病菌中原来就有抗药性的个体和对抗生素敏感的个体,在滥用抗生素的过程中,对抗药性的个体进行多次选择

答案

参考答案:D

解析: 本题考查对现代生物进化理论的理解。由题意可获得以下信息:①该超强细菌为原核生物;②该菌传染方式为接触传染;③该菌对多种抗生素有抗性。根据这些信息可知:该菌变异的来源只可能为基因突变,其核区内无染色体,故A说法错误;该菌超强抗性的产生是抗生素与该菌相互选择的结果,抗生素的选择作用使细菌的耐药基因频率不断增大,最终表现为整体抗药性增强;由于不同抗生素的滥用,能存活下来的个体就对多种抗生素具有抗性。故只有D说法正确。解答本题时应注意把握两点:①突变和基因重组为进化提供了原材料;②自然选择决定着进化的方向。

阅读理解

阅读理解。

                                                               

     Amelia Earhart was born in America in 1897. As a little girl, she could climb trees and catch rats. When

she was seven years old, she discovered she was interested in flying. In 1920, Amelia took a plane and knew

she had to fly! Just days after that, she took her first flying lesson. Six months later, she bought her own

plane! 

    A Life-Changing Flight On June 18, 1928, Amelia became world-famous because she flew across the

Atlantic with others as the first woman. And then she was called the "Queen of the Air".

    Making and Breaking Records Although Amelia was well-known in the flight, she never stopped practicing

it. In 1932, she became the first woman to fly across the Atlantic by herself, and later in 1935, she was the

first person to fly over the Pacific from Hawaii to California by herself.

    The Last Flight When her 40th birthday was coming, Amelia prepared for her biggest challenge-an

around-the-world flight. On June 1, 1937, she began her 46,671-kilometer flight. Something unlucky happened

on June 29. She never came back again.

    However, her name still lives on till now.

1. What was Amelia interested in when she was seven years old? [ ]

A. Jumping.

B. Flying.

C. Climbing trees.

D. Catching rats.

2. When did Amelia take her first flying lesson? [ ]

A. In 1897.

B. In 1904.

C. In 1920.

D. In 1928.

3. Why was Amelia called the "Queen of the Air"? [ ]

A. Because she bought her own plane.

B. Because she used to practice flying.

C. Because she could fly faster than others.

D. Because she was the first woman to fly across the Atlantic.

4. Where did Amelia fly over in 1935? [ ]

A. Japan.

B. England.

C. Part of the Atlantic (大西洋).

D. Part of the Pacific.

5. What can we know about Amelia from this article? [ ]

A. She died in 1937.

B. She made a plane in 1897.

C. Her last flight was successful.

D. Her biggest challenge was to fly across America.

单项选择题