题干

取经过编号的5支试管分别加入2mL 0.5mol/L过氧化氢溶液,进行如下实验,根据实验内容,下列说法正确的是                                                                                                                    
试管编号
1
2
3
4
5
加入物质
适量唾液
锈铁钉
生土豆块
熟土豆块
生土豆块+稀盐酸
实验结果
几乎无气泡
少量气泡
大量气泡
几乎无气泡
几乎无气泡
        

A:说明酶具有高效性的是3号和4号实验

B:1号和3号对照不能说明酶有专一性

C:实验中不能体现酶的活性与温度之间的关系

D:3号和5号对照可以说明酶的活性受PH的影响

上一题 下一题 0.0难度 选择题 更新时间:2017-10-12 06:46:43

答案(点此获取答案解析)

D

同类题4

   Eileen Collins is the first woman ever chosen to be a spaceship pilot. She is also the first woman to command(指挥) a spaceship. Today she has flown more than 5, 000 hours in more than 30 kinds of airplanes.
   Talking about high school, she said, “I began reading all kinds of books about famous women pilots. These women went and flew into dangerous places. Their stories encouraged me.” In 1977 Eileen got a pilot’s license and the following year she graduated from university. She went into space in 1999 at the age of 43. She took with her the hopes and dreams of a nation of young people on the earth.
   Eileen is not only an astronaut but also a wife and the mother of a young daughter. She has short curly hair and friendly brown eyes. She met her husband, Pat, while they were together in the air force(空军).
   When she was named as the First Woman Spaceship Commander in 1998, Eileen smiled and said, “When I was a child, I dreamed about space. It was only a dream that I would be one of the astronauts someday. I hope all children will be encouraged to reach for their dreams, when they see I go into space. I believe dreams do come true!”  
____ How many hours has Eileen flown?
                                                                             
____ When did Eileen go into space?
                                                                             
____ What does Eileen look like?
                                                                             
____ Who did Eileen meet in the air force?
                                                                             
____ Did Eileen believe that her dream would come true?