题干

下列关于细胞膜的流动性和选择透过性的叙述,不正确的是(  )

A:流动性的基础是组成细胞膜的磷脂分子和蛋白质分子大多是流动的

B:选择透过性的基础是细胞膜上的载体蛋白和磷脂分子具有特异性

C:细胞的胞吞和胞吐体现了细胞膜的流动性

D:钾离子通过主动运输的形式进入细胞体现了细胞膜的选择透过性

上一题 下一题 0.0难度 选择题 更新时间:2018-04-29 10:38:04

答案(点此获取答案解析)

B

同类题1

下表为改革开放30年来北京城镇居民家庭的恩格尔系数变化表,此表直接表明北京城镇居民                                                                (   )
年份
1979年
1999年
2009年
系数
57.9%
42.1%
30.2%

同类题3

阅读理解
    Growing up in Puerto Rico, our family was no different from so many others. My parents got married after my father came back when the war ended. Both of my parents were struggling with the hard economic realities of the time. But somehow, they found time to cherish those cultural values that shaped our everyday life.
    In our daily life, we celebrated together with our friends or family members every birthday, every graduation, and all holidays with music and dancing, and typical foods. When we visited our family in the countryside—a trip that took about two hours in a car, with five children fighting as to who would get a window or the front seat —we would break into song, and somehow the trip would turn into one full of happiness and fun. We would sing not only interesting children's songs but also beautiful love songs — songs about the love of our country though we didn't understand the meaning of the words many times.
    I came to Philadelphia for the first time in 1973 to do a residency(实习) in family medicine. I remember the many hours of work. I was facing issues of life and death and suffering the clearly social unfairness and issues of poverty and race. These were all worsened by my feeling of cultural differences.
    An important turning point in my life happened one Saturday night when I attended a concert of Puerto Rico singer and composer Antonio Caban Vale. The music showed my familiar rhythms, and the words spoke to my heart. I had found a space to express, celebrate, and share my culture in Philadelphia. Therefore, I believe diversity is seen as an advantage and not as a disadvantage. As a Puerto Rican, I am a mixture of races and I believe in my strength because of this.