问题
单项选择题
影响化学物简单扩散最主要的因素是（）
A.生物膜的厚度
B.化学物的分子量
C.化学物的解离状态
D.化学物的脂／水分配系数
E.生物膜两侧化学物的浓度差
答案
参考答案：E
解析：外源化学物经过简单扩散的条件是膜两侧有浓度梯度，外源化学物呈脂溶性，外源化学物是非解离状态。其中主要因素是膜两侧存在的浓度梯度。
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影响化学物简单扩散最主要的因素是（）
A.生物膜的厚度
B.化学物的分子量
C.化学物的解离状态
D.化学物的脂／水分配系数
E.生物膜两侧化学物的浓度差
参考答案：E
解析：外源化学物经过简单扩散的条件是膜两侧有浓度梯度，外源化学物呈脂溶性，外源化学物是非解离状态。其中主要因素是膜两侧存在的浓度梯度。
完形填空（共12分，每小题1分） 阅读下面的短文，掌握其大意，然后从短文后各题所给的A、B、C、D四个选项中，选择最佳选项。 When I was in the third grade, I was picked to be the princess in the school play. For weeks my mother had helped me 1 my lines. But once on stage, every word 2 from my head. Then my teacher told me she had written a narrator's (旁白) part for the play, and asked me to change 3 . Though I didn't tell my mother what had happened that day, she 4 my unhappiness and asked if I wanted to take a walk in the yard. It was a lovely spring day. We could see dandelions(蒲公英)popping（炸开）through the grass in bunches, I watched my 5 carelessly bend down by one of the bunches. “I think I am going to dig up all these weeds(杂草),” she said. “From now on, we’ll have 6 roses in this garden.” “But I like dandelions,”I said.“All flowers are 7 —even dandelions!” My mother looked at me seriously. “Yes, every flower gives pleasure in its own way, doesn’t it?”she asked thoughtfully. I nodded. “And that is 8 of people, too,”she added. When I 9 that she had guessed my pain, I started to cry and told her the truth. “ 10 you will be a beautiful narrator,” she said, reminding me of how much I loved to read stories aloud to her. Over the next few weeks, with her continuous 11 , I learned to take pride in the role. The big day finally came. A few minutes before the play, my teacher came over to me. “Your mother asked me to give 12 to you,” she said, handing me a dandelion. After the play, I took the flower home, laughing that I was perhaps the only person who would keep such a weed.
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