问题
单项选择题 A型题
遗传异质性是指（）
A.同一种疾病临床表现相同，引起疾病的遗传基础不同
B.同一家系中有不同的遗传病
C.同一遗传病出现在不同的家系中
D.同一地区出现相同的遗传病
E.以上都不是
答案
参考答案：A
解析：一种临床表现可以由几种病变基因所引起，不同致病基因可有相同的临床表现。这种表型相同而基因型不同的现象称为遗传异质性。
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遗传异质性是指（）
A.同一种疾病临床表现相同，引起疾病的遗传基础不同
B.同一家系中有不同的遗传病
C.同一遗传病出现在不同的家系中
D.同一地区出现相同的遗传病
E.以上都不是
参考答案：A
解析：一种临床表现可以由几种病变基因所引起，不同致病基因可有相同的临床表现。这种表型相同而基因型不同的现象称为遗传异质性。
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| "What's it like to have a gap between your teeth?" a girl asked me one day. Nobody had ever 1 before. My hand unconsciously rose to cover my mouth. But, as she looked at me, sincerely waiting for 2 , I realized she was not trying to be rude. "I never think about it," I truthfully replied. She nodded and turned away. I was left wondering if people 3 me and saw only happy teeth. Later that day at home, I began to 4 my teeth again. I felt upset. I thought my life would be somehow better if my teeth were not happy. How I wanted the perfect teeth that everyone else seemed to have! Of course, Mom 5 everything. She has lived her entire life with happy teeth, and tried to convince me that there was nothing to 6 . When I refused to listen, she told me I could get the surgery to close the gap if it was that important. "Let's be 7 , though," she said. "If everyone got surgeries to become pretty, everyone would be exactly the same. There is beauty in differences." Her 8 made me consider my teeth seriously. the thought of losing my gap was more terrible than the reality that people were going to notice it. I realized how important it was to me. It is part of my 9 . Nowadays many people do ridiculous things to realize their dream of "perfection." The 10 is that no one is perfect. When all potential for ugliness is removed, so is all of the potential for 11 . So if that girl ever asked about my teeth 12 , I would truthfully answer, "You know? It's really cute." | ||||
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