问题 实验题

资料分析 下面表示的是一对基因的遗传图解,读图后请回答下列各问。

1.如果上方的基因型表达的是眼睑的性状(即双眼皮、单眼皮),则父方的眼睑性状是        ,母方的眼睑性状是       

2.如果上图中的基因型表达的是“能否卷舌”的性状,则父方的性状是       ,母方的性状是       

3.请在图解下方的括号内填写子女应具有的性状,如果性状与父亲相同,就填写“同父”,与母亲相同的,就写“同母”。

4.如果这是一个多子女的家庭,该父母总共有四名儿女,如果以耳垂性状为例(有耳垂是显性性状),那么在子女中,有几人有耳垂,几人没有耳垂?你应该怎样回答?为什么?

答案

1.双眼皮 单眼皮   2.能卷舌 不能卷舌    3.同父 同父 同母 同母  4.无法判定。因为上述遗传图解表示的是一种概率,即对每次即将诞生的生命来说,它的某一种性状出现的机率应该是多少。

题目分析:(1)(2)当控制某个性状的基因都是显性或一个是显性,一个是隐性时,只表现出显性基因控制的性状,当控制某个性状的基因都是隐性基因时表现隐性性状,通常用大写字母表示显性基因,小写字母表示隐性基因,如果图的基因型表达的是眼睑的性状(即双眼皮、单眼皮),则父方的眼睑性状是双眼皮,母方的眼睑性状是单眼皮,如果上图中的基因型表达的是“能否卷舌”的性状,则父方的性状是能卷舌,母方的性状是不能卷舌;

(3)在生物的体细胞中,染色体是成对存在的,基因也是成对存在的,分别位于成对的染色体上,在形成生殖细胞的过程中,成对的染色体分开,每对染色体中的一条进入精子或卵细胞中,基因也随着染色体的分离而进入不同的生殖细胞中,当精子和卵细胞结合形成受精卵时,染色体又恢复到原来的水平,一条来自父方,一条来自母方,父方的基因型是Aa,能产生2种精子,分别是含A的和含a精子,母方的基因组成是aa,只能产生1种卵细胞a;

(4)遗传图解表示的是一种概率,即对每次即将诞生的生命来说,它的某一种性状出现的机率应该是多少,所以无法判断四名儿女有耳垂和无耳垂的人数。

单项选择题 案例分析题
单项选择题

It’s not easy to be an astronaut’s son. Everybody expects you to be special or perfect. I often wonder how my father ever had a son like me. I mean he’s so special and so good at everything he does. Even in middle school he was class president and captain of the football team.
Well, to be honest, I often dream about being some kind of hero or doing something special-like saving a child from a burning building or discovering a new star. I was daydreaming at school one morning when my teacher said there would be a Father’s Day writing competition for the whole school. "I hope we have a winner right here in my class. "
When I got home, I started to think about what to write. My father is an astronaut. No, I wouldn’t start like that. That was the way others saw him. How did I see my father Hmm.
I saw him sitting with me in the dark when I had a terrible dream. I remembered how he hugged me for hours when my dog Spotty was killed by a car. Yes, these were the things I was going to write. To me, he wasn’t just a world-famous astronaut. He was my dad.
My parents and I went to school Thursday night. There were so many people in the big hall! My dad looked at me, and I shrugged (耸肩).
The third prize was announced and it was not me. I was relieved (释然) and disappointed at the same time. The second prize was announced. It was me.
I went up to the stage and read what I had written, My Father’s Son. When I finished, the people stood up and cheered. I saw my father blowing his nose. Tears were running down my mother’s face. Dad cleared his throat and put his hand on my shoulder. "Son, this is the proudest moment of my life. "
It was the proudest moment of my life, too. Maybe I’ll never be a great hero or win a Nobel Prize, but it was enough just to be my father’s son.

What is the best title of the passage______

A.My Daydream
B.My Father’s Son
C.My Famous Father
D.My Happy Family