下列哪种变异不能遗传给后代（） A．安康羊的短腿性状 B_爱下问搜题

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问题选择题

下列哪种变异不能遗传给后代（　　）

A．安康羊的短腿性状

B．由于水肥充足而造成的小麦粒多粒大

C．人类的白化病

D．通过杂交重组在一起的优良性状

答案

变异是指子代与亲代之间的差异，子代个体之间的差异的现象．按照变异对生物是否有利分为有利变异和不利变异．有利变异对生物生存是有利的，不利变异对生物生存是不利的．按照变异的原因可以分为可遗传的变异和不遗传的变异．可遗传的变异是由遗传物质改变引起的，可以遗传给后代；由环境改变引起的变异，是不遗传的变异，不能遗传给后代．人类的白化病、安康羊的短腿性状、通过杂交重组在一起的优良性状，都是遗传物质变化引起的变异，可以遗传给后代，是遗传的变异；由于水肥充足，小麦粒多粒大，是环境条件变化引起的变异，遗传物质没有发生变化，不能遗传给后代，是不遗传的变异．

故选：B．

单项选择题 A1/A2型题

右心衰竭和肝硬化主要鉴别点是（）。

A.肝火

B.水肿

C.腹胀

D.颈静脉怒张，肝颈回流征（+）

E.胸腔积液

完形填空

Michael O’her lived alone with his father, and the two of them had a very special relationship. The father believed in encouragement.
Though Michael was the    1  of the class when he entered high school, his    2     continued to encourage him, but also made it very clear that he did not have to play    3    if he didn’t want to.
However, Michael loved football and was    4   to try his best at every practice. All through high school, he never     5    a practice or a game, but remained a bench warmer (替补队员) all four years. His    6   father was always in the stands, with words of    7   for him.
It was the end of the football season, and as Michael ran slowly onto the practice field shortly     8   the big final game, the coach met him with a telegram. Michael    9     the telegram and became deathly silent—his father died that morning, and the sad man left for   10   immediately.
In the third quarter, when the team was ten points    11  , a silent young man eagerly    12   onto the sidelines. The coach and his players were shocked to see their team-mate back so    13 .
“Coach, please let me    14  . I have to play today,” said Michael. Feeling sorry for him, the coach     15  . Before long, nobody could believe their eyes. This small bench warmer played like a(n)    16  . He helped his team win finally.
When the team was cheering for their    17  , Michael was sitting in the corner all alone. The coach came to him and said, “You were fantastic! Tell me    18  you did it?”
Tears in eyes, Michael said, “Well, you knew my dad died, but did you know he was blind?” He    19   a smile, “Dad came to all my games, but today was the first time he could   20   me play, and I wanted to show him I could do it!”

A．sympathetic

A．encouragement

A．went through

B．turned over