题目内容

【题目】某生物兴趣小组对学校草坪的某种雌雄同花的植物进行了遗传学研究，发现该种植物的花色有红色和白色两种。他们查阅资料后发现，该对性状受一对遗传因子控制。为了对该对性状做进一步研究，该小组随机取红花和白花植株各60株均分为三组进行杂交实验，结果如表所示：

组别

杂交方案

杂交结果

A组

红花×红花

红花︰白花=14︰1

B组

红花×白花

红花︰白花=7︰1

C组

白花×白花

全为白花

（1）根据 组结果，可以判断 色为显性．

（2）试解释A组结果没有出现3︰1性状分离比的原因 ．

（3）B组亲本的红花中，纯合子与杂合子的比例为 ．

（4）要判断B组杂交结果中某红花植株是否为纯合子，最简单的方法是 ．

【答案】

（1）A 红

（2）红花亲本中并非都是杂合子

（3）3︰1

（4）让该红花植株自交，看后代是否发生性状分离

【解析】

（1）根据图表A组分析，红花×红花的杂交后代出现14红花︰1白花，发生了性状分离，说明红色是显性，白色是隐性．

（2）A组结果没有出现3︰1性状分离比的原因是红花亲本中并非都是杂合子。

（3）B组中的白花个体为隐性纯合子，F1中出现7红花︰1白花，说明亲代中的所有红花亲本所含显隐性遗传因子的比为显性遗传因子︰隐性遗传因子=7︰1．如果设显性遗传因子为R，则RR︰Rr=3︰1．

（4）要判断B组杂交结果中某红花植株是否为纯合子，最简单的方法是让该红花植株自交，看后代是否发生性状分离．

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