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26.【答案】(9分,除说明外,每空1分)(1)雄Z:ZSW:ZZ:W=2:2:1:1(2分)(2)ZSZS×ZSW银色(3)①杂交方案:让该金色羽公鸡与多只银色母鸡交配,观察统计子代的表现型及分离比。(2分)②若子代表现型及比例为银色羽公鸡:金色羽母鸡=1:1,则该公鸡基因型为Z$Z;若子代表现型及比例为银色羽公鸡:银色羽母鸡:金色羽公鸡:金色羽母鸡=4:1:1:4,则该公鸡基因型为ZZSW(2分)【命题意图】本题考查伴性遗传,旨在考查综合运用和实验探究能力。【解析】(1)性染色体增加一条的鸡(ZZW),其DMRT1基因表达量高,开启睾丸发育,性别为雄性。Z$ZSW的三条染色体随机均分,可形成四种类型的配子,种类及分离比是ZS:ZSW:ZZ:W=2:2:1:1。(2)由于羽色是伴性遗传,且性别决定方式是ZW,可用“雌显雄隐”杂交,子代出现“雌隐雄显”,即可根据子代表现型判断性别。(3)让该金色羽公鸡与多只银色母鸡交配,观察统计子代的表现型及分离比。若子代表现型及比例为银色羽公鸡:金色羽母鸡=1:1,则该公鸡基因型为Z$ZS;若子代表现型及比例为银色羽公鸡:银色羽母鸡:金色羽公鸡:金色羽母鸡=4:1:1:4,则该公鸡基因型为ZsZsW。(还有一种特殊情况,性反转,若子代表现型及比例为银色羽公鸡:金色羽母鸡:银色羽母鸡=1:1:1,则该公鸡基因型为ZSW)若学生答出也可得分
第一节One possible version:Dear Eric,Learning that you were awarded first prize in the poster design competition held in your city,with thetheme"Protecting the World's Wildlife",I'm writing to offer my congratulations to you.I think it is a prize that you deserve.First of all,you have a talent for art.Secondly,your richimagination is one of the advantages over other competitors.Furthermore,you have been interested inwildlife from an early age,which makes your work stand out among the posters.Please accept my congratulations again.I wish you every success in the future.Yours sincerely,Li Hua