第三节书面表达wersionDear Sir or MadamMy name is Li Hua. As an exchange student fromChina, I am studying in a local school. I am reallydelighted to learn that a volunteer for your Chinese culturallic exhibition is required and I'm confident that I amtruly fit for thestart with, my advantage first lies in the fact that IChina and used to beand quite familiar with Chinese relics. Further-more, being an outgoing and optimistic boy, I am good atcommunicating with others and introducing Chinese cultureto the world is always my honor and my pleasure. Finallythere is no problem with my spoken English, as I havelived here for almost a year and I have no difficulty commu-dicating with others in EnglishI would really appreciate it if you can offer me thechance to be a volunteer in your museum. I am looking forward to your early reply.Li Hua

39.(11分,除标注外,每空1分)(1)常X(2)AAXX3/16(2分)4(3)如图所示(3分)黑毛雄鼠白毛雌鼠aa.Xb配子AdAFI AaXaXAaXbY 8aXBXbsaXbY黑毛雌黄毛雄白毛雌白毛雄(4)① AaDdXX②【解析】(1)由题干信息可推知,等位基因A/a位于常染色体上,等位基因B/b位于X染色体上(2)已知两亲本都是纯合子,黄毛雌性家鼠的基因型是AAXX,白毛雄性家鼠的基因型是aXBY,F1雌雄鼠的基因型分别是 MaXX与AaXY,相互杂交所得F2中黄毛雌家鼠占3/4×1/4=3/16,白毛家鼠的基因型为aaXX、aaxY、aXbY、 naXX4种。(3)杂合黑毛雄鼠的基因型为 AaXY,与其测交个体的基因型为aXx,注意遗传图解写出P配子及子一代的符号;亲本的表现型及基因型;子代的表现型、基因型及比例要准确。(4)该家鼠的基因型为 AaDdXX,通过减数分裂能产生2种基因型的配子。

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