题目内容

一个男人是红绿色盲患者(此性状是X隐性遗传)，假定他不是此性状的突变体，可认为______

A. 他一定是从其母亲那儿遗传来的这一致病基因
B. 他一定是从其父亲那儿遗传来的这一致病基因
C. 他可能是从双亲之一遗传来的这一致病基因
D. 由于隐性性状只在纯合时才能表达，所以他一定是从双亲遗传来的这一致病基因

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造成46，XX男性和45，XO男性的可能原因是______

A. X和Y发生交换，X染色体上带有睾丸基因
B. 常染色体的雄性基因占了优势
C. 上述答案都正确

简答题Directions: Complete the sentences by translating into English the Chinese given in brackets. Please write your translation on Answer Sheet 2. But for the storm，______(船一定会准时到达目的地).

在家猫中，黑毛和黄毛是由一对X连锁基因控制的，且以下列方式遗传，基因B在纯合和半纯合时均为黑色，基因b在纯合和半纯合时均为黄色，两个基因的杂合体为玳瑁猫。现有4个小猫的表型是：一个黄色雌猫，一个黑色雄猫，一个黄色雄猫，一个玳瑁猫，下列何种亲本组合可产生这些猫______

A. 黑毛♂×黄毛♀
B. 黑毛♂×玳瑁猫♀
C. 黄毛♂×玳瑁猫♀
D. 黄毛♂×黑毛♀
E. 以上组合都会产生这些子代

案例分析题Domestic pets in Britain are often treated like a member of the family. The most (36) pets are of course cats and dogs, but then there are the (37) birds, fish and rabbits, all found in homes. Pets are thought to bring an "animal (38) " into the home. Cats make the perfect reading (39) , while dogs are widely believed to be man’s best friend. There are dozens of animal rescue (40) across Britain, and animal lovers are encouraged to go to these centers if they want to get a pet, rather than going to pet shops, which may be (41) and sell animals bred in harsh conditions.Although there is no annual (42) fee to keep pets, the cost of keeping a pet can be relatively high. Food, grooming, and (43) can mount up over the years (44) . Most primary schools also have class on pets and children are encouraged to look after them and are taught to treat them. (45) , the UK is one of Europe’ s largest markets for exotic pets. Thousands of snakes, lizards, crocodiles and other reptiles make their way to Britain every year to support the booming exotic pet business. (46) . 43（）