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【简答题】
二倍体动物缺失一条染色体称为单体。大多数单体动物不能存活,但在黑腹果蝇中,点状染色体 ( IV号染色体 ) 缺失一条可以存活,而且能够繁殖后代。 (1) 果蝇群体中存在无眼个体,无眼基因位于常染色体上,将无眼果蝇个体与纯合野生型个体交配,子代的表现型及比例如下表: 无眼 野生型 F 1 0 85 F 2 79 245 据此判断,显性性状为 ________ ,理由是 ________________________________ _____________ ____________ 。 (2) 根据上述判断结果,可利用正常无眼果蝇与野生型 ( 纯合 ) 单体果蝇交配,探究无眼基因是否位于IV号染色体上。 请完成以下实验设计: 实验步骤: 让正常无眼果蝇与野生型 ( 纯合 ) 单体果蝇交配,获得子代;统计子代的 ________________ ,并记录。 实验结果预测及结论: 1若子代中出现 ____________________________ _____ ________ ___ ________________ , 则说明无眼基因位于IV号染色体上; 2 若子代全为 ____________ ,说明无眼基因不位于 IV 号染色体上。
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【简答题】气门的功用是控制进排气道的（）和（），它分为（）和（）两种。
【单选题】Which of the following statements is correct when you deliver a presentation?
A.
When you speak to a key point, you should make a pause.
B.
Always look at your notes.
C.
Hunch up and shuffle your feet.
D.
Speak in a monotone.
【单选题】When you deliver the presentation, you should _____.
A.
give the audience amiable facial expressions
B.
keep your pitch and speed of your presentation
C.
mumble and avoid direct eye contacts with the audience
D.
speak quickly so as to finish the presentation efficiently
【简答题】如何加强学风建设。
【单选题】When you deliver the presentation, you should _____.
A.
mumble and avoid direct eye contacts with the audience
B.
keep your pitch and speed of your presentation
C.
speak quickly so as to finish the presentation efficiently
D.
give the audience amiable facial expressions
【单选题】When you deliver the presentation, you should _____.
A.
mumble and avoid direct eye contacts with the audience
B.
speak quickly so as to finish the presentation efficiently
C.
keep your pitch and speed of your presentation
D.
give the audience amiable facial expressions
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