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    【题目】下列关于噬菌体侵染细菌实验的叙述，正确的是（ ）

    A．用含35S的培养基培养可获得标记的噬菌体

    B．搅拌能使大肠杆菌破裂，释放出子代噬菌体

    C．用35S标记的一组实验，部分子代噬菌体中能检测到35S

    D．用32P标记的一组实验，放射性同位素主要分布在沉淀中

    【答案】D

    【解析】噬菌体属于病毒，必须寄生在活细胞内才能存活，A错误。搅拌是为了使大肠杆菌和噬菌体分开，B错误。用35S标记的一组实验，子代噬菌体中不能检测到35S，因为新合成的噬菌体蛋白质外壳是在噬菌体自身遗传物质的指导下，利用细菌的原料合成的，C错误。用32P标记的一组实验，因为只有噬菌体头部的被标记的DNA侵入到细菌体内，所以放射性同位素主要分布在沉淀中，D正确。

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