单选题不在细胞质游离核糖体合成的蛋白质是：

单选题在效应物作用下，蛋白质产生的变构效应是由于蛋白质的

单选题真正的、具有生物活性的维生素D是______。

单选题人类双雄受精产生受精卵的核型不可能是( )。

单选题有关肾小管的作用，错误说法是

单选题长期服用异烟肼的结核病患者应同时服用

单选题DNA聚合酶Ⅰ大片段不具有下面哪种功能( ) A．5→3聚合酶活性 B．3→5核酸外切酶活性 C．5→3核酸外切酶活性 D．补齐双链DNA的3末端 E．3末端标记

单选题下列氨基酸中，可参与肝内初级胆汁酸的合成的是 A.甘氨酸 B.甲硫氨酸 C.鸟氨酸 D.丙氨酸 E.精氨酸

单选题前导链为连续合成，随从链为不连续合成的DNA复制方式是 A.全不连续复制 B.全连续复制 C.全保留复制 D.半不连续复制 E.混合式复制

单选题真核生物基因的特点是______ A.编码区连续 B.多顺反子RNA C.内含子不转录 D.断裂基因 E.外显外数目=内含子数目-1

单选题σ因子专一性表现在( )。

单选题同源异型域蛋白( )。

单选题既可利用上游启动子，又可利用下游启动子的RNA聚合酶是______。 A．RNA聚合酶Ⅰ B．RNA聚合酶Ⅱ C．RNA聚合酶Ⅲ D．RNA聚合酶Ⅳ

单选题证明DNA是遗传物质的两个关键性实验是：肺炎球菌在老鼠体内的毒性和T2噬菌体感染大肠杆菌。这两个实验中主要的论点证据是______。 A．从被感染的生物体内重新分离得到DNA作为疾病的致病剂 B．DNA突变导致毒性丧失 C．生物体吸收的外源DNA(而并非蛋白质)改变了其遗传潜能 D．DNA是不能在生物体间转移的，因此它一定是一种非常保守的分子 E．真核生物、原核生物、病毒的DNA能相互}昆合并彼此替代

单选题正常细胞质膜上磷脂酰丝氨酸的分布______。

单选题质粒的重要特性不包括

单选题关于生长因子不正确的是 A.蛋白多肽类分子 B.有内分泌、旁分泌和自分泌作用 C.促进细胞生长 D.不需要与细胞质膜特异受体结合即可发挥作用 E.大量异常表达导致肿瘤

单选题关于化学渗透假说的叙述，错误的是 A.必须把内膜外侧的H+通过呼吸链泵到膜内 B.需要在线粒体内膜两侧形成电位差 C.由英国Peter Mitchell首先提出 D.H+顺浓度梯度由膜外回流时驱动ATP的生成 E.电子传递过程中，质子泵出的作用在于存储电子传递释放的能量

单选题真核生物的翻译过程说法不正确的是

单选题In his book The Tipping Point, Malcolm Gladwell argues that "social epidemics" are driven in large part by the actions of a tiny minority of special individuals, often called influentials, who are unusually informed, persuasive, or well connected. The idea is intuitively compelling--we think we see it happening all the time--but it doesn't explain how ideas actually spread. The supposed importance of influentials derives from a plausible-sounding but largely untested theory called the "two-step flow of communication": Information flows from the media to the influentials and from them to everyone else. Marketers have embraced the two-step flow because it suggests that if they can just find and influence the influentials, those select people will do most of the work for them. The theory also seems to explain the sudden and unexpected popularity of certain looks, brands, or neighborhoods. In many such cases, a cursory search for causes finds that some small group of people was wearing, promoting or developing whatever it is before anyone else paid attention. Anecdotal evidence of this kind fits nicely with the idea that only certain special people can drive trends. In their recent work, however, some researchers have come up with the finding that influentials have far less impact on social epidemics than is generally supposed. In fact, they don't seem to be required at all. The researchers' argument stems from a simple observation about social influence, with the exception of a few celebrities like Oprah Winfrey--whose outside presence is primarily a function of media, not interpersonal influence--even the most influential members of a population simply don't interact with that many others. Yet it is precisely these non-celebrity influentials who, according to the two-step-flow theory, are supposed to drive social epidemics, by influencing their friends and colleagues directly. For a social epidemic to occur, however, each person so affected must then influence his or her own acquaintances, who must in turn influence theirs, and so on; and just how many others pay attention to each of these people has little to do with the initial influential. If people in the network just two degrees removed from the initial influential prove resistant, for example, the cascade of change won't propagate very far or affect many people. Building on the basic truth about interpersonal influence, the researchers studied the dynamics of populations, manipulating a number of variables relating to people's ability to influence others and their tendency to be influenced.