表现型不同的母牛生育出基因型完全相同的牛，产生这一结果的最可能的原因是（      ）

A．试管动物培养              B．胚胎移植

C．胚胎分割移植              D．用同一公牛配种

单克隆抗体与血清抗体相比，优越之处在于   (     )

A．单克隆抗体能够制成“生物导弹”

B．单克隆抗体可以在体外制备

C．单克隆抗体的特异性强、灵敏度高，产量也大大高于血清抗体

D．单克隆抗体的制备过程简单

遇海难而漂浮在海面的人，因缺乏淡水，此人                      （  ）

A．血浆渗透压升高，抗利尿激素增加   B．血浆渗透压升高，抗利尿激素减少

C．血浆渗透压降低，抗利尿激素增加   D．血浆渗透压降低，抗利尿激素减少                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   &n

在闷热的房间里开会，有的人容易打“哈欠”，其调节方式是          （  ）

A．神经调节     B．体液调节     C．神经—体液调节       D．激素调节

生态系统的营养结构是                                        (   )

A．食物链和食物网    B．群落的垂直结构和水平结构

C．群落和无机环境    D．物质循环和能量流动

细胞核具有什么功能？科学家通过下列实验(见下图)进行探究：①用头发将蝾螈的受精卵横缢为有核和无核的两半，中间只是很少的细胞质相连，结果无核的一半(a)停止分裂，有核的一半(b)能继续分裂；②b部分分裂到16～32个细胞时，将一个细胞核挤入到不能分裂的a部分，结果a部分开始分裂、分化，进而发育成胚胎。下列叙述中，不正确的是

A．实验结果可以说明细胞核与细胞的分裂、分化有关

B．实验①中，b部分细胞属于对照组，a部分属于实验组

C．实验②中，a部分的操作与实验①中形成对照

D．实验说明细胞的寿命与细胞核有关

下列关于蛋白质和氨基酸的叙述，正确的是

A.具有生物催化作用的酶都是由氨基酸组成的

B.高等动物能合成生命活动所需的20种氨基酸

C.细胞中氨基酸种类和数量相同的蛋白质是同一种蛋白质

D.在胚胎发育过程中，基因选择性表达，细胞会产生新的蛋白质

下列对实验的相关叙述，正确的是（    ）

A．鉴定蛋白质时，应将双缩脲试剂A液和B液混合以后再加入待检组织样液中

B．纸层析法分离叶绿体色素的实验结果表明，叶绿b在层析液中溶解度最低

C．可用紫色洋葱在普通显微镜下观察质壁分离、的分布

D．健康人的胃液、唾液和甲状腺激素3种液体样本都可以和双缩脲试剂发生紫色反应

水在生物体内是一种良好的溶剂，是各种化学反应的介质．下列有关水的说法不正确的是（   ）

A．水是生物体内进行一切生物化学反应的必需条件

B．当人体缺水时，血浆的渗透压会降低，从而产生渴觉

C．在核糖体上进行的生理过程有水生成

D．休眠或越冬的植物体内自由水与结合水的比值下降

动物细胞工程技术的基础是                                               （    ）

A．动物细胞融合                             B．动物细胞核移植

C．动物细胞培养                             D．胚胎移植