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【单选题】In the 1920s demand for American farm products fell, as European countries began to recover from World War I and instituted austerity (紧缩) programs to reduce their imports. The result was a sharp drop...
A.
might cause greater scarcity of farm products
B.
didn't give the Secretary of Agriculture enough power
C.
would benefit neither the government nor the farmers
D.
benefited one group of citizens at the expense of others
【单选题】当F+×F-杂交是下列说法对的是( )
A.
F因子几乎总不转移到F+细胞中
B.
F- 菌株几乎总成为F+
C.
基因重组的发生频率较高
D.
F因子经常插入到F-细胞染色体上
相关题目：
【单选题】当F+×F-杂交时：( )
A.
F因子几乎总不转移到F+细胞中
B.
F-菌株几乎总是成为F+
C.
基因重组的发生频率较高
D.
F因子经常插入到F-细胞染色体上
【单选题】对种子的生活力影响最大的环境因素是（）
A.
温度
B.
湿度
C.
氧气
D.
光照
【多选题】多亲杂交的类型包括（）
A.
两亲杂交
B.
回交
C.
合成杂交
D.
多父本授粉
【单选题】Northern杂交是检测（ ）的方法。
A.
DNA
B.
蛋白
C.
总RNA
D.
mRNA
【单选题】Southern杂交通常是指（）。
A.
DNA和RNA杂交
B.
DNA和DNA杂交
C.
RNA和RNA杂交
D.
蛋白质和蛋白质杂交
E.
DNA和蛋白质杂交
【单选题】Northern印迹杂交是（）
A.
检测DNA的方法
B.
检测RNA的方法
C.
检测蛋白的方法
D.
检测酶的方法
E.
既可检测DNA，又可检测RNA的方法
【多选题】远缘杂交的困难是()
A.
杂交不孕
B.
杂种不育
C.
疯狂分离
D.
都不是
【单选题】In the 1920s demand for American farm products fell, as European countries began to recover from World War I and instituted austerity (紧缩) programs to reduce their imports. The result was a sharp drop...
A.
might cause greater scarcity of farm products
B.
didn't give the Secretary of Agriculture enough power
C.
would benefit neither the government nor the farmers
D.
benefited one group of citizens at the expense of others
【单选题】当F+×F-杂交是下列说法对的是( )
A.
F因子几乎总不转移到F+细胞中
B.
F- 菌株几乎总成为F+
C.
基因重组的发生频率较高
D.
F因子经常插入到F-细胞染色体上