A. 由两条脱氧核苷酸链组成 B. 左手螺旋 C. 脱氧单核苷酸之间靠磷酸二酯键连接 D. 5'端是磷酸,3'端是OH E. 碱基配对为A=T,G≡C
A. RNA中的戊糖成分不是脱氧核糖,而是核糖 B. RNA和DNA都是以3',5'-磷酸二酯键相连 C. RNA的结构以单链为主,而非双螺旋结构 D. RNA中的嘧啶成分为胞嘧啶和尿嘧啶,而不是胸腺嘧啶 E. DNA的二级结构是超螺旋结构
A. Km值增大 B. Vmax值不变 C. Km值降低 D. Vmax值增加 E. Vmax值减小
A. 叶酸 B. 维生素A C. 维生素C D. 维生素B12 E. 维生素PP
A. 丝氨酸 B. 羟赖氨酸 C. 半胱氨酸 D. 脯氨酸 E. 羟脯氨酸
A. make use of the scientific method. B. try to address their subject with a scientist’s objectivity. C. devise theories, collect data, and then analyze these data in an attempt to verify or refute their theories. D. All of the above are correct.
A. It is often difficult to formulate theories in economics. B. It is often difficult and sometimes impossible to perform experiments in economics. C. Economics cannot be addressed objectively; it must be addressed subjectively. D. The scientific method cannot be applied to the study of economics.
A. provide issues for political discussion. B. make a complex world easier to understand. C. make it easier to teach economic concepts and analysis. D. create policy alternatives that are incomplete or subject to criticism.
A. neither allows economic analysis to occur. B. neither can be represented visually on a graph. C. both make use of assumptions. D. both make use of complex equations to arrive at solutions.
A. assumptions. B. theories. C. details. D. equations.