The basic unit of composing nucleic acid is ( )
A. ribose and deoxyribose
B. phosphate and ribose
C. base
D. mononucleotide
E. Polynucleotide
查看答案
in certain DNA molecule, the content of adenine is 30%,then, the content of guanine is ( )
A. 15%
B. 20%
C. 30%
D. 60%
E. 80%
Which of the following is true about the composition of DNA bases ()
A. DNA is mainly composed of four bases: A, G, C and U
B. In DNA, (A+T)/(C+G) = (A+C)/(G+T).
C. In DNA, (A+G)/(T+C) =1
D. The base composition of DNA is species-specific and organ-specific
E. none of the above
The secondary structure of DNA is ( )
A. α-helix
B. Β-pleated sheet
C. Β-turn
D. supercoil
E. double helix
the analogue of sulfonamides is ( )
A. FH4
B. FH2
C. para-amino –benzoic acid
D. folic acid
E. pyrimidine
微信支付 
支付宝支付