The prokaryotic organism that has been the subject of many genetic studies is（）
A. Saccharomyces cerevisiae
B. Neurospora crassa
C. E. coli
Drosophila melanogaster
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In his transformation experiments, Frederick
Griffith observed that virulent strains of Streptococcus pneumoniaeproduced ___ colonies（）In his transformation experiments, Frederick
Griffith observed that virulent strains of Streptococcus pneumoniaeproduced ___ colonies（）
A. smooth
B. shiny
C. B．rough
D. dry
E. C．exceptionally
F. large
G. D．unusually
H. colored
A DNA nucleotide may consist of（）
A. a
B. ribose sugar, a phosphate group, and adenine
C. B．a phosphate group, deoxyribose, and cytosine
D. C．uracil
E. deoxyribose, and a phosphate group
F. D．deoxyribose
G. thymine, and a hydroxyl group
A nucleoside consists of a（）
A. pentose
B. sugar and a nitrogenous base
C. B．phosphate
D. group and a nitrogenous base
E. C．pentose
F. sugar and a phosphate group
G. D．pentose
H. sugar, a phosphate group, and a nitrogenous base
The following preparations should be made before meeting visitors（）
A. necessary items
B. image preparation
C. knowledge preparation
D. itinerary preparation
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