Because of the stress in society, the type of food people eat, obesity, and the lack of exercise, cardiologists are concerned about the increase in myocardial infarctions.Cardiologists study（）
A. the nerves
B. the heart
C. the lungs
D. the mind
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The characteristics of mRNA are（）
A. Uneven molecular size
B. Has 3′-polyadenylation tail
C. There is a coding area
D. Has 5’C-C-A structure
The high-level structure of eukaryotic DNA includes（）
A. Nucleosome
B. Circular DNA
Chromatin fiber
D. α-helix
What happens after double-stranded DNA is heat denatured（）
A. Decreased viscosity
B. Decreased settlement coefficient
C. Decreased buoyancy density
Decreased UV absorption
8 Which of the following related statements is correct（）
A. The 1st carbon atom of pentose is connected to the 9th nitrogen atom of purine to form a l,9-glycosidic bond
B. Dehydration between the free hydroxyl group of pentose sugar in nucleoside and phosphoric acid generates nucleotides through condensation of phosphoester bond
C. Both deoxyribonucleoside and ribonucleoside can form 2′-3′- or 5′-ribonucleotide
D. 5′-nucleotides are mostly free in organisms
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