First carbon of pentose sugar of nucleic acid joins: (A) N-9 of pyrimidine, (B) N-1of pyrimidine, (C) N-1 of purine, (D) None of the above
Answer is B. Pentose sugar present in DNAs is deoxyribose and in RNAs it is ribose. A pentose sugar (ribose or deoxyribose) is linked to a nitrogenous base (purine or pyrimidine) covalent N-glycosidic bond to form nucleoside. This linkage joins the Carbon-I of pentose sugar with nitrogen-9 of the purine base or nitrogen-I of pyrimidine base.