<prompt> 1 carbon of pentose sugar of nucleic acid joins -N-9 of pyrimidineN-1 of pyrimidineN-1 of purineNone of the above  <response>: Ans. is b i.e., N-1 of pyrimidinePenose sugars 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-1 ofpentose sugar with nitrogen-9 of the purine base or nitrogen-I of pyrimidine base.Nucleoside is linked to phosphoric acid to form nucleotide.For example, purine base adenine combines with ribose sugar to form adenosine, a nucleoside ribonucleoside. o This, adenosine nucleoside combines with phosphate group to form adenosine monophosphate : AMP, a nucleotide ribonucleotide.If the pentose sugar is deoxyribose instead of ribose the resulting nucleotide is deoxyribonucleotide.Adenine Ribose Adenosine ribonucleoside 4 AMP ribonucleotidePhosphate groupAdenine Deoxyribose Deoxyadenosine Deoxynucleoside 4 dAMP deoxyribonucleotide Phosphate group 