1" carbon of pentose sugar of nucleic acid joins -

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 (ribonucleotide)Phosphate groupAdenine + Deoxyribose Deoxyadenosine (Deoxynucleoside) 4 dAMP (deoxyribonucleotide) Phosphate group