Can nucleic acid, protein and starch be considered as step growth polymers?

Yes, nucleic acids, proteins and starch can be considered as step growth polymers. Step growth polymers are actually condensation polymers in which large number of polynucleotides, ($\alpha$-amino acids and $\alpha$-D-glucose units combine together with the loss of $H _{ 2 }O$ molecules leading to the formation of high molecular mass nucleic acids, proteins and starch.