<unk> s are a class of polymers produced by living organisms.  
Starch, proteins and peptides, DNA, and RNA are all examples of<unk> s, in which the monomer units, respectively, are sugars, amino acids, and nucleic acids.
Biopolymer
Metal
Phytochemical
Heterocyclic compound
Polycyclic compound
Cyclic compound
Organic compound
Nucleoside