  A behavior of the nucleon structure functions in the resonance region is
investigated. Expressions for resonance production form factors, dependent on
photon virtuality $Q^2$, which have correct threshold behavior and take into
account available data on resonance decays, are obtained. Contributions of
resonances to nucleon structure functions are calculated. Obtained expressions
are used to investigate the quark-hadron duality in the electron-nucleon
scattering processes with the structure function $F_2$ as an example.
