We show that an extended vector dominance model which incorporates quark dynamics at large Q2 via perturbative QCD gives an excellent description of existing data on elastic electron-proton/neutron cross-sections. Results of a simultaneous fit of the nuclep,n on form factors GM, E to the cross-sections are given. Information is obtained about the QCD-scale parameter AQcD, as well as on the range of applicability of perturbative QCD calculations. Constraints on the hadronic wavefunctions are also obtained. PACS : 13.40.FnOne of the fundamental aims in physics is the understanding of the structure of the nucleon. Electromagnetic interaction gives us a unique tool for its investigation. Concerning the elastic electron-nucleon scattering the properties of the nucleon are hidden in the four structure functions GE,M( Qp'" 2).It is believed now that the theory of strong interaction is given by quantum chromodynamics (QCD) [1]. Perturbative QCD can be applied to exclusive processes at large momentum transfer [2,3]. One of the questions to be answered is down to which momentum transfer Q2 perturbation theory can be applied, and in which range of momentum transfer we can still obtain valuable information by comparison with experiment. The answer to that question is still controversial 1-4 I. * Work supported by the Department of Energy, contract DE-AC03-76SF00515 1 Permanent addressWe know that at low momentum transfer IQ2]

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