Are resonances the reason receptors work?
Photoreceptors themselves dont act as oscilators, a single receptor is either 'on' or 'off' - it does not respond differently to different wavelenghts. Humans have Trichromatic vision, which means that we have 3 different kinds of photo-receptors that respond differently to light of a given wavelength at a given intensity. By combining multiple signals from these 3 different receptor types the brain can translate this to different colors (its actually kind of similar to how RGB color works).

Therefore I would say that even photo-receptors don't work like oscilators, only their specific ligands switch between the 11-cis &amp; trans state, but this is more of a statistical and physico-chemical process (which does involve resonance between the energy of the photons and the electrons in the cis bond)