  General relations between the form factors of B decays to light mesons are
derived using the heavy quark and large recoil expansion. On their basis the
complete account of contributions of second order in the ratio of the light
meson mass to the large recoil energy is performed. Both ground and excited
final meson states are considered. It is shown that most of the known form
factor relations remain valid after the inclusion of quadratic mass
corrections. The validity of some of such relations requires additional
equalities for the helicity amplitudes. It is found that all these relations
and equalities are fulfilled in the relativistic quark model based on the
quasipotential approach in quantum field theory. The contribution of 1/m_b
corrections to the branching fraction of the rare radiative B decay is
discussed.
