Possible scenarios for synchronization of some biological processes with variations in Lunar-Solar gravitational tide acceleration, based on the trigger influence of the tidal force on geological environment and the relevant modulation of the emanation and activity fields of radon and other radioactive elements, are considered. Mechanisms and models of sensitivity of biological systems to the tidal variations of natural background radiation, including mitochondrial permeability transition, generation of reactive oxygen species and reactive nitrogen species, bystander factors, secondary biogenic radiation, modulation of cell signaling and rhythmic gene expression, are discussed.