The electronic states of a 'quantum dot-graphene monolayer-SiO + n-Si substrate' system in an external magnetic field are studied. An analytical expression for charge transfer in this system is obtained. The electronic states of a 'quantum dot-graphene bilayer-SiO + n-Si substrate' system are considered. The systems under study are interesting from the viewpoint of controlling the optical properties of a quantum dot by means of an applied electric field.