The short answer is no.
Entity Bean class attributes can only be persisted to a database if you provide the mapping information to the EJB container. You do this via the deployment descriptor for container managed persistence.
In regard to passivation, it relates to object serialization, but the mechanism is not specified in the EJB spec. In short, if you don't want certain attribute values retained during passivation, mark them with the 'transient' keyword.
[This message has been edited by Jim Thomas (edited September 21, 2000).]