1) DRAM is the memory used by the Macintosh to temporarily hold the
information or data that the user is working on until it is saved to a
hard disk, floppy disk, or another storage medium.
2) Once power is no longer supplied to RAM, the contents is lost. If a
user is working on a Macintosh and turns the system off without saving
the work, what was in DRAM during the work session will be lost. The
data lost is the data that the user was working on before the power was
removed.
3) Yes, DRAM is volatile. That's the nature of DRAM (Dynamic Random Access
Memory); it needs to be constantly powered with electricity to remember
its contents. The same applies to SRAM (Static Random Access Memory);
however, SRAM does not need to be refreshed the way DRAM does, and this
provides data retention for extended periods, which is why this
type of RAM is used in Macintosh Portable computers.