(a) Scientific name of the source organism of thermostable DNA polymerase used in PCR:
The thermostable DNA polymerase used in PCR is Taq polymerase, which is derived from the bacterium Thermus aquaticus.
Thermus aquaticus is a thermophilic bacterium that is typically found in hot springs. Its ability to withstand high temperatures makes it well-suited for the high-temperature conditions required during the PCR process.