The DNA polymerase used in the polymerase chain reaction (PCR) was initially isolated from the bacterium Thermophilus aquaticus that lives in hot springs like Old Faithful in Yellowstone Park. Now called Taq polymerase, this enzyme can be produced synthetically and ordered from a catalog. What best explains why Taq polymerase must be used in PCR rather than human DNA polymerase?

Choose one:
A. Human DNA polymerase would need to be extracted from humans, which would be unethical.
B. Taq polymerase adds DNA bases more quickly than human DNA polymerase.
C. Taq polymerase is much easier to synthesize than human DNA polymerase.
D. Taq polymerase can withstand the high temperature needed to separate the DNA strands.

Polymerase chain reaction or PCR is the technique which creates the copy or replicates the DNA from a sample. The PCR technique is based on the DNA replication mechanism which employs the DNA polymerase enzymes and primers.

Since PCR is a technique therefore, to break the hydrogen bonds of the DNA, the sample is heated at a temperature above 94° C in which the natural DNA Polymerase will not withstand. So, an equivalent enzyme called Taq polymerase enzyme is used.

Since the Taq polymerase enzyme is extracted from a Thermophilic bacteria known as Thermus aquaticus therefore, the temperature can withstand the high temperature which is provided during the PCR.

Thus, option-D is the correct answer.