Final answer:
PCR is a highly valuable tool in molecular biology as it enables the amplification of specific DNA sequences for various applications in research and diagnostics.
Step-by-step explanation:
PCR, or Polymerase Chain Reaction, is one of the most useful tools of molecular biology because it allows scientists to amplify a particular piece of DNA and generate millions of copies of it in a short amount of time. This is important for various applications in biology research and diagnostics. For example, PCR is used in genetic fingerprinting for forensic identification, paternity testing, and diagnosing hereditary diseases. It is also used in detecting pathogens in infections and mapping specific parts of the genome.