Final answer:
The primer used in the synthesis of a new DNA strand is a small DNA fragment that provides the starting point for DNA polymerase. It is complementary to the base sequence of the template DNA strands and is later replaced with DNA nucleotides.
Step-by-step explanation:
The primer used in the synthesis of a new DNA strand is a small DNA fragment of 10-20 bases long. It is complementary to the base sequence of the template DNA strands at the 3'-ends. The primer is synthesized chemically and provides the starting point for DNA polymerase to add new nucleotides. This primer is later removed and replaced with DNA nucleotides.