Final answer:
The precursor molecule used in nucleic acid synthesis is a nucleotide, which consists of a phosphate group, a pentose sugar, and a nitrogenous base.
Step-by-step explanation:
The precursor molecule used in nucleic acid synthesis is a nucleotide. Nucleotides are the repeating units that are linked together to form nucleic acids. They consist of three components: a phosphate group, a pentose sugar, and a nitrogenous base.