Final answer:
The absence of primase would most directly affect the synthesis of Okazaki fragments, which is essential for lagging-strand synthesis during DNA replication, as primers are needed to start the elongation of each fragment.
Step-by-step explanation:
If primase were not present during DNA replication, the most directly affected process would be the synthesis of Okazaki fragments or the lagging-strand synthesis. Primase is the enzyme responsible for synthesizing a short RNA primer, which DNA polymerase requires to initiate DNA synthesis. Without primase, DNA polymerase would not have the necessary starting point for nucleotide addition, and Okazaki fragment synthesis, which takes place discontinuously on the lagging strand, would be unable to proceed. Each Okazaki fragment must be initiated with a new primer, and so the inability to synthesize primers would prevent the extension of the lagging strand altogether. On the other hand, leading-strand elongation occurs continuously from a single primer and, although it would also be initially affected by the lack of primase, it is the synthesis of Okazaki fragments that would be most critically impaired.