Answer:
Complementary DNA strands are separated or "unzipped" for the replication process. Weak hydrogen bonds between complementary strands are easily disrupted during DNA replication because they are not high-energy chemical bonds.
Step-by-step explanation:
S phase can be described as the phase of cell division which occurs between the G1 phase and G2 phase. The S phase is known as the synthesis phase. In this phase, the DNA of a cell is duplicated to form two new strands. The S-phase is very crucial as duplication of DNA in a correct manner is important for cell division, hence this phase is regulated appropriately.
The two strands of DNA are linked together by hydrogen bonds. The hydrogen bonds form the ladder-type structure. Guanine connects with cytosine and adenine connects with thymine by the hydrogen bonds. As these bonds are not high energy bonds, it is easier for the enzymes to break these bonds.