DNA Replication: Cell Cycle Phase

Correct Answer: Interphase

DNA replication occurs during the S-phase of Interphase (the phase between two successive mitotic divisions). Interphase is the non-dividing phase of the cell cycle.

Interphase Sub-stages

• G1 phase: Cell growth; protein synthesis
• S phase (Synthesis): DNA replication ✔ — each chromosome is duplicated
• G2 phase: Further growth; preparation for division

Distinction Between Q19 and Q90

• Q19 asked 'which phase of cell division' → answer = S-phase (specific sub-stage)
• Q90 asks 'which phase of cell cycle' → answer = Interphase (the broader phase containing S-phase) ✔

Both S-phase and Interphase are correct depending on how the question is framed — the notes give both answers in their respective questions.