In which phase of cell cycle does replication of DNA take place?

The correct answer is Option (3) → S phase

The cell cycle has an interphase (G₁, S and G₂) and an M phase.

Option (1) G₁ phase — Incorrect. In G₁ the cell grows and prepares for DNA replication. The DNA is not yet copied.

Option (2) M phase — Incorrect. M phase is the phase of cell division (mitosis). The DNA copied earlier is shared out between the two daughter cells.

Option (3) S phase — Correct. S stands for synthesis. In this phase the DNA is replicated, so the amount of DNA in the cell doubles.

Option (4) G₂ phase — Incorrect. G₂ comes after DNA replication. The cell makes proteins and gets ready for mitosis.

Note: A similar question was also asked in CUET (UG) 2025 on 15-05-2025 (Slot 1).

NCERT Extract:
The Machinery and the Enzymes – “… The vectors provide the origin of replication. Further, not every detail of replication is understood well. In eukaryotes, the replication of DNA takes place at S-phase of the cell-cycle. The replication of DNA and cell division cycle should be highly coordinated. A failure in cell division after DNA replication results into polyploidy(a chromosomal anomaly).”