During which phase of the cell cycle the cellular content of DNA is doubled -: (A) Mitotic phase, (B) G1 phase, (C) G2 phase, (D) S phase
Answer is D. There are two resting phases and two active phases in the cycle.
Resting phases → G1 & G2
Active phases


S-phase (synthetic phase) - As the name suggests, synthesis of new DNA takes place, i.e. doubling of DNA occurs.
M-phase (mitotic phase) - Mitosis takes place and the daughter cells receive one copy of DNA. In this phase, cell number is doubled.