Chromosomes are duplicated (DNA is replicated) during which stage of the cell cycle?

• A. M phase (mitosis)
• B. G2 phase of interphase
• C. S phase of interphase
• D. G1 phase of interphase

Answer: (C)

Verified step by step guidance

1. Understand the phases of the cell cycle: G1 phase (cell growth), S phase (DNA synthesis), G2 phase (preparation for mitosis), and M phase (mitosis).
2. Recall that DNA replication, or chromosome duplication, must occur before mitosis to ensure each daughter cell receives a complete set of chromosomes.
3. Identify that the S phase (Synthesis phase) of interphase is specifically dedicated to DNA replication.
4. Recognize that during G1 phase, the cell grows and performs normal functions, but does not replicate DNA.
5. Note that G2 phase involves preparation for mitosis, and M phase is when the cell actually divides, so DNA replication does not occur in these phases.