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WBCS Preliminary Examination 2023 — General Studies · Question 174 of 200

Q174
General ScienceBiology
In which substage of interphase is DNA doubled?
  1. a.$G_1$
  2. b.S
  3. c.$G_2$
  4. d.$G_0$

Answer: (B) S

Interphase has three sub-stages. In $G_1$ the cell grows and makes RNA and proteins; in the S (synthesis) phase DNA replicates, so the amount of DNA doubles (2C to 4C) while the chromosome number stays the same; in $G_2$ the cell prepares for division. $G_0$ is the resting or quiescent stage of cells that have stopped dividing, such as nerve cells, and is not a DNA-synthesis stage. Interphase takes up over 95% of the cell cycle and is followed by the M phase (mitosis and cytokinesis).

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