Questions & Answers

Restorage of the nucleocytoplasmic ratio is performed in
A. ${G_1}$ phase
B. $S$ phase
C. ${G_2}$ phase
D. $M$ phase

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Hint: The $M$Phase or Mitosis phase. It starts with the division of nucleus known as karyokinesis (separation of daughter chromosomes). Interphase is divided into 3 phases: ${G_1}$ phase i.e. Gap 1 phase, $S$ phase i.e. synthesis phase and ${G_2}$ phase i.e. Gap 2 phase. This phase is also referred to as the resting phase.

Complete answer:
A period between the outset of DNA replication or starts of DNA replication is known as the ${G_1}$ phase. During this phase, the cell is metabolically effective and grows continuously but does not replicate its DNA. This phase occurs for about 8-12 hours. The nucleocytoplasmic ratio is the ratio between the volume of the nucleus to the volume of the cytoplasm. Hence the nucleocytoplasmic ratio is high in the big cell or the cell that undergoes growth only in the ${G_1}$phase.
A phase in which the synthesis of DNA or replication occurs is known as the $S$ phase. During this period, the quantity of DNA per cell duplicates. A phase in which the synthesis of proteins occurs in preparation for the process of mitosis while the development of the cell continues is known as ${G_2}$ phase.
A phase in which substantial nuclear and cell division occurs is known as the $M$ phase. During this phase, duplicated chromosomes are divided equally among the 2 progeny cells.

Hence, the correct answer is option (A).

Note: Inside the cells of an animal, during the $S$ phase or synthesis phase, replication of DNA proceeds in the nucleus and the duplication of centriole occurs in the cytoplasm. It occurs for about 6-8 hours. In the $S$and ${G_2}$phases, the new DNA molecules which are produced are not unique but intertwined.