Question

Which one is the longest phase of cell cycle?

• A. Prophase
• B. Telophase
• C. $G_{1-}$ Phase
• D. $G_{2-}$ Phase

Answer 1

The correct option is A

Explanation of the correct option:

1. The G1 phase is the longest in the cell cycle. It’s the beginning of the interphase.
2. The cell prepares for division during the G1 phase. During the G1 phase, cells are extremely metabolically active.
3. During this phase, the associated proteins in DNA replication, as well as the energy required for DNA replication, are synthesized.
4. The interphase’s G1 phase is followed by the S phase.
5. Hence, Interphase is the longest phase of cell division.
6. In a 24-hour cell cycle, 23 hours are for the Interphase -phase and 1 hour for the Mitosis phase.

Explanation of the incorrect option:

Option B

$G_2$ Phase the period in the cell cycle from the completion of DNA replication to the beginning of cell division.

Option C

Prophase is the first step of cell division in mitosis. As it occurs after G2 of interphase, DNA has been already replicated when prophase begins.

Option D

Telophase is the fifth and final phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.

Final answer: G1 phase is the longest phase of cell cycle.