Question

G₀ state of cell denotes
(a) Death of cell
(b) Permanent pause
(c) Exit of the cell from cell cycle
(d) Checkpoint before entering the next phase

Answer 1

Hint: The phase G₀ in the cell cycle is also called the resting phase. In the phase G₁, cells reach the phase G₀ from a cell cycle checkpoint. Cells then stay in phase G₀ until they have a reason to split.

Complete answer:
The cell cycle consists basically of four phases G₁, S, G₂, and M. G₀ phase also known as the extended G₁ phase which is a period during which the cell exits from the cell cycle. The cell exists in a quiescent state at this stage and does not divide. If cells are not to be separated after the G₁ process and begin to undergo differentiation into various cell types such cells are said to be in G₀ state.
G₀ is often referred to as a "post-mitotic" condition because cells in G₀ are outside of the cell cycle in a non-dividing period. Cells in the G₀ state remain metabolically active but no longer proliferate unless they are called upon to do so depending on the organism's requirement.
So, the correct answer is ‘Exit of the cell from cell cycle’.

Note: While several cells that die along with the organism in the G₀ phase, not all cells entering the G₀ phase are doomed to die; this is mostly simply a consequence of the cell's lack of any ability to re-enter the cell cycle. Some cells temporarily join G₀ before an external signal activates G₁ initialization. Other cells, such as mature cardiac muscle and nerve cells, which never or rarely divide, remain permanently in G₀.