Q. 17 - Biology

Question

What is the main prerequisite for clearance at the G₂ checkpoint?

a.    cell has reached a sufficient size

b.    an adequate stockpile of nucleotides

c.    accurate and complete DNA replication

d.    proper attachment of mitotic spindle fibres to kinetochores

Step-by-Step Solution

Answer

The main prerequisite for clearance at the G₂ checkpoint is accurate and complete DNA replication. The correct option is (c).

Step 1. Introduction

If specific criteria are not satisfied, the G2 checkpoint prevents entrance into mitosis.

Step 2. Explanation for Correct Answer

To guarantee that all chromosomes have been duplicated and the replicated DNA is undamaged, the G2 checkpoint is the most critical. Cell cycle halts when checkpoint systems identify issues with the DNA. The cell then seeks to either complete or replace or repair damaged DNA.

Thus, the correct option is - (c).

Step 3. Explanation for Incorrect Answers

The cell has reached a sufficient size which is monitored by the G₁ phase, not G₂. So, this is not the main prerequisite for clearance at the G₂ checkpoint.

Thus, option (a) is incorrect.

An adequate stockpile of nucleotides is not checked by G₂. So, this is not the main prerequisite for clearance at the G₂ 

checkpoint.

Thus, option (b) is incorrect.

Proper attachment of mitotic spindle fibres to kinetochores is not checked by G₂, instead, it is checked by the M phase. So, this is not the main prerequisite for clearance at the G₂ 

checkpoint.

Thus, option (d) is incorrect.