Question

In what phase do our cells make a copy of our chromosomes before mitosis starts?

A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase

Answer 1

B) S Phase

Cells make a copy of their chromosomes during the S Phase, which is the phase before mitosis wherein DNA replication occurs to ensure each daughter cell receives an identical set of chromosomes.

Step-by-step explanation:

In what phase do our cells make a copy of our chromosomes before mitosis starts? The correct answer is B) S Phase.

During the S Phase (Synthesis of DNA) of interphase, the DNA replication occurs, which results in the formation of identical pairs of DNA molecules, known as sister chromatids. These sister chromatids, which are duplicates of each chromosome created during the S Phase, are essential because they ensure that each daughter cell will have an identical set of chromosomes after mitosis. It is imperative that the replication of DNA is completed during the S Phase so that the cell can later enter mitosis with the correct number of chromosomes.