means two complete sets of chromosomes (2n), and mitosis maintains this ploidy across daughter cells.​

Cell Cycle Overview

The mitotic cell cycle consists of interphase (G1, S, G2) and M phase (mitosis + cytokinesis). In G1, the cell has 2n chromosomes and 2C DNA content (C = haploid DNA amount). S phase doubles DNA to 4C via replication, while chromosome number stays 2n. G2 retains 2n chromosomes and 4C DNA. M phase divides replicated chromosomes equally, restoring G1-like state in daughters.​

Option Analysis

• (a) G2 & S: Incorrect. G2 ends with replicated DNA (4C, still 2n chromosomes), but S phase ends mid-replication or at its close with 4C DNA, not emphasizing diploid restoration uniquely.​

• (b) G1 & M: Correct. G1 ends pre-replication (2n, 2C diploid). M phase (post-cytokinesis) yields two diploid daughters (each 2n, 2C), matching G1 ploidy and content.​

• (c) M & S: Incorrect. While M ends diploid, S ends with doubled DNA (4C), not purely diploid in content sense.​

• (d) G1 & G2: Incorrect. Both are diploid (2n chromosomes), but G2 has 4C DNA post-replication, unlike G1’s 2C.​

In the human mitotic cell cycle, understanding when the genome is diploid at phase ends is key for biology students tackling exams on cell division. The diploid genome (2n chromosomes) persists at the end of G1 and M phases, as DNA content resets to 2C post-mitosis.​

Diploid Genome Basics

A diploid cell starts with 46 chromosomes (23 pairs) and 2C DNA. Mitosis ensures daughter cells inherit identical diploid sets, vital for growth and repair. Unlike meiosis, no ploidy reduction occurs.​

Phase-by-Phase DNA Status

This table clarifies why only G1 & M fully align with pre- and post-division diploid states.