AP BIOLOGY

Detailed explanation-1: -S phase is the period during which DNA replication occurs.

Detailed explanation-2: -Interphase is composed of G1 phase (cell growth), followed by S phase (DNA synthesis), followed by G2 phase (cell growth). At the end of interphase comes the mitotic phase, which is made up of mitosis and cytokinesis and leads to the formation of two daughter cells.

Detailed explanation-3: -The interphase of a normal cell cycle will thus, consist of the G1 (Gap 1) phase, S (Synthesis) phase, and G2 (Gap 2) phase. The S phase is the phase in which replication of DNA will take place which is then followed by histones synthesis. This is the phase taking place between the G1 phase and G2 phase.

Detailed explanation-4: -Initially in G1 phase, the cell grows physically and increases the volume of both protein and organelles. In S phase, the cell copies its DNA to produce two sister chromatids and replicates its nucleosomes. Finally, G2 phase involves further cell growth and organisation of cellular contents.