Florida Biology EOC Practice Test

During which phase of interphase is DNA copied?

1. G1 phase

2. G2 phase

3. Metaphase

4. S phase

The correct answer is: G1 phase

The correct phase during which DNA is copied is the S phase. During this phase of interphase, the cell duplicates its genetic material in preparation for cell division. The S phase stands for "synthesis," indicating that this is when DNA synthesis occurs. Each chromosome is replicated to produce two sister chromatids, which are essential for the proper segregation of genetic material during mitosis or meiosis. In contrast, the G1 phase is primarily focused on cell growth and the synthesis of RNA and proteins necessary for DNA replication. The G2 phase, following the S phase, is dedicated to further growth and the preparation for mitosis, primarily checking for any errors in the DNA that was copied during the S phase. Metaphase, on the other hand, is a stage of mitosis where chromosomes line up along the cell's equator, having already been replicated during the S phase. Thus, the S phase is distinctly designated for DNA copying within the interphase of the cell cycle.