Which phase follows the G1 phase in Interphase?

In the cell cycle, the G1 phase, or the first gap phase, is a period of growth and preparation for DNA replication. Following the G1 phase, the cell enters the synthesis phase (often abbreviated as S phase). During this crucial stage, DNA is replicated so that each chromosome is duplicated, which ensures genetic material is accurately passed on to daughter cells during cell division.

The synthesis phase is pivotal because it sets the stage for the subsequent phases of the cell cycle, specifically the G2 phase and mitosis. Without the successful completion of the synthesis phase, the cell would not have two complete sets of chromosomes to distribute during cell division, which could lead to issues such as chromosomal abnormalities in the resulting cells.

Other choices do not fit sequentially in the interphase. For instance, G2 is the phase after synthesis, while mitosis is the complete cell division that follows interphase. Cell differentiation, although an important process, occurs after a cell has completed the cell cycle and is not part of interphase. Thus, the synthesis phase is appropriately identified as the key phase that follows G1 in the cycle.