Which phase of the cell cycle is the longest?

Interphase is the longest phase of the cell cycle and is crucial for the preparation of a cell to divide. During interphase, the cell undergoes various processes that ensure it is fully equipped for mitosis or meiosis. This phase consists of three subphases: G1 (cell growth), S (synthesis, where DNA is replicated), and G2 (final preparation for division). Each of these stages allows the cell to grow, replicate its genetic material, and produce proteins necessary for cell division.

While meiosis is a type of cell division that can take considerable time, especially in organisms with prolonged meiotic stages, it is part of a cycle that incorporates interphase. Gastrulation and differentiation are developmental processes that occur after cells have divided and are not phases of the cell cycle per se. Thus, interphase remains the longest phase within the context of the overall cell cycle due to its multiple preparatory functions before the actual division occurs.