Which statement about the cell cycle is false?

The statement that the time from start to finish of the cell cycle is the same in all eukaryotic cells is false because the duration of the cell cycle can vary significantly depending on the type of eukaryotic cell and the conditions in which it resides. For instance, certain rapidly dividing cells, like those found in embryos, may have much shorter cell cycles compared to differentiated cells, such as nerve or muscle cells, which may take longer to complete their cycles or might even exit the cell cycle altogether. This variability underscores the adaptability of cells to their specific environments and developmental stages.

In contrast, the other statements reflect well-established biological concepts. An unfavorable environment can indeed lead cells to arrest in the G1 phase, as they assess conditions before committing to DNA synthesis and division. Additionally, during the G2 phase, a cell has twice the amount of DNA compared to G1, as it has completed DNA replication. Furthermore, early embryonic cleavage divisions typically proceed without the G1 and G2 phases, leading to rapid cell division without the growth and synthesis stages characteristic of older or differentiated cells.