G1 phase is primarily about cells _______________.

The G1 phase, or Gap 1 phase, is a crucial part of the cell cycle that occurs after cell division and before DNA replication begins in the S phase. During this phase, the cell is primarily focused on cell growth and preparation for the next steps in the cycle. One of the main activities during G1 is the duplication of the cell's organelles and the increase of its size, which ultimately prepares the cell to divide and results in an increase in the overall cell number.

This growth and preparation set the foundation for subsequent phases, and while the cell does engage in RNA synthesis and energy production throughout the cell cycle, these activities are more about supporting the growth process rather than being the primary focus of G1. Therefore, identifying the G1 phase as centered on doubling in number highlights the essential process of cell growth and readiness for division.