Final answer:
The checkpoint verifying that conditions are suitable for cell division is the G1 checkpoint, which checks for sufficient reserves, cell size, and DNA integrity before allowing the cell to enter the S phase.
Step-by-step explanation:
The checkpoint that ensures the environment is favorable for cell division is the G1 checkpoint. This checkpoint, also referred to as the restriction point, is crucial for assessing whether the cell is ready to proceed with division. Key factors such as adequate reserves, appropriate cell size, and absence of genomic DNA damage are evaluated.
If a cell does not meet all the necessary requirements, it will not be allowed to progress into the S phase of the cell cycle. Essentially, the G1 checkpoint plays a pivotal role in preventing the replication of damaged or unprepared cells, thereby maintaining genomic integrity.