Cell cycle is divided into two phases: interphase (G1, S and G2 phases) and M phase. M phase is the phase of actual cell division while interphase is the preparatory phase. The S phase of interphase is marked by DNA replication. Error free completion of DNA replication designates the cell to enter the M phase. Any error in DNA replication during S phase is detected by check point and the cell is prevented from M phase.
Answer: The earth's atmosphere support life on earth by protecting us from the UV rays and slows down asteroids before they hit the earth. And protects us from much more stuff.
