<span>Two checkpoints during the cell cycle that regulate cell division are right before S phase and M phase.
</span>Cell cycle checkpoints are control mechanisms <span>necessary for proper cell division. </span><span>In the cell cycle, there are two checkpoints: </span><span>the G1 checkpoint and the G2 checkpoint. <u>The G1 checkpoint is right before the S phase, and G2 checkpoint is right before the M phase.</u> If something is wrong at the G1 checkpoint, the cell will not enter the cell cycle. It is important to be delayed before cell enters S phase where DNA replication commences. The G2 checkpoint is a DNA damage checkpoint and if DNA is damaged, entering the cell cycle is delayed before mitosis (M phase).</span>
All living things need energy;it is requirement for life. In a a typical cell ATP, the hogh energy, is produced in the mitochondria in the presence of sugar(glucose and oxygen
The best answer to the question that is being given above would be letter A. The most complex level of organization hierarchy that climate change could potentially affect is Earth's Biosphere - which holds every living thing in the planet. This climate change will destroy it more destruction to Mother Nature occurs.
