Ans: Cells are so small because it allows them to have a better surface area to volume ratio. This makes it much easier for the cell to bring in necessary nutreints and excrete wastes. Also the smaller the cell is, the less time it takes to replicate the small cell as opposed to a bigger cell.
The correct answer would be:
<em>Cycles.</em>
The answer is aerobic. Although cellular respiration can happen anaerobically and aerobically, the question states that it requires oxygen. Therefore, it is aerobic.
