Final answer:
In a single-cellular organism, if a single organelle stops functioning, the cell will most likely die as each organelle is vital for survival and there's no redundancy or replacement source.
Step-by-step explanation:
In single-cellular organisms, each organelle performs specific and essential functions. If one organelle stops working, it can have a detrimental effect. For example, if the mitochondria, which produce energy, cease to function, the cell will lack the necessary energy to sustain its life processes. In multi-cellular organisms, there might be some redundancy, and other cells can sometimes compensate for the loss of function. However, in a single-cell organism, there is no backup; the entire burden of survival is on this lone cell.
Therefore, the failure of any single organelle often leads to the death of the entire organism, since there is no way to replace the organelle from another cell, and it is unlikely that the cell will grow a new one in time to save itself. In fact, cells rely on the coordination of all their organelles to stay alive, and the malfunction or failure of one can disrupt critical life-sustaining processes. While cells have mechanisms to degrade and recycle some of their organelles, the process of replacing a non-functioning organelle is complex and not guaranteed to prevent cellular death.