Here's why:

* Mitochondria are the powerhouses of the cell, primarily responsible for aerobic respiration (which requires oxygen).

* Anaerobic respiration occurs in the absence of oxygen.

* The first stage of both aerobic and anaerobic respiration, glycolysis, takes place in the cytoplasm.

* In anaerobic respiration, after glycolysis, the pyruvate produced is further broken down in the cytoplasm through various pathways like fermentation (lactic acid fermentation or alcoholic fermentation).

Let me know if you have any more questions!