Here's a breakdown:

* Anaerobic respiration is a metabolic process that occurs in the absence of oxygen.

* Glycolysis, the first step of both aerobic and anaerobic respiration, is where glucose is broken down into pyruvate. This step generates 2 ATP molecules, not consumes them.

The 2 ATP molecules used in glycolysis are actually consumed to activate glucose and phosphorylate it to initiate the breakdown process. This initial investment of ATP is quickly recouped, and the net gain from glycolysis is 2 ATP molecules per glucose molecule.

So, instead of starting the process, the 2 ATP molecules used in glycolysis are used to initiate the breakdown of glucose.

While anaerobic respiration doesn't require ATP to start, it does require the initial investment of 2 ATP molecules in glycolysis for it to proceed.