How do the products of glycolysis and krebs cycle relate to the electron transport chain?

During the process of glycolysis and krebs cycle (which is also known as tricarboxylic acid (TCA) cycle or citric acid cycle), there is breakdown of large molecules to product smaller molecules and energy including ATP.

So the answer to this would be:

Glycolysis and Krebs cycle produce the molecules that shuttle electrons to the electron transport chain