Question

What passes electrons in the etc

Answer 1

There are different electron carrier carriers in the mitochondria that helps in transferring electron in the Electron Transport Chain.

Explanation:

There are different reactions like Kreb's Cycle and others going in the mitochondrial matrix. These reactions synthesize different reduced proton  like NADH₂ and FADH₂. These reduced carriers then go to the inner mitochondrial membrane where there are different electron carriers - four in types namely complex 1,2, 3,and 4 respectively. NADH₂ goes to complex 1 and release the Hydrogen and gets back to NAD and FADH₂ goes to complex 2 and release Hydrogen and gets back to FAD.

The electron that is released to the complex 1 goes to complex 2 and then to Q complex. Then it goes to complex 3 and 4 respectively where the final electron is taken by the oxygen atom to produce oxide ion.