<em>in the process of glycolysis ,, the products are
<u>1 net gain of 2 ATPs..
</u><u>2 2 pyruvic acid
</u><u>3 2NADH2...:)</u>
</em>
Oxygen is the final electron acceptor in the electron transport chain, which allows for oxidative phosphorylation. Without oxygen, the electrons will be backed up, eventually causing the electron transport chain to halt.
By means of natural selection.
I think natural could be the word