Answer:
In the conversion of pyruvate to acetyl CoA, each pyruvate molecule loses one carbon atom with the release of carbon dioxide. During the breakdown of pyruvate, electrons are transferred to NAD+ to produce NADH, which will be used by the cell to produce ATP.
Answer:
1/ Climate change
2/ Asteroid impacts
3/ Massive volcanic eruptions
4/ Sun explodes
etc. (all the things above are most likely to happen but alien invasion or things like that is also a theory that you can add depends mostly if you like it or not)
Answer:
You would find microscopic bacteria
It would have to be immersed in the CELL