why we breathe oxygen and not something like carbon dioxide or nitrogen?

Question

why we breathe oxygen and not something like carbon dioxide or nitrogen?

In: 40

Answer 1

Because we don’t have photosynthesis.

We break Carbohydrate chains and it makes Energy.

Creating new chains requires energy.

We can’t use more energy then we are making because if you run out of energy you are dead.

If we wanted to breath in CO2 we would need to use a lot of energy to turn it into C6-H12-O6 (glucose) because it has a lot of bonds and we would require an additional energy source.