[frgoff]

We also now know of life forms that do not use the krebs cycle as their basis of energy intake. Chemosynthesis has been found in animals near hydrothermal vents which use sulfur as their primary energy source.

And you'll find the organic molecules they use are just as complicated, involved, and delicate as those in the Krebs Cycle, so the initial point still stands.

[Clorinox]

"And you'll find the organic molecules they use are just as complicated, involved, and delicate as those in the Krebs Cycle, so the initial point still stands."

This point cannot be proven just because you say it is so. It definitely would take a chemist who has knowledge in this subject well beyond my own to prove this one way or another.