Question

What are organisms that use chemical substances as a source of energy?

Answer 1

Is this not ALL organisms?

Explanation:

Autotrophs (green plants for instance) use solar energy to fix carbon dioxide to make simple sugars..

`6CO_2 +6H_2Ostackrel(Delta,"photosynthesis")rarrC_6H_12O_6 + 6O_2uarr`

Heterotrophs consume the sugar so produced...
in the process of respiration...

`C_6H_12O_6 + 6O_2rarr6CO_2 + 6H_2O + Delta`

Is respiration the reverse of carbon fixation?