Heterotrophs are organisms that are not able to produce food on their own.
On the basis of the source of their energy, heterotrophs can be chemoheterotrophs (energy from a chemical source) or photoheterotrophs (energy from a light source).
Humans extract nutrients from chemical substances.
They break down the complex substances into simpler substances by digestion and respiration.
Energy is synthesized after the oxidation of the food consumed.