Autotrophic Nutrition

1. Food: It is self manufactured.

2. External Energy: An external source of energy is required for synthesis of food.

3. Inorganic Substances: They constitute the raw materials for manufacturing food.

4. Digestion: It is absent.

Heterotrophic Nutrition:

1. Food: Food is obtained ready-made from outside.

2. External Energy: An external source of energy is not required. The required energy is present in the food obtained from outside.

3. Inorganic Substances: Inorganic substances are not much required.

4. Digestion: An external or internal digestion is required for conversion of complex organic materials into simpler and soluble ones.