Autotrophic and Heterotrophic organisms


Organisms need nutrition to survive and reproduce. Plants and animal differ in terms of mode if nutrition. Depending on the ability to produce food and energy, plants are dividwed into autotrophic or heterotrophic. All autotrophic plants are self-dependent as they can synthesize their food through photosynthesis. Autotrophs can be further classified as photoautotrophs or chemoautotrophs. Phototrophs are those plants that use sunlight as an energy source, while chemotrophs use electron donors as a source of energy. Chemotrophs may receive the energy from organic or inorganic sources. In an autotroph, if these electron donors come from inorganic chemical sources, they are called lithotrophs. Both the Photoautotrophs and lithoautotrophs utilize some portion of the ATP produced during photosynthesis to reduce NADP+ to NADPH. This can ultimately form organic compounds. Heterotrophs can be further subdivided into chemotrophs and photoheterotrophs. Chemotrophs are those plants that obtain energy by the oxidation of electron donors in their environments. These are commonly found in the ocean floors with a minimal to no chance of light being available for their photosynthesis. Therefore, these plants accommodate chemotrophic nutrition as their primary mode of food production. On the other hand, photoheterotrophs use light as their source of energy, thereby converting carbon dioxide into oxygen through the release of glucose. 



Differences between the autotrophs and heterotrophs





Heterotrophs cannot prepare their own food instead they depend on other sources to obtain their food.

These plants are the primary producers as they can prepare their food by themselves.


Most of the animals and some carnivores plants

Almost all green plants, algae, some bacteria etc.


2 categories; Photoheterotrophs and Chemoheterotrophs.

2 categories are Photoautotroph and Chemoautotroph.

Source of energy

Heterotrophs rely on other organisms to get their energy.

Autotrophs obtain energy from inorganic sources, by converting sunlight into chemical energy.


Heterotrophs rely on other organisms for their food.

They are highly independent.

Hierarchy level

Heterotrophs are the consumers in the food chain

Autotrophs are the primary producers in the food chain.

Storage of energy

Heterotrophs are not capable of storing energy.

Autotrophs are capable of storing sunlight and chemical energy.


They act as consumers.

They act as producers.


Heterotrophs can move from one place to another in search of food.

Autotrophs (plants) cannot move from one place to another.




Saprotrophs are mushroom-like structures grown on the rooting of wooden plants during the rainy season. They obtain nutrients from dead matter of other plants and animals hence they are parasitic organisms. Some of the common saprotrophs are Rhizopus (bread mould), mucor (pin mould), Yeast, and Agaricus (a mushroom).


Heterotrophic plants 

Carnivorous plant

Heterotrophic plants do not have chlorophyll, so they cannot synthesize food by themselves. Seldom some plants can eat insects, they are called carnivorous plants. They can trap many smaller insects and digest them inside. Such plants form a pouch-like structure in the apex of their leaves called pitcher. The pitcher (pouch) is automatically closed when the insect comes in contacts with the pouch. 


Read more


 Introduction to plant nutrition                     


Coordination in plants


Plant breeding techniques


Sexual reproduction in plants

5  .

Respiration in plants


Check your Understanding

  1. Distinguish between photoautotrophs and photoheterotrophs.

  2. What are chemoheterotrophs?

  3. Explain about heterotrophic plants.

  4. Distinguish between autotrophs and heterotrophs.






Course List