Autotroph Vs Heterotroph - Difference And Comparison - Diffen

Monotropastrum humile, a myco-heterotroph dependent on fungi throughout its lifetime

Energy Production

Autotrophs produce their own energy by one of the following two methods:

• Photosynthesis - Photoautotrophs use energy from sun to convert water from the soil and carbon dioxide from the air into glucose. Glucose provides energy to plants and is used to make cellulose which is used to build cell walls. E.g. Plants, algae, phytoplankton and some bacteria. Carnivorous plants like pitcher plant use photosynthesis for energy production but depend on other organisms for other nutrients like nitrogen, potassium and phosphorous. Hence, these plants are basically autotrophs.

• Chemosynthesis - Chemoautotrophs use energy from chemical reactions to make food. The chemical reactions are usually between hydrogen sulfide/methane with oxygen. Carbon dioxide is the main source of carbon for Chemoautotrophs. E.g. Bacteria found inside active volcano, hydrothermal vents in sea floor, hot water springs.

Heterotrophs survive by feeding on organic matter produced by or available in other organisms. There are two types of heterotrophs:

• Photoheterotroph – These heterotrophs use light for energy but cannot use carbon dioxide as their carbon source. They get their carbon from compounds such as carbohydrates, fatty acids and alcohol. E.g. purple non-sulfur bacteria, green-non sulfur bacteria and heliobacteria.

• Chemoheterotroph – Heterotrophs that get their energy by oxidation of preformed organic compounds, i.e. by eating other organisms either dead or alive. E.g. animals, fungi, bacteria and almost all pathogens.

Type of organism	Energy source	Carbon source
Photoautotroph	Light	Carbon dioxide
Chemoautotroph	Chemicals	Carbon dioxide
Photoheterotroph	Light	Carbon from other organisms
Chemoheterotroph	Other organisms	Other organisms

A flowchart explaining the various types of trophs

Food Chain

Autotrophs do not depend on other organism for their food. They are the primary producer and are placed first in the food chain. Heterotrophs that depend on autotrophs and other heterotrophs for their energy level are placed next on the food chain.

Herbivores that feed on autotrophs are placed in the second trophic level. Carnivores that eat meat and omnivores that eat all types of organisms are placed next in the trophic level.

Food cycle between autotrophs and heterotrophs

References

• Wikipedia: Autotroph
• Wikipedia: Chemoheterotroph
• Wikipedia: Heterotroph