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Overview of Autotrophs

Autotrophs often refer to organisms that prepare their own food. Autotrophs can prepare their food either by using light, chemicals, water, carbon dioxide or any other component of the environment. Organisms that produce their own food are known as autotrophs and since due to their this property they are referred to as producers. Producers produce their food either by chemicals, light etc. Producers produce their own food by a popular profession known as photosynthesis. Photosynthesis is the process by which plants or other green organisms prepare their own food by using the sunlight.

Plants are the most common type of autotrophs but if we talk about other autotrophic animals there can be many such as green algae, which lives in water. These algae when together in large form are known as seaweeds, phytoplankton and some bacteria are also some type of autotrophs. They can be either photoautotrophs or chemoautotrophs.

If we talk about photoautotrophs then they use the process of photosynthesis in which energy of sunlight is used to prepare food or glucose from the carbon dioxide from air and water from the soil. All plants whether they are shrubs, fir, trees, mosses or algae they all are the photoautotrophs that prepare their food by using energy from the sun.

Saying about chemoautotrophs, they prepare their food by chemosynthesis. Such autotrophs do not produce their food from the sunlight but from the chemicals. These autotrophs survive in an extremely toxic environment. Often when there is a combination of hydrogen sulphide or methane with oxygen food is produced by them. In such a dictionary extremely toxic chemicals are needed for oxidation. Let us take an example of bacteria that live in volcanoes. In volcanoes Sulphur is oxidised to produce their own food. Bacteria that live in extremely deep oceans are also chemoautotrophs. 

Beside this there are organisms that are dependents on other organisms or on these autotrophs that prepare their own food that is they just get good from autotrophs and cannot prepare their own food like autotrophs. Further details about the autotrophs you will get from this article. In this article you will get information about autotrophs, importance of these autotrophs, further details about their types, examples of autotrophs and what is the Difference between the autotrophs and heterotrophs . Beside this at the end toys are provided with frequently asked questions that will help to clear most of your queries. Vedantu  has specially designed this article for your help to understand autotrophs well.

The organisms in an ecosystem that act as primary producers in a food chain are known as autotrophs. Their major source of energy is harnessed from sunlight through the photosynthesis process, because of this reason they are also known as photoautotrophs. Along with that they also obtain their energy through the oxidation process and because of that they are known to be chemoautotrophs. Through chemical processes, they make organic substances into an inorganic form. One of the major features of autotroph is that they do not consume other organisms as consumed by heterotrophs. In the word ‘autotrophs’, ‘auto’ means self and ‘troph’ means food i.e. they are the organism which feeds itself, without taking assistance of any other organism.

Importance of Autotrophs

Autotrophs have their own specific importance in society, as without them no other life form can exist in society. Plants are the one which create sugar by taking carbon dioxide, gas and sunlight by the process called photosynthesis. Because of this reason, they are called producers. They form the base for the formation of higher ecosystems i.e. they act as a base for energy pyramids and also provide fuel to heterotrophs.

From this, we can say that the first life on earth must be an autotroph. Heterotrophs are further evolved from autotrophs. 

Types of Autotrophs

On the basis of the process of obtaining energy, autotrophs are classified into two types, they are:

  1. Photoautotrophs

These are the organisms that obtain their energy from sunlight to make organic material. Examples of autotrophs are plants, green algae, and bacteria which perform photosynthesis. All of these photoautotrophs perform photosynthesis to make their food. In photosynthesis, the word photo means light and synthesis means to prepare or to make. In this process, organisms capture sunlight and use their energy to perform important biochemical processes such as making ATP. The amount of fuel or energy prepared by photoautotrophs is more than any other organisms like heterotrophs. 

Whereas some photoautotrophs take carbon from the atmosphere and use this carbon for preparing sugar and other molecules that store the Sun’s energy in their molecular bonds. 

  1. Chemoautotrophs

These are the organisms that obtain their energy from inorganic chemical processes. They are majorly found in deep water where the source of sunlight is almost negligible. For obtaining energy they use volatile chemicals such as molecular hydrogen, hydrogen sulphide, elemental sulphur, ferrous iron, and ammonia as their energy sources.

Examples of Autotrophs

Some of the common examples of autotrophs are:


B.Algae- Green algae and red algae

C.Bacteria such as cyanobacteria

D.Lichens located in the tundra region are autotrophic in nature as they are considered to be primary producers as they undergo mutualism and combine photosynthesis by algae. 

Different Terms Related to Autotrophs

A. Energy Pyramid – It is a structure that explains the flow of energy in different organisms. 

B.Heterotroph – These are organisms that are dependent on another organism for food. Example: animals like Goat, Lion etc. 

C.Photosynthesis – In this process phototrophs do the extraction of energy from sunlight.

Difference Between Autotrophs and Heterotrophs 



Members of the plant kingdom and few unicellular species come under autotrophs. 

All members of the animal kingdom come under heterotrophs. 

They prepare their own food. 

They are dependent on other organisms for their food. 

They are classified into two types they are: 

photoautotrophs and chemoautotrophs.

They are also classified into two types, they are photoheterotrophs and chemoheterotrophs. 

Chloroplast plays a major role in preparing food.

The chloroplast is absent in them. 

They can store light energy and chemical energy.

They cannot store any source of energy. 

MCQ Questions

1. From the options below, which of the following is not an example of photoautotrophs?

A. Daisies

B. Iron bacteria

C. Cyanobacteria

D. None of the above.

Ans:  Iron bacteria

2. Which of the following organisms first appeared on the earth surface?

A. A photoautotroph.

B. A chemoautotroph.

C. Neither of the above.

D. No one knows.

Ans: Neither of the above

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FAQs on Autotrophs

1. Name organisms that are both autotrophs and heterotrophs.

Some organisms are there that can prepare their own food when the conditions are suitable and when not they can take food from the other organisms that is they can act as heterotrophs Cyanobacteria are organisms that are both autotrophs and heterotrophs as they show photoautotrophic nutrition. Another example of organisms that act as both autotrophs and heterotrophs is Archaea. These organisms act as both autotrophs and heterotrophs, that is they can prepare their own food and can take it from the environment or other autotrophs also.

2. Explain the term photoheterotrophs and chemolithoheterotrophs.

Certain  heterotrophic organisms are there which make the use of light energy as their energy source. They can use the environmental carbon dioxide but they cannot use it as their sole source of carbon also. They fulfil their requirements of energy by feeding on dead organic matter or other organisms , the reason they are referred to as heterotrophs.

Photoheterotrophs are organisms that obtain carbon from organic compounds but obtain energy from light, whereas chemolithoheterotrophs obtain carbon from organic compounds and energy from the oxidation of inorganic compounds.

3. Explain different types of autotrophs?

Autotrophs refers to organisms which are capable of preparing their own food. They are further of two types: photoautotrophs,that use light energy to prepare their own food and chemoautotrophs that make use of chemicals or carbondioxife as their source of energy by using inorganic energy sources. Plants are mainly referred to as autotrophs whether they are small mosses, algae, shrubs or large trees and I'd we talk about chemoautotrophs than bacteria like cyanobacteria Ackles under this category or the bacteria that ate in the volcanoes can also be referred in it.

4. What is the  main purpose of photosynthesis?

Photosynthesis is a process by which the organisms make use of sunlight in order to prepare their own food. If we talk about their importance in plants or autotrophs, then by this process only the glucose or nutrients are formed in autotrophs by the use of light energy along with water from soil and carbon dioxide from air. If we refer to its other benefit then by the process of photosynthesis only the oxygen is released into the air through this process of photosynthesis.

5. Can we refer to plants as chemoautotrophs?

Basically chemoautotrophs are those cells which make their own energy and the biological material by using various inorganic chemicals. While photoautotrophs are those organisms that make use of the energy provided by the sunlight to prepare their own food. If we talk about plants, they come under the category of photoautotrophs and not chemoautotrophs as they prepare their food using sunlight and not from inorganic cereals available in the environment. To prepare their food or glucose they take energy from the sunlight and along with this they carbon dioxide from the environment and water from the soil.