Autotrophic Nutrition

Dhristi NEET 2022-24

What is Autotrophic Nutrition?

Before understanding autotrophic nutrition we must look into the meaning of the term nutrition itself.  Nutrition is the process of ingesting and using food. The collected food is used to supply energy for the organism's different metabolic functions during this procedure. Carbohydrates are the most prevalent source of energy in food, which is an organic material. Food also includes fats and proteins. Glucose, often known as a simple sugar, is the most basic carbohydrate meal. Starch is a more complicated food that is also generated from glucose.


Let us now answer the question of what is autotrophic nutrition. In layman terms, the word can be split into auto = self, trophic = nutrition. The exact meaning of this word is self-nutrition. Autotrophic nutrition is a process in which the organism produces its food from simple inorganic materials such as water, carbon dioxide and mineral salts in the presence of sunlight. All the green plants have an autotrophic mode of nutrition.


The article entails the description of what is autotrophic nutrition, the source of nutrition in plants is discussed in the article. The types of autotrophic nutrition and a brief description of photosynthesis is also mentioned in the article.

Image illustrating process of autotrophic nutrition in plants


Plants such as blue-green algae and cyanobacteria could be considered as some examples of autotrophic nutrition.

Modes of nutrition

Since we have developed a basic understanding of the meaning of nutrition, let us look into the types of nutrition. There are mainly two modes of nutrition namely, autotrophic nutrition and heterotrophic nutrition. The organisms that follow the autotrophic mode is known as autotrophs similarly organism which has a heterotrophic mode of nutrition is known as heterotrophs. The major distinction between these two modes is the ability to synthesize organic compounds containing energy-rich molecules from inorganic sources. As mentioned earlier autotrophs can produce their food from inorganic sources like water, carbon dioxide, hydrogen sulphide sunlight etc whereas heterotrophs can not. The autotrophic is further classified into:

  • Photosynthetic autotrophs

  • Chemosynthetic autotrophs


Photosynthetic autotrophs

Plants that can produce their food are called autotrophs. The method by which plants produce their own food is known as photosynthesis. The photosynthesis process happens mostly in the leaves of the plant which are also known as the ‘kitchen of the plant’. In certain cases, even the stems have the potential to carry out photosynthesis. Photosynthesis is a method to transform solar energy into chemical energy to produce starch. Different parts of a plant play different roles to complete photosynthesis.

  • Leaves – They are the food factories of the plant.

  • Stomata – It is present in the lower epidermis of the leaf which uses carbon dioxide CO2 from the air.

  • Roots – They absorb minerals and water from the soil and carry it to different parts of the plant.


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Apart from plants, there are certain bacterias that are categorized as autotrophic bacteria. It is important to note that these bacteria differ from plants as they do not yield oxygen as a byproduct of their metabolic reaction. It is mainly because the electron donor used in such bacteria is water but chemical compounds like hydrogen sulphide. 


Chemoautotrophic Nutrition

The organism can make their own food with the help of chemical energy and they do not need sunlight. The oxidation of chemical substances, whether organic or inorganic, produces chemical energy. Chemosynthetic bacteria are important in the recycling of nutrients such as nitrogen, phosphorus, iron, and sulphur. An example includes Nitrifying bacteria, Methanomonas, sulphur bacteria, Nitrosomonas, hydrogen bacteria, etc.


Plants and Their Nutrition Requirements

Plants are also a part of living things that require some form of energy. They have cells and tissues. They also grow in girth and size. And they are the creators of the ecosystem. So, in order to create food, they do have nutrient necessities. Of course, the kind of nutrient requirements differs. This type of nutrition in plants is so-called the “autotrophic mode of nutrition”. What does this actually stand for? It means that plants have the special ability to make their own food, with the help of simple inorganic substances to harvest organic substances. They get energy sources from non-living things like the sun and carbon dioxide.


Plants also contain chlorophyll in them, the green colour pigment. With the help of all these above elements, plants can yield simple carbohydrates. The carbohydrates thus made are utilized by the plant and give it energy. When there is a surplus of carbohydrates in the plants, then it is stored as a backup for later use.

Image illustrating the plant cell structure


Factors Affecting Photosynthesis Process

There are some factors that encourage or inhibit photosynthesis depending on their concentration :

  • Light

  • Temperature

  • Oxygen

  • CO₂


Purpose of Photosynthesis

For plants, photosynthesis helps produce glucose to be able to produce energy to perform other functions such as transport of water and minerals throughout the plant and respiration. Plants require energy also to make other biological and biochemical methods to enable them to multiply. For other organisms, plants serve as food.



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FAQs (Frequently Asked Questions)

1. What are chemolithotrophs?

The oxidative portion of the biological cycles of inorganic molecules such as hydrogen, nitrogen, sulphur, metal ions, and carbon is represented by the chemolithotrophs and methylotrophs. Chemolithotrophs are a taxonomically varied group of bacteria that get all of their nutrition out from oxidizing inorganic compounds including hydrogen, hydrogen sulphide, and reduced metals. They are categorized under the group of autotrophs. Examples of it include sulfur-oxidizing bacteria like Beggiatoa and Thiomargerita.

2. What is the role of chloroplast in plant nutrition?

Chloroplast is the organelle in plant cells that serves as the site of photosynthesis. Photosynthesis is the process by which plants derives their energy from inorganic molecules. The chloroplast is a membrane-bound, semi-autonomous organelle.

3. What are detrivores?

A detrivore is defined as an organism that derives its energy from dead and decaying materials, it is important to note they are categorized as heterotrophs. Detrivires generally includes microbes such as bacteria and fungus. They play an important role in maintaining the balance of ecosystems.

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