Modes of Nutrition in plants – Autotrophic and Heterotrophic Nutrition

From genetics to ecology, Biology Topics cover a vast array of life sciences.

What is nutrition in plants? What are different modes of Nutrition?

All the living organisms (plants and animals require food. The organisms need to take food

1. to obtain energy
2. to obtain materials for growth, and
3. to obtain materials for the repair of damaged parts of the body. The process of taking food by

The methods of obtaining food are called modes of nutrition. On the basis of their modes of nutrition, all the organisms can be divided into two main groups :

1. Autotrophs (or Autotrophic), and
2. Heterotrophs (or Heterotrophic).

We will now describe both these modes of nutrition of organisms in detail, one by one.

Autotrophs : Autotrophic Mode of Nutrition

Those organisms which can make food themselves from simple substances (like carbon dioxide and water) by the process of photosynthesis, are called autotrophs (and their mode of nutrition is called autotrophic). All the green plants are autotrophs.

This is because green plants can make their own food from simple substances like carbon dioxide and water present in their surroundings by the process of photosynthesis. In other words, green plants have autotrophic mode of nutrition. For example, wheat plants are autotrophs (having autotrophic mode of nutrition). Autotrophs contain a green pigment called chlorophyll which helps them make food by absorbing energy from sunlight. Most of the plants are green and hence synthesise (make) their own food (see Figure).

This means that most of the plants have autotrophic mode of nutrition. The green plants produce food not only for themselves, they also make food for non-green plants as well as for animals (including human beings).

Our body (and that of other animals) cannot make food from carbon dioxide and water present around us by the process of photosynthesis (like the plants do) because our body does not have the green pigment called chlorophyll (which the plants have).The green pigment chlorophyll is necessary to absorb energy from sunlight required for making food by photosynthesis.

Heterotrophs : Heterotrophic Mode of Nutrition

Those organisms which cannot make food themselves by the process of photosynthesis and take food from green plants or animals, are called heterotrophs (and their mode of nutrition is called heterotrophic). All the non-green plants and animals (including human beings) are heterotrophs. The non-green plants do not have chlorophyll for carrying out the process of food making called photosynthesis. So, they depend on other organisms (plants or animals) for obtaining their food.

The non-green plants called fungi (such as mushroom, yeast and bread mould) are heterotrophs. They have heterotrophic mode of nutrition. Certain bacteria are also heterotrophs. All the animals (including human beings) are categorised as heterotrophs because they cannot make their own food, they depend on plants or other animals for obtaining their food. Thus, all the animals like cat, dog, goat, cow, buffalo, deer, lion, tiger and human beings are heterotrophs having heterotrophic mode of nutrition (see Figure).