Definition of Nutrition

All organisms need nutrients to survive and function. The biochemical and physiological process of obtaining these nutrients ( proteins, carbohydrates, fats, vitamins, minerals, and electrolytes) from different types of food is called the nutrition of the organism. This process includes ingestion, digestion, absorption, assimilation, biosynthesis, catabolism, and excretion.

Types of Nutrition:

Types of nutrition in different animals can be easily expressed by the following diagram:

1. Autotrophic Nutrition

Autotrophic nutrition is the widest in all types of nutrition. In this type of nutrition, an organism makes its food from simple inorganic materials like water, minerals, and carbon dioxide in the presence of Sunlight with the help of chlorophyll. This process is called photosynthesis. Photosynthesis, the process by which green plants, certain bacteria, algae, etc. transform light energy into chemical energy. In this process, green plants, bacteria, algae, etc light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and carbohydrates. All green plants and certain bacteria, algae, etc examples of autotrophs.

2. Heterotrophic Nutrition

In heterotrophic nutrition, organisms take their food from another organism because it cannot prepare their food due to a lack of chlorophyll. All animals and non-photosynthetic plants are known as heterotrophs. There are three types of heterotrophic nutrition:

a) Holozoic Nutrition 

Holozoic nutrition (Greek: holo-whole; zoos-of animals) is a type of heterotrophic nutrition in which the organisms take their food in the form of solid or liquid from other organisms. This process involves ingestion, digestion, absorption, assimilation, and egestion of liquid or solid food particles. All animals are examples of holozoic. Mainly It can be divided into these two groups as mentioned below:

1. Herbivores

All animals that take their nutrition through the different parts of plants are called herbivores. They have special digestive systems that let them digest all kinds of plants, including grasses.

2. Carnivores

The animals that take their nutrition by eating other animals are known as carnivores. Organisms that carnivores hunt are called prey. Carnivores are sometimes known by their type of prey. For example, animals that eat mainly insects are called insectivores, while those that eat mainly fish are called piscivores.

‘Omnivores’ is another type of holozoic nutrition in which an organism get their nutrients from both plants and animals, like a human, cow, etc.

b) Parasitic Nutrition

In parasitic nutrition, an organism lives on the surface or inside of the body of another living organism (known as a host) and take nutrients directly from their host. In other words, parasitic nutrition is that nutrition in which an organism derives its food from the body of another living organism (which is known as a host) without killing it. eg. Tapeworm, Dodders, Cascuta, Loranthus, Viscum, Rafflesia, etc.

c) Saprozoic Nutrition

In Saprozoic nutrition, an organism fulfills its own nutrients requirements from the surroundings through the absorption of simple organic materials and dissolved salts in the water. Such types of organisms are called scavengers, saprotrophic, saprobic, saprozoic, and saprophytic. Mainly protozoa and fungi possess this type of Nutrition.

The need for Food or Nutrition

Nutrients provide nourishment to the organisms. Proteins, carbohydrates, fat, vitamins, minerals, water, etc are nutrients. There are four reasons to create the need for food or nutrition for an organism as mentioned below:

For Supply of Energy 

All biological activities need the energy to perform this. This need for energy fulfills by nutrients and these nutrients are found in the food intake or prepare by the organism.

For Protection From Diseases

Nutrients develop immunity in the body of organisms for protection from diseases. In the lack of these nutrients, many diseases develop in our bodies.

For Physical Growth 

Without the balanced quantity of nutrients like carbohydrates, proteins, fat, vitamins, etc proper growth of the body is impossible. For perfect development of the body, a well-balanced diet is highly required.

For Regeneration of Body 

In our body, many cells degenerate daily. nutrients play a very important role in the process of regeneration of the body.