Question

What are the modes of nutrition? Explain in detail various types of modes of nutrition in living beings.

Answer 1

Hint: Nutrition is the procedure of proceeding food and using it for obtaining energy, growth and repair of the body. Animals depend upon other animals or plants for food for their nutritional needs.

Complete answer:
Modes of Nutrition
The method of obtaining food by an organism is named modes of nutrition.
There are two modes of nutrition. Which are -
1) Autotrophic
2) Heterotrophic

Autotrophic mode of Nutrition:
Autotrophic nutrition refers to that kind of nutrition when organisms are involved in making their own food.
They can be classified into:
Photoautotrophs: The organisms that make their own food by using sunlight as the source of energy are called photoautotrophs. Eg- Green plants, photosynthetic bacteria and algae.
Chemoautotrophs: The organisms that synthesise food with the oxidation of chemicals. Eg-Cyanobacteria and iron-oxidising bacteria, Sulphur-oxidizing bacteria.

Heterotrophic Mode of Nutrition
They depend upon other organisms for food. This is often called heterotrophic mode of nutrition. The organisms which depend upon plants or other organisms for food are called heterotrophs. For example – tiger, man, cow, yeast are all heterotrophs.

There are three types of heterotrophic mode of nutrition. Which are:
i) Saprotrophic nutrition
ii) Parasitic nutrition
iii) Holozoic nutrition

Saprotrophic nutrition
There are organisms which prey on dead and decaying organic matter for obtaining their food. These organisms prey on rotting wood of dead and decaying trees, rotten leaves, dead animals, etc. Such organisms are called saprophytes. For example - Fungi and lots of bacteria.

Parasitic Nutrition
It is that mode of nutrition during which organisms prey on other living organisms, called their host, without killing them. The organisms which obtain food by this way are called parasites. For example- Fungi, bacteria, plants like cuscuta and animals like plasmodium and roundworms.

Holozoic Nutrition
Holozoic may be a mode of nutrition during which organisms eat solid food. The food could also be a plant material or animal material. During this process, an organism ingests the complex organic food material into its body then digests the food which is then absorbed into the body cells. For example- Man, cow, fish, etc.

Note: Nutrition in living organisms varies according to their way of food consumption. Animals which feed on plants for nutrition are Herbivorous. Animals which feed on other animals or animal products are Carnivorous. Animals having mixed diets are Omnivorous.