What Is Nutrition | Types Of Nutrition Class 10

What Is Nutrition | Types Of Nutrition Class 10: The word 'nutrition' is derived from the word 'nutrient'. Nutrition is a process of intake, as well as utilisation of nutrients by an organism.All organisms require food. But the manner in which they obtain food may be different in different organisms. Thus, on the basis of mode (manner) of obtaining food, the nutrition in various organisms can broadly be divided into two main types of nutrition are : autotrophic and heterotrophic. The nutrition in Amoeba is a holozoic organisms so, it does not absorb its food but ingests its food.

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What Is Nutrition?

The word 'nutrition' is derived from the word 'nutrient'. Nutrition is a process of intake, as well as utilisation of nutrients by an organism.Therefore, nutrition involves the sum total of all the activities, which are concerned with the intake of food (ingestion) and its digestion and assimilation in the body for growth and work.

Nutrients are the substances, which are essential for the biosynthesis of body constituents. Every living organism requires nutrients. The organism obtains nutrients from its surroundings mainly in the form of food.

Types Of Nutrition

All organisms require food. But the manner in which they obtain food may be different in different organisms. Thus, on the basis of mode (manner) of obtaining food, the nutrition in various organisms can broadly be divided into two main types of nutrition are : autotrophic and heterotrophic.

1. Autotrophic Nutrition

• Some organisms, like green plants do not obtain their food from surroundings. Instéad they can synthesise their food by themselves by using sunlight and inorganic raw materials (like Carbon dioxide and Water). Such organisms (green plants and some bacteria) are called autotrophs. (Auto' means self and 'troph' means nutrition).

• Thus, autotrophic mode of nutrition can be defined as a type, in which organism itself prepares its food by using sunlight and simple inorganic raw materials like Carbon dioxide and water.

• This process of synthesising food by green plants, using sunlight, CO2 and water is called photosynthesis. Photosynthesis is an energy transformation process, in which solar energy is transformed to chemical energy of food (like carbohydrates). For trapping and fixing the solar energy, these organisms contain special light absorbing pigments. One most important pigment is chlorophyll.

Examples-of autotrophs-Green plants and cyanobacteria (or autotrophic bacteria). If food synthesised by plants, is not used up immediately, it gets converted into starch (complex carbohydrate). Starch is, therefore, the reserve food material in plants.

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2. Heterotrophic Nutrition

• Other organisms (i.e., other than green plants and cyanobacteria), can not synthesise their food by using inorganic matter and sunlight (i.e., they do not perform photosynthesis). So, for their food requirement, these organisms depend on green plants, directly or indirectly.

• These organisms, obtain nutrients in complex-organic forms (such as carbohydrates, fats, proteins and vitamins etc.) directly from plants (or indirectly from some animal source). Such organisms are called heterotrophs. ("Hetero' means different or other).

• Heterotrophic nutrition can be defined as, "a type of nutrition in which energy is derived from the intake and digestion of the organic substances, normally of plant or animal source".

• In heterotrophic nutrition, organic substances present in the food are first broken down into simple forms inside the body of the organisms. This process of simplification of components of food is known as digestion. For quick simplification, these organisms use biocatalysts, called digestive enzymes The simplified molecules are then utilised by the organism for various purposes, including growth.

• Heterotrophic types of nutrition, therefore, involves ingestion (intake of food), digestion (simplification of food), assimilation (mixing and use of digested food) and egestion (elimination of undigested part of food).

Examples-All organisms other than green plants and cyanobacteria are heterotrophic. These include-all animals, bacteria (except cyanobacteria) and all fungi. The heterotrophic types of nutrition can further be divided into following types:

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Saprophytic Nutrition

The word 'sapro' means rotten (or decaying). Saprophytic nutrition refers to the mode in which organisms obtain its nutrients from the dead and decaying (rotten) organic matter. The organism does not obtain food from any living organism. In this mode, the organism releases some digestive enzymes on the food, outside its body. The enzymes simplify the food. After simplification, the food is absorbed by the organism.

Examples-Many fungi, such as mushrooms (Agaricus) bread moulds (Rhizopus) and Yeast etc. These organisms are known as saprophytes and decomposers.

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Parasitic Nutrition

The term 'para' means other'. Thus, parasitic nutrition refers to the mode of nutrition, in which an organism obtains its food from other living organisms, without killing them. Such organisms are called parasites.

The organisms, from which parasites obtain their food, are called hosts. Host may be either a plant or an animal. Parasites are intimately attached to their hosts and continuously obtain food from them. In return, parasites do not give any benefit to their host. Instead, they cause severe harm to their hosts.

Examples-Various fungi (such as Ustilago, Puccinia, Albugo etc.), some higher plants (such a Cuscuta or amar-bel), many animals like Plasmodium, roundworm (Ascaris), tapeworm (Taenia), leeches, lice, ticks and many bacteria.

Holozoic Nutrition

In holozoic nutrition, organism does not absorb the food particles from its body surface. Instead, it takes in whole food article i.e., holozoic nutrition is a mode of nutrition in which, organisms actively intake the food with the help of some specialised mechanisms. This intake of food is called ingestion.

Example-This method is found mainly in animals (cockroach, earthworm, frog, human beings) and some protists (protozoans like Amoeba, Paramecium).

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How do Organisms Obtain their Food ?

Student should note that in saprophytic nutrition, as well as in parasitic nutrition, food is not ingested. Instead, food is absorbed. If it is absorbed from dead/decaying matter, it is called saprophtic nutrition, if it is derived from a living being it is called parasitic nutrition. In other words, these organisms have no specialised mechanisms and structure for the intake of food. In fact, the food is taken in by simple sucking or absorption from the general body surface.

On the other hand, in holozoic nutrition, the organisms usually have mouth or some specialised structures for the intake of food. In other words, these organisms do not obtain their food by simple sucking (absorption). Instead, specialised mechanisms are present for the active intake of food material.

NUTRITION IN AMOEBA

Amoeba is a holozoic organisms so, it does not absorb its food but ingests its food. Being unicellular in nature, the process of food capturing in Amoeba is called phagocytosis. (Term phagocytosis = cell feeding). Different stages of nutrition in Amoeba include ingestion (phagocytosis), digestion, absorption and assimilation and egestion.

• Ingestion: It eccurs with the help of special structures, called pseudopodia (which are protoplasmic extensions). When Amoeba approaches a food particle, it sends out pseudopodia around the food particle. Gradually the food particle becomes trapped in the form of food vacuole.

• Digestion: The food vacuole, contain the food moves in the cytoplasm and various digestive enzyme enter the vacuole and digest the food. So, digestion in intracellular, i.e., inside the cell.

• Absorption and assimilation: The digested food from the vacuole diffuses out into the cytoplasm There is no complex system like higher organisms. The food in the cytoplasm is now utilized for respiratory needs (energy production) and also for growth, wear and tear functions.

• Egestion: There is no fixed place in Amoeba as there is no anus for the egestion of food The undigested food is removed off from the cell from any part by a small rupture in the cell membrane This process is called exocytosis.

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