Every living organism requires a supply of food for the maintenance of life and the processes connected with life including growth, movement, reproduction etc. A living organism synthesizes or collects its necessary food from the surrounding environment. Mineral, vitamins, and water also required for various life processes. All these essential substances are collectively called nutrients. Nutrition is the process which deals with the breakdown of complex food materials into simple substances and its subsequent transformation to protoplasmic materials.
Nutrition helps to receive and utilize the materials necessary for the maintenance of its function and for the growth and renewal of its components.
Nutrients and Food
The organic and inorganic material which the living organism collects from nature to perform all the fundamental activities of the body is called nutrients. All nutrients which are collected by the living organisms from their surroundings are not considered as food and that material needs no digestion. The essential substances like minerals, vitamins, and water are collectively known as nutrients.
All eatable substances which need for growth, nutrition, energy production, and help for building a new tissue within the living body are known as food. All foods are synthesized within the body are nutrients and need digestion.
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Types of Nutrients
On the basis of the quantity of nutrients in food, nutrients are of two types:
(1) Macronutrients: Macronutrients are the basic food components for the living organisms which are required in large amounts for proper maintaining the body. Macro-nutrients include carbohydrate, lipids or fats and proteins. They act as a main source of energy (sugars, amino acids) for the living organisms.
(2) Micronutrients: Micronutrients are necessary substances for the living organisms which are required in small amount for the maintenance of the body, This type of nutrients plays a great role in the growth and development of living organisms. The lack of micronutrients can lead to various diseases to the organisms.
Types of Food
Food can be divided into two types according to their function in the body.
(1) Proximate Principles of Food: The food substances which help in energy production, body growth and maintenance of life are known as proximate principles of food such as carbohydrate, protein, fat or lipid.
(2) Protective Principles of Food: The food substances which prevent the body from the attack of various diseases are known as Protective Principles of Food. These types of food are also known as secondary food which helps in the metabolism of food. These types of food are vitamins, minerals, salt, and water.
Types of Nutrition
There are two types of nutrition:
Autotrophic Nutrition:
It is a process by which green plants and some bacteria can produce their own food from simple inorganic substances like water, mineral salts and carbon dioxide by the process of photosynthesis using solar energy.
Heterotrophic Nutrition:
Non-autotrophic organisms depend on autotrophic organisms for their food which is known as heterotrophs. Heterotrophs are animal and non-photosynthetic plants which cannot produce their own food. Nutrition exhibited by heterotrophs is known as heterotrophic nutrition
Types of Heterotrophic Nutrition
There are four types of heterotrophic nutrition such as:
- Holozoic Nutrition
- Saprophytic Nutrition
- Parasitic Nutrition
- Symbiotic Nutrition
Holozoic Nutrition: The term ‘holozoic’ comes from ‘holo’ meaning whole and ‘zoikos’ meaning animals where the animals take their food whole. It is one type of heterotrophic nutrition. In this case, organisms take solid or liquid food through the digestive system and break down into small pieces to be absorbed. Generally, this type of nutrition consists of the following stages: ingestion, digestion, absorption, assimilation, and ingestion. Most of the animals show this type of nutrition.
Saprophytic Nutrition: When organisms feed on dead and decaying organic remains of other organisms to get energy, then it is known as saprophytic nutrition. This type of nutrition helps to clean the environment. In this case, organisms receive their nourishment from the dead and decomposed organic substance formed as a result of the decay of plant and animals. Organisms secrets certain enzymes which digest the decayed organic substances and this simplified food in liquid condition is absorbed by the saprophytes later on. Fungi, moulds, some bacteria, and some protists obtain their food from dead and decaying organic matters and they are known as saprophytes.
Parasitic Nutrition: The process by which a living organism (parasites) obtains its necessary nutrient from any other plants or animals (host) is known as parasitic nutrition. In this case, parasites obtain the nutrients from the host body and parasites are harmful to the host body and even kill the hosts. Example, Human louse, tapeworm etc
Symbiotic Nutrition: When two organisms live in close association with each other for their mutual benefit in nutrition, then the type of nutrition is known as symbiotic nutrition. Each of the pair organisms is called symbiont and the mode of their association is termed as symbiosis. Symbiotic nutrition is of two types:
(i) Mutualism: When two organisms live in close association for their mutual benefits in obtaining their nutrition, the type of nutrition is called mutualism. e.g. Lichen. This is formed of an alga and a fungus. The alga obtains water, CO2, and minerals from the fungus whereas the fungus draws in carbohydrate type of food matters and O2 from the alga. The fungus protects the alga from drying up.
(ii) Commensalism: When two organisms living together and obtain their nutrition independently then the type of nutrition is known as commensalism. In this case, one organism gets benefits and other is unaffected.
Importance of Nutrition
- Nutrition plays an important role in the production of heat in the animal body.
- It meets the caloric demand of living organisms.
- It develops the disease resistance power of the living body.
- It controls the different metabolic functions of the living body.
- It provides energy which helps for growth and repairing of tissue.
- It helps to store future food matters within the living body.
- It helps to store potential energy and transform into usable energy within the living body.
- It controls different physiological functions of the living body like movement, locomotion, excretion, reproduction etc
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