Nutrition and Types of Nutrition

Nutrition is defined as the process by which living organisms obtain and utilize food materials from external environment for metabolic activities such as respiration, growth, excretion and reproduction.

Food is any substance which when absorbed into the body cells yields energy and materials for growth, repairs of damaged tissues and regulation of body processes without harming the living organism.

Anabolism is defined as the synthesis of complex organic compound from simple substances. Living things require food( carbohydrtate, protein, lipids,mineral salt ,vitamins and water) for the following activities

  1. production of new protoplasm
  2. growth.

iii.Repair of body cells and tissues.

iv.production of energy for life activities.

Types of Nutrition

1.Autotrophic Nutrition:

is the type of nutrition in which organisms are able to manufacture their own food. organism which can manufacture or synthesize their own food are called autotrophs. Autotrophic mode of nutrition is carried out by green plants through the process of photosynthesis and some certain bacteria through the process of chemosynthesis..

Photosynthetic (Holophytic) Nutrition is the process where green plants manufacture their own

organic food from simple inorganic substances such as carbondioxide, water, sunlight and chlorophyll with the release of oxygen as by-product.


Chemosynthetic Nutrition: is a process where certain bacteria which are autotrophic manufacture their own food through simple inorganic substances such as carbon (iv) oxide, water, hydrogen sulsphide by using the chemical energy released during the process as source of energy.

These bacteria do not depend upon sunlight energy. They have enzyme system capable of trapping chemical energy. For example, the sulphur bacteria in the soil can oxidize hydrogen around it to chemical energy


2. Heterotrophic Nutrition:

is a type of nutrition in which organisms cannot manufacture their own food but depends directly on plants for their own food. Such organisms are called heterotrophs. Most heterotrophs are fungi, protozoa and some bacteria. Heterotrophs take food items into their gut in three different forms

1.Macrophagous  feeder are animal such as mammals that take large food item which need the aid of teeth to break down before entering digestive gut

2.Microphagous feeders are other heterotrophs which take tiny food particles into their gut without being broken down by teeth. Examples are paramecium, mosquito larvae and tilapia galilaea

3.Some other heterotrophs feed on fluid and they are referred to as fluid feeders. Examples are adult mosquitoes, aphids, butter flies and sunbird.

There are four main types of heterotrophs nutrition

  1. holozoic
  2. Saprophytic
  3. Symbiosis
  4. Parasitic


Plants require mineral nutrients or elements obtained from the soil in form of solution for good growth and healthy development. The source is the main source of mineral salts while gaseous elements such as oxygen, hydrogen and carbon are mainly derived from the atmosphere. These plants nutrients elements are grouped into two classes depending on the quantity required by the plants

(1)Macro nutrients or elements are mineral elements required in large quantities for healthy growth of plants. Example are nitrogen, phosphorus, potassium, magnesium, calcium, oxygen, hydrogen, carbon, sulphur and iron. These macro element are called essential element.

(2)Micro nutrients or elements or traced element are those mineral elements required in small quantities for healthy growth of plants. Examples are zinc, copper, boron, molybdenum, colbat, chlorine and manganese. When a plant lacks any of these elements, it shows certain signs and these signs are called deficiency symptoms. The micro nutrients are also called non-essential element.

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