Nutrition (Feeding)
Nutrition is the process by which food is taken in by living organisms in order to supply the nutrients required for the continuous metabolic reaction going on in the body. Food is the source of nutrients.
Usefulness of Food
Living organisms require food for various reasons.
1. To provide energy needed for various physical and metabolic activities.
2. To make essential substances such as hormones and enzymes available.
Types of Nutrition
There are 2 major types of nutrition namely;
1. Autotrophic Nutrition: This is the type of nutrition in which organisms are able to manufacture their own food and they are called autotrophs.
Autotrophic nutrition can be sub-divided into 2 namely;
(a) Photosynthetic Nutrition (Holophytic): It is the type of nutrition in which all green plants are able to manufacture their own food making use of carbon dioxide and water in the presence of sunlight. This process is called photosynthesis.
(b) Chemosynthetic Nutrition: It is the type of nutrition in which certain bacteria are able to synthesise organic compounds from simple inorganic materials.
2. Heterotrophic Nutrition: It is the type of nutrition in which organisms cannot manufacture their food but depend directly or indirectly on plants for their food. Heterotrophic nutrition can be sub-divided into 2 namely;
a. Holozoic Nutrition: is a method of nutrition that involves the ingestion of liquid or solid organic material, digestion, absorption and assimilation of it to utilize it. It includes taking in the complex substances and converting them into simpler forms. Examples of organisms that exhibit holozic mode nutrition are:
· Carnivores like dog and cat that feed on flesh.
· Herbivores like sheep and goat that feed on plants.
· Omnivores like man and pig that feed on both flesh and vegetables or plants.
· Scavengers like vulture that feed on dead animals.
b. Parasitic animals: These are animals that feed on another organism in order to derive nourishment from it. Parasitic animals are divided into two:
c. Ecto parasite: These are parasites that live outside the body of the host where they derive food and shelter from e.g. tick, bedbug, etc.
d. Endo parasite: These are parasites that live inside the body of their host such as man and other animals e.g. man and tapeworm.
3. Saprophytic nutrition: It is the type of nutrition in which certain organisms called the saprophytes, feed on dead and decaying organic materials.
4. Symbiotic nutrition: It is the type of nutrition in which two organisms of different species called symbiosis live together and derive nutrition from each other.
5. Carnivorous: These are organisms equipped with devices for trapping, digesting and absorbing nutrition compounds from the bodies of insect and other small organisms.
Roles of Enzymes
Enzymes are organic catalysts, usually pretentious in nature, which promote or speed up chemical changes in living cells but are not themselves used in the process.
Functions of Enzymes
1. It helps in breaking down protein in foods into amino acids.
2. They also help in breaking down fats and oil into fatty acids and glycerol.
Mineral Salts
Plant cells require mineral salts or elements obtained from the soil in form of solution for healthy growth and development.
Classes of Plant Nutrients
1. Macro nutrient or major elements: These are nutrients required in large quantities for plants growth and development such as nitrogen, hydrogen, sulphur, etc.
2. Micro nutrient or trace elements: These are nutrients that are required by the plants in small quantities for their growth and development e.g. zinc, copper and cobalt.
Metabolism
Metabolism in living organisms is grouped into parts namely:
(a) Anabolism: It is defined as the building up of complex organic molecules from simple ones in a biological system. Common examples of anabolic processes include;
i. The formatting of glycogen from glucose
ii. The formation of starch from glucose
Catabolism
This is defined as the breaking down of complex organic molecules into simple substances coupled with the release of energy. The catabolism process includes; respiration, digestion, etc.
Tests and Exercises
1. Parasite can be classified into two types (a)Endo and Ecto parasite (b) Endo and hydrostatic (c)Endo and Exo (d)None of the above. Answer: Endo and Ecto parasite
2. The two major types of nutrition are (a)Autotrophic and holizoic (b) Autotrophic chemosynthetic (c) Parasitic and carnivorous. Answer: Autotrophic and Chemosynthetic.
3. 6Coz + H20 sunlight chlorophyll. C6H1206+602
The above equation is (a) Respiration (b)Digestion (c) Photosynthesis (d) Enzymes. Answer: Photosynthesis
4. Zinc is an example of …………… nutrient. (a)Micro nutrient (b) Macro (c)Single nutrient (d) Plant nutrient. Answer: (micro nutrient)
5.Metabolism can be grouped into …………… (a) Respiration and inspiration (b) Combustion and respiration (c) Anabolism and catabolism (d)None of the above. Answer: Anabolism and catabolism
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