TYPES OF NUTRITION [CSEC BIOLOGY & HSB]

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SYLLABUS REFERENCE 

CSEC Biology 

[B2.1] distinguish among heterotrophic, autotrophic and saprophytic nutrition. 



Nutrition is one of the CHARACTERISTICS OF LIFE 

It is how living organisms obtain the food chemicals (called nutrients) they need for energy, growth, development, defense against disease and self-repair. 

In the living world, there are several ways in which organisms obtain these nutrients. These strategies can be classified as either autotrophic (manufacture your own food) or heterotrophic (depending on other organisms as food sources). 

AUTOTROPHIC NUTRITION

Autotrophic organisms, such as green plants, are able to manufacture their own food chemicals. 

They are able to convert simple inorganic chemicals, such as nitrates and carbon dioxide, to complex organic substances, which are most nutrients. A source of energy is required. 

For example, green plants, via the process of PHOTOSYNTHESIS, uses light energy to power the conversion of carbon dioxide to glucose. This glucose is then converted to other nutrients, such as starch, fats, and proteins. 



HETEROTROPHIC NUTRITION 

Heterotrophic organisms cannot manufacture nutrients on their own. Therefore, they obtain nutrients by consuming other organisms and/or their products (called FEEDING). 

SAPROPHYTES feed by depositing digestive enzymes on the food material, outside their bodies. These enzymes break down the food to their component nutrients, which are then absorbed into the organism. Their preferred food source is dead and decaying organisms. 

Examples are bacteria, mushrooms and other fungi. 


Most heterotrophs, including human beings, are HOLOZOIC. This means that they ingest other organisms and/or their products. This means they take the food materials into their bodies. The food materials are then digested and absorbed inside their bodies.  

All Holozoic Heterotrophs Have Digestive Systems

This allows them to break down and absorb nutrients inside of their bodies. 





AUTOTROPH VS HETEROTROPH VS SAPROTROPH 





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