Modes Of Nutrition - SS1 Biology Lesson Note

All living organisms need to carry out the function of nutrition to survive. This function can be grouped into two classes: autotrophic nutrition and heterotrophic nutrition. 

AUTOTROPHS

Autotrophic nutrition is a type of nutrition where organisms can produce their own organic compounds using inorganic substances and an external energy source. Autotrophs can synthesize their own food, typically through photosynthesis or chemosynthesis.

1.     Photosynthesis: Plants, algae, and some bacteria are examples of organisms that use photosynthesis to convert sunlight, carbon dioxide, and water into glucose (a form of carbohydrate). The process takes place in chloroplasts, where pigments such as chlorophyll capture sunlight energy. Oxygen is released as a byproduct.

Figure 73 image from khanacademy.com

1.     Chemosynthesis: Certain bacteria and archaea in extreme environments, such as deep-sea hydrothermal vents, use chemosynthesis to obtain energy. They utilize inorganic molecules, such as hydrogen sulfide or ammonia, and convert them into organic compounds without the use of sunlight.

In both cases, autotrophs can produce their own food and energy sources, making them self-sustaining. They serve as the primary producers in ecosystems, forming the foundation of the food chain. Heterotrophs, including animals and some bacteria, depend on autotrophs for their energy needs by consuming them or their byproducts.