Types Of Nutrition - SS1 Biology Lesson Note

In cells, there are two primary types of nutrition: autotrophic nutrition and heterotrophic nutrition. These two types of nutrition describe how cells obtain energy and nutrients to support their metabolic activities.

1.     Autotrophic Nutrition: Autotrophic nutrition is the process by which certain cells or organisms can produce their own food using inorganic substances and an external energy source. These organisms are called autotrophs. Autotrophs convert light energy (in the case of photosynthesis) or chemical energy (in the case of chemosynthesis) into organic molecules that can be used as a source of energy and nutrients.

a.     Photosynthesis: Photosynthetic autotrophs, such as plants, algae, and some bacteria, use sunlight, water, and carbon dioxide to produce glucose and oxygen. They contain specialized organelles called chloroplasts that contain the pigment chlorophyll, which captures light energy and initiates the process of photosynthesis.

Figure 50 Images from istockphoto.com

b.     Chemosynthesis: Chemosynthetic autotrophs, found in certain bacteria and archaea, use chemical energy derived from inorganic compounds (such as hydrogen sulfide or ammonia) to synthesize organic molecules. These organisms are often found in extreme environments, such as deep-sea hydrothermal vents or hot springs.

1.     Heterotrophic Nutrition: Heterotrophic nutrition is the process by which cells or organisms obtain energy and nutrients by consuming organic molecules produced by other organisms. These organisms are called heterotrophs. Heterotrophs depend on the organic matter generated by autotrophs or other heterotrophs to meet their nutritional needs. Heterotrophic nutrition can be further classified into different modes, including:

c.     Herbivores: Herbivores are organisms that primarily consume plant material (such as leaves, stems, or fruits) as their source of energy and nutrients. Examples include cows, rabbits, and grasshoppers.

Figure 51 Image from unsplash.com

d.     Carnivores: Carnivores are organisms that primarily consume other animals for energy and nutrients. They can be further classified into different types based on their hunting strategies and food preferences. Examples include lions, snakes, and spiders.

Figure 52 Image from dreamstime.com

e.     Omnivores: Omnivores are organisms that have a diverse diet and consume both plant and animal material. Humans are an example of omnivores, as we consume a variety of plant and animal-based foods.

f.     Detritivores and Decomposers: Detritivores and decomposers obtain their energy and nutrients by breaking down dead organic matter or waste materials. Detritivores, such as earthworms, feed on decaying organic matter, while decomposers, such as bacteria and fungi, break down complex organic substances into simpler molecules.