How Autotrophs Differ from Heterotrophs in Obtaining Energy

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An ecosystem is an ecological and biological environment where its members include plants, animals, sun, soil and water. The components in an ecosystem interact with each other for survival.  The food chain is a complex representation of the producer-consumer relationship in an ecosystem.  The energy from food is passed on from one living organism to the next.  The food chain is a sequence of different trophic levels where one organism eats another organism.  At the base of the food chain are the producers or the autotrophs.

The autotrophs are organisms that are able to produce food for their own consumption. Examples are plants. Plants derive their energy from the sun through photosynthesis. The chlorophyll in plants is responsible for absorbing the light energy. Combined with the carbon dioxide present in plants, the photosynthetic activity produces sugar and carbohydrates. These are components for food.   Autotrophs that use that light as the source of energy are called phototrophs. Autotrophs that derive their energy from inorganic compounds through biosynthesis are called lithotrophs. Examples are bacteria. Lithotrophic bacteria use the electron from an inorganic donor to be used in cellular respiration. Energy is thereby generated in the process.

In the next level of the food chain are the consumers or heterotrophs. Unlike autotrophs, heterotrophs cannot produce their own food for their energy consumption. Heterotrophs use the carbon compounds from plants and animals by eating them. Heterotrophs use the carbon compounds that autotrophs produce. By breaking them down through digestion, the resulting compound is then used for energy. This energy is then absorbed and transported to the cells.

Heterotrophs may consume other heterotrophs. This makes them secondary and tertiary consumers.  An example of such a food chain is the grass-grasshopper-snake-hawk chain. Grass is the autotroph. The grasshopper, a heterotroph, consumes the grass. The grasshopper is called the primary consumer. When the snake eats the grasshopper, it becomes the secondary consumer.  The hawk becomes the tertiary consumer when it consumes the snake that ate the grasshopper.  The energy is passed on primarily from the sun to the autotophs then to the heterotrophs.

Given that an ecosystem is the environment where autotrophs, heterotrophs and other elements interact, it is safe to say that all these elements are dependent on one another. Thus, achieving a balance in the ecosystem is essential for its survival.  Eliminating autotrophs can be detrimental to the heterotrophs. Eliminating the heterotrophs can also be detrimental to the autotrophs because the heterotrophs exhale the carbon dioxide the autotrophs use for photosynthesis.


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