Autotrophs are organisms that can produce their own food from the substances available in their surroundings using light (photosynthesis) or chemical energy (chemosynthesis). Heterotrophs cannot synthesize their own food and rely on other organisms — both plants and animals — for nutrition. Technically, the definition is that autotrophs obtain carbon from inorganic sources like carbon dioxide (CO2) while heterotrophs get their reduced carbon from other organisms. Autotrophs are usually plants; they are also called "self feeders" or "primary producers".
Yes | No |
Primary | Secondary and tertiary |
Photoautotroph, Chemoautotroph | Photoheterotroph, Chemoheterotroph |
Plants, algae, and some bacteria | Herbivores, omnivores, and carnivores |
An organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide. | Heterotrophs cannot produce organic compounds from inorganic sources and therefore rely on consuming other organisms in the food chain. |
Produce their own food for energy. | They eat other organisms to get proteins and energy. |
Autotrophs produce their own energy by one of the following two methods:
- Photosynthesis - Photoautotrophs use energy from sun to convert water from the soil and carbon dioxide from the air into glucose. Glucose provides energy to plants and is used to make cellulose which is used to build cell walls. E.g. Plants, algae, phytoplankton and some bacteria. Carnivorous plants like pitcher plant use photosynthesis for energy production but depend on other organisms for other nutrients like nitrogen, potassium and phosphorous. Hence, these plants are basically autotrophs.
- Chemosynthesis - Chemoautotrophs use energy from chemical reactions to make food. The chemical reactions are usually between hydrogen sulfide/methane with oxygen. Carbon dioxide is the main source of carbon for Chemoautotrophs. E.g. Bacteria found inside active volcano, hydrothermal vents in sea floor, hot water springs.
Heterotrophs survive by feeding on organic matter produced by or available in other organisms. There are two types of heterotrophs:
- Photoheterotroph – These heterotrophs use light for energy but cannot use carbon dioxide as their carbon source. They get their carbon from compounds such as carbohydrates, fatty acids and alcohol. E.g. purple non-sulfur bacteria, green-non sulfur bacteria and heliobacteria.
- Chemoheterotroph – Heterotrophs that get their energy by oxidation of preformed organic compounds, i.e. by eating other organisms either dead or alive. E.g. animals, fungi, bacteria and almost all pathogens.
Photoautotroph | Light | Carbon dioxide |
Chemoautotroph | Chemicals | Carbon dioxide |
Photoheterotroph | Light | Carbon from other organisms |
Chemoheterotroph | Other organisms | Other organisms |
Food Chain
Autotrophs do not depend on other organism for their food. They are the primary producer and are placed first in the food chain. Heterotrophs that depend on autotrophs and other heterotrophs for their energy level are placed next on the food chain.
Herbivores that feed on autotrophs are placed in the second trophic level. Carnivores that eat meat and omnivores that eat all types of organisms are placed next in the trophic level.
References
- Wikipedia: Autotroph
- Wikipedia: Chemoheterotroph
- Wikipedia: Heterotroph
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views updated Jun 11 2018
Photoautotrophs
Chemoautotrophs
An autotroph is an organism able to make its own food. Autotrophic organisms convert inorganic molecules into organic compounds. Autotrophs are referred to as primary producers, and they occupy the ecological niche at the base of all food chains. There are two categories of autotrophs, distinguished by the type of energy each uses to synthesize organic products. Photoautotrophs use light energy and chemoautotrophs use chemical energy.
Photoautotrophs
Photoautotrophs are the most common autotrophs. Plants and some photosynthetic bacteria comprise the majority of photoautotrophs. Photoautotrophs contain organelles called chloroplasts, which have the ability to convert the energy from photons into chemical energy stored in sugars and other energy-containing molecules. This process is known as photosynthesis. Photosynthesis also requires water, which plants usually acquire through their roots and atmospheric carbon dioxide, which plants acquire through their leaves. In addition, photosynthesis results in the production of inorganic oxygen.
Plants and other photoautotrophs play an important ecological role in nearly all terrestrial ecosystems. Because photoautotrophs convert light energy into energy that is stored in energy-rich molecules, animals depend on them as a source of both energy and nutrients. Photosynthesizers form the base of common ecological food webs. For example, the base of the forest food chain may be trees; the base of a savannah food chain may be grasses; and the base of a desert food chain may be cacti.
Chemoautotrophs
Chemoautotrophs are bacteria that use chemical energy in inorganic compounds as a source of energy. They synthesize sugars from the inorganic molecule carbon dioxide.
Sulfur reducers are chemoautotrophs that use the energy in inorganic sulfur compounds as a source of energy. Sulfur reducers can be found living near vents and active volcanoes on the ocean floor, where inorganic sulfur from within the Earth’s core is released into the ocean water. These bacteria may live as symbionts with tube worms and clams found near the vents, providing them with a source of nutrition as well. These chemoautotrophic bacteria thrive at extremely high temperatures. Many of these bacteria, called extremophiles, are classified in the Domain Achaea.
views updated May 29 2018
An autotroph is an organism able to make its own food. Autotrophic organisms take inorganic substances into their bodies and transform them into organic nourishment. Autotrophs are essential to all life because they are the primary producers at the base of all food chains. There are two categories of autotrophs, distinguished by the energy each uses to synthesize food. Photoautotrophs use light energy; chemoautotrophs use chemical energy.
Photoautotrophs
Plants are the most abundant and recognizable autotrophs on Earth . If you have noticed a houseplant on a windowsill imperceptibly turn its leaves toward the sun , you have probably guessed that plants are photoautotrophs. Plant leaves soak up the energy in sunlight and use it to make food. Plants take in water through their roots and atmospheric carbon dioxide through their leaves. Plant cells absorb light energy to fuel the synthesis of inorganic hydrogen , oxygen , and carbon into a sugar that nourishes them. This process is known as photosynthesis .
Because plants, as autotrophs, make living tissue solely out of nonliving material, they form the foundation of all food chains. Can you think of one thing you eat that does not, ultimately, come from plants? Plants are called primary producers because they create themselves out of transformed inorganic matter and, thus, are the "original food" that sustains all living things.
Chemoautotrophs
Until recently, scientists believed there existed only a few kinds of bacteria that used chemical energy to create their own food. Some of these bacteria were found living near vents and active volcanos on the lightless ocean floor. The bacteria create their food using inorganic sulfur compounds gushing out of the vents from the hot interior of the planet .
In 1993, scientists found many new species of chemoautotrophic bacteria living in fissured rock far below the ocean floor. These bacteria take carbon dioxide and water into their bodies and use the chemical energy in sulfur compounds to create nourishing carbohydrates and sugars. A unique characteristic of these chemoautotrophic bacteria is that they thrive at temperatures high enough to kill other organisms. Some scientists believe these unique bacteria should be classified in their own new taxonomic kingdom.
views updated Jun 11 2018
An organism that derives its carbon for building body tissues from carbon dioxide (CO2) or carbonates and obtains its energy for bodily functions from radiant sources, such as sunlight, or from the oxidation of certain inorganic substances. The leaves of green plants and the bacteria that oxidize sulfur, iron, ammonium, and nitrite are examples of autotrophs. The oxidation of ammonium to nitrite, and of nitrite to nitrate, a process called nitrification , is a critical part of the nitrogen cycle . Moreover, the creation of food by photosynthetic organisms is largely an autotrophic process.
views updated May 21 2018
autotroph An organism that uses carbon dioxide as its main or sole source of carbon. Compare heterotroph.
views updated Jun 08 2018
autotroph An organism that uses carbon dioxide as its main or sole source of carbon. Compare HETEROTROPH.
views updated May 17 2018
autotroph An organism that uses carbon dioxide as its main or sole source of carbon. Compare HETEROTROPH.
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