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Photosynthesis is the main means by which plants, algae and many bacteria produce organic compounds and oxygen from carbon dioxide and water ( green arrow ). An autotroph is an organism that can convert abiotic sources of energy into energy stored in organic compounds, which can be used by other organisms. Autotrophs produce complex organic ...
The food chain is an energy source diagram. The food chain begins with a producer, which is eaten by a primary consumer. The primary consumer may be eaten by a secondary consumer, which in turn may be consumed by a tertiary consumer. The tertiary consumers may sometimes become prey to the top predators known as the quaternary consumers.
Primary production is the production of chemical energy in organic compounds by living organisms. The main source of this energy is sunlight but a minute fraction of primary production is driven by lithotrophic organisms using the chemical energy of inorganic molecules. The Calvin cycle of photosynthesis. Regardless of its source, this energy ...
The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way ...
Consumer (food chain) A consumer in a food chain is a living creature that eats organisms from a different population. A consumer is a heterotroph and a producer is an autotroph. Like sea angels, they take in organic moles by consuming other organisms, so they are commonly called consumers. Heterotrophs can be classified by what they usually ...
e. In ecology, the term productivity refers to the rate of generation of biomass in an ecosystem, usually expressed in units of mass per volume (unit surface) per unit of time, such as grams per square metre per day (g m −2 d −1 ). The unit of mass can relate to dry matter or to the mass of generated carbon. The productivity of autotrophs ...
The organisms responsible for primary production are called primary producers or autotrophs . Most marine primary production is generated by a diverse collection of marine microorganisms called algae and cyanobacteria. Together these form the principal primary producers at the base of the ocean food chain and produce half of the world's oxygen.
Decomposer. Fungi acting as decomposers of a fallen tree branch. Decomposers are organisms that break down dead or decaying organisms; they carry out decomposition, a process possible by only certain kingdoms, such as fungi. [1] Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substrates to get their ...