FOOD CHAINS

From Big Medical Encyclopedia

FOOD CHAINS (synonym: mains circuits, trophic chains) — ranks of organisms in which the previous organism serves as food for the subsequent organism of this row (e.g., a plant — a herbivore — a predator — the microorganisms assimilating the substances which are formed at decomposition of a corpse of a predator).

P.'s existence c. perhaps thanks to the fact that organisms all of them links are constructed of identical elementary organic matters. Organisms depending on their place in P. of c. are subdivided on producers, konsument and reducers. Producers are autotrophic organisms (see), the synthesizing complex organic compounds from simple inorganic matters. Most often them are green plants. Consumers of organic matters — konsument — the organisms eating producers (e.g., vegetarians), predators, a shouting-ganizmy-parasites. The last link in P. of c. represent reducers — the microorganisms destroying corpses and assimilating the substances which are formed at their decomposition. The c entering P. organisms form consecutive chain links and its trophic levels. Animals are capable to use for creation of organic matters of the body only apprx. 10 — 20% of the energy concluded in substances of food, other energy is used for maintenance of life activity and dissipates in the form of heat therefore the substances synthesized by primary producers are enough for maintenance only 4 — 5 links of P. of c.

Along with food organic matters and the energy concluded in them through P. of c. also mineral substances, including heavy metals, radioactive nuclides, toxic organic compounds, etc. are transferred. In separate links of P. of c. cumulation of toxicants in the quantities dangerous to the person can be observed. Toxicants come to P. of c. of the environment or are formed by organisms. Significant effect on levels of toxicants in P. of c. renders anthropogenous environmental pollution. Levels of mineral substances, adverse for the person, in P. of c. are caused in some cases by features of geochemical regions (see. Biogeochemical division into districts ).



Bibliography: Willie K. and Detye V. Biologiya, lane with English, page 122, etc., M., 1974; Konyshev V. A. Evolutionary aspects of assimilation of food, Usp. sovr, biol., t. 89, No. 3, with, 433, 1980; About d at m Yu. Fundamentals of ecology, the lane with English, page 85, etc., M., 1975.


V. A. Konyshev.

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