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Food chain:- The sequence of transfers of matter and energy in the form of food from organism to organism. Food chains intertwine locally into a food web because most organisms consume more than one type of animal or plant. Plants, which convert solar energy to food by photosynthesis, are the primary food source. In a predator chain, a plant-eating animal is eaten by a flesh-eating animal. In a parasite chain, a smaller organism consumes part of a larger host and may itself be parasitized by even smaller organisms. In a saprophytic chain, microorganisms live on dead organic matter.

Types of Food Chain:-

Grazing food chain:- This type of food chain is exhibited when living green plants are fed on by grazing herbivores, which are, in turn, fed on by carnivores. Ecosystems with this type of food chain are highly dependent on an influx of solar radiation. This is because, in predator food chains, the energy source is the sun and the green plants, due to their possession of chlorophyll (a pigment contained in the leaves and stems of green plants) use solar energy to make food for the ecosystem in a process referred to as ‘Photosynthesis’. This type of chain thus depends on autotrophic energy capture and the transfer of this captured energy to herbivores. Most of the ecosystems in nature exhibit this type of food chain. Examples of food chains in this category include: Phytoplankton -> zooplanktons -> Small fish -> Larger fish -> Birds -> Decomposer Detritus Food Chain:- This type of food chain starts from dead organic matter, which is fed on by microorganisms to organisms feeding on detritus and their predators. Such ecosystems are, therefore, less dependent on direct solar energy. These depend chiefly on the influx of organic matter produced in another system. For example, such type of food chain operates in the decomposing accumulated litter in a temperate forest. It is also referred to as ‘decomposer food chain’. Bacteria and fungi feed on the feces of animals, the cellulose of fallen trees, dead bodies of animals, etc. However, as bacterial cells of a decomposer species exhaust their supply of detritus (food), the bacterial population decreases as a result of an insufficient amount of food necessary for the sustenance of the whole bacterial population. The organic remains of the bacterial cells are decomposed by another set of microbial decomposer cells. Therefore, the end product of detritus food chains includes carbon dioxide and inorganic compounds such as nitrates, sulphates, phosphates. At the end of the detritus cycle, no combustible organic matter is usually left. A typical example of this type of food chain is illustrated below: Humus → Earthworm → Domestic fowl → Human being → Decomposers

Importance of Food Chain:- 1) The study of food chain improves our understanding of the problems of bio-magnifications (That is, the increasing concentration of a toxic substance in tissues of tolerant organisms, which build up at successively higher levels in a food chain). 2) The studies of food chain help us to understand the feeding relationships and the interactions between organisms in an ecosystem. 3) Having knowledge of the food chain in an ecosystem enables us to appreciate the energy flow mechanism and circulation of matter in an ecosystem. 4) It improves our knowledge about the movement of toxic substances in an ecosystem. Examples of Food chain:- 1) Decayed plants – worms – birds – eagle (Grazing food chain) 2) Corn – chick – snake – man (Grazing food chain) 3) Dandelions – snail – frog – bird – fox (Grazing food chain) 4) Carrots – rabbit – snake – eagle (Grazing food chain) 5) Solar energy – algae – fish – storks – crocodiles – decomposers (Grazing food chain) 6) Humus – Earthworm – Domestic fowl – Human being – Decomposers (Detritus food chain)