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Jeremy Ryan Z. Arroyo Science ReviewerA food chain is a linear sequence of links in a food web starting from a speciesthat are called producers in the web and ends at a species that is called decomposers species in the web. A food chain also shows how the organisms are relatedwith each other by the food they eat. A food chain differs from a food web, because the complex polyphagous network of feeding relations are aggregated into trophic species and the chain only follows linear monophagous pathways. A common m

etric used to quantify food web trophic structure is food chain length. In its simplest form, the length of a chain is the number of links between a trophic consumer and the base of the web and the mean chain length of an entire web is thearithmetic average of the lengths of all chains in a food web.A food web (or food cycle) depicts feeding connections (what-eats-what) in an ecological community and hence is also referred to as a consumer-resource system.Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs. To maintain their bodies, grow, develop, and toreproduce, autotrophs produce organic matter from inorganic substances, including both minerals and gases such ascarbon dioxide. These chemical reactions require energy, which mainly comes from the sun and largely byphotosynthesis, although a very small amount comes from hydrothermal vents and

hot springs.Biomagnification, also known as bioamplification or biological magnification, occurs when the concentration of a substance, such as DDT or mercury, in an organism exceeds the background concentration of the substance in its diet.[1] This increase can occur as a result of:

Persistence where the substance can't be broken down by environmental processes

Food chain energetics where the substance concentration increases progressivelyas it moves up a food chain

Low or non-existent rate of internal degradation or excretion of the substance often due to water-insolubilityThe following is an example showing how bio-magnification takes place in nature:An anchovy eats zoo-plankton that have tiny amounts of mercury that the zoo-plankton has picked up from the water throughout the anchovies lifespan. A tuna eat

s many of these anchovies over its life, accumulating the mercury in each of those anchovies into its body. If the mercury stunts the growth of the anchovies, that tuna is required to eat more little fish to stay alive. Because there are more little fish being eaten, the mercury content is magnified.

Ecological PyramidAn ecological pyramid of biomass shows the relationship between biomass and trophic level by quantifying the biomass present at each trophic level of an ecological community at a particular time. It is a graphical representation of biomass(total amount of living or organic matter in an ecosystem) present in unit area

in different tropic levels. Typical units are grams per meter2, or calories permeter2. The pyramid of biomass may be "inverted". For example, in a pond ecosystem, the standing crop of phytoplankton, the major producers, at any given pointwill be lower than the mass of the heterotrophs, such as fish and insects. Thisis explained as the phytoplankton reproduce very quickly, but have much shorterindividual lives.Water CycleThe water cycle, also known as the hydrologic cycle or the H2O cycle, describesthe continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time but the partitioningof the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables. Thewater moves from one reservoir to another, such as from river to ocean, or from

the ocean to the atmosphere, by the physical processes of evaporation, condensation,precipitation, infiltration, runoff, and subsurface flow. In so doing, thewater goes through different phases: liquid, solid (ice), and gas (vapor).

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Oxygen And Carbon Cycle

?When you inhale, you take in oxygen.?When you exhale, you release the waste gas carbon dioxide.?If something used carbon dioxide and released oxygen, it would balance your useof oxygen.?That something is producers such as green plants and certain microorganisms.

?These producers use carbon dioxide gas, water, and the energy of sunlight to make carbon containing compounds that are often referred to as "food."?During the food making process, the producers also produce oxygen, which is released into the environment.?Through this process, known as the oxygen cycle, there is always a plentiful supply of oxygen available for air-breathing organisms.

The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is nitrogen, making it the largest pool of nitrogen. Howeve

r, atmospheric nitrogen has limited availability for biological use, leading toa scarcity of usable nitrogen in many types of ecosystems.The phosphorus cycle is the biogeochemical cycle that describes the movement ofphosphorus through the lithosphere,hydrosphere, and biosphere. Unlike many otherbiogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth. The production of phosphine gas occurs only in specialized, local conditions.

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