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Dumber Dumber
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8 years ago
energy flow, biomagnification, and the cycling of matter?
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Answer rejected by topic starter
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Staff Member
8 years ago
Biodiversity is the diversity of life in an area. There are three kinds of biodiversity. One type is genetic diversity, which is the diversity of genes in a species. Species need certain genes, which produce variation, to survive. If the diversity is lacking, the species may die out (in that the species will not be able to adapt). Species diversity (another kind of biodiversity) is the variety of living things in areas such as rainforests, reefs, deserts, tundra, etc. The last type of biodiversity is ecological diversity. It’s the complexity and richness of an entire ecosystem.

Biodiversity increases ecosystem productivity; all of the species in that ecosystem, no matter their size, have a big role. A diverse ecosystem can prevent and recover from lots of disasters. Humans depend on plants and animals. For example, one quarter of all prescription medicines in the U.S. have ingredients from plants. If a diverse ecosystem is more productive, it's easier to get these plants.

Biomagnification is the increase in concentration of a substance, such as the pesticide DDT, that occurs in a food chain as a consequence of:

* Food chain energetics
* Low (or nonexistent) rate of excretion/degradation of the substance.

It is an important concept in ecology, environmental science, and ecotoxicology: it says that the solution to certain types of pollution is not dilution, because food chains will concentrate the pollutant.

In ecology, energy flow (calorific flow) refers to the flow of energy through a food chain.

In following energy flow in an ecosystem, ecologists seek to quantify the relative importance of different component species and feeding relationships.

A general energy flow scenario in an ecosystem enabling it to be a self-sustaining unit is as follows:

(1) Solar energy is fixed by the photoautotrophs, the so called primary producers, like green plants which fix the energy in forms such as glucose and ATP by photosynthesis.

(2) The primary consumers consuming these photoautotrophs are herbivores. They absorb most of the stored energy in the plant through digestion, and transform it into the form of energy they need, adenosine triphosphate, through respiration. A part of the energy received by the herbivore is converted to bodily heat (an effect of respiration), which is radiated away and lost from the system. Energy loss also occurs in the expulsion of egesta, which contains undigested energy compounds.

(3) Secondary Consumers, which are the lowest trophic level of carnivores, such as insectivores, then consume the primary consumers. Energy that had been used by the primary consumers for growth and storage is thus absorbed into the secondary consumers through the process of digestion. As with primary consumers, secondary consumers convert this energy into a more suitable form (ATP) during respiration. Again some energy is lost from the system, since energy which the primary consumers had used for respiration cannot be utilized by the secondary consumers.

(4) Tertiary consumers, which are the next trophic level of carnivores, then consume the secondary consumers, and most of the energy is passed along, while some is again lost in the ways described above and below, including heat and egesta loss.

(5) A final link in the food chain is decomposers, which break down the organic matter of the tertiary consumers (or whichever consumer is at the top of the chain) and release nutrients into the soil. Saprotrophic bacteria and fungi are decomposers, and play a pivotal role in the nitrogen and carbon cycles.

The energy is passed on from trophic level to trophic level, and each time some (about 10%-20%) of the energy is lost, with some being lost as heat into the environment (an effect of respiration) and some being lost as egesta. This means the top consumer of a food chain receives the least energy, as a lot of the food chain's energy has been lost between trophic levels. This loss of energy at each trophic level limits typical food chains to only 4-6 links.
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