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Concepts for Population and Ecosystems
Populations
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Primary |
Intermediate |
Middle |
| A population consists of all individuals of a species that occur together at a given place and time. | Populations
of organisms can be categorized by the function they serve in a community
(eg. producer and consumer). Plants and some microorganisms are producers- they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. |
The population of an ecosystem depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic and no disease of predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of a population in specific niches in the ecosystem. Releationships may be competitive or mutually beneficial. Some species have adapted to each other to the point that they could not survive without each other. |
Ecosystems
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Food chains identify the relationships among producers and consumers. Food cycle includes producers, consumers, and decomposers. |
Food
webs identify the relationships among producers, consumers, and decomposers
in an ecosystem. An ecosystem includes all populations living together and the physical environmental factors with which they interact. For ecosystems, the major source of energy is sunlight which is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food. In the process of decomposing organic matter they create nutrients for plants. |