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Food chains & food webs - Khan Academy
A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. Let's look at the parts of a typical food chain, starting from the bottom …
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Review of trophic levels in ecology, including producers, consumers, and decomposers.
Energy flow & primary productivity (article) | Khan Academy
Learn about primary productivity, the (in)efficiency of energy transfer between trophic levels, and how to read ecological pyramids.
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An ecosystem is a community of living organisms and their physical environment interacting as a system.
可汗学院 - Khan Academy
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Unit 10: Cellular respiration - Khan Academy
This unit is part of the Biology library. Browse videos, articles, and exercises by topic.
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Effect of temperature, water, light, and soil on habitat selection.
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Plants need food to live, just like animals do. And chloroplasts use photosynthesis to produce sugars that plant cells use as food. Plant cells also have a layer outside their cell membrane …
The Production Possibilities Frontier - Khan Academy
The Production Possibilities Frontier (PPF) is a graph that shows all the different combinations of output of two goods that can be produced using available resources and technology.