Chapter55A2.4Notes

Chapter55A2.4Notes - Chapter 55 Notes Group A2.4 Observing...

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Chapter 55 Notes Group A2.4 Observing Ecosystems Ecosystem – sum of all organisms living within an area and all the abiotic factor with which they interact o Boundaries of an ecosystem sometimes are not distinct o Involves two important processes: Energy flow Energy enters as sunlight converted to chemical energy by autotrophs passed to heterotrophs in organic compounds of food let off as heat Energy cannot be recycled Chemical cycling Chemicals cycled by biotic and abiotic components of ecosystem Photosynthetic organisms take chemicals in inorganic from air, soil, and water and put them into their biomass chemicals returned to environment in organic form by metabolism of plants, animals, and other organisms Physical Laws Govern Energy Flow and Chemical Cycling Conservation of energy o First law of thermodynamics – energy cannot be created or destroyed, only transferred or transformed Total amount of energy as passes through ecosystem is not changed o Second law of thermodynamics – every exchange of energy increases the entropy of the universe Energy conversions cannot be totally effective Sometimes energy is lost as heat Conservation of mass o Law of conservation of mass – matter cannot be created or destroyed Chemicals are constantly cycled
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Elements not lost, just moved between ecosystems as outputs and inputs Energy, mass, and trophic levels o Species are assigned to trophic levels based on main source of nutrition and energy Primary producers – level that supports all others; consists of autorophs that are mainly photosynthetic Some are chemosynthetic Trophic level about primary producers = heterotrophs that depend on output of primary producers Primary consumers – herbivores that eat plants and other primary producers Secondary consumers – carnivores that eat herbivores Tertiary consumers – carnivores that eat carnivores Detritivores/Decomposers – consumers that obtain energy from nonliving organic material (remains of dead organisms, feces, etc.) Many eaten by secondary and tertiary consumers Two important groups: prokaryotes and fungi o Secret enzymes that digest organic material o Absorb breakdown components, linking consumers and primary producers Recycle chemical elements back to primary producers Energy and Other Limiting Factors Control Primary Production Primary production – amount of light energy converted to chemical energy by autotrophs during time period Ecosystem energy budgets o Amount of all photosynthetic production sets spending limit for ecosystem’s energy budget (primary producers use light energy energy-rich organic molecules broken down to make ATP) o Amount of solar radiation that ultimately hits Earth’s surface as absorption, scattering, and reflection by clouds and dust limits photosynthetic output
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Only small fraction of this radiation utilized for photosynthesis (some hits areas
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Chapter55A2.4Notes - Chapter 55 Notes Group A2.4 Observing...

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