- ultimately, this energy source is the sun (in most ecosystems) provides light energy to plants and other autotrophic organisms through photosynthesis, these organisms make organic tissue from the basic chemical components around them Photosynthesis creates oxygen keeps all heterotrophic life alive had strong implications in Earth s history &egrave; one exception to the Sun as an energy source: CHEMOSYNTHESIS occurs at hydrothermal vents radioactive decay deep in the Earth provides heat Chemoautotrophs - bacteria -without the presence of sunlight, they can convert dissolved hydrogen sulfide (H 2 S) and CO 2 into organic molecules (sugars, etc ) (3) Ecosystems also require Nutrients : essential building blocks of all life they cycle on the planet: biogeochemical cycles 17 nutrients are essential if a specific key nutrient is "limited", organism development is inhibited Some dynamic properties of ecosystems: food chain : group of organisms that feed on each other food web : a complicated network of food chains trophic structure: pyramid shape refers to the pathways by which energy is transferred and nutrients are cycled through trophic levels primary producers autotrophic plants and microscopic photosynthetic organisms first and essential producers of organic material in any ecosystem primary and secondary consumers heterotrophic feed directly or indirectly on producers primary consumers : feed directly on autotrophs ( herbivores ) secondary consumers : feed on primary consumers Characterizing trophic levels: biomass productivity gross productivity net productivity ecological efficiency the % transfer of energy from one level to the next decomposers fungi and bacteria, also heterotrophic reintegrate or break down detrital material Summary: 3 components of ecosystems: energy flow nutrients and nutrient cycling biotic and abiotic interactions But what s the bigger picture beyond the "ecosystem"?
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also require provides is is transferred Characterizing are provides refers cycle can convert occurs creates make heterotrophic feed keeps feed
essential building blocks of all life they cycle on the planet: biogeochemical cycles
light energy to plants and other autotrophic organisms
limited
trophic levels
essential
heat Chemoautotrophs - bacteria -without the presence of sunlight
to the pathways
L:on the planet
dissolved hydrogen sulfide into organic molecules
L:at hydrothermal vents
oxygen
organic tissue
all heterotrophic life
on each other food web