bio 2 - ch 34 nature of ecosystems (post)

ecoystem

the level of biological organization that includes both abiotic and biotic components

abiotic components to an ecosystem

includes the nonliving aspects, such as sunlight, inorganic nutrients, and water availability; and the conditions like soil, average temperature, and windspeed

biotic components to an ecosystem

the various populations of organisms that form the community

• the populations are categorized by their food source

autotrophs

self feeders that require only inorganic nutrients and an outside energy source to produce organic nutrients for their own use as food

• since they produce food for themselves and other members of the community they are also called producers

photoautotrophs

photosynthetic organisms such as algae and plants that produce most of the organic nutrients for the biosphere

chemoautotrophs

organisms that reduce carbon dioxide to an organic compound by using energetic electrons derived from inorganic compounds such as hydrogen sulfides, hydrogen gas, or ammonium ions

• they support communities at hydrothermal vents along deep-sea oceanic ridges

• some bacteria are these type of feeders

heterotrophs

also called other feeders which need an outside source of organic nutrients

• called consumers

• includes herbivores, carnivores, and omnivores

what are tertiary consumers called?

top predators

decomposers

heterotrophic bacteria and some species of protists and fungi (such as molds and mushrooms) that break down nonliving organic matter

• important because they release inorganic nutrients taken up by plants back into the environment

• detritus is partially decomposed matter in the water or soil - detritivores are found in all ecosystems and include Earthworms. termites, maggots, and some beetles

what are the two fundamental phenomena that ecosystems are characterized by?

energy flow and chemical cycling

energy flow

process that begins when producers absorb solar energy

chemical cycling

process that begins when producers take in inorganic nutrients (food) directly for themselves and indirectly for the other populations of the ecosystem

• only a portion of the organic nutrients made by autotrophs are passed onto heterotrophs because plants use some of the organic molecules to fuel their own cellular respiration

• only some of the nutrients from heterotrophs are available to higher level consumers

• some food eaten by herbivores is eliminated as feces that are recycled by decomposers

energy flow described by the laws of thermodynamics

1. energy cannot be created or destroyed

2. in every energy transformation some energy is lost as heat

food webs

interconnecting paths of energy flow within ecosystems represented by diagrams

• includes a grazing or detrital food web

trophic level

composed of all the organisms that feed at a particular level in a food chain

ecological pyramid

method used to show the large energy losses that occur between successive trophic levels

• in general about 10% of the energy of one trophic level is available to the next trophic level

• ecologists are hesistant to use pyramids to describe ecological relationships for all situations

biomass

the number of organisms multiplied by their weight - can be helpful instead of just numbers of organisms

what are pathways where chemicals circulate through ecosystems involve both biotic and geological components called?

biogeochemical cycles

for each element chemical cycling may involve which three steps?

• a reservoir - a source normally unavailable to producers like fossilized remains and rocks

• exchange pool - a source from which organisms generally take chemicals like atmosphere or soil

• the biotic community - how chemicals move along food chains perhaps never entering an exchange pool

what are the two biogeochemical cycles?

the gaseous cycle and sedimentary cycle

gaseous cycle of biogeochemical cycle

exemplified by the carbon and nitrogen cycles, the element is withdrawn from and returns to the atmosphere as gas

sedimentary cycle of biogeochemical cycle

exemplified by the phosphorus cycle, the element is absorbed from soil by plant roots, passed to heterotrophs, and eventually returned to the soil by decomposers

water cycle

also called the hydrologic cycle in which fresh water is first distilled from salt water through evaporation and then condensation followed by transpiration

aquifers

rock layers that contain water and release it in appreciable quantities to wells or springs

phosphorus cycle

cycle in which phosphorus moves from rocks on land to the oceans where it gets trapped in sediments and then it moves back onto the land following a geological upheaval. on land the very slow weathering of rocks makes phosphate ions available to plants which take up phosphate from the soil

what do produces use phosphate for

a variety of molecules like phospholipids, ATP, and nucleotides that become a part of DNA and RNA