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Ecosystems
| Question | Answer |
|---|---|
| define ecosystem | communities of living organisms and their interactions with their abiotic environment. Ecosystems are complex with many interacting parts and routinely exposed to various disturbances |
| what is a disturbance to an ecosystem? | changes in the environment that affect their compositions, ex. yearly variations in rainfall & temperature |
| define ecological succession | transition in the species composition of a community following a disturbance; succession is the orderly replacement of populations of plants and animals in an area following a disturbance until a stable community is reached |
| what causes succession? | succession is the result of changes induced by the vegetation itself |
| how does the composition of a community change during succession? | less diversity (less species) -> more diversity (more species); fewer individuals -> more individuals; more r-selected species -> more K-selected species |
| describe primary succession in terms of conditions at the beginning, sources and types of first species, and time frame over which succession occurs | at the start, substrate is bare; first colonizers are prokaryotes, unicellular protists, lichen & moss by windblown spores; could take hundreds to thousands of years to reach climax community |
| what is the climax community? | the most stable form of a community reached after a full process of succession, where little change occurs until a new disturbance |
| describe secondary succession in terms of conditions at the beginning, sources and types of first species, and time frame over which succession occurs | at the start, substrate is "pre-owned" where remnants of the previous community remain; first colonizers are grasses from windblown or animal-borne seeds or annual plants within a few years; often takes decades to reach climax community |
| describe lichens' roles in primary succession | may break down a rocky surface by physical penetration by hyphae; chemical digestion by enzymes to break down substrate into useable soil; trapping windblown soil or seeds; adding nitrogen to the substrate |
| why are pioneer species replaced by other species during succession? | they change the environment to make it more suitable for other organisms (e.g. they contribute matter to soil as they die & decompose so it holds more water & nutrients), and these organisms often have evolutionary advantages over the pioneer species |
| describe succession from bare rock to climax community (glacial moraines) | 1.exposed moraine colonized by pioneering plants (liverworts, mosses, Dryas, willows) 2.after ~30yr, Dryas dominant plant due to N2-fixing bacteria 3. alder invades & forms dense thickets, blocking sunlight 4.on slopes, alders overtaken by spruce, hemlock |
| define biome | a major type of ecosystem that occupies large geographical areas of land and water |
| describe abiotic factors determining biomes | distance to equator, latitudinal & seasonal variations in sunlight, air circulation & precipitation, temperature & humidity, altitude |
| characterize changes in temperature & available sunlight from equator to poles. how does curvature of earth affect these changes? | temperature is highest & sunlight most available at equator, gradually both decrease moving towards the poles as the curvature of earth lowers angle of incoming sunlight, spreading solar energy over a larger area |
| characterize changes in precipitation from equator to the poles - air circulation patterns | across earth's surface, air circulation patterns form alternate tropic & arid zones; tropical areas receive high amounts of precipitation & arid zones receive low amounts; tropics at equator, around 40 S & 40 N latitude, arid zones at 30 S & 30 N & poles |
| describe seasonality and in reference to the tilt & rotation of the earth | as the earth rotates around the sun, due its curvature & fixed axis, the northern & southern hemispheres of earth experience opposite cold and warm season depending on which side is directly facing the sun |
| define abiotic & biotic | abiotic: non-living; biotic: living |
| describe how altitude affects biomes | as elevations rise on earth's surface, temperatures drop as land moves away from earth's warm surface and into less dense, cooler air |
| describe the global pattern of terrestrial biomes | typically, farther from equator = colder & more arid: tropical forests & occasional savanna common around equator, near Tropics of Cancer & Capricorn - deserts, chaparral; then temperate biomes; then taiga; then tundra; then polar ice |
| what is an ecotone? | a boundary (area of intergradation) between one biome to the next. highly diverse |
| define primary production | percentage of energy entering the ecosystem incorporated into biomass at a specific trophic level |
| what is gross primary production (GPP)? | rate at which photosynthetic primary producers incorporate energy from the sun |
| what is net primary production (NPP)? | the energy that remains in the primary producers after the loss of energy thru the organisms' energy use (respiration & heat loss) |
| which terrestrial biome(s) has the highest NPP? why (abiotic factors)? (don't worry too much abt this question) | tropical wet forest because of: warm temperatures, intense sunlight, abundance of water & year-round growing season -> photosynthesis proceeds at a high rate, enzymes work most efficiently, leaf stomata remain open, allowing max amount of CO2 to enter |
| which terrestrial biome(s) has the lowest NPP? why (abiotic factors)? (don't worry too much abt this question) | extreme tundras, deserts or rocky biomes because of: low temperatures, low available sunlight, lack of available water & short growing seasons -> all cellular processes slowed and much more energy funneled into adaptations for survival |
| which aquatic biome(s) has the highest NPP? why (abiotic factors)? (don't worry too much abt this question) | coral reefs because: corals harbour photoautotrophs & live in shallow, warm waters where sunlight reaches them |
| which aquatic biome(s) has the lowest NPP? why (abiotic factors)? (don't worry too much abt this question) | open oceans & lakes because: low nutrient concentrations, low or too-high oxygen availability, absorption of sunlight & cold temperatures in deep waters |
| describe the key physical factors that limit production in aquatic ecosystems | temperature, sunlight (absorbed by ocean) & limiting nutrients. in freshwater, the limiting nutrient in phosphorous; in marine, limiting nutrients are phosphorous, nitrogen & iron |
| describe the key physical factors that limit production in terrestrial ecosystems | temperature, moisture (plants need lots of adaptations for dry environments) & limiting nutrients (phosphorous & nitrogen) |
| what is a limiting nutrient? | an element that must be added for production to increase in an ecosystem |
| explain carbon's role in the formation of biological structures and/or biological functioning | essential for all organic macromolecule structures (carbohydrates, lipids, proteins, nucleic acids) |
| explain oxygen's role in the formation of biological structures and/or biological functioning | used in the process of cellular respiration - the most efficient way to make ATP used in all aerobic organisms (most eukaryotes) |
| explain nitrogen's role in the formation of biological structures and/or biological functioning | essential building block for nucleic acids (DNA & RNA), amino acids/proteins, urea |
| explain phosphorous's role in the formation of biological structures and/or biological functioning | essential nutrient for living processes: major component of nucleic acids & phospholipids; as calcium phosphate, supportive components of bones; used in ATP |
| compare/contrast flow of energy and flow of nutrients (or matter) through an ecosystem | both flows involve interactions across ecosystems, between abiotic and biotic components and throughout different biomes; however energy flows directionally & does not replenish itself while nutrients are constantly cycling thru various chemical processes |
| describe one of the four nutrient cycles, identifying the main reservoirs for the nutrient, forms available to life & key processes that drive the cycle | ex. carbon: reservoir = biomass, atmospheric CO2; processes = photosynthesis, cellular respiration, burning of fossil fuels; forms available = sugars, carbon dioxide (CO2), carbonic acid (H2CO3-) |
| describe abiotic factors that affect the rate of decomposition | temperature & nutrient availability. in aquatic ecosystems: oxygen availability, water movement (ocean upwelling, seasonal turnover in lakes). in terrestrial ecosystems: moisture |
| describe vertical zones of production & decomposition in terrestrial & aquatic ecosystems | terrestrial: productive in forest canopy, decomposition forest floor - these are linked. aquatic: production in photic zone (surface water), decomposition on bottom sediments (benthic zone) - these aren't linked. |
| describe the role of vegetation in nutrient cycling | vegetation is important in taking up and holding nutrients in terrestrial ecosystems, keeping them available for organisms to use |
| describe how agriculture leads to nitrogen enrichment of terrestrial & aquatic ecosystems | 1.agriculture depletes nutrients in the soil 2. fertilizers add N to ecosystem 3. excess of nutrients leaches into ground, runoff to water 4. runoff&sewage -> phytoplankton blooms in lakes & oceans 5. decomp. of phytoplankton -> dead zones -> low O2 level |
| describe the two types of environments found in lakes | oligotrophic lake: nutrient poor, oxygen-rich, deep; eutrophic lake: nutrient-rich, oxygen-poor, shallow |
| what is eutrophication? | process by which nutrients become highly concentrated in a body of water, leading to increased growth of organisms such as algae and bacteria. Often caused by humans, barely possible by natural processes |
| what carbon reservoirs do humans use for fuel & energy? why does the use of these reservoirs increase the amount of atmospheric carbon? | humans use fossil fuels & animals as carbon sources. Burning of fossil fuels releases high amounts of CO2 & other chemicals into air; farming practices, respiration & methane production of large numbers of land animals lead to increased CO2 levels |
| how does increased atmospheric carbon influence primary productivity of ecosystems? | can increase photosynthetic rates, but global warming do not lead to increase in productivity in all ecosystems - results in communities thrown out of sync & abiotic factors changing faster than primary producers can adjust to |
| how does increased atmospheric carbon influence global climate? | CO2 is a primary greenhouse gas (GHG). When heat energy reaches Earth, GHGs trap the heat in the atmosphere -> more GHGs, more thermal energy reflected back to Earth's surface, heating it up and the atmosphere above it |
| implications of global climate change on ecosystems | loss of habitats (ex. sea ice), rising global temperatures (seasonal changes, changes in precipitation, loss of freshwater), thinning ozone layer -> increased sunlight intensity, These lead to loss of biodiversity as earth shifts to extreme conditions |
Created by:
AntBanana
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