6.3.1 Ecosystems Flashcards
What is an ecosystem?
-all the living organisms living in a certain area and all the non-living physical factors(abiotic) that are present in that area—} includes biotic and abiotic factors
What are biotic factors and give examples
-biotic factors are the living features of an ecosystem and the interaction between organisms i.e food, space, territory, presence of predators, breeding partners
What is abiotic factors and give examples
-non living features of an ecosystem, such as:
-light(affects photosynthesis), -temp(affects enzyme controlled metabolic reactions—} changes can trigger migration/ hibernation & leaf-fall, dormancy, and flowering)
-rainfall/humidity(lack of water= water stress—} causes plants to wilt)
-soil nutrient availability
-wind speed= increases rate of water loss by evaporation + cooling rate
Abiotic factors- physiographic
-altitude/oxygen conc= affects animals that respire aerobically
-topography(shape of land)
-aspect(north or south facing)
-water supply
-salinity
Abiotic factors- Edophic(soil features)
-pH of water or soil(affected by enzyme activity + ion uptake)
-availability of inorganic ions(affects growth)
What is decomposition?
-chemical process in which a compound is broken down into smaller molecules–} normally because the compound cannot be directly used in its organic form
What is a decomposer?
-organism that feeds on + breaks down dead plant or animal matter–} turns organic compounds inorganic/into nutrients that are available to producers in ecosystems
Why are decomposers known as saprotrophs?
-because they obtain their energy from dead/waste organic material(saprobiotic nutrition)
-digest food externally by secreting enzymes onto dead organisms/organic waste matter–} enzymes break down complex organic molecules into simpler soluble molecules + the decomposers can absorb those molecules
What are detritivores?
-a class of organisms that help speed up decaying process by feeding on dead/decaying material-
-} break it down into smaller pieces of organic material which increases the SA for decomposition
What is the carbon cycle?
-how carbon moves through living organisms + the non-living environment—} needed to make essential compounds i.e plants use it in photosynthesis to make glucose
Carbon cycle: photosynthesis
-CO2 is absorbed by plants when they carry out photosynthesis–} converted into small carbon-containing molecules i.e glucose in plants + photosynthetic organisms
-carbon is also used in production of macromolecules i.e carbs, proteins in producers
(atmospheric CO2 and CO2 dissolved in oceans provides major source of inorganic carbon in plants)
Carbon cycle: Respiration
-carbon is returned to the air + water as all living organisms carry out respiration which produces CO2
Carbon cycle: consumption of organic molecules containing carbon
-carbon is passed onto primary consumers when they eat plants(then passed to secondary and tertiary consumers via the food chain)
Carbon cycle: decomposition
-all living organisms die + their carbon compounds re released via decomposers–} released into the atmosphere as CO2 when decomposers respire
Carbon cycle: combustion
-if dead organic matter accumulates in areas with no decomposers i.e ocean bed or bogs then the carbon can become ‘trapped’ and form fossil fuels over millions of years
-carbon is released when it is burned
Carbon cycle: release from volcanoes
-rock can be formed from dead organic matter deposited on the sea floor
-carbon can be returned to the atmosphere from these rocks via movement of tectonic plates–} undergo chemical changes + release CO2(returned to atmosphere by volcanoes)
Carbon cycle: weathering
-rocks can be eventually become land which is then weathered(broken down by exposure to the atmosphere)
-can happen chemically by rainwater(slightly acidic due to the CO2 dissolved in it) and physically i.e by plant roots, animals etc
-causes CO2 to be released back into the atmosphere
Carbon cycle: Release from + absorption into the oceans
-CO2 can also dissolve directly into the oceans from the atmosphere + be transported in the oceans by underwater currents
-CO2 can eventually return to surface and be released back into the atmosphere
How does energy enter an ecosystem?
-via photosynthesis, as plants convert energy from the sun into a form that can be used by other organisms i.e biomass
What is biomass?
-the mass of living material present in a particular place or in a particular organism
What are trophic levels and how can they be used to show energy transfer?
-trophic level= each stage in a food chain/web(diagrams that show the transfer of biomass + therefore energy through the organisms in an ecosystem)
-level 1= producer: converts light energy into chemical energy via photosynthesis
-subsequent levels= consumers: organisms that obtain their energy by feeding on other organisms
(food chains rarely go past quaternary as there is not sufficient biomass + stored energy left to support any further organism)
What is the role of decomposers in food webs?
-break down dead organisms, releasing nutrients back into the ecosystem–} recycle energy trapped in things that can’t be eaten i.e bones
How is biomass calculated?
-multiply the biomass present in each organism by the total no. of organisms in that trophic level
How is biomass represented?
-in a pyramid of biomass that shows the total dry mass (gm-2) of all organisms at each trophic level at a given time (doesn’t take into account seasonal changes)
-organisms gain biomass through the assimilation of digested compounds into organic molecules for storage + growth
