6.5-ecosystems :) Flashcards
what is an ecosystem?
any group of living or non living things and the relationships between them.
what are the components of an ecosystem?
habitat
population
community
what is a population?
all the organisms of 1 species who live in the same place at the same time and breed together.
what is a community?
all the populations of different species who live in the same place at the same time and who can interact with eachother.
what is the niche of a species?
the role of each species in an ecosystem.
what are the biotic factors affecting an ecosystem?
producers
consumers
decomposers
how do biotic factors affect ecosystems?
affect other organsisms’ food supplies
predation
disease
what are examples of abiotic factors affecting ecosystems?
pH
relative humidity
temperature
pollutant conc
what are the 3 types of change in ecosystems?
cyclic
directional
unpredictable
what are cyclic changes?
changes that repeat themselves in a rhythm, eg tides
what are directional changes?
changes which go in 1 direction+are usually longer lasting than the lifetimes of organisms.
what are 2 examples of directional changes?
deposition of silt in an estuary
erosion of a coastline
what is a trophic level?
the level at which an organism feeds in a food chain.
why is biomass lost at each trophic level?
metabolic processes eg respiration
waste material
parts that can’t be digested
ecological efficiency=?
(biomass at higher trophic level/biomass at lower trophic level) x 100
what is productivity?
the rate of production of new biomass by producers.
what is gross primary productivity?
the rate at which plants convert light energy to chemical energy through photosynthesis
get your notes on net primary productivity
do it
what are saprotrophs?
organisms that feed on decaying/dead organic matter.
what is nitrogen fixation?
when nitrogen gas in the air is converted to useful organic nitrogen compounds
chemical symbol for nitrates?
NO3-
chemical symbol for nitrites?
NO2-
when can nitrogen fixation occur?
lightning
bacteria
haber process
what free living bacteria in the soil do nitrogen fixation?
Azotobacter
what bacteria that live in root nodules do nitrogen fixation?
Rhizobium
how do nitrogen fixing bacteria in nodules work?
use nitrogen reductase to turn n2 into nh4+ which is used by plant
what does Nitrobacter bacteria do?
oxidises nitrites to nitrates
what does Nitrosomonas bacteria do?
oxidises NH4+ to nitrites
what does Azotobacter bacteria do?
nitrogen fixing (lives free in soil)
what does Rhizobium bacteria do?
nitrogen fixation in root nodules
what are the 4 processes of the nitrogen cycle?
nitrogen fixation
nitrification
decomposition/ammonification
denitrification
what are chemoautotrophic bacteria?
bacteria which get their energy not from sunlight but from chemical reactions, eg oxidising NH4+ to NO2- or No2- to N03-.
what is nitrification?
oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate.
what is denitrification?
turning nitrates to nitrogen gas.
what part of the nitrogen cycle needs well aerated soils?
nitrification: requires oxygen.
what can nitrates be used for in a plant?
making nucleotide bases and amino acids.
under what conditions does denitrification take place?
anaerobic, eg waterlogged soils.
why does denitrification take place?
no o2: bacteria use nitrates as source of o2, producing n2 and n20.
what do aquatic plants use for photosynthesis?
dissolved carbonates.
what is a climax community?
the final stable community that exists after the process of succession has occurred.
what are pioneer species?
species that begin the process of succession, often colonising an area as the 1st living things there.
what is succession?
progressive change in a community of organisms over time.
what is primary succession?
development of a community from bare rock.
what is a pioneer community?
all the living organisms that occupy an area undergoing primary succession in the beginning stages
where does secondary succession take place?
on a previously colonised but disturbed or damaged habitat.
what is the sub climax community 9result of deflected succession) called?
plagioclimax
what 2 types of data can you collect using a quadrat?
% distribution
abundance (no of individuals)
how can you make your quadrat more accurate?
use a point frame
what are the 2 types of transect?
line
belt
what do you do with a line transect?
make a note of which species is touching it at eregular intervals
what do you do with a belt transect?
place quadrat next to it
what’s an interrupted belt transect?
when you place the quadrat next to it at regular intervals.
what is a continuous belt transect?
when you just move the quadrat along the transect.
