Population Size and Ecosystems Flashcards
population
group of organism of same species living in a particular area
intraspecific + interspecific species
between same species + between different species
population growth
births + immigration - deaths + emigration
lag phase
period of slow population growth
bacteria adapting/preparing for growth (e.g. enzyme synthesis)
log (exponential) phase
period of rapid cell division, cell production exceeds cell death
abundance of nutrients, low toxic waste, bacteria divide at constant rate, population doubles per unit per time
stationary phase
period where number of cells produced is equal to number of cells that die, population reaches carrying capacity
limiting factors take effect
death (decline) phase
period where cell death exceeds cell production
shortage of nutrients, build-up of toxic waste
carrying capacity
maximum population size a particular environment can support
population density
number of organisms in a given space
factors that limit population growth called
‘environmental resistance’
density dependent factors
- pop density increases, factors (biotic) have stronger effect
- food supply
- predation
- disease + parasitism
- accumulation of toxic waste
- components for limited resources (nesting sites)
- oxygen concentration
density independent factors
- affects pop no matter its density (abiotic factors)
- weather
- natural disasters
- temperature (lab flask/fermenter)
biotic
caused by living organisms
abiotic
caused by non-living components of environment
limiting factors
determine carrying capacity of an environment for a species
population fluctuates
around a ‘set point’, regulated by negative feedback
sampling techniques
measuring abundance = capture - mark - recapture
measuring distribution = belt transect
habitat
place where organism lives
community
interacting population of sexual species living in same habitat at same time
ecosystem
characteristica community of interdependent species interacting with biotic + abiotic components and their habitats
sun as energy source for ecosystems
photosynthesis, light energy to chemical
trophic level
feeding level
biomass
mass of biological material in living/recently living organisms
biomass transfer
food chain
plants, herbivores, carnivores
decomposition
decomposition
producers/consumers die, detritivores + decomposers feed as saprobients
photosynthetic efficiency
quantity of light energy incorporated into product ÷ quantity of energy falling on plant × 100
primary productivity
rate at which energy is converted by producers into biomass (kg/m2/yr) or rate of producing glucose in plants (kJ/m2/yr)
secondary productivity
rate at which consumers convert chemical energy of food into biomass
gross primary productivity
rate at which energy (kJm-2yr-1) is fixed inside new organic products in plants
net primary productivity
energy (kJm-2yr-1) in plants biomass available to primary consumers
GPP - respiration = NPP
efficiency of energy transfer
energy available after transfer ÷ energy available before transfer × 100
succession
change in structure + composition of species which make up a community over time due to changes in environment produced by species at each stage
seral stage
stage in succession
pioneer species
first organisms to colonise a habitat
found in first seral stage
climax community
stable community, reached equilibrium
final seral stage
primary succession
happena in new habitat never colonised before
primary succession
happena in new habitat never colonised before
secondary succession
series of changes in a community which take place in damaged previously colonised habitat
human interference affecting succession
sheep grazing
crops
burning heather moors
3 factors that have a role in succession
immigration
facilitation
interspecific competition
carbon cycle
atmospheric CO2
respiration (feeding + assimilation and decomposition involved), photosynthesis, combustion (fossilisation involved)
deforestation
reduced photosynthesis, reduced rate CO2 removed from atmosphere, tress burn/decay add to CO2
burning fossil fuels
adds to CO2
consequences of global warming
melting of polar ice, drought, forest fires affect distribution of species
extinction
rising sea levels
carbon footprint
total amount of CO2 generated by actions of an individual/product/service over 1 year
nitrogen cycle
nitrogen fixation, nitrification, putrefaction (ammonification), denitrification
bacteria in nitrogen cycle
azobacter - nitrogen fixation (nitrogen to ammonia)
rhizobium - nitrogen fixation (nitrogen to ammonia)
nitrosomonas - nitrification (ammonia to nitrite)
nitrobacer - nitrification (nitrite to nitrate)
pseudomonas - denitrification (nitrate to nitrogen)
ploughing
aerate + drain soil prevents waterlogging
removes anaerobic conditions for denitrifying bacteria
promotes aerobic conditions for nitrifying bacteria
plant roots can take up nitrogen to make organic nitrogen compounds (improves growth)
fertilisers
manure + slurry contain nitrogen compounds that can be broken down by putrifying bacteria into nitrate ions/nitrogen for plants
artificial fertilisers
ammonium ions taken up by plants for protein synthesis
negative impacts of fertilizers on ecosystems
increased growth of grass + nettles shade smaller plants (biodiversity reduced)
drainage ditches reduce biodivirsity
eutrophication
eutrophication
- leaching of nitrogen into rivers by rain
- eutrophication water (high in nitrates)
- plant growth sped up
- algae grows quickly
- algal bloom blocks sunlight reaching plants at bottom
- plants can’t photosynthesis, die
- short lived algae dies
- dead plants decomposed by aerobic bacteria + fungi (biochemical oxygen demand)
- fish + other oxygen requiring species die
