6.3.1 ecosystems Flashcards
population
all the members of a single species living in an area
community
all the populations of different species which intera t together in the same habitat
ecosystems
the interactions of the living (biotic) and a biotic factors in an environment
1st step of food chain
producer
- synthesise their own organic molecules using light energy from the sun
after producers are
primary consumers
how does interdependence arise
- food chains are all connected as food webs
- as pop of one species increases, that of another increases who eats it, and that of its prey decreases
decomposers
break down dead naterial and allow nutrients to be recycled
how is energy lost between trophic levels
- egestion
- not all of an organism is eaten
- faeces
- heat loss in respiration
efficiency of biomass transfer
(biomass transferred/ biomass intake) * 100
how to measure biomass
- choose the SAME one area u want to sample
- take a sample of both trophic levels
- dry orgs in an ocen until constant mass
- calroimetry to work out kj
- scale up fpr total area , kj/m2/year
- efficiency = tropic level2 energy/trophiv level1 energy * 100
LIMIT: assumes everyone only eats one organism , inaccurate
net productivity
the amount of biomass availabel to next trophic level
gross productivity and units
total energy consumed by organism (kj per m2 per year)
how to calc net productivity
gross productivity - respiratory loss
efficienc of energy transfer
net/total * 100
how can farmers maximise efficeincy
ANIMALS
1. keep animals in small cages to restrict movement -> less energy lost in resp so more for biomass, higher gross production
2. keep warm
2. antibiotics to prevent energy needed to kill infections
3. selective breeding
PLANTS
3. herbicides to reduce competition
4. insecticides
5. fungicides (less energy required to kill fungal infections)
carbon cycle steps
- co2 to atmosphere => respiration and combustino of fossil fuels
- co2 out of atmosphere =>photosynthesis
- aninals feed on plants
- when plants and animals die, decomposers break down their material and RESPIRE, RELEASING CO2
- In ABSENCE OF DECOMPOSERS (no o2), carbon compounds form fossil fuels (high t and p over millions of years)
nitrogen cycle descriibe
- rhizobium in root nodules, azobacter in soil, lightning do NITROGEN FIXING, n2 in atmosphere to AMMONIA/nh4 +
NITRIFICATION
2.nitrifying bacteria (nitrosomonas) convert nh4+ to no2-
3.nitrobacter do no2- to no3-
4.no3- active transported (taken in ) by plants for eg dna
5.denitrifying bacteira do no3- back to atmospheric n2 (usually in anaerobi)
6.death and decomposition, decomposers do ammonification of dead stuff to nh4+
succession
progressive change in an ecological tommunity over time
describe succession
seral stages
1. PIONEER species eg algae lichen live on bare rock. they may have advantageous adaptations eg can fix n2, can photosynthesise, produce large vol of seeds and spores which can be wind carries. biomass is LOW
2. PS die and decompose, forming a basic soil called humus. soil ph and salinity and nutrient content changes, becomes deeper and thicker
3. INTERMEDIATE SPECIES larger simple plants eg shrubs can grow => biodiversity increases
4. may block light from lower down plants, so they die and decompose, soil content changes
5. eventually u have the largest species, climax community, DOMINANCE by a few large trees, no more succession
deflected suvvession
CLIMAX COMMUNITY PREVENTED FROM DEVELOPING
- grazing
- fertiliser
- herbicide
- the community that results is a plagioclimax
how to sample (quadrats)
- set down 2 tape measures ppd to each other
- RNG to generate coordinates
- place quadrats at coords
- estimate eg % cover
- more quadrats = more respresentative
stratified sampling
- number of samples proportional to area
transect used when u wann asee
how the distribution of different species changes along a habitat
line transect
tape measure placed along a line, any species that touch tape masure are recorded
belt transect
- leay tape measure out eg from edge of sea
- quadrats placed one after the other in a ‘belt’
- use a key to identify the species in each
- measure % cover of each
- repeat along tape
interrupted transect
quadrats at regular intervals
which steps of n cycle can happen anaerobically
- denitrification
- nitrogen fixation
eg biotic factors
- predation / herbivory
- competition
keystone species (2)
- significant effect on ecosystem
- many animals rely on their activities
how can habitat diversity impact species diversity
- more diverse habitat = wider range of conditions for species ot live
- diff selection pressures, diff natural selection, allopatric speciation
units for production on land
kj/m2/year
units for production in a body of water
kj/m3/year
why might plants be inefficient
- sunlight reflected
- sunlight doesnt shine on the parts that photosynthesise
which parts of plants cant be digested; contribute to egestion
lignin
cellulose
after dead plant/ animal is decomposed it is
urea -> ammonia
goes straight to nitrosomonas nitrite then nitrobacter nitrate
capture recapture works best with which populations
smaller
describe what happens to make anmal proteins from plant proteins
- animals feed on plants
- protesin hydrolysed to amino acids
- move into blood
- translation of more proteins
why are tertiary consumers more efficeint than herbivores
- more neergy absorbed
- less egested
- meat more digestible as is largely protein and fat
- no indigestible CELLULOSE or LIGNIN
outlie the importance of decomposers
- bacteria
- saprophytic digestion, release extracellular enzymes
- and absorb the products p=broken down
- nutrient cycling eg to NH4+
- release co2 and water => carbon cycle as they aerobic respiration
what can light do to auxins
destroy
trophic level
stage in a food web
consumer defintion
feeds to derive energy from other organisms
heterotrophic
