6.3.1 Ecosystems 6.3.2 Populations and Sustainability Flashcards
decomposer
breaks down dead matter
examples of decomposers
bacteria, fungi
detritivores: speed up decay process by breaking down matter into smaller fragments - increasing surface area
why does decomposition release CO2
glucose, from digestion, is respired = releasing CO2 into the atmosphere
saprotrophic nutrition
energy obtained from dead, organic matter
autotrophic nutrition
nutrients obtained from photosynthesis
importance of nitrogen for living organisms
make nucleic acids: DNA/RNA
make amino acids: proteins
why is nitrogen not directly absorbed
N≡N bond is too strong to break (lightning can break triple bond)
N must be combined with H, O atoms to increase the ability to be absorbed
nitrogen fixation
anaerobic, reduction
nitrogen-fixing bacteria use the NITROGENASE enzyme
bacteria involved in nitrogen fixation
rhizobium: found in root nodules of legumes
azobacter: free in soil
ammonification
decomposers break down dead matter and/or products of egestion + excretion
proteins digested as amino acids are converted into urea
bacteria use urea to respire
bacteria involved in ammonification
saprotrophic micro-organisms
nitrification
aerobic, oxidation
1. ammonium ions converted to nitrites
2. nitrites converted to nitrates
takes place in well-drained soils
bacteria involved in nitrification
- nitrosomonas
- nitrobacter
denitrification
anaerobic, reduction
nitrates are converted into nitrogen gas
takes place in water-logged soils
bacteria involved in denitrification
pseudomonas denitrificans
use nitrates for respiration
leghaemoglobin
produced by plants to absorb oxygen
oxygen is transported to mitochondria
removes excess oxygen: provides an anaerobic environment for nitrogenase
where is leghaemoglobin found
root nodules
nitrogen cycle
carbon cycle
succession
the directional change in the composition of species in a community that occupy a given area through time
causes of succession
changes in the community of organisms = changes in the physical environment - allows community to become established
established community
new community outcompetes former community
succession occurs in a number of serial stages
at each stage, the key species that are responsible for changing the abiotic factors can be identified
abiotic factors
the non-living conditions in a habitat that affect the environment
examples of abiotic factors
land-based ecosystem: temperature, light, water
marine ecosystem: salinity, ocean currents.
biotic factors
a living organism that affects the environment
examples of biotic factors
any living organism
freshwater ecosystem: aquatic plants, fish, amphibians, algae
pioneer community
a species adapted to survive in harsh/inhospitable conditions
they stabilise the environment + lead to soil development
climax community
final, stable community
very little change overtime
few, dominant species
humus
dead material
primary succession
- bare rock
- pioneer community introduced
- organisms cause erosion, provide dead material
- intermediate species grow, reproduce, disperse seeds, die, decompose
- intermediate species replace pioneer community
secondary succession
faster than primary succession as minerals are already available in the soil
occurs on land that is clear of plants/animals - only soil remains
deflected succession
when human activities halt primary succession from occurring
stops climax community forming
human activities that cause deflected succession
agriculture e.g. mowing, sustainable timer production, cattle farming
plagioclimax
final community in a deflected succession ecosystem
affected by grazing, burning
beach, bare sand
hostile environment
very salty = low water potential
very windy
no organic matter
mini dunes, embryo dunes
result of windblown sand
builds up around the base of pioneer plants
dunes increase in height as plants grow
supports primitive species e.g. maram grass
young yellow dunes
increases stability
more minerals = more maram grass species growth
old grey dunes
support intermediate plant species - able to outcompete pioneer plant species
increases species diversity
increase in species diversity as you move further from the sea
why do dunes become darker as you move further away from the sea
soil quality improves
soil depth increases
larger root networks
how would you measure change across a sand dune system
interrupted belt transects
quadrats are placed at regular intervals between 2 tape measures + number of organisms of each species is recorded
take multiple readings at each interval + calculate a mean - ensures sample is as representative as possible
kite diagram
allows frequencies of different species to be recorded along the length of a transect
the higher the kite, the greater proportion of that species
conservation
maintaining biodiversity by actively managing ecosystems
a dynamic process involving human action
preservation
protecting an ecosystem by restricting human access and use so it remains untouched
economic importance of conservation
sources of raw materials for industries; for example, timber products from natural and plantation forests for the construction and paper industries
source of natural income from exporting biological resources: timber, fish, paper products
employment for people in transport, marketing, retailing, and ecotourism provides employment for people in places with high biodiversity
social importance of conservation
human communities in rural areas with little industry or commerce gain stability from the employment provided by fishing/forestry
areas set aside for forestry provide spaces for recreation. the forestry commission and private forestry owners manage their forests as an amenity for people to enjoy the visual appeal of forested areas, opportunities to take exercise and observe wildlife
ethical importance of conservation
the duty that we have to conserve resources for the livelihoods and well-being of future generations
the support of indigenous peoples across the world who maintain their traditional ways of life relying on certain biological resources
e.g. the Arctic rely on seals and whales, the people of the Amazon and central Africa depend on foods that they harvest from the forests
