6.3.1 Flashcards
What is an ecosystem?
all living organisms and non-living components and their interactions
What is a population?
the number of individuals of the same species, living in the same place at the same time
What is community?
all the organisms, all of the different species living in a habitat`
What is a habitat?
the place the organism lives in
What are biotic factors?
factors that involve other living organisms
What are some examples of biotic factors?
feeding of herbivores on plants
predation
parasitism
mutualism
competition
What is a niche?
The role of an organism in the ecosystem?
What are abiotic factors?
involve the non-living components of the environment
What are some examples of abiotic factors?
temperature
light intensity
oxygen concentration
Carbon dioxide concentration
Water supply
pH
availability of inorganic ions
edaphic features
atmospheric humidity
wind speed
end of a
start of b
What factors could influence the net primary production
high temperature
and increase in sunlight
the more photosynthesis occurs
more storage of biomass
What are trophic levels?
stage in a food chain
What is the primary consumer?
eats/feeds on producer
What is the secondary consumer?
eats/feeds on primary consumer
What is the producer?
converts light energy into chemical energy by photosynthesis
How is energy content of the dry mass obtained?
- using a bomb calorimeter
- burn the sample in a high pressure of oxygen
- the rise in the temperature of the water is measured
Why is the biomass in each trophic level nearly always less than the trophic level below?
not all biomass is eaten
some is transferred to the environment as heat
What is biomass?
mass of living material in a particular food chain/web
What is ecological efficiency?
efficiency with which biomass or energy is transferred from 1 trophic level to the next
What is the units for net primary production?
Kjm-2yr-1
Why do producers only convert 1-3% of the sunlight they receive into chemical energy?
not all light hits the chlorophyll
not all light hitting the leaves is absorbed,
it can be reflected, transmitted through the leaf
or the wrong wavelength
What is productivity?
rate at which the plant converts light energy into chemical potential energy
What is gross primary productivity?
total quantity of energy converted by a plant in photosynthesis
What happens to the 90% of biomass lost?
not all biomass is eaten (bones,roots)
some is lost to the environment as heat through respiration
some is excreted in urine and feaces
some biomass is of previous trophic level and not digestible
end of b
start of c
What is a decomposer?
organism that feeds on or breaks down dead plant / animal matter
it turns organic compounds into inorganic compounds
What is a rhizobium an example of?
nitrogen fixing bacteria
Where is Rhizobium found?
root nodules or leguminous plants like peas
What bacteria converts nitrites into nitrates?
nitrobacter
What is nitrobacter?
Nitrifying bacteria that changes nitrites into nitrates
What is the function of nitrosomonas?
changes ammonia into nitrites
What bacteria converts ammonia into nitrites?
nitrosomonas
What is the function of Azotobacteria?
bacteria that converts nitrogen gas into ammonia
Where is Azotobacteria found?
free living in the soil
What are sapropionts?
fungi / bacteria
that make ammonia from animal protein
secrete enzymes onto food which hydrolyses polymers and allows monomers to be absorbed
What do plants do with the nitrates that they take up from the soil?
make protein
What do plants use protein to do?
grow
What fixes nitrogen gas into nitrate compounds?
bacteria
root nodules
lightning
What does bacteria, root nodules and lightning do to nitrogen gas?
fix it into nitrate compounds
What do decomposers do?
convert protein and urea into ammonia
What is ammonification?
production of ammonia from organic compounds
What do rhizobium and azotobacter do?
convert nitrogen and oxygen into ammonia
How does lightning fix nitrogen gas?
energy release during lightning storms
causes unreacted nitrogen in the air to form reactive N compounds that are added to the soil when it rains
What happens when azotobacter die?
release amino acids
What enzyme does rhizobacter and azotobacter both contain?
nitrogenase enzyme
What does the nitrogenase enzyme do?
converts nitrogen and oxygen into ammonia
What happens during nitrification?
ammonia is converted into nitrites
nitrites are converted into nitrates
What is nitrosomas bacteria?
bacteria that get energy from reactions involving inorganic ions
What type of reaction is a nitrification reaction?
oxidation reaction
releases energy
What do saprobiotic micro-organisms do?
feed on these N and O to release ammonia in the soil
What does denitrifying bacteria do?
converts nitrates into nitrogen gas
What happens to nitrogen gas?
released into atmosphere
What type of bacteria is used in denitrification?
anaerobic bacteria as there is a shortage of oxygen
Why does soil need to be well-aerated?
to avoid nitrogen gas going into the atmosphere
What do farmers use to add nitrates into the soi?
nitrates and fertiliser
What is sucsession?
Process by which
ecosystems change over time
What does sucsession occur due to?
changes in the environment causing plant and animal species present to change
What is primary sucsession?
occurs on land newly-formed / exposed
no soil present
What is secondary sucsession?
occurs where soil is present but no animal/plant species
What is each stage in succession called?
a seral stage
How can key species be identified?
the change the abiotic factors make to become more suitable for existence of next species
What is a pioneer community?
arrive before climax community
subject to greater change
less stable
low biomass
Why are pioneer species important?
fix nitrogen
photosynthesis
tolerate extreme conditions
weather the rocks to create a layer of humus
What is an intermediate community?
when pioneer species die they add to the soil which can now support grasses and small flowering plants
these outcompete pioneer speciesW
What happens when pioneer species die?
add to the soil that can support grasses and flowering plants
which outcompete pioneer species
What is a climax community?
when intermediate species die they add to the soil which can now support larger shrubs and trees
these outcompete grasses and flowering plants for light, space and nutrients
What happens when an intermediate species dies?
they add to the soil which can now support larger shrubs and trees
these outcompete flowering plants
What 2 groups complete when the intermediate species dies?
larger shrubs and trees
grasses and flowering plants
What 2 groups compete with each over when the pioneer species dies?
pioneer species
small flowering plants and grasses
What are examples of pioneer species?
moss
lichen
What are the conditions like at the beginning of primary sucsession?
hostile
What is the Simpson’s index like at the beginning of primary sucsession?
low
What are conditions like at the end of primary sucsession?
less hostile
What is simpsons index like at the end of primary sucsession?
high
What is deflected sucsession?
where human activity
can halt natural flow of sucsession
prevents it form reaching climax community
What is it called when sucsession is artificially stopped?
plagioclimax
