Studied by 4 people
state the definition of a population
group of organisms
same species
living in the same place
at the same time
state the definition of a community
includes all populations
living in the same area
at the same time
state the definition of interdependence
when within a community
each species relies on another for survival
and if one species is removed from the community
it affects the whole community
state the definition of an ecosystem
all the biotic and abiotic factors
that interact in an area at one time
state the definition of an individual
a single member of a species
state the definition of biotic
a living factor in an environment
state the definition of abiotic
a non-living factor in an environment
explain how communities can be affected by temperature
affects the rate of photosynthesis in plants
explain how communities can be affected by light intensity
light is needed for plants to photosynthesise
the rate of photosynthesis affects the rate at which plants grow
plants can be food sources or shelter for many organisms
explain how communities can be affected by moisture levels
plants and animals require water to survive
explain how communities can be affected by carbon dioxide concentration
carbon dioxide affects the rate of photosynthesis in plants
it also affects the distribution of organisms as some thrive in high carbon dioxide concentration environments
explain how communities can be affected by soil pH/mineral content
soil pH affects the rate of decay and therefore how fast mineral ions return to the soil
different species of plants thrive in different nutrient concentration levels
explain how communities can be affected by wind intensity and direction
wind affects the rate of transpiration in plants
transpiration affects the temperature of plants
which affects enzyme action in the plant
transpiration also affects the rate of photosynthesis because it transports water and mineral ions to the leaves
plants are used for shelter and food by communities
increasing the rate of transpiration increases plant growth
explain how aquatic communities can be affected by oxygen levels
oxygen levels vary greatly in water compared to in air
most fish need a high concentration of water to survive
explain how communities can be affected by competition
species compete for the same resource
the better adapted one is more likely to outcompete the other
this may continue until there are too few members of the lesser adapted species
to survive to reproduce successfully
explain how communities can be affected by predation
damages equilibrium within ecosystem
could wipe out a prey species
by over-eating
or wipe out a predator species
by over-eating their prey
as they do not have enough food to survive to reproduce
explain how communities can be affected by food availability
INCREASE IN FOOD:
more food means more organisms can survive to reproduce
and therefore the population can increase in number
DECREASE IN FOOD:
less food = less organisms that can survive to reproduce
therefore decreasing the population
and increasing competition between species
explain how communities can be affected by new pathogens
when a new pathogen arises, the population has no resistance to it
so they can be wiped out quickly
explain the importance of interdependency within a community
interdependency creates stable communities
as it ensures all species and environmental factors are in balance
so that population sizes remain fairly constant
state the definition of parasitism
when a parasite
living very close to a host
gains resources
but the host doesn’t benefit from the relationship
state the definition of mutualism
a relationship between two species in a community
where both organisms benefit from the relationship
state the method of how to investigate the relationship between organisms and their environment
divide the area into an equal number of squares (e.g. 1m x 1m) and assign each one a number
use a random number generation to select a random single square
take a quadrat the size of the square and place it in the area of the selected square
count the number of the organism in the square
repeat steps 2-4 with different random squares
compare the number of organisms in one square to another
depending on the number of organisms within the different squares, try to identify environmental factors that might change the number
state what a belt transect is
a method of systematic sampling
that gives abundance of species
as well as presence/absence of species
explain how to use belt transects
lay out a measuring tape in a straight line
place quadrats at regular intervals along the tape
record the abundance of each species within each quadrat
explain how to use quadrats
divide the area into equal sized squares with an assigned number
use a random number generator to select a single square to avoid sampling bias
lay the quadrat in the assigned area and measure the abundance of different species present
state approximately how much of the biomass of each tropic level is transferred to the next
10%
explain how some energy is transferred to less useful forms at each trophic level
respiration - generates waste thermal energy
excretion - energy transferred to metabolic waste
energy may remain in non-ingested parts of animals
explain how energy be transferred to less useful sources between trophic levels affects the number of organisms in each trophic level
the inefficient loss of energy at each trophic level explain why food chains are rarely longer than 5 levels long
as the percentage of energy and biomass being passed up the chain decreases each level you go up
meaning there is not enough for more organisms in the top trophic levels to survive to reproduce
explain how energy being transferred to less useful sources between trophic levels determines the pyramid shape of biomass in an ecosystem
biomass pyramids - width of each level is determined by the number of organisms in each one
90% loss of energy and biomass as trophic levels increase
number of organisms in the top levels able to survive to reproduce dwindles
as less energy/resources for them to survive to reproduce
causing pyramid to narrow as the top trophic levels are reached
state the equation to calculate the percentage efficiency of energy transfers
efficiency = (useful energy / total energy) x 100
state the symbol equation to calculate the percentage efficiency of energy transfers
η = (Euseful / Etotal) x 100
state the benefits of fish farming
most fish are still caught in the wild
fish farming is a reliable way to provide protein for humans
fish farms minimise energy loss
fish farms maximise yield
state the disadvantages of fish farming
overfishing leads to a dramatic decrease in fish population
predators may be attracted to the fish farms and get caught in the nets
diseases can spread quickly in fish farms due to the enclosed spaces and amount of fish
if the caged fish escape, they can cause problems with the native fish species
eutrophication can occur
explain how selective breeding can maximise the yield of fish farms
it ensures high-quality, fast-growing fish
explain how preventing interspecific predation can maximise the yield of fish farms
it decreases the chances of fights between fish
decreasing chances that fish numbers decrease
state the ways to prevent interspecific predation in fish farms
nets
cages
grouping fish based on categories
explain how water quality can maximise the yield of fish farms
water pH and temperature is monitored
ensuring conditions don’t reach outside optimum
as optimum pH and temperature are needed to increase fish yield
explain how controlling diet can maximise the yield
explain the affects non-indigenous species have on biodiversity
negative affects
increases competition between non-indigenous and the indigenous species
impacts the food chain
more of the prey is being eaten
less food for both species to survive to reproduce
decreases biodiversity of the habitat
explain the affects eutrophication has on biodiversity
runoff fertiliser from farm fields enters the water
which causes an increase in algal growth in the water
the algal bloom blocks sunlight from entering the water
this stops aquatic plants from photosynthesising and producing oxygen, causing them to die
as the aquatic plants continue to die, the amount of decomposing bacteria increases and uses up oxygen when aerobically respiring
as there is a vast decrease in oxygen in the water, aquatic organisms are no longer able to survive
this results in the biodiversity of the habitat
explain how the conservation of animal species maintains biodiversity
reduces damage to the food chain
as if an animal species goes extinct
every organism in the chain is affected
explain how reforestation can maintain biodiversity
reforestation is the replanting of trees in areas that have previously been cut down
this supports symbiotic relationships within an ecosystem
and forests can create high levels of biodiversity
explain how the changes in the human population affects levels of food security
increasing human population
due to increased birth rates
threatening food security in some countries
as there are not enough food resources for the growing population
explain how changes in demand for animal products affects levels of food security
increase in demand for animal products globally
due to increasing population
puts larger strain on countries exporting animal products
causing food scarcity
as there are less animal products available to meet local demand
explain how changes new pests/pathogens affect levels of food security
farming is often threatened by new pests/pathogens
as the crops/livestock have not yet developed resistance to them
which increases the risk of the crops/livestock being wiped out
decreasing food resources locally and globally
explain how climate change affects levels of food security
climate change can affect food production
as it can cause natural disasters such as drought
which can cause famine locally and globally
explain how agriculture costs affect levels of food security
inputs such as irrigation, machinery and livestock are expensive
causes lack of farming in lower income areas
causing food scarcity in these areas
explain how the use of land for biofuel production affects level of food security
takes up large areas of land
could have been used for agriculture/livestock
decreasing rates of farming in these areas
causing food scarcity
state what form carbon is found in in the atmosphere
carbon dioxide
explain how carbon is transferred from the atmosphere to plants
carbon is stored as carbon dioxide in the atmosphere
carbon dioxide is needed for photosynthesis in plants
so it is absorbed by plants to complete photosynthesis
explain how carbon is transferred from plants to the atmosphere
when plants respire, they release both oxygen and carbon dioxide into the atmosphere
through their stomata
explain how carbon is transferred from plants to animals
plants absorb carbon dioxide from the atmosphere
for photosynthesis
plants are eaten and ingested
by animals
transferring the carbon compounds through ingestion
explain how carbon is transferred from animals to decomposers
when animals die, they are decomposed by decomposing microorganisms
which ingest the decaying animals
explain how carbon is transferred from decomposers to the atmosphere
when decomposers ingest decaying organisms, they aerobically respire
when they respire, they release carbon dioxide into the atmosphere
explain how carbon is transferred from decaying organisms to fossil fuels
over time, the decaying organisms become subject to heat and pressure
this causes them to fossilise
and become fossil fuels
explain how carbon is transferred from fossil fuels to the atmosphere
when fossil fuels are combusted, they release carbon dioxide into the atmosphere
explain the importance of the carbon cycle
carbon is a component of all living organisms
the carbon cycle allows the movement of carbon between global reservoirs
the balance of carbon between these reservoirs is fundamental
due to the role carbon plays in sustaining life
state the 4 global reservoirs in the carbon cycle
atmosphere
biomass
ocean
soil
explain how water is transferred from the ocean to water vapour
water is evaporated off the surface of the ocean by thermal energy from the sun
which forms water vapour
explain how water is transferred from water vapour to clouds
as the water vapour cools and condenses, it forms clouds
explain how water is transferred from clouds to precipitation
as the water in the clouds cools further, more water droplets are formed
this makes the cloud heavier
the water droplets will then begin to fall
in the form of rain, snow or sleet
explain how water is transferred from precipitation to plants
through percolation, water enters the ground/soil
it will then be absorbed by root hair cells in the roots of plants
explain how water is transferred from precipitation to oceans
through percolation, water from precipitation enters the ground/soil
from here it can enter the ocean
precipitation also forms surface water runoff
which can enter the ocean above ground
explain how water is transported from plants to water vapour
water is evaporated from the surface of plants leaves by thermal energy from the sun
the water leaves the plant through transpiration
explain the importance of the water cycle
all life on earth depends on water, especially plants for photosynthesis
the water cycle is fundamental as it distributes fresh, potable water globally
providing organisms with clean water
which is especially pertinent in areas of drought
explain the importance of the water cycle in desalination
ocean water contains salt
when water is evaporated from the ocean, it no longer contains salt
thus causing the water cycle to distribute desalinated water globally
explain how nitrogen is transferred from the atmosphere to plants
nitrogen from the atmosphere is converted to nitrate compounds by nitrate-fixing bacteria
in soil or root nodules
from here it can be absorbed by root hair cells in plant roots
explain how nitrogen is transferred to plants by the Haber process
the Haber process is man-made process where nitrogen gas is converted into ammonia
to make fertilisers
famers use fertilisers like ammonium nitrate to help crops grow and increase crop yield
ammonia is converted into nitrates by nitrifying bacteria in the soil
explain how lightning can convert nitrogen in the atmosphere into nitrate compounds
lighting splits the covalent bond between nitrogen atoms
to form nitrous oxides
which dissolve in rainwater
to leach into the soil
explain how nitrogen is transferred from plants to animals
plants absorb nitrogen compounds through their roots
these plants are eaten by animals
where the nitrogen is now transferred to the animal
explain how nitrogen is transferred from animals to decomposers
decomposers break down animal organisms, urine and faeces
which results in the nitrogen from the animals being returned into the soil in the form of ammonia
the ammonia is then converted into nitrates by nitrifying bacteria
explain how nitrogen is transferred from the soil to the atmosphere
denitrifying bacteria in the soil
breaks down nitrates
into nitrogen gas
which returns back to the atmosphere
state what conditions are needed for nitrogen to be transferred from the soil to the atmosphere
waterlogged soil
anaerobic conditions
explain what crop rotation is
farmers will often grow crops that can form nitrates
as they have nitrogen-fixing bacteria in their roots
this increases the nitrate content and fertility of the soil
the crops the farmers plants will take in the nitrate and uses its proteins for growth
one year the farmer will grow these plants and then the following year, the farmer will plant another crop in the nutrient-dense soil
explain the role of bacteria in nitrogen fixation
nitrogen-fixing bacteria convert nitrogen gas
into ammonium compounds
these can then be converted to useable nitrates
explain the role of bacteria in ammonification
nitrogen compounds in waste products and dead organisms
are converted into ammonia
by ammonifying bacteria
explain the role of bacteria in nitrification
ammonium ions in the soil
are converted into nitrates
by nitrifying bacteria
that can be used by plants
explain the role of bacteria in denitrification
denitrifying bacteria use nitrates in the soil during respiration
this process produces nitrogen gas, which returns to the atmosphere
explain how bloodworms/sludge worms are used as evidence that water is polluted
bloodworms/sludge worms are adapted to live in water with high pollution contents
the presence of bloodworms/sludge worms in water thus indicates a very high level of water pollution
explain how freshwater shrimp/stonefly are used as evidence that water is clean
stonefly and freshwater shrimp are highly sensitive to the concentration of dissolved oxygen in the water
thus the presence of stonefly/freshwater shrimp indicates the water is clean and has a high concentration of oxygen
explain how lichen is used as evidence of clean air
lichen are highly sensitive to sulfur dioxide concentrations
if lichen is more abundant, this indicates that the surrounding air is clean
if bushy lichen is abundant, this indicates that the surrounding air is very clean
as this type of lichen needs even cleaner air than most types
explain how blackspot fungus on roses is used as evidence of clean air
blackspot fungus on roses is highly sensitive to sulfur dioxide concentrations
which is released from car exhausts and power stations
if black spot fungus is abundant, the surrounding air is clean
state the disadvantages of using indicator species to assess pollution levels
don’t generate accurate quantitative readings of pollution
the presence/absence of indicator species can be affected by factors other than pollution
state the advantages of using indicator species to assess pollution levels
they’re simple
they’re cost-effective
state what non-living indicators can be used instead of indicator species to assess levels of pollution
dissolved oxygen meters
dissolved chemical tests
electronic meters
laboratory tests
explain how dissolved oxygen meters/chemical tests are used to assess oxygen concentration
they can be used to accurately determine
the quantitative concentration of dissolved oxygen in the water
and can be used to show changes in water pollution levels over time
explain how electronic meters/laboratory tests are used to assess sulfur dioxide concentration
they can be used to accurately determine
the quantitative concentration of sulfur dioxide in the air
and can be used to show changes in air pollution levels over time
explain the effects of temperature on the rate of decomposition in food preservation
decomposition of food requires enzyme action
the rate of enzyme action increases with temperature
so at higher temperatures, the rate of decay will be quicker
and at lower temperatures, the rate of decay will be slower
however, once the temperature is past the enzyme’s optimum temperature, the enzyme will denature
and the rate of decay will decrease
explain the effects of water content on the rate of decomposition in food preservation
decomposers require water to survive
as water is essential for their biological processes
without water, these reactions cannot occur
as water content decreases, the rate of decay decreases
explain the effects of oxygen availability on the rate of decomposition in food preservation
oxygen is needed by most decomposers for aerobic respiration
without it they can’t survive
for these decomposers, the rate of decay decreases as oxygen availability decreases
state the equation to work out the rate of decay
rate of decay = mass lost / number of days
state what is needed for decomposition
oxygen
higher temperatures
water
Note 
Flashcard (102)