B10: Ecosystems Flashcards
define population
group of organisms of one species,
living and interacting in the same area at the same time.
define community
all of the populations of different species interacting with each other in an ecosystem.
define habitat
place where organisms live.
define ecosystem
unit containing the community of organisms and their environment,
interacting together.
living factors=
biotic
non living factors=
abiotic
abiotic factor example
availability of oxygen availability of water light intensity pH (of water or soil) pollution temperature mineral ions.
biotic factor examples
competition
disease
food supply
predation.
intraspecific competition
between organisms of the same species
for resources such as food, territory, a mate or a nesting site.
These factors would have a negative effect on population size if they were in short supply.
interspecific competition
between organisms of different species
for resources such as food.
In this case, one species is often successful in forcing the other species out of the community.
sufficient food for the population=
organisms will be more likely to thrive,
survive to breeding age and
then breed successfully to produce more offspring. The size of the population will grow.
insuffiient food for population=
increase in deaths or
an increase in migration (emigration)
to find new sources of food.
The size of the population will be reduced.
Factors that cause the size of the population to change includ
food supply predation disease. human interactions: pollution climate change. war
lag phase of population growth
population is very small
and takes time to acclimatise new environment, become mature and start reproducing.
A doubling of small numbers does not have a big impact on the total population size,
so the line of the graph only rises slowly with time.
log phase (exponential stage) of population growth
there are no limiting factors.
Rapid breeding occurs in the population,
resulting in significant increases in numbers.
There are far more births than deaths.
stationary phase in population growth
Limiting factors such as shortage of food or a build-up of toxic materials in the environment start to have an effect,
slowing down population growth.
number of deaths equals the number of births,
so the line of the graph flattens to form a plateau.
death phase in population growth
The number of deaths (mortality rate) becomes greater than the number of births
so the population numbers start to decrease.
may be due to lack of food, an accumulation of waste materials, disease spreading through the population, or an influx of predators.
mutalism
close relationship between two organisms of
different species
where both organisms benefit.
parasitism
only one of the two organisms involved gains any benefit.
The other is harmed.
At each successive stage in a food chain, the amount of biomass…
decreases
At each successive stage in a food chain, the amount of biomass… why?
the organisms use some of food obtained
for energy to move, respire and maintain their body temperature.
some of the material is not digested or even eaten
largest bar at the base of pyramid
producer
food chains have….
trophic levels
The key processes in carbon cycle
photosynthesis, respiration, combustion and decomposition
how do photosynthesis and respiration ….
balance each other,
maintaining the concentration of carbon dioxide in the atmosphere
how is the balance disrupted
mass deforestation
by releasing carbon dioxide into the atmosphere by other processes such as combustion of fossil fuels,
the level of carbon dioxide in the atmosphere will increase.
can cause environmental problems such as global warming.
When organisms die….
they provide food for detritus feeders
detritus feeders
decompose (break down) the organic molecules in the dead plants and animals through the process of respiration to release energy. Again, carbon dioxide is released into the atmosphere.
Some animals form…
shells or exoskeletons
from calcium carbonate, using carbon dioxide.
These can also become fossilised,
trapping the carbon in them.
equation for complete combustion of carbon
C + O2 → CO2
detrimental effects of deforestation
fewer trees photosynthesising,
so less carbon dioxide is removed from the air.
when the trees are cut down, the small branches and foliage are burned,
adding more carbon dioxide back into the air.
which process doesnt release heat energy
photosynthesis
Transpiration
plants release water vapour into the atmosphere, throughstomata in the leaves.
water evaporates inside the leaf before it is released.
Evaporation
occurs from the surface of bodies of water
such as rivers, lakes and the sea.
Condensation
the water vapour in the atmosphere condenses to form clouds.
Precipitation
water in the clouds forms rain, snow, etc.
which falls to the land
and drains into water systems.
Osmosis
process used by plant roots, bacteria and other organisms to take up water.
Excretion
from animals.
Water is lost from animals in the form of
sweat, exhaled air and urine.
Faeces (a product of egestion not excretion) also contains some water.
