Zusammenfassung der Ressource
OCR 21st Century B3.1
- Life on Earth-
Interdependence of Species
- Classification- look
at the similarities
and difference
between two living
organisms to
cateogorise them
- A species is a group of organisms
that can breed together to
produce fertile offspring
- living organisms are dependent
on the environment and other
species for their survival
- Light-needed for
plants to make food
- Food for animals
and minerals for
plants
- Oxygen- for respiration
and CO2 for plants
photosynthesis
- there is competition for
these resources between
different species of animals
or plants in the same habitat
- Water
- adaptation of living organisms to
their environment increases the
species’ chance of survival by
making it more likely that
individuals will survive to reproduce
- e.g. Cactus- Store water in large
stems. Large root systems to get
water from deep into he soil.
Hard spines instead of leaves
- Fish- absorb oxygen
dissolved in water. Oxygen
diffuses across the large
Surface Area of the gills .
Streamlined body and
smooth surface move with
little resistance. Swim
bladder-buoyancy and depth
change without energy
wastage
- a change in the environment may
cause a species to become extinct, for
example, if:
- the environmental
conditions change
beyond its ability
to adapt
- a new species that is a
competitor, predator or
disease organism of that
species is introduced
- another species (animal,
plant or microorganism) in its
food web becomes extinct
- If the shrew was to become extinct, the woodmouse would be the
sole source of food for the owl. Owl numbers would decrease,
caterpillar numbers would increase and woodmouse numbers would
decrease. If there are more caterpillars, that's less food for the
squirrel and so there may be a decline in squirrel numbers. As the
woodmouse numbers have severely decreased the fox is forced to eat
more squirrels and so their numbers decrease
- nearly all organisms are ultimately
dependent on energy from the Sun
- Plants, which are usually the producers use
sunlight to build glucose from CO2 and water.
Through photosynthesis, they trap 1-3% of the
light energy that reaches their leaves
- A consumer e.g. greenfly eats the
plants and the energy is
transferred. Energy is transferred
when detritivores feed on dead
organisms and waste materials
e.g. excrement and uneaten parts
- Energy is lost at
each stage. In
respiration and
other life
processes e.g.
movement. Most is
eventually lost to
the surroundings
as heat
- Energy available at the previous stage
- x100%
- It's not
sustainable to
have a food chain
which is more
than 5 stages.
There isn't enough
energy to support
more organisms
- Efficiency= Energy available at the next stage/
- carbon is
recycled
through the
environment
to include the
processes of
combustion,
respiration,
photosynthesis
and
decomposition
- The combustion of
fossil fuels release
stored carbon into
the atmosphere in
the form of carbon
doxide
- Plants and
animals
respire
producing
carbon
dioxide
- Plants use light to convert
Carbon dioxide and water
into glucose to use for
respiration and to make
proteins, cellulose,
enzymes and chlorophyll
- The dead organisms are eaten by
decomposers and the carbon in
their bodies is returned to the
atmosphere as carbon dioxide.
- In some conditions
decomposition is
blocked. The plant
and animal material
may then be
available as fossil
fuel in the future for
combustion.
- In the sea, marine animals may convert some of the
carbon in their diet to calcium carbonate which is
used to make their shells. Over time the shells of
dead organisms collect on the seabed and form
limestone. Due to Earth movements this limestone
may eventually become exposed to the air where it's
weathered and the carbon is released back into the
atmosphere as carbon dioxide. Volcanic action may
also release carbon dioxide.
- The Carbon
Cycle
- The
Nitrogen
Cycle
- Unreactive N2 is fixed by nitrogen
fixing bacteria in the soil and
roots of plants, to form nitrogen
compounds including nitrates.
- Lightning- nitrogen is fixed as there is
enough energy in a bolt of lightning to make
nitrogen react with oxygen
- conversion of nitrogen
compounds to protein
in plants and animals
- transfer of nitrogen compounds through food
chains- animals eat plants and receive their
protein through the nitrates that they've eaten
- excretion, death and decay of plants and animals resulting in release
of nitrates into the soil- urea is decomposed by microorganisms and
turned into ammonia. This ammonia can be nitrified by nitrifying
bacteria to produce useful nitrogen compounds
- denitrification-
denitrifying
bacteria turns
nitrates back into
nitrogen
- uptake of
nitrates by
plants
- Living and
Non-living Indicators
- Non-living
- nitrate levels
- Used to measure changes in
cleanliness of water.
Increase in nitrate level
caused by sewage or
fertilisers= polluted water.
- temperature
- Measurements taken
over long periods of
time could indicate
global warming
- carbon dioxide levels
- Used to measure the
environmental change in
the air/atmosphere. An
increase in CO2 is an
increase in global warming
- pH
- Living
- Lichen
- Sensitive to
sulfur dioxide
levels in the
atmosphere
- If present: clean
- Can give a good
idea about the
pollution from cars,
power stations, etc.
- Mayfly larvae
- Sensitive to
oxygen levels in
water
- If present: clean
- If sewage is released,
bacterial populations
increase and use the
oxygen so mayfly
nymphs leave
- Phytoplankton
- Sensitive to
Nitrate and
Phosphate
levels in
water
- If present: polluted
- Adding fertilisers or sewage to
water increases the amount of
nitrates and phosphates causing
algal blooms. Phytoplankton like
nitrate/phosphate rich
environments