Command terms
Low order –usually require short answers
• Define - give the precise meaning
• Draw- use a labeled diagram or
graph to illustrate
• Label- a diagram that you should
label.
• List- a very brief response with no
explanation.
• Measure- You have to work out a
value for a quantity.
• State- give a name/value or a brief
answer without explanation or
calculation
• Medium order
• Annotate- similar to the label
command term but with this one you
must add brief notes to the labels on
a diagram or graph.
• Apply- Use your existing knowledge
or a given piece of information to
solve a problem or issue
• Calculate- From a given set of
numbers or a graph you must
determine a numerical answer
showing your calculations.
• Describe- you must give some
detail.
• Distinguish- Don’t just define the
two concepts; you must draw out the
differences between them.
• Estimate- You have to give an
approximate value
• Identify- You must pick an answer
based on a number of possibilities
• Interpret- You have to identify
trends and draw conclusions from a
piece of information
• Outline-You must give
a brief summary of something.
Highest order thinking
This calls for you to show you can
synthesis new knowledge, justify your
choices, evaluate information and present
arguments for and against a particular
position.
• Analyse- clarify the essential
elements or structures of a particular
piece of information, graph or
concept.
• Comment- You should make an
observation of a statement or the
result of a calculation.
• Compare and contrast-You
must bring out the similarities and
differences between two or more
items.
• Construct- You have to show a set
of information in a logical way,
which may be a diagram, graph or
something else
• Deduce- You must draw a
conclusion from given information.
• Demonstrate- You should use
reasoning, evidence, examples or
practical applications to make
something clear.
• Derive-You have to develop a
mathematical relationship to give a
new equation or show a relationship.
• Design- You must propose a plan,
simulation or model as a solution to
a problem.
• Determine-You give the only
possible answer.
• Discuss-You must give a balanced
review of something including a
range of arguments, factors or
hypotheses(with evidence)
• Evaluate-You should assess the
strengths and limitations of
something
• Explain- This is the next stage up
from outline, and you will need to
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give a detailed account with
including reasons or causes.
Examine- You have to study an
argument or concept to expose any
assumptions or interrelationships that
may exist.
Justify- A very simple command
term that requires you to look at data
and give an expected result.
Predict- requires you to look at data
and give an expected result.
Sketch-you will have to draw a
labeled diagram or graph to show a
feature or relationships with any
relevant features
Suggest- You have to recommend a
possible course of action or answer
to a problem or situation.
To what extent- You have to reflect
on the pros and cons of an argument
or concept and then present you
opinions and conclusions
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Systems and models
What is a system?
It is a set of interrelated parts working
together to make a complex whole.
An open system exchanges matter and
energy with its surroundings (for example,
an ecosystem).
• A closed system exchanges energy but not
Matter. Strictly, closed
systems do not occur naturally on Earth, but
all the global cycles of matter, for example,
the water and nitrogen cycles, approximate
to closed systems.
• An isolated system exchanges neither
matter nor energy. No such systems exist
(with the possible exception of the entire
cosmos).
Components of a system.
• Inputs
• Outputs
• Feedback mechanisms
• Storage/sinks
• Processes
• Flows
Distinguish between flows (inputs and
outputs) and storages (stock) in relation to
systems. (Ecosytems, water systems, soil
and food systems and atmospheric
systems.
Construct and analyse quantitative
models involving flows and
storages in a system.
• Arrows for flows,
• Boxes for storage.
• Inputs arrows in
• Outputs arrows out
• Boundaries a line.
Evaluate the strengths and limitations of
models.
A model is a simplified description designed
to show the structure or workings of an
object,
system or concept.
Evaluate the strengths and limitations of
models.
Strengths of models
• Models allow scientists to predict
and simplify complex systems.
• They allow inputs to be changed and
outcomes examined without having
to wait a long time, as we would
have to if studying real events.
• Models allow results to be shown to
other scientists and to the public, and
are easier to understand than detailed
information about the whole system.
Limitations of models
• Different models may show different
effects using the same data. For
example, models that predict the
effect of climate change may give
very different results.
• Systems may be very complex and
when models of them are
oversimplified they may become less
accurate. For example, there are
many complex factors involved in
atmospheric systems.
• Because many assumptions have to
be made about these complex
factors, climate models may not be
accurate.
• The complexity and
oversimplification of climate models
has led some people to criticise the
limitations of these models.
• Any model is only as good as the
data that are used in them. In
addition, the data put into the model
may not be reliable.
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Models rely on the expertise of the
people making them and this can
lead to inaccuracies.
Different people may interpret
models in different ways and so
come to different conclusions.
People who would gain from the
results of the models may use them
to their advantage
Describe how the first and second
laws of thermodynamics are
relevant to environmental systems.
Energy is needed in ecosystems to create
order, such as to hold complex molecules
together. Natural systems cannot be isolated
because there must always be an input of
energy for work to replace energy that is
dissipated. Because of this energy loss, the
maintenance of order in living systems
needs a constant input of energy to replace
the energy lost as heat through the
inefficient transfer of energy.
One way energy enters an ecosystem is as
sunlight energy. This sunlight energy is then
changed into biomass by photosynthesis.
That is, photosynthesis captures sunlight
energy and transforms it into chemical
energy. Chemical energy in producers may
be passed along food chains as biomass, or
given off as heat during respiration.
Available energy is used to do work such as
growth, movement, and making complex
molecules. The transformation and transfer
of useable energy is not 100 per cent
efficient; whenever energy is converted
there is less usable energy at the end of the
process than at the beginning. This means
that there is a dissipation of energy which is
then not available for work. The total
amount of energy in a system does not
change but the amount of available energy
for work does change. All energy eventually
leaves the ecosystem as heat. No new energy
has been created, it has simply been
transformed and passed from one form to
another. Heat is released because of the
inefficient transfer of energy. This is true of
all systems. Although matter can be
recycled, energy cannot, and once it has
been lost from a system in the form of heat
energy, it cannot be made available again.
Because the transfer and transformation of
energy is inefficient, food chains tend to be
short.
Explain the nature of equilibria.
Equilibrium can be defined as a state of
balance among the components of a system.
This means that although there may be slight
fluctuations in the system, these are within
closely defined limits.
Equilibrium allows systems to return to an
original state after there has been
disturbance. There may be long-term
changes to the equilibrium of some systems
while at the same time they retain integrity;
for example, ecological succession.
Steady-state equilibrium
Most open systems in nature are in steadystate equilibrium. This means that even
though there are constant inputs and outputs
of energy and matter, there is overall
stability within the system. Although there is
overall stability there are usually changes, or
fluctuations, in the system. These changes
follow a fixed path and when there are
deviations away from this path then there is
always a return to equilibrium. The stability
of this form of equilibrium means that the
system can return to the steady-state after
there has been disturbance. For example,
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when a tall tree that forms part of the roof of
a tropical rainforest dies, the space it leaves
behind is fi lled up again through the process
of succession
Abiotic factors: Non living, physical factors
that influence the organisms and ecosystem.
Biotic factors: Living components of an
ecosystem.
Define and explain the principles
of positive feedback and negative
feedback.
Negative feedback is a self-regulating
method of control leading to the
maintenance of a steady-state
equilibrium—it counteracts deviation, for
example, predator–prey relationships.
• Positive feedback leads to increasing
change in a system—it accelerates
deviation, for example, the exponential
phase of population growth.
Define the term trophic level.
Trophic level is the position an organism (or
group of organisms in a community)
occupies in the food chain.
Describe transfer and
transformation processes.
Transfers normally flow through a system
and
involve a change in location.
Transformations lead to an interaction
within a system in the formation of a new
end product,or involve a change of state.
Using water as an example, run-off is a
transfer process and evaporation is a
transformation process. Dead
organic matter entering a lake is an example
of a transfer process; decomposition of this
material is a transformation process.
Construct and analyse quantitative models
involving flows and storages in a system
THE ECOSYSTEM
Distinguish between biotic and
abiotic (physical) components of an
ecosystem.
Identify and explain trophic
levels in food chains and food
webs selected from the local
environment.
Relevant terms like producers,
consumers, decomposers, herbivores,
carnivores,
top carnivores should be applied to local,
named
examples and other food chains and food
webs.
Explain the principles of pyramids
of numbers, pyramids of biomass,
and pyramids of productivity, and
construct such pyramids from
given data.
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Pyramids are graphical models of the
quantitative differences that exist between
the trophic levels of a single ecosystem.
A pyramid of biomass represents the
standing stock of each trophic level
measured in units such as grams of biomass
per square metre (g m–2). Biomass may also
be measured in units of energy, such as J m–
2.
In accordance with the second law of
thermodynamics, there is a tendency for
numbers and quantities of biomass and
energy to decrease along food chains;
therefore the
pyramids become narrower as one ascends.
Pyramids of numbers can sometimes
display different patterns, for example, when
individuals at lower trophic levels are
relatively large.
Similarly, pyramids of biomass can show
greater quantities at higher trophic levels
because they represent the biomass present
at a given time (there may be marked
seasonal variations). Both pyramids of
numbers and pyramids of biomass
represent storages.
Pyramids of productivity refer to the flow
of energy through a trophic level and
invariably show a decrease along the food
chain. For example, the turnover of two
retail outlets cannot be compared by simply
comparing the goods displayed on the
shelves; the rates at which the shelves are
being stocked and the goods sold also need
to be known. Similarly, a business may
have substantial assets but cash flow may be
very limited. In the same way, pyramids of
biomass simply represent the momentary
stock, whereas pyramids of productivity
show the rate at which that stock is being
generated. Biomass, measured in units of
mass or energy (for example, g m–2 or
J m–2), should be distinguished from
productivity measured in units of flow (for
example, g m–2 yr–1 or J m–2 yr–1).
Discuss how the pyramid structure
affects the functioning of an ecosystem
This should include the concentration of
non biodegradable toxins in food chains,
limited length of food chains, and
vulnerability of top carnivores.
Define the terms species,
population, habitat, niche,
community and ecosystem with
reference to local examples.
Species: A group of organisms sharing
common characteristics that interbreed and
produce fertile offspring.
Habitat: The environment in which a
species normally lives.
Niche: The set of particular set of abiotic
and biotic conditions to which an organism
responds.
• Fundamental niche: full range of
conditions and resources in which a
species could survive and reproduce.
• Realized niche: the actual
conditions and resources in which a
species exists due to biotic
interactions.
Population: A group of living organisms of
the same species living in the same area, at
the same time and are capable of
interbreeding.
Community: A group of populations living
and interacting with each other in a common
habitat.
Ecosystem: is a community and the physical
environment it interacts with.
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Describe and explain the population
interactions using examples of
named species.
Predation is where one organism (the
predator) hunts and kills another (the prey)
in order to provide it with the energy for
survival and reproduction.
Herbivory is the consumption of plant
material by an animal (Herbivores).
Parasitism is when an organism (the
parasite) takes nutrients from another
organism (the host).
Mutualism is where two organisms of
different species exist in a mutually
beneficial relationship
• Corals and algae live in a mutualistic
relationship, within each coal polyp
is a zooxanthellae algae. The algae
photosynthesize and give off oxygen
and other nutrients that the coral
polyp needs to live. The algae get
CO2 and protection from predators.
Competition is where organisms compete
for a resource that is in limited supply
(water, food, territory, mates, habitat etc.)
The resource must be limited for
competition to occur, if it is plentiful there is
no need for competition and the population
will grow exponentially giving the J curve.
Unlimited resources are rare so competition
becomes important and population growth
will slow resulting in the S-shaped curve.
Intraspecific competition occurs when
members of the same species compete for a
limited resource – water, space, mates, food
etc.
Interspecific competition is where
members of different species compete for a
resource that they both need.
List the significant abiotic (physical)
factors of an ecosystem.
Describe and evaluate methods
for measuring at least three
abiotic (physical) factors within an
ecosystem
• Marine—salinity, pH, temperature,
dissolved oxygen, wave action
• Freshwater—turbidity, flow velocity, pH,
temperature, dissolved oxygen
• Terrestrial—temperature, light intensity,
wind speed, particle size, slope, soil
moisture, drainage, mineral content.
Salinity, pH, temperature, dissolved oxygen,
light intensity, and soil moisture and mineral
content are all measured using a probe.
Consider:
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If you are investigating changes
through the day make sure the probe
is held at the same spot each time
you take the measurement.
If you are investigating changes
through the week/month/year then
take the measurement at the same
time of the day every time.
If you are investigating changes over
space then always take the
measurements at the same time.
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Changes over horizontal
areas mean that the probe
must be at the same height
(or depth) each time.
o With changes in altitude try
and keep the surroundings
similar – do not take one
reading under a tree and
another in the open.
Always repeat the measurement
five times and take the mean of the
five readings.
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Construct simple keys and
use published keys for the
identification of organisms.
Describe and evaluate methods for
estimating abundance of organisms
❖ Capture–mark–release–
recapture (Lincoln index)
1. Capture as many animals as possible
2. Mark the organisms in some way
that does not harm them or make
them more or less prone to predation.
o Insects can be marked with a
non-toxic spot of paint/dye.
o Mammals can have their fur
clipped.
o Fish can have a fin clipped.
o Birds and bats may have a
ring attached to their leg.
3. Record the number of animals that
were caught and marked.
4. Release the animals back into their
environment and give them sufficient
time to reintegrate into the
population (one week to a month).
Fast-moving animals like mice will
reintegrate quicker than slowmoving ones such as snails.
5. Resample the population and record
the number of animals that are
marked and unmarked.
6. Use the following formula to
calculate the total population:
N = n1 × n2 / m2
Where:
• N = total population.
• n1 = number of animals marked in
the first capture and released.
• n2 = number of animals recaptured
(second sample).
• m2 = number of animals marked in
the recapture (second sample).
Evaluation:
There are a number of assumptions linked
to this method and they are that:
• The proportion of marked animals in
the second sample is the same as the
proportion of marked animals to
unmarked animals in the whole
population.
• Enough time has elapsed to allow
full mixing of marked and unmarked
animals.
• All animals are just as easily caught
– that is unlikely as some animals
may be more easily caught in both
samples giving a biased sample.
• The population is closed and that
there is no immigration or
emigration.
There are also a few problems associated
with the Lincoln index:
• Capturing the animals may injure
them or alter their behaviour.
• The mark may be toxic to some
animals but not others – you may not
know until it is tested on the
organism under study.
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Marks may rub off between release
and recapture.
Marks may make the animal more or
less attractive to predators.
Some animals become trap happy
(causing an overestimation of
numbers) whilst others become trap
shy (causing an under-estimation).
❖ Quadrats for measuring population
density, percentage frequency and
percentage cover.
Quadrats are used to measure non
motile organisms like grass.
Percentage frequency is how often
a particular species appears in an
area.
1. Take a minimum number of quadrat
samples, usually at least five.
2. Calculate the mean from those
samples.
3. Extrapolate for the whole study area.
Percentage cover is easily assessed if the
quadrat is subdivided into 100 smaller
squares – each square represents 1%
coverage.
Evaluation of quadrats for assessing
percentage coverage.
Describe and evaluate methods for
estimating the biomass of trophic
levels in a community.
Method for small vegetation:
1. Decide on an appropriate sampling
strategy for the area of study.
2. Identify five quadrats (size will
depend on the vegetation but 1 × 1
meter is ideal).
3. Harvest all the vegetation in one
quadrat.
4. Remove soil, insects and other nonplant material.
5. Wash the vegetation.
6. Place the sample in an oven to dry
overnight.
7. Weigh the sample then return it to
the oven.
8. Repeat steps 6 and 7 until the weight
of the sample remains constant.
9. Repeat steps 3 to 8 for all
five quadrats and calculate the mean
dry weight biomass m-2.
10. Multiply by the study area to
estimate the biomass for the whole
area.
The same method can be applied to trees but
instead of selecting quadrats select
five typical branches, estimate how many
branches are on the trees and extrapolate for
the whole tree.
Evaluation
Advantage:
• You can extrapolate from a small
sample
Disadvantages:
• Highly destructive as the vegetation
is harvested and dried.
• Does not take account of
underground mass (roots).
• Not very accurate for large
vegetation like trees.
• It is not possible to get accurate
figures for animals in the ecosystem.
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Net primary productivity
NPP = GPP – R
Species diversity is a function of the number
of species and their relative abundance.
Apply Simpson’s diversity index
and outline its significance.
Evaluation:
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It is highly unlikely that all three
quadrats are identical as regards the
vegetation.
•
This can really only be done once as
three quadrats are needed.
Secondary productivity
Gross secondary productivity (GSP) which
is the food eaten – fecal loss.
Net secondary productivity is GSP – R
(respiration)
1. Keep the organism under study in a
cage.
2. Weigh it at the beginning and end of
the study (that gives NSP).
3. Weigh all the food it is given and all
the feaces is produces (that gives
GSP).
Evaluation:
Advantage:
• You can extrapolate from a small
sample and get some idea of the
amount of productivity in a trophic
level.
Disadvantage:
• Not very accurate as it is not dry
weight.
• Can only be used easily for small
non-aggressive animals.
• Captivity may stress the animals and
change their levels of productivity.
Define the term diversity.
D = diversity index
N = total number of organisms of all species
found
n = number of individuals of a particular
species
D is a measure of species richness.
A high value of D suggests a stable and
ancient site, and a low value of D could
suggest pollution, recent colonization or
agricultural management. The index is
normally used in studies of vegetation but
can also be applied to comparisons of
animal (or even all species) diversity.
Define the term biome.
A collection of ecosystems sharing similar
characteristics and organisms.
• Aquatic - which are further
subdivided into:
o Freshwater: ponds and lakes,
streams and rivers and
wetlands such as bogs and
swamps.
o Marine: deep ocean, coral
reefs, estuaries and mangrove
swamps.
• Forest – tropical rainforest,
temperate forests and boreal or taiga.
• Grassland – savanna and temperate.
• Desert – hot, coastal and cold.
• Tundra – arctic and alpine.
Explain the distribution, structure
and relative productivity of tropical
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rainforests, deserts, tundra and any
other biome.
• Refer to prevailing climate and
limiting factors.
For example, tropical rainforests are found
close to the equator where there is high
insolation and rainfall and where light and
temperature are not limiting.
The other biome may be, for example,
temperate grassland or a local example.
Limit climate to temperature,
precipitation and insolation.
Explain the role of producers,
consumers and decomposers in the
ecosystem.
Describe photosynthesis
and respiration in terms of
inputs, outputs and energy
transformations.
Photosynthesis should be understood as
requiring carbon dioxide, water, chlorophyll
and certain visible wavelengths of light to
produce organic matter and oxygen. The
transformation of light energy into the
chemical energy of organic matter should be
appreciated.
Respiration should be recognized as
requiring organic matter and oxygen to
produce carbon dioxide and water. Without
oxygen, carbon dioxide and other waste
products are formed.
Energy is released in a form available for
use by living organisms, but is ultimately
lost as heat
Describe and explain the transfer
and transformation of energy as it
flows through an ecosystem.
Explain pathways of incoming solar
radiation incident on the ecosystem
including:
• loss of radiation through reflection and
absorption
• conversion of light to chemical energy
• loss of chemical energy from one trophic
level to another
• efficiencies of transfer
• overall conversion of light to heat energy
by
an ecosystem
• re-radiation of heat energy to the
atmosphere.
Describe and explain the transfer
and transformation of materials as
they cycle within an ecosystem.
• Processes involving the transfer and
transformation of carbon, nitrogen and water
as they cycle within an ecosystem should be
described, and the conversion of organic and
inorganic storage is noted where
appropriate.
Construct and analyse flow diagrams of
these cycles.
The carbon cycle.
Human impacts on carbon cycle.
Negative
• Burning fossil fuels
• Deforestation for agriculture and
urban growth releases carbon from
the soil and plant biomass. To make
matters worse it also means fewer
trees are available to remove
CO2 from the atmospheric store.
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Positive
Afforestation and reforestation.
increased cropland efficiencies there
is an overall increase of land based
photosynthesis CO2 uptake.
The nitrogen cycle
With the increase in human
population we are draining wetlands
to allow for expansion of urban areas
and agricultural expansion.
Since denitrification takes place in
wetland areas denitrification is
reduced and less nitrogen enters the
atmosphere.
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The application of inorganic
fertilizers increases denitrification
and leaching. Increased leaching can
lead to eutrophication in water
bodies.
• Pastoral (livestock ranching)
agricultural practices impact the
nitrogen cycle by increasing the
amount of ammonia that enters the
soil. Livestock releases large
amounts of ammonia in their waste
and that enters the soil and
potentially nearby aquatic
ecosystems
Positive.
Adoption of organic farming.
•
Define the terms gross productivity,
net productivity, primary
productivity and secondary
productivity.
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Human impacts on the Nitrogen cycle
Negative
• Fossil fuel combustion and forest
fires increases nitrogen oxides,
an urban air pollutant that also
contribute to acid
rain and photochemical smog.
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Biomass: The mass of living
organisms in a given area expressed
as dry weight of mass per unit of
area or g m–2.
Productivity: the conversion of
energy into biomass in a given time
expressed as J m-2 yr-1. The rate of
growth of plants and animals in the
ecosystem.
Gross: It refers to the total amount
of products made. In ecosystems that
would be the total amount of
biomass that is made and in business
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•
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that could be the total amount of
money made in a month or year.
Net: this is a more meaningful figure
as it is what is left over after losses.
Ecosystem losses include
respiration and fecal loss.
Primary is to do with plants
and secondary to do with animals.
meters there is not enough light for
photosynthesis.
Define the terms and calculate
the values of both gross secondary
productivity (GSP) and net secondary
productivity (NSP) from given data
Gross Secondary Productivity (GSP)
represents the total amount of energy or
biomass assimilated by consumers.
GSP = food eaten – fecal loss
Net secondary productivity(NSP) is the
total gain in energy or biomass per unit area
per unit time by consumers after allowing
losses for respiration.
Define the terms and calculate
the values of both gross primary
productivity (GPP) and net primary
productivity (NPP) from given data.
Gross primary productivity (GPP) is all
the biomass produced by primary producers
in a given amount of time
Net Primary productivity (NPP) takes into
account respiratory losses (R) and is shown
as the following equation:
NPP = GPP – R
In terrestrial ecosystems temperature,
water availability and solar radiation
influence the rate of primary productivity.
In aquatic ecosystems, water is not a
limiting factor – though salinity is.
Temperatures vary less in the ocean than on
land, water has a high specific capacity,
which buffers changes. A major limiting
factor in aquatic ecosystems is light
availability – once you go below 200
NSP = GSP – R
Where R is respiratory losses.
Explain the concepts of limiting factors and
carrying capacity in the context of
population growth.
• Carrying capacity is the maximum
number of individuals of a species
that the environment can sustainably
support in a given area.
• Limiting factors are the resources in
the environment that limit the
growth, abundance and distribution
of organisms/populations in an
ecosystem.
•
Describe and explain S and J
population curves.
• Explain changes in both numbers
and rates of growth in standard S
and J population growth curves.
• Population curves should be
sketched, described, interpreted and
constructed from given data.
J curve.
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particular amount of sunlight
and water.
According to theory, density-dependent
factors operate as negative feedback
mechanisms leading to stability or
regulation of the population.
Both types of factors may operate on a
population.
Many species, particularly
r strategists, are probably regulated by
density independent factors, of which
weather is the most important. Internal
factors might include density-dependent
fertility or size of breeding territory, and
external factors might include predation
or disease.
Describe the principles associated
with survivorship curves including,
K and r strategists.
S CURVE
Describe the role of density dependent and
density independent factors, and internal
and external factors, in the regulation of
populations.
•
•
K and r strategists represent idealized
categories and many organisms occupy a
place on the continuum.
Density dependent factors are ones
that affect the population only when
it reaches a certain density. These
include competition, disease,
parasitism and predation - they tend
to be the biotic factors. Disease
spreads best when there are a lot of
organisms for it to infect.
Density-independent factors will
control populations no matter what
the density of it is. They include
sunlight, temperature, water
and natural disasters. High density or
low density the organisms still
need a certain temperature range or a
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NB: Be conversant with survivorship
curves including logarithmic scales.
Describe the concept and processes of
succession in a named habitat.
The concept of succession, occurring over
time, should be carefully distinguished
from the concept of zonation, which refers
to a spatial pattern.
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Type I survivorship curve: this is
indicative of the K-selected species.
The curve starts out very flat
showing a high survival rate in early
life. This long life expectancy causes
the line to have a sharp drop at the
end as the mortality increases
dramatically.
Type II survivorship curve: this
shows the middle ground with a
more or less constant mortality rate
throughout the organism’s life. That
is they are as likely to die at birth as
they are at old age.
Type III survivorship curve: this is
typical of the r-selected species. The
curve drops sharply immediately
showing very low survival rates after
birth. Very few individuals make it
into later life.
•
Succession is a change over time;
zonation is a spatial change in
response to changing conditions.
In succession the changes in the
plant community cause changes in
the physical environment but in
zonation the plant communities adapt
to the different environmental
conditions.
Succession may occur alone – on
fresh lava the whole area will go
through succession through time.
Zonation occurs without succession,
the rocky shore demonstrates
zonation due to tidal changes not
succession.
In a sand dune succession and
zonation are seen together. The area
closest to the sea is at the beginning
of succession and is largely sand. As
you move away from the sea the
sand dunes succession has
progressed further and you move
through areas of grass and in to
woodland (the oldest dunes). The
physical conditions change as you
move away from the sea so zonation
also appears.
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Explain the changes in energy flow, gross
and net productivity, diversity and mineral
cycling in different stages of succession.
• In early stages, gross productivity is
low due to the initial conditions and
low density of producers. The
proportion of energy lost through
community respiration is relatively
low too, so net productivity is high,
that is, the system is growing and
biomass is accumulating.
• In later stages, with an increased
consumer community, gross
productivity may be high in a climax
community. However, this is
balanced by respiration, so net
productivity approaches zero and the
production:respiration (P:R) ratio
approaches one.
Human factors frequently affect this process
through, for example, fire, agriculture,
grazing and/or habitat destruction.
Describe and evaluate methods for
measuring changes in abiotic and biotic
components of an ecosystem along an
environmental gradient.
Describe and evaluate methods for
measuring changes in abiotic and
biotic components of an ecosystem
due to a specific human activity.
• Methods and changes should be
selected appropriately for the human
activity chosen.
• Suitable human impacts for study
might include toxins from mining
activity, landfills, eutrophication,
effluent, oil spills and
overexploitation. This could include
repeated measurements on the
ground, satellite images and maps.
Describe and evaluate the
use of environmental impact
assessments (EIAs).
You should realize that an EIA
involves production of a baseline study
before any environmental development,
assessment of possible impacts, and
monitoring of change during and after the
development
What is assesed in a baseline study?
Describe factors affecting the nature of
climax communities.
Climatic and edaphic factors determine the
nature of a climax community(see above
table)
•
•
Assess all flora and fauna present
(Habitats, are they endangered, can
they be relocated)
Assess the abiotic environment of
soil, water supply, climate and
landscape features.
16
Assess the existing human features,
cultural heritage and material assets
that are there.
HUMAN POPULATION, CARRYING
CAPACITY AND RESOURCE USE.
•
Describe the nature and explain
the implications of exponential
growth in human populations.
Calculate and explain, from given
data, the values of crude birth rate,
crude death rate, fertility, doubling
time and natural increase rate.
Crude birth rate (CBR) is the number of
births/1000/year
CBR = number of births/total population ×
1000
Total fertility rate (TFR) is the number of
children a woman is expected to have in her
lifetime. A TFR of 2.2 means that the
population will remain stable, less than that
and the population will decline and more
means it will increase.
Factors affecting fertility and birth rate.
In some of the less economically developed
countries (LEDCs) children are seen as an
economic asset where they till the land
hence high fertility rate.
In many of the more economically
developed countries (MEDCs) children are
seen as an economic burden. High costs of
raising children causes a low fertility rate
Urban Living
Urban areas tend to have lower fertility rates
because:
• Space is more limited in urban
accommodation.
• Access to health care and family
planning services is better.
• Access to education is better so more
children go to school and stay out of
the labour force.
Women’s status
In many economically developed nations
women are highly educated and the
traditional role of “housewife” rarely
applies. Educated women often have the
means and knowledge to control their own
fertility and often seek paid employment
outside of the home. Once employed,
women tend to delay marriage and
motherhood. This means that they often
have less children, and hence the fertility
rate is lower.
Life style choices and cultural norms
In many developed countries the cultural
norm has changed from getting
married young (late teens to early twenties)
and having three or four children to later
marriages and smaller families. It is better to
have fewer children and focus your
resources on giving them the best of
everything.
Family planning and abortions
The availability of family planning,
contraception and legal abortions will
impact fertility. If any or all of these are
easily available women can make the choice
as to how many children they have. That
choice brings down fertility rates.
Religious beliefs and traditions
Many religions do not allow the use of
artificial contraception or abortion and they
actively encourage large families saying that
children are a gift from God. In some
countries having multiple children is seen as
a sign of the man's virility and because men
control fertility, large families are the result.
This combination naturally increases the
fertility rate
Government policy
Countries may have pro-natalist or antinatalist policies.
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Pro-natalist policies encourage people to
have more children though they have
historically been largely unsuccessful and so
have had a limited impact on the fertility
rates.
Anti-natalist policies on the other hand
encourage smaller families and the use of
family planning and contraception. These
are often highly successful and bring the
fertility rates down, but there are other
consequences, such as China’s OneChild Policy
•
crude death rate (CDR) is the number of
deaths/1000/year
CDR = number of Deaths/total population ×
1000
•
Doubling time (DT) and natural increase
rate (NIR)
The natural increase rate is the rate of
human growth expressed as a percentage
change per year.
•
•
•
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The model is Eurocentric/MEDC
based and the relationship between
economic development and
population growth does not seem to
be the same in LEDCs.
Some LEDCs are going through the
stages much faster as the medical
advances have been made,
contraception is already in existence
and education is widespread.
It does not take account of natural
disasters, epidemics such as AIDS or
wars etc.
It does not take into account
government policies designed to
manage the population.
It does not factor in migration, which
can have a significant impact on
population change.
Cultural and religious factors have
maintained high birth rates in many
LEDCs so they are stuck in stage 2.
NIR = (CBR – CDR)/10
Doubling time (DT) – how long it will take
a given population to double in size
Explain the concept of resources in terms
of natural income.
DT = 70/NIR
This income may consist of marketable
commodities such as timber and grain
(goods) or may be in the form of ecological
services such as the flood and erosion
protection provided by forests (services).
Similarly, non-renewable resources can be
considered in parallel to those forms of
economic capital that cannot generate
wealth without liquidation of the estate.
Analyse age/sex pyramids and
diagrams showing demographic
transition models.
Discuss the use of models in
predicting the growth of human
populations
This might include computer simulations,
statistical and/or demographic tables for
LEDCs and MEDCs, age/sex pyramids and
graphical extrapolation of population curves.
Evaluation of DEMOGRAPHIC
TRANSITION MODEL
Define the terms renewable,
replenishable and non renewable
natural capital.
• Renewable natural capital, such as
living species and ecosystems, is
self-producing and self-maintaining
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and uses solar energy and
photosynthesis. This natural capital
can yield marketable goods such as
wood fibre, but may also provide
unaccounted essential services when
left in place, for example, climate
regulation.
Replenishable natural capital, such
as groundwater and the ozone layer,
is nonliving but is also often
dependent on the solar “engine” for
renewal.
Non-renewable (except on a
geological timescale) forms of
natural capital, such as fossil fuel
and minerals, are analogous to
inventories: any use implies
liquidating part of the stock.
Explain the dynamic nature of the
concept of a resource.
Consider how cultural, economic,
technological and other factors influence the
status of a resource over time and space. For
example, uranium, due to the development
of nuclear technology, has only recently
become a valuable resource.
Discuss the view that the environment can
have its own intrinsic value.
Organisms or ecosystems that are valued on
aesthetic or intrinsic grounds may not
provide commodities identifiable as either
goods or services, and so remain unpriced or
undervalued from an economic viewpoint.
Organisms or ecosystems regarded as
having intrinsic value, for instance from an
ethical, spiritual or philosophical
perspective, are valued regardless of their
potential use to humans. Therefore, diverse
perspectives may underlie the evaluation of
natural capital.
Attempts are being made to acknowledge
diverse valuations of nature (for example,
biodiversity, rate of depletion of natural
resources) so that they may be weighed
more rigorously against more common
economic values (for example, gross
national product (GNP)).
However, some argue that these valuations
are impossible to quantify and price
realistically. Not surprisingly, much of the
sustainability debate centres on the problem
of how to weigh conflicting values in our
treatment of natural capital.
Explain the concept of sustainability in
terms of natural capital and natural income.
Sustainability means living, within the
means of nature, on the “interest” or
sustainable income generated by natural
capital.
Any society that supports itself
in part by depleting essential forms of
natural capital is unsustainable. If human
well-being is dependent on the goods and
services provided by certain forms of natural
capital, then long term harvest (or pollution)
rates should not exceed rates of capital
renewal.
Discuss the concept of sustainable
development.
was defined as “development that meets
current needs without compromising the
ability of future generations to meet their
own needs.” The value of this approach is a
matter of considerable debate and there is
now no single definition for sustainable
development. For example, some
economists may view sustainable
development as a stable annual return on
19
investment regardless of the environmental
impact, whereas some environmentalists
may view it as a stable return without
environmental degradation. Consider the
development of changing attitudes to
sustainability and economic growth, since
the Rio Earth Summit (1992) leading to
Agenda 21. International summits on
sustainable development have highlighted
the issues involved in economic
development across the globe, yet the
viewpoints of environmentalists and
economists may be very different.
pollutants such as particulates, SO2,
NOx and secondary pollutants such
as ozone.
• Reduced GHG emissions e.g. CO2.
Factors which could accelerate growth in the
use of renewable energy:
•
•
•
Calculate and explain sustainable yield
from given data.
•
Sustainable yield (SY) may be calculated as
the rate of increase in natural capital, that is,
that which can be exploited without
depleting the original stock or its potential
for replenishment. For example, the annual
sustainable yield for a given crop may be
estimated simply as the annual gain in
biomass or energy through growth and
recruitment
•
Decline in fossil fuel reserves
forcing prices up.
Technological developments
improving the efficiency of
renewable energy and capital cost.
Governmental support through
economic incentives e.g. subsidies.
Increase awareness of the
environmental impact of using fossil
fuels e.g. climate change.
Need to meet agreed international
targets e.g. reduction in carbon
dioxide emissions.
Evaluate the advantages and disadvantages
of two contrasting energy sources.
NB: Consider one non-renewable (fossil
fuels or nuclear) and one renewable energy
source
Fossil fuels
Comprise of coal, oil and natural gas. Our
reliance on fossil fuels is expected to
continue in the near future, with overall use
increasing to meet rising energy demands.
Outline the range of energy resources
available to society.
Renewable sources of energy include solar,
wind, hydropower, biomass, geothermal,
wave and tidal.
Advantages of using renewable energy
compared to fossil fuel sources include:
• Improvements to local air quality, for
example production of less primary
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•
•
•
•
•
•
Wind power/energy
Further reading: Jill Rutherford, Gillian
Williams pages 312-315.
•
Availability of supply
Technological developments- finding
new sources of energy e.g shale oils
and harnessing wave power. E.g
USA shale oil.
Politics can lead to conflict over
energy supplies. Influences decisions
to go nuclear or not. E.g Ukraine
Russia gas disputes
Economics – globalization of
economies can make it cheaper to
import than produce your own
power.
Cultural Attitudes-Love for fuel
powered cars means people are
reluctant to shift to electric cars
Sustainability-Only renewable
energy are sustainable yet makes the
smallest percentage of the world
energy supply
Environmental considerationsBacklash against nuclear power
generation e,g being phased out in
Germany after Fukushima accident
when people felt it was too
dangerous.
Outline how soil systems integrate aspects
of living systems.
The soil as a living system should be
considered with reference to a generalized
soil profile.
Soil is not static; it is continually changing
and developing through physical, chemical
and biological processes such as weathering,
erosion and translocation (internal
reorganisation of matter and energy).
Discuss the factors that affect the choice of
energy sources adopted by different societies
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Consider mineral content, drainage, water
holding capacity, air spaces, biota and
potential to hold organic matter, and link
these to primary productivity.
Transfers of material (including deposi on)
result in reorganiza on of the soil. There are
inputs of organic and parent material,
precipita on, in ltra on and energy.
Outputs include leaching, uptake by plants
and mass movement. Transforma ons
include decomposi on, weathering and
nutrient cycling.
Compare and contrast the structure and
properties of sand, clay and loam soils,
including their effect on primary
productivity.
Outline the processes and consequences of
soil degradation
Human activities such as overgrazing,
deforestation, unsustainable agriculture and
irrigation cause processes of degradation.
These include soil erosion, toxification and
salinization. Desertification (enlargement of
deserts through human activities) can be
associated with this degradation.
Outline soil conservation measures
Consider:
• soil conditioners (for example, use of lime
and organic materials)
• wind reduction techniques (wind breaks,
shelter belts, strip cultivation)
• cultivation techniques (terracing, contour
plowing)
• efforts to stop plowing of marginal lands
Evaluate soil management strategies in a
named commercial farming system and in a
named subsistence farming system.
The type of farming chosen and levels of
food production will dependent on:
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•
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Environmental conditions e.g.
weather (precipitation, sunlight,
temperature), topography and soil
conditions that determine whether
the area is suitable for growing
specific plants or for rearing certain
animals.
Access to vehicles and technology,
such as tractors and animal feeding
systems.
Available financial funds to purchase
land and inputs, such as seeds,
fertilizers, pesticides, equipment and
labour.
Cultural and environmental value
systems that influence methods of
farming. For example some
communities will use specific
traditional methods of husbandry
whereas other communities with
technocentric beliefs will embrace
the use of modern technology.
Government and political initiatives.
For instance, farmers can be
encouraged to produce certain
products or employ particular
methods through education
programmes and financial incentives.
Animal production(COMMERCIAL)
Intense animal husbandry aims at obtaining
maximum and cheapest output. A wide
range of animals can be reared in this way,
such as cows, pigs and chickens.
Animals are kept indoors in a limited space
to restrict their movements. This stops them
moving around and using energy and so
increases muscle mass which results in a
higher final yield.
It also has the advantage of making the
meat more tender.
Concerns of intensive animal farming
include:
High density of animals increases the
risk of rapid spread of disease
through the animal population.
• Ethical concern over keeping
animals under such confined
conditions.
• Use of growth hormones to promote
faster growth. There are concerns
that hormone residues within milk
and meat may cause health problems
in humans such as developmental
issues, reproductive problems, and
cancers. These growth hormones
may also enter the environment
through animal waste. Research
studies have demonstrated that
hormones in aquatic systems can
affect the gender and reproduction
within fish.
• Regular use of medication such
as antibiotics to prevent diseases.
Use of antibiotics increases the risk
of developing resistance within
bacteria. This makes future
infections more difficult to treat.
• High concentration of organic waste
matter produced that can pollute
water systems.
Shifting agriculture
• This method of cultivation involves
clearing land, typically tropical
forest by cutting and burning (often
referred to as slash and burn). The
land is farmed for a few years until
crop yields fall due to loss of soil
fertility.
• The farmer then moves to a new
area, again clearing the trees to use
the land for cultivation. Over time
trees will begin to grow in the
previously farmed area and gradually
the soil and biomass will recover.
•
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At a low human population density
this can be a sustainable system.
However, with a high population
there is a shortening of fallow
periods leading to low crop yields
and greater soil damage.
•
Inputs for this system are low in terms of
technology and labour. Outputs are
relatively low and the aim is usually for
yields to be sufficient to meet the needs of
the family.
Outline the issues involved in the imbalance
in global food supply
• Poverty that prevents people being
able to afford food.
• Poor infrastructure that limits access
and distribution of food.
• Extreme weather events, such as
drought or floods.
• War and associated displacement of
people.
• Food waste. The FAO estimate that
approximately a third of food
produced is lost or wasted each year.
Compare and contrast the efficiency of
terrestrial and aquatic food production
systems.
In terrestrial systems, most food is harvested
from relatively low trophic levels (producers
and herbivores). However, in aquatic
systems, perhaps largely due to human
tastes, most food is harvested from higher
trophic levels where the total storages are
much smaller. Although energy conversions
along the food chain may be more efficient
in aquatic systems, the initial fixing of
available solar energy by primary producers
tends to be less efficient due to the
absorption and reflection of light by water.
Compare and contrast the inputs and
outputs of materials and energy (energy
efficiency), the system characteristics, and
evaluate the relative environmental impacts
for two named food production systems.
The systems selected should be both
terrestrial or both aquatic. In addition,
the inputs and outputs of the two systems
should differ qualitatively and
quantitatively (not all systems will be
different in all aspects)
The pair of examples could be North
American cereal farming and subsistence
farming in some parts of South-East Asia,
intensive beef produc on in the developed
world and the Maasai tribal use of livestock,
or commercial salmon farming in Norway/
Scotland and rice- sh farming in Thailand.
Factors to be considered should include:
• inputs—for example, fertilizers (artificial
and natural), irrigation water, pesticides,
fossil fuels, food distribution, human labour,
seed, breeding stock
• system characteristics—for example,
selective breeding, genetically engineered
organisms, monoculture versus polyculture,
sustainability
• sociocultural—for example, for the
Maasai, cattle equals wealth and quantity is
more important than quality
• environmental impact—for example,
pollution, habitat loss, reduction in
biodiversity, soil erosion
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• outputs—for example, food quality and
quantity, pollutants, soil erosion.
Discuss the links that exist between social
systems and food production systems.
• The way in which the low population
densities and belief systems of
shifting cultivators links with the
ecosystem of “slash and burn”
agriculture
• The relationship between high
population densities, culture, soil
fertility and the wet rice ecosystem
of South-East Asia
• The link between the political
economy of modern urban society,
corporate capitalism and agroecosystems.
Describe the Earth’s water budget
Only a small fraction (2.6% by volume) of
the Earth’s water supply is fresh water. Of
this, over 80% is in the form of ice caps and
glaciers, 0.6% is groundwater and the rest is
made up of lakes, soil water, atmospheric
water vapour, rivers and biota in decreasing
order of storage size.
Describe and evaluate the sustainability of
freshwater resource usage with reference to
a case study. E.g Lake Victoria..
•
•
Irrigation, industrialization and
population increase all make
demands on the supplies of fresh
water.
Global warming may disrupt rainfall
patterns and water supplies. The
hydrological cycle supplies humans
with fresh water but we are
withdrawing water from
underground aquifers and degrading
it with wastes at a greater rate than it
can be replenished.
• Consider the increased demand for
fresh water, inequity of usage and
political consequences, methods of
reducing use and increasing supplies.
A case study must be explored that
covers some of these issues and
demonstrates either sustainable or
unsustainable water use.
Explain the difficulties in applying
the concept of carrying capacity to
local human populations.
• The range of resources used by
humans is usually much greater than
for any other species. Furthermore,
when one resource becomes limiting,
humans show great ingenuity in
substituting one resource for another.
• Resource requirements vary
according to lifestyles, which differ
from time to time and from
population to population.
Technological developments give
rise to continual changes in the
resources required and available for
consumption.
• Human populations also regularly
import resources from outside their
immediate environment, which
enables them to grow beyond the
boundaries set by their local
resources and increases their
carrying capacity. While importing
resources in this way increases the
carrying capacity for the local
population, it has no influence on
global carrying capacity.
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Explain how absolute reductions in energy
and material use, reuse and recycling can
affect human carrying capacity.
• Human carrying capacity is
determined by the rate of energy and
material consumption, the level of
pollution and the extent of human
interference in global life-support
systems. While reuse and recycling
reduce these impacts, they can also
increase human carrying capacity.
Explain the concept of an ecological
footprint as a model for assessing the
demands that human populations make
on their environment.
The ecological footprint of a population is
the area of land, in the same vicinity as the
population, that would be required to
provide all the population’s resources and
assimilate all its wastes.
As a model, it is able to provide a
quantitative estimate of human carrying
capacity hence help plan for the future. It is,
in fact, the inverse of carrying capacity. It
refers to the area required to sustainably
support a given population rather than the
population that a given area can sustainably
support.
Calculate from appropriate data the
ecological footprint of a given population,
stating the approximations and assumptions
involved.
The total land requirement (ecological
footprint) can then be calculated as the sum
of these two per capita requirements,
multiplied by the total population.
This calculation clearly ignores the land or
water required to provide any aquatic and
atmospheric resources, assimilate wastes
other than carbon dioxide (CO2), produce
the energy and material subsidies imported
to the arable land for increasing yields,
replace loss of productive land through
urbanization, and so on.
Describe and explain the differences
between the ecological footprints of two
human populations, one from an LEDC and
one from an MEDC.
• In MEDCs, about twice as much
energy in the diet is provided by
animal products than in LEDCs.
• Grain production will be higher with
intensive farming strategies.
• Populations more dependent on
fossil fuels will have higher CO2
emissions.
• Fixation of CO2 is clearly dependent
on climatic region and vegetation
type.
These and other factors will often explain
the differences in the ecological footprints of
populations in LEDCs and MEDCs.
Discuss how national and international
development policies and cultural influences
can affect human population dynamics and
growth.
•
Domestic and international
development policies (which target
the death rate through agricultural
development, improved public
health and sanitation, and better
26
service infrastructure) may stimulate
rapid population growth by lowering
mortality without significantly
affecting fertility.
• Some analysts believe that birth
rates will come down by themselves
as economic welfare improves and
that the population problem is
therefore better solved through
policies to stimulate economic
growth.
• Education about birth control
encourages family planning.
• Parents may be dependent on their
children for support in their later
years and this may create an
incentive to have many children.
• Urbanization may also be a factor in
reducing crude birth rates.
• Policies directed towards the
education of women, enabling
women to have greater personal and
economic independence, may be the
most effective method for reducing
population pressure.
Describe and explain the relationship
between population, resource
consumption and technological
development, and their influence on
carrying capacity and material
economic growth.
• Because technology plays such a
large role in human life, many
economists argue that human
carrying capacity can be
expanded continuously through
technological innovation. For
example, if we learn to use
energy and material twice as
efficiently, we can double the
population or the use of energy
without necessarily increasing
the impact (load) imposed on the
environment. However, to
compensate for foreseeable
population growth and the
economic growth that is deemed
necessary, especially in
developing countries, it is
suggested that efficiency would
have to be raised by a factor of 4
to 10 to remain within global
carrying capacity.
Conservation and biodiversity
De ne the terms biodiversity, gene c
diversity, species diversity and habitat
diversity
Biodiversity refers to the degree of
varia on of all life on earth, both within and
between species and habitats.
Species diversity is the number of di erent
species in a given area taking into account
the richness and evenness of the species.
Gene c diversity is the varia on of genes
within the gene c pool of a popula on of a
species.
Habitat diversity is the range of di erent
habitats in an area
Outline the mechanism of natural
selec on as a possible driving force
for specia on.
Specia on is the forma on of a new species
through biological processes.
Specia on occurs as a result of the isola on
(geographical or reproduc ve) of
popula ons.
State that isola on can lead to di erent
species being produced that are unable to
interbreed to yield fer le o spring.
• Geographic isola on: Popula ons
are physically separated and can no
longer interbreed (as shown in the
video)..
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Temporal isola on: Popula ons live
their lives at di erent mes of the
day and so do not meet to breed.
Behavioural isola on: They have
di erent ma ng rituals.
•
•
Explain how plate ac vity has in uenced
evolu on and biodiversity
• New biodiversity is formed by
the process of specia on.
Specia on takes place when
popula ons are separated into
new surroundings and then
natural selec on occurs when
the popula ons adapt to their
new surroundings.
The forma on of geographical barriers such
as mountains and ri valleys
• The forma on of new mountain
or ri valleys forms a barrier
between two popula ons.
• New habitats are created.
• The increase in habitat diversity
leads to an increase in species
diversity as the number of
available niches increases.
• The geographical barrier could
separate species and put them
in two di erent ecosystems with
climates that might be
completely di erent.
• Separated popula ons would
adapt to their new surroundings
and eventually evolve into new
species.
Explain the rela onships among ecosystem
stability, diversity, succession and habitat.
As a succession progresses, the complexity
of an ecosystem increases. As complexity
increases, diversity becomes greater: 1.
Each seral stage of succession helps create a
deeper soil with more nutrients, which
allows larger plants to grow. 2. Changes in
the plant community increase habitat
diversity. 3. This leads to greater species
diversity and gene c diversity. 4. Greater
habitat diversity leads to an increase in
niches, which allows more species to live
together. 5. Greater species diversity
increases gene c diversity because there is
a greater range of gene c material in the
greater number of species. 6. Climax
communi es have a more complex system
and so are more stable than earlier seral
stages, such as pioneer communi es.
Consider how:
• diversity changes through succession
• greater habitat diversity leads to greater
species and gene c diversity
• a complex ecosystem, with its variety of
nutrient and energy pathways, provides
stability
• human ac vi es modify succession, for
example, logging, grazing, burning
• human ac vi es o en simplify
ecosystems, rendering them unstable, for
example, North America wheat farming
versus tall grass prairie
• an ecosystem’s capacity to survive change
may depend on diversity, resilience and
iner a.
Iden fy factors that lead to loss of diversity
These include:
• natural hazard events
(for example,
volcanoes, drought,
ice age, meteor
impact)
• habitat degrada on,
fragmenta on and
loss
• agricultural prac ces
(for example,
monoculture, use of
pes cides, use of
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28
•
•
The vulnerability of other systems
The regenera on rate of tropical
rainforests Total area and species
diversity
Rainforest and “green poli cs”.
•
Discuss current es mates of numbers of
species and past and present rates of
species ex nc on.
The total number of species on Earth today
is s ll not well understood. Es mates of the
current number of species on the planet
range from 5 million to 100 million. So far,
science has iden ed about 1.8 million
species. It is impossible to get an accurate
count of the number of species because
many species have not been discovered yet.
Many species that have not yet been
discovered are very small, such as insects,
bacteria, and other microbes. There are
areas of the Earth that we s ll know li le
about, such as the canopy of rainforest and
the deep ocean, where many undiscovered
species may live. Without a reliable
es mate of the number of species, it is
di cult to calculate ex nc on rates.
The fossil record shows that there have
been ve periods of mass ex nc on in the
past. Mass ex nc ons are when species
disappear in a geologically short me
period, usually between a few hundred
thousand to a few million years.
Causes of mass ex nc on include meteorite
strikes and huge volcanic erup ons. Animals
and plants died from both the ini al event
and the events that followed. Events that
followed meteorite strikes and massive
volcanic erup ons include climate change
and planetary cooling.
The sixth mass ex nc on is therefore the
rst mass ex nc on event to have bio c,
rather than abio c, causes.
Describe and explain the factors that may
make species more or less prone to
ex nc on.
• Small popula on size and limited
distribu on
Species with small popula on sizes and
limited distribu on are more likely to
become ex nct than common and
widespread species. For example, the
slenderbilled grackle (Cassidix palustris) was
a bird that once occupied a single marsh
near Mexico City and became ex nct
through human ac vity. Species with small
popula ons are also more likely to have low
gene c diversity and their inability to adapt
to changing condi ons can be fatal. Many of
the large cat species have low gene c
diversity, for example, the cheetah, snow
leopard, and ger.
• Degree of specializa on
Specialist species are more likely to become
ex nct than generalist species. Specialized
species have a narrow niche so, if their
surroundings change, they may not be able
to adapt and change. For example, a
species’ food resources may be very
specialized, such as the giant panda, which
mainly eats bamboo.
•
Reproduc ve poten al
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gene cally modi ed
species)
• introduc on and/or
escape of non-na ve
species
• pollu on
• hun ng, collec ng
and harves ng
Discuss the perceived vulnerability of
tropical rainforests and their rela ve value
in contribu ng to global biodiversity
Species that live for a long me are more
likely to have a low reproduc ve rate and
this makes them vulnerable to ex nc on. If
there is a change in habitat or a predator is
introduced, the popula on drops and there
are not enough reproduc ve adults to
support and maintain the popula on.
Because they are slow-reproducing, any loss
in numbers means a fast decline
• Poor compe tors
Species that show weak interspeci c
compe on are more likely to become
ex nct than good compe tors. Flightless
and slow-moving birds, such as the great
auk, great elephant bird, and the dodo, are
helpless under the pressures of hun ng and
preda on. Their lack of mobility and poor
defensive ins ncts mean that they are easily
preyed upon. Animals that have evolved in
areas where they have no predators, such
as the dodo on Mauri us, are prone to
ex nc on when a predator is introduced.
• Trophic level
Top predators are sensi ve to any
disturbance in the food chain. Any
reduc on in the number of species at lower
trophic levels can have drama c
consequences. Top predators are more
likely to be rare because energy is lost
through food chains. This means that there
is li le energy le by the end of the food
chain. Top carnivores are therefore
par cularly sensi ve to hunters and
reduc ons in popula on size
Outline the factors used to determine a
species’ Red List conserva on status.
• The popula on size of a species
Smaller popula ons are more likely to go
ex nct
•
Reduc on in popula on size
A reduc on in popula on size may indicate
that a species is under threat.
• The numbers of mature individuals
Species with few mature individuals have
lower reproduc ve rates. Example of Red
List species: orang-utan (Pongo pygmaeus).
Orang-utans have one of the slowest
reproduc ve rates of all mammal species.
They give birth to a single o spring only
once every 6 to 8 years. With such a low
reproduc ve rate, even a small decrease in
numbers can lead to ex nc on.
• Geographic range
Species with a limited geographic range may
be under greater threat from ex nc on
• Degree of fragmenta on
Species in fragmented habitats may not be
able to maintain large enough popula on
sizes. Example of Red List species: the
Sumatran rhinoceros (Dicerorhinus
sumatrensis). Fragmenta on of tropical
rainforest in South-East Asia has led to a
reduc on in habitat area for this species.
• Quality of habitat
Species that live in habitats that are poorer
in quality are less likely to survive than
species in habitats that are be er in quality.
• Area of occupancy
Species that live in a smaller area are under
greater threat from ex nc on than more
widespread species. Loss of the area they
live in will lead to loss of the species.
Describe the case histories of three
di erent species: one that has become
ex nct, another that is cri cally
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endangered, and a third species whose
conserva on status has been improved by
interven on
(PICK AN EASY ONE IN EACH CATEGORY)
Describe the case history of a natural area
of biological signi cance that is threatened
by human ac vi es.
The Great Barrier Reef is the world’s biggest
single structure that is made by living
organisms. It is large enough to be seen
from space. The Great Barrier Reef has high
levels of biodiversity. It is found along the
Queensland coastline of eastern Australia. It
is home to 1500 species of sh, 215 bird
species, and more than 30 species of sea
mammals, including vulnerable dugongs
(sea cows). In addi on, there are thousands
of di erent sponges, worms, and
crustaceans, and 800 species of
echinoderms (star sh, sea urchins).
Ecological, socio-poli cal, and economic
pressures are causing the destruc on of the
coral reef. The destruc on of the coral reef
is threatening the biodiversity of the area.
Threats include:
• Tourists damage the coral when they
break bits o as souvenirs.
• The coral is very fragile and is easily
damaged by divers’ ns.
• Over- shing can disturb the balance of
species in the food chain.
• There is accidental damage from anchors
and pollu on from boats.
• Fishing for prawns along the sea bed
results in the uninten onal catching of
other species and the destruc on of the sea
bed.
• Sugar planta ons have replaced forests
that once grew along the coast of
Queensland. The planta ons use a lot of
fer lizers. Run-o from the soil into the sea
has led to high levels of nutrients in the
water and to algal blooms. Algal blooms
cause eutrophica on.
• Sedimenta on has increased due to the
deforesta on of mangroves as land has
been cleared. Land has been cleared to
make space for tourist developments,
housing, and farming. Sedimenta on
reduces coral reef produc vity as it blocks
sunlight from reaching the reef.
• Global warming is also having an e ect on
the reef. Increases in sea temperature
through global warming have caused two
mass coral bleaching events. Bleaching
events kill the reef, which leads to a loss of
biodiversity.
• Climate change may be causing some sh
species to move away from the reef in order
to nd waters that are at a temperature
they prefer. This leads to increased deaths
in seabirds that prey on the sh. The habitat
available for sea turtles will also be a ected,
which will lead to a reduc on in popula on
numbers.
State the arguments for preserving species
and habitats.
Ethical reasons
Everyone has a responsibility to protect
resources for future genera ons. Ethical
reasons also include the idea that every
species has a right to survive.
Aesthe c reasons
Species and habitats are pleasant to look at
and provide beauty and inspira on.
Economic reasons
Species and habitats provide nancial
income. Species should be preserved to
maintain gene c diversity so that gene c
resources will be available in the future. An
example of why gene c diversity is
important is that it will allow crops to be
improved in the future. Other reasons for
preserving biodiversity are that commercial
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31
resources, such as new medicines, are s ll
wai ng to be discovered. Ecotourism is
successful when habitats are preserved that
are high in biodiversity, which a racts
people to see them.
Ecological reasons
Rare habitats should be conserved as they
may contain endemic species that require
speci c habitats. In addi on, ecosystems
with high levels of biodiversity are generally
more stable and more likely to survive into
the future. Healthy ecosystems are also
more likely to provide ecosystem services
such as pollina on and ood preven on.
Species should be preserved because if they
disappear they could have e ects on the
rest of the food chain and ecosystem.
Compare and contrast the role and
ac vi es of intergovernmental and nongovernmental organiza ons in preserving
and restoring ecosystems and biodiversity.
An intergovernmental organiza on (IGO) is
an organiza on that is established through
interna onal agreements in order to protect
the Earth’s natural resources. Eg UNEP
A non-governmental organiza on (NGO) is
an organiza on that is not run by the
governments of any country. E.g WWF,
Greenpeace.
Similari es between IGOs and NGOs are:
• They look to resolve concerns that a ect
the world.
• They use the media to get their message
across and to in uence decision making.
• They operate both locally and globally to
preserve and restore ecosystems and
biodiversity.
• They publish reports and ar cles about
their ac vi es
Di erences.
State and explain the criteria used to design
protected areas.
•
•
•
•
•
•
Reduce amount of edge to area ra o
as much as possible e.g. a circular
shaped protected area is more
desirable to reduce edge e ect.
The edge e ect is reduced with a
larger protected area.
Aim for the largest protected area
possible because the larger it is the
more ecosystems, habitats and
species it can support.
O en larger species favour larger
areas that support greater amounts
of resources such as food and water.
Speci c migratory routes should be
considered in the design of the
protected area.
Incorporate wildlife corridors
between protected areas that allow
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migra on to occur/wildlife corridors
can reduce isola on of popula ons.
• If possible avoid proximity of
protected areas to human
se lements.
• Incorporate a bu er zone to reduce
impact from humans.
• Involve local people (with their
knowledge of the area) in the design
and management of the protected
area.
Evaluate the success of a named protected
area.
Discuss and evaluate the strengths and
weaknesses of the species based approach
to conserva on.
The species-based approach to conserva on
is an approach that focuses on speci c
individual species that are vulnerable. The
aim is to a ract interest in their
conserva on. The species-based approach
a racts a en on, and therefore funding for
conserva on, and can successfully preserve
a species in zoos and botanic gardens.
Evalua on of CITES CITES is an interna onal
agreement between governments that aims
to ensure that interna onal trade in wild
animals and plants does not threaten their
survival. Trade in animal and plant
specimens and parts, in addi on to factors
such as habitat loss, can seriously reduce
their wild popula ons and bring some
species close to ex nc on. Some strengths
of CITES include: • It is supported by many
countries (178) and it protects many species
(ca. 35 000).
• It is legally binding and so countries that
have signed the conven on must accept its
condi ons.
• The treaty works across interna onal
borders. Limita ons of CITES include:
• It does not replace na onal laws;
countries that have signed the agreement
must make their own laws to ensure that
CITES is put into prac ce at the na onal
level.
• It is di cult to enforce.
• Fines are rela vely small and may not stop
poaching and smuggling.
• In some countries it is only weakly
supported and is not very e ec ve. Despite
the agreement, illegal hun ng s ll occurs.
However, taken overall, CITES has been
responsible for preven ng the interna onal
trade in endangered animals and plants.
Evalua on of cap ve breeding,
reintroduc on programmes, and zoos
There are many strengths to modern zoos:
• Educa on of the public about species and
conserva on
• Research in zoos increases the knowledge
of individual species
• There is gene c monitoring, which makes
it possible for the gene c diversity of
species to be maintained
• Zoos allow species to be held while
habitats are being restored.
Weaknesses of zoos include:
• Possibility that cap ve animals may be
unable to adapt to being back in the wild
• Some people object to animals being kept
in cap vity for pro t
• A species can be ar cially preserved in a
zoo while its natural habitat is destroyed.
For example the Sumatran ger is being
kept in zoos while its rainforest habitat in
Sumatra is disappearing.
Strengths of cap ve breeding programs
include:
• They can improve reproduc ve success
• Popula ons can build up quickly as
habitat and food are abundant
• Cap ve breeding allows individual animals
to be exchanged between zoo collec ons in
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order to prevent inbreeding and to maintain
gene c diversity; successful examples of
cap ve breeding include the Arabian oryx
and golden lion tamarin. Weaknesses of
cap ve breeding and reintroduc on
programmes include:
• They do not directly conserve natural
habitat diversity of the species
• Not all species breed easily in cap vity, for
example giant pandas
• Cap ve animals released into the wild
may be easy prey for predators.
Pollu on management
De ne the term pollu on.
Pollu on is the addi on of a harmful
substance or agent (such as heat) to an
environment which has a no ceable e ect
on the organisms within that environment.
Pollu on can be natural or the result of
human ac vi es. It can also be a
combina on of the two. An example of a
natural source of pollu on is a volcanic
erup on. Volcanoes emit large quan es of
sulfur dioxide, which can cause acid rain
Dis nguish between the terms point source
pollu on and nonpoint source pollu on,
and outline the challenges they present for
management.
Point source pollu on refers to the release
of pollutants from a single site.
This could be a factory chimney or the
waste disposal pipe from a sewage works
into a river.
Non-point source pollu on refers to the
release of pollutants from a number of
widely dispersed origins, such as the gases
from the exhaust systems of many vehicles.
A type of pollu on can some mes be a
point source and at other mes non-point
source. If there is only one source of the
pollu on, then it is point source pollu on. It
is possible that many poten al sources
could be involved when the pollu on is
located at a distance from the possible
source of pollu on. This makes it non point
source pollu on.
Challenges
Point source pollu on is generally more
easily managed because its impact is more
localized. This makes it easier to control
emission. It is also easier to iden fy the
source of the pollutant and the polluter.
This makes it easier to take legal ac on.
Non-point source pollu on is much harder
to control. Many polluters emit sulfur
dioxide and oxides of nitrogen. The main
sources are power sta ons and vehicles.
These contribute to acid deposi on. It is
impossible to blame the e ects of acid
deposi on on emissions from one par cular
power sta on or vehicle. It is impossible to
blame it on the emissions from one
par cular country. Therefore, it is very
di cult to manage the problem
State the major sources of pollutants.
• Fossil fuels
The burning of fossil fuels releases carbon
dioxide and sulfur dioxide. It can also
release oxides of nitrogen and par culate
ma er. These can contribute to many
impacts, such as acidi ca on and global
warming. In some cases, they may have an
e ect on human health.
• Domes c waste
The main pollutants from domes c waste
include solid domes c waste and sewage.
Solid domes c waste includes paper and
glass. Solid domes c waste can cause the
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release of methane gas from land ll sites.
Sewage can cause eutrophica on.
• Agriculture
The main pollutants from agriculture
include run-o of manure and fer lizers.
This may cause eutrophica on. The use of
pes cides can also cause pollu on. The use
of pes cides may eventually kill animals
though biomagni ca on and
bioaccumula on.
• Manufacturing industry
The main pollutants from the
manufacturing industry include solid waste
and industrial dumping. These may result in
land contaminated with heavy metals, such
as cadmium and copper.
Describe two direct methods of monitoring
pollu on
Air pollu on There are many pollutants that
can be monitored or measured. These
include chemicals and par culate ma er.
Chemicals include SOx , and NOx .
Par culate ma er includes dust.
Measured using:
• use of a monitor or probe
Method
• use of lter paper in a container
• weighing the lter paper before and a er
collec on
• taking the material ltered for chemical
analysis.
Water pollu on
Water quality can be measured using
standard water tes ng kits. These kits
include tests for phosphates and nitrates.
The readings can then be compared with a
table of cri cal values.
Clean water has less than 5 mg dm-3 of
nitrates. Polluted water
contains 5 to 15 mg dm-3
De ne the term biochemical oxygen
demand (BOD) and explain how this
indirect method is used to assess pollu on
levels in water
Biochemical oxygen demand (BOD) is a
measure of the amount of dissolved oxygen
required to break down the organic material
in a given volume of water through aerobic
biological ac vity.
• Using BOD to assess pollu on levels
in water
Aerobic organisms use oxygen in
respira on. When there are more organisms
and a faster rate of respira on, more
oxygen will be used.
The biochemical oxygen demand at any
point is a ected by two main factors.
These are:
1. The amount of aerobic organisms
2. Their rate of respira on.
Describe and explain an indirect method of
measuring pollu on levels using a bio c
index.
Measuring pollu on using a bio c index
When using a bio c index, it is important to
compare a polluted and an unpolluted site,
such as upstream and downstream of a
pollu on source. Seasonal changes may also
be important. The Trent Bio c Index is
based on the disappearance of certain
indicator species as the levels of pollu on
increase. Changes in the amount of light
and dissolved oxygen cause less-tolerant
species to die out. As pollu on increases,
diversity decreases
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Certain species have di erent levels of
tolerance to environmental condi ons and
change.
May y nymphs are found in non-polluted
water.
Tubifex worms are found in polluted water.
Tubifex worms can tolerate high levels of
pollu on, such as organic ma er. May y
nymphs cannot tolerate high levels of
pollu on. The presence or absence of
indicator species can be used to indirectly
suggest condi ons in the water.
In a polluted stream, there might be very
large numbers of Tubifex worms. This is
because very few organisms can tolerate
highly polluted condi ons. Tubifex worms
can tolerate high levels of pollu on and so
become abundant. Thus, the stream has a
low level of biodiversity but a high level of
species abundance. Many species can
survive in a non-polluted stream. They can
tolerate the low levels of pollu on.
Therefore, the stream has a high level of
biodiversity. No single species will be very
abundant. Thus, the non-polluted stream
has high biodiversity and low levels of
species abundance.
Outline approaches to pollu on
management
Discuss the human factors that a ect the
approaches to pollu on management.
Evaluate the costs and bene ts to society of
the World Health Organiza on’s ban on the
use of the pes cide DDT.
Bene ts of DDT
DDT is a man-made pes cide. Its main
advantages are in the control of disease and
in improving farm yields. During the 1940s
and 1950s, it was used extensively to
control lice and mosquitoes. Lice spread the
disease typhus and mosquitoes spread the
disease malaria. Today there are about 250
million cases of malaria each year.
DDT was also used as a pes cide in farming.
This helped to raise agricultural yields.
The costs of DDT
In the 1960s, public opinion turned against
DDT. This was largely as a result of the
publica on of the book Silent Spring by
Rachel Carson. Carson claimed that the
largescale spraying of pes cides was killing
top predators. It a ected top predators
because of bioaccumula on and
biomagni ca on. Bioaccumula on refers to
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the build-up of non-biodegradable or slowly
biodegradable chemicals in the body.
DDT can cause cancer in humans.
There are also links between DDT and
premature births.
DDT has also been linked to low birth
weight and reduced mental development.
Recent developments in the management
of DDT In the 1970s and 1980s, the use of
DDT in farming was banned in many MEDCs.
In 2001, the Stockholm Conven on on
persistent organic pollutants (POPs)
regulated the use of DDT – it was banned
for use in farming but was permi ed for
disease control. Cases of malaria increased
in South America a er countries stopped
spraying DDT. Cases of malaria in Ecuador
decreased by over 60 per cent following an
increase in the use of DDT. In 2006, the
WHO changed its recommenda ons. It
recommended the use of DDT for regular
treatment in buildings and in areas with a
high incidence of malaria. WHO s ll aims for
a total phase out of the use of DDT by the
early 2020s.
Conclusion Thus, there are many
advantages and disadvantages in using DDT.
As the WHO is sugges ng the total phase
out of DDT by the early 2020s, it suggests
that they believe the disadvantages
outweigh the advantages.
Outline the processes of eutrophica on.
Evaluate the impacts of eutrophica on.
Describe and evaluate pollu on
management strategies with respect to
eutrophica on
Strategy 1: Altering human ac vity
These include:
• use fewer chemical fer lizers
• use organic fer lizers (manure) on
agricultural elds as these contain less
phosphorus than most chemical fer lizers
• avoid spreading fer lizers in winter when
the soil is bare and run-o may wash
fer lizers into rivers and streams
• use autumn-sown crops as a cover crop
during the winter
• use less fer lizer if the previous year was
dry as more will be le in the soil
• use mixed cropping or crop rota on so
fewer fer lizers are needed
• do not use fer lizers in elds that are next
to streams and rivers.
Strategy 2: Regula ng and reducing
pollutants
Regula ng and reducing pollutants at the
point of emission can be illustrated by
sewage treatment processes that remove
nitrates and phosphates from waste.
These can be done in many ways:
• reduce the use of fer lizers in elds and
gardens
• only use washing machines with a full load
of washing
• use zero- or low-phosphorus detergents
• use phosphate stripping to remove
phosphorus from sewage treatment works.
Strategy 3: Cleaning and restoring
ecosystems
There are many ways in which ecosystems
can be cleaned and restored a er they have
become eutrophic:
• removal of nutrient-rich sediment by
pumping sediment out of lakes
• pumping air through lakes to increase
oxygen levels
• removal of biomass, such as algae
• reintroduc on of plant and animal
species into the ecosystem
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• using barley bales to lock up nitrates in
the water, since barley takes in nitrogen in
its inorganic form (nitrates or ammonium)
• using a solu on of aluminum or ferrous
salt to precipitate phosphates.
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It is cheaper and more efficient to alter
human activities than to regulate and reduce
pollutants at the point of emission. It is also
cheaper and more efficient to alter human
activities than to clean up and restore
ecosystems following eutrophication, for
example by dredging or removing sediment.
In conclusion, most action over pollution is
treating the effects of pollution rather than
altering behaviour and the causes of
pollution. Treating pollution is very costly
and wasteful. Not every country has the
resources to implement these strategies.
Outline the types of solid domestic waste.
Describe and evaluate pollution
management strategies for solid domestic
(municipal) waste,
Strategy 1: Recycling
Recycling is the processing of household
and industrial waste so that it can be used
again.
Advantages
• Prevents the loss of useful raw
materials.
•
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Reduces the consumption of new
raw materials.
Reduces energy usage in some areas
(though collection and processing
does use energy).
Reduces pollution at the extraction
phase of the process - getting the raw
materials out of the ground.
Lowers the release of greenhouse
gases.
Reduction in the amount of material
in landfill sites
Disadvantages.
• The transport of heavy goods, which
requires lots of energy
• The production of toxic waste.
Strategy 2: Incineration
Incineration is the burning of household and
industrial waste so that it is reduced in
volume
Advantages
• The reduction of the volume of
waste, thereby reducing the need for
landfills
• The production of energy from waste
• The production of ash that can be
used in construction.
Disadvantages.
• The production of greenhouse gases
• The release of toxic chemicals
• People may object to the building of
new incinerators in their
neighborhood.
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It is a cheap and easy means of waste
disposal.
Disadvantages
• The production of methane, which is
a greenhouse gas
• The pollution of watercourses and
groundwater by leachate
• The increase of vermin, which can
spread diseases.
•
Strategy 3: Composting
Composting is the decomposition of
biodegradable material and its use as a
fertilizer in soil.
Advantages
• The production of organic fertilizer
• A reduction in the use of chemical
fertilizer
• A reduction in the volume of organic
waste.
Disadvantages
• The production of unpleasant smells
• The attraction of vermin if not done
properly
• It is a slow process.
Strategy 4: Landfill
Landfill is the dumping of material in a hole
in the ground or on the ground.
Advantages
• The production of energy in the form
of methane gas
• The amount of time and labour that
are required are relatively small
Factors affecting the choice of waste
disposal
• Government policy, for example a
strategy to encourage recycling
• International agreements to cut
greenhouse gases or dumping at sea
• Population density and the amount of
land available for landfill.
Many poorer communities are much better
at recycling materials than richer
communities
Outline the overall structure and
composition of the atmosphere.
The atmosphere is a mixture of solids,
liquids, and gases that are held to the Earth
by its gravitational force. The atmosphere is
quite similar in composition up to a height
of about 80 km. It consists mainly of
nitrogen (78 per cent), oxygen (21 per cent),
and argon (0.9 per cent). There are also a
variety of other trace gases, such as carbon
dioxide and ozone. There is also water
vapour and solids (aerosols), such as dust
and soot.
The troposphere is the lowest part of the
atmosphere. The next upper part of the
atmosphere is the stratosphere. It is
separated from the troposphere by the
tropopause. Above the stratosphere is the
mesosphere. The mesosphere is separated
from the stratosphere by the stratopause.
The highest layer of the atmosphere is the
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thermosphere. It is separated from the
mesosphere by the mesopause
Ozone occurs in the stratosphere. It is
mostly found at around 10–50 km above the
Earth. It is important for the filtering of
harmful ultraviolet radiation
Describe the role of ozone in the absorption
of ultraviolet radiation.
The ozone layer shields the Earth from
harmful radiation that would otherwise
destroy most life on the planet. Ultraviolet
radiation is absorbed by ozone. Ozone also
absorbs some out-going, long-wave
radiation, so it is a greenhouse gas too.
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Ozone is created by oxygen rising up
from the top of the troposphere and
reacting with sunlight.
Ultraviolet radiation (short-wave
radiation) breaks down oxygen
molecules (O2 ) into two separate
oxygen atoms.
The oxygen atoms (O) combine to
form ozone (O3 ). Thus natural
processes create ozone
Human production of chloroflorocarbons (CFCs) is linked to a
decrease in ozone.
Explain the interaction between ozone and
halogenated organic gases.
The chemicals that cause stratospheric
ozone depletion include halogenated organic
gases. Halogenated organic gases (halogens)
include chlorofluorocarbons (CFCs). These
are found in many products, including
aerosol sprays and refrigerators. They can
also be found in air conditioners, foamed
plastics, pesticides, fire extinguishers, and
solvents.
Halogenated organic gases are very stable
under normal conditions but can release
halogen atoms when exposed to ultraviolet
radiation in the stratosphere. Halogen atoms
react with monatomic oxygen and slow the
rate of ozone reformation.
State the effects of ultraviolet radiation on
living tissues and biological productivity.
• Sunburn and premature aging of the
skin (i.e. wrinkled and leathery)
which may increase risk of skin
cancers.
• Skin cancers e.g.:
o Non-melanomas such as
basal or squamous cancers
(both can usually be treated if
found early).
o Malignant melanomas that
can spread rapidly and be
fatal.
• Cataracts, in which clouding of the
lens reduces vision. If untreated it
can lead to blindness.
• Immune-suppression in which the
ability of the immune system to
function is impaired and this can
increase risk of infections.
• Health problems in animals e.g.
cancers and damage to their eyes.
• Reduction in crop production e.g.
studies have demonstrated impaired
growth and subsequent lower yields
from crops such as rice, soya beans
and sorghum.
• Reduced phytoplankton growth
which could have impacts
throughout the aquatic food web.
Human food supply could also be
affected through the reduction in
available seafood. In addition with
less primary production, the uptake
of carbon dioxide falls impacting on
climate change.
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Reduction in forest productivity
which will reduce the amount of
carbon dioxide absorbed from the
atmosphere further exacerbating
climate change.
Describe three methods of reducing the
manufacture and release of ozone-depleting
substances.
Reduction of ODSs in refrigerants
The use of CFCs in refrigeration was one of
the most important uses for CFCs. Now a
combination of HFCs and hydrocarbon
refrigerants has largely replaced CFCs in
fridges. Fridges with ODS refrigeration can
be replaced with ‘greenfreeze’ technology
that uses propane and/or butane. Old CFC
coolants in fridges and air conditioning units
can be recycled.
•
Alternatives to gas-blown plastics and
propellants
Huge quantities of CFCs were used as
propellants in aerosol sprays. Alternatives to
aerosol sprays can be used. A good example
is using soap instead of shaving foam.
Pump-action sprays and trigger sprays can
be used instead of aerosols.
Phase out of methyl bromide
Methyl bromide gas is an ODS that has been
used to control pests. Its production and
import in the USA and Europe was phased
out in 2005. There are some exceptions. It
can be used to eliminate quarantine pests
and it can be used in farming where there
are no alternatives.
Describe and evaluate the role of national
and international organizations in reducing
the emissions of ozone-depleting substances,
The 1987 Montreal Protocol on Substances
that Deplete the Ozone Layer is the most
significant and successful international
agreement relating to an environmental
issue.
Nearly 200 governments have signed up and
implemented the agreed changes according
to the Montreal Protocol; as a result it is
believed that ozone could recover by 2050.
It has been revised seven times since it was
first introduced in 1987.
The Protocol provided an incentive for
countries to find alternatives. It also raised
public awareness of the use of CFCs.
Technology has been transferred to lowincome countries to allow them to replace
ozone-depleting substances.
Problems.
Some substances that replaced CFCs are
powerful greenhouse gases, such as HFCs
(hydrofluorocarbons). The long life of the
chemicals in the atmosphere means that
damage will continue for some time – some
argue until 2100. It is harder for LEDCs to
make changes. The second-hand appliance
market means old fridges are still in
circulation.
State the source and outline the effect of
tropospheric ozone
Tropospheric ozone – or ground-level ozone
– is a pollutant. It is a secondary pollutant
because it is formed by reactions involving
oxides of nitrogen (NOx ). The main cause
of ground-level ozone is the volume of road
transport concentrated in cities. Two
important pollutants are released when fossil
fuels are burnt. These are hydrocarbons
(from unburnt fuel) and nitrogen monoxide
(also called nitric oxide or NO). Nitrogen
monoxide reacts with oxygen to form
nitrogen dioxide (NO2 ). This is a brown gas
that contributes to urban haze. It can also
absorb sunlight and break up to release
oxygen atoms that combine with oxygen in
the air to form ozone.
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The effects of tropospheric ozone
• Ozone is a toxic gas and an oxidizing
agent. It irritates eyes and can cause
breathing difficulties in humans.
• It may also increase susceptibility to
infection.
• Ground-level ozone reduces plant
photosynthesis and can reduce crop
yields significantly.
• It damages crops and forests.
• Ozone pollution has been suggested
as a possible cause of the die-back of
German forests (previously it was
believed these had died as a result of
acid rain).
• Ozone is highly reactive and can
attack fabrics and rubber materials.
Outline the formation of photochemical
smog.
Photochemical smog occurs when sunlight
activates reactions between nitrogen
oxides (NOx) and volatile organic
compounds (VOCs) resulting in the
formation of ozone and peroxyacyl nitrates
(PAN). VOCs are carbon based compounds
with a low boiling point such as propane,
butane and formaldehydes.
Sources of NOx are emissions from
• industry,
• power stations
• vehicles.
Sources of volatile organic compounds
(VOCs)
• industry,
• vehicles
• solvents (e.g. used in paints and
adhesives).
Forest fires, whether accidental or
intentional (e.g. slash and burn), also
increase levels of VOCs and particulate
matter.
Factors influencing production of
photochemical smog
Photochemical smog is mostly likely to be
formed under the following conditions:
• High emissions of pollutants from
combustion of fossil fuels e.g.
through industrial activity and
vehicle use. This is often influenced
by:
o The amount of industry.
o Population size.
o Mode of transport adopted in
an area. Use of private cars
will produce more air
pollution than the use of
public transport, which in
turn produces more pollution
than cycling or walking.
• High levels of sunlight, hence the
highest levels of ozone occur during
the sunniest part of the day.
• Calm or light winds which reduces
dispersion and dilution and allows
pollutants to accumulate at ground
level.
• Dry weather conditions in which rain
does not wash the pollutants out of
the air.
• Where the topography allows
pollutants to accumulated such
as a valley surrounded by hills. The
hills reduce the flow of air and allow
the pollutants to concentrate within
the valley. Tall buildings can also
reduce air flow and allows pollution
levels to increase.
• When a thermal inversion occurs:
o Normally air at ground level
warms and rises which also
dissipates the
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air pollutants. This air
expands and cools resulting
in a temperature gradient.
Describe and evaluate pollution
management strategies for urban air
pollution.
Reducing urban air pollution
• Some measures may lead to a
reduction in the use of fossil fuels,
such as reducing demand for
electricity and switching to
renewable energy.
• Increased use of public transport and
‘park and rides’ reduces individual
car use, hence reduces emissions of
fossil fuels.
• The promotion of clean technology/
hybrid cars also reduces the use of
fossil fuels. Preventing cars from
entering parts of a city can result in
improved air quality (in Mexico City,
cars with an odd-numbered number
plate are allowed into the city centre
on certain days, whereas cars with an
even-numbered number plate are
allowed in on other days).
• By providing more bus lanes and
cycle lanes, more people are
encouraged to cycle or travel by bus.
• Tolls for private cars to enter a city
centre, such as the London
Congestion Charge, can reduce the
number of vehicles entering.
• Other strategies include the
development of catalytic converters
in cars to reduce emissions of NOx.
Weaknesses of pollution-management
strategies
• Most urban pollution comes from
cars.
• Old cars tend to be more polluting
than new cars.
Vehicles using diesel fuel produce
emissions of particulate matter.
• The use of catalytic convertors
reduces fuel efficiency and increases
CO2 emissions.
• Public transport can be expensive
and may be inconvenient
• Sustainable urban design is
expensive.
Outline the chemistry leading to the
formation of acidified precipitations.
Acid precipitation is the increased acidity of
rainfall. This is largely as a result of human
activity. Rain and snow are naturally acidic.
This is caused by carbon dioxide in the
atmosphere combining with moisture in the
atmosphere to produce a weak carbonic
acid. Rainfall has a pH of about 5.5. Dry
deposition is the fallout of particulates of
SOx and NOx close to their sources. The
causes of acidification.
The major causes of acidification are the
sulfur dioxide and nitrogen oxides produced
when fossil fuels are burnt.
Sulfur dioxide and nitrogen oxides are
released into the atmosphere. There they are
absorbed by moisture and become sulfuric
and nitric acids. The pH of this rain can be
as low as 3.
Dry deposition typically occurs close to the
source of emission. Wet deposition occurs
when the acids are dissolved in water vapour
and travel in clouds to fall at great distances
from the sources.
Wet deposition has been called trans-frontier
pollution, as it crosses international
boundaries.
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Describe three possible effects of acid
deposition on soil, water and living
organisms
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Acid deposition can enter aquatic
ecosystems either directly (e.g. precipitation
as rain) or indirectly as run-off.
• It can lower the pH of the aquatic
environment beyond the ability of
some organisms to survive.
• Species of phytoplankton,
invertebrate (e.g. crayfish) and fish
(e.g. trout and salmon) can be
sensitive to changes in pH.
• Loss of some species can cause a
knock on effect through the food
chain, adversely affecting other
organisms (e.g. due to lack of prey).
• Some species may suffer from
reproductive failure and many fish
eggs do not hatch at pH below five.
Acid deposition on land can increase soil
acidity. This lowering of soil pH can result
in:
• Leaching of plant nutrients such as
calcium, magnesium and potassium.
This reduces the nutrients available
for plant uptake.
• Mobilisation of aluminum ions that
can damage plant root systems and
can also be leached into nearby
watercourses adversely affecting
fish, as discussed above.
• Mobilisation of other toxic metals
from the soil such as cadmium, lead
and mercury which can then be
leached into aquatic ecosystems
adversely affecting aquatic
organisms and potentially
contaminating drinking water
supplies.
Exposure of plants to acid deposition also
results in:
• Damage to the cuticle wax found on
leaves which reduces plant
photosynthesis.
Lower tolerance to pests, disease and
low temperatures.
Overall these effects result in:
• Reduction in crop yield in
agricultural areas.
• Loss of biodiversity and reduction in
forest areas.
Explain why the effect of acid deposition is
regional rather than global.
The areas affected by acid deposition are
closely linked to areas of sulfur dioxide and
nitrogen dioxide emissions.
Acid deposition is called trans-frontier
pollution because it crosses international
boundaries. The area producing the acid
deposition is not the same as the regions
receiving it.
Areas experiencing acid deposition are
downwind from the main sources of sulfur
dioxide and nitrogen dioxide. Coal-fired
power stations and heavy concentrations of
vehicles emit large quantities of sulfur
dioxide and nitrogen dioxide. Areas are
affected by acidification.
The main areas experiencing acid rain are
those areas downwind of major industrial
regions, such as Scandinavia. Scandinavia is
downwind from major industrial belts in
Western Europe. There is also much acid
deposition in the northeast of the USA and
eastern Canada. These areas are downwind
from the US industrial belt. There is less
acidification in Scandinavia now compared
with the 1980s, as there is less heavy
industry in Western Europe.
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Describe and evaluate pollu on
management strategies for acid deposi on.
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Carbondioxide is a green house gas.
There have been considerable changes in the
levels of carbon dioxide in geological times.
Generally, higher levels of carbon dioxide
are associated with higher temperatures.
Lower levels of carbon dioxide are
associated with lower temperatures and with
glacial periods. The following two diagrams
show changes in carbon dioxide levels and
associated temperatures during the
geological past
The issue of global warming
Describe the role of greenhouse gases in
maintaining mean global temperature.
The greenhouse effect is a normal and
necessary condition for maintaining life on
Earth.
Describe how human activities add to
greenhouse gases.
The main greenhouse gases include water
vapour, carbon dioxide (CO2), methane and
chlorofluorocarbons (CFCs). Human
activities are increasing levels of CO2 and
methane in the atmosphere.
Carbon dioxide produc on
The increase in carbon dioxide levels is due
to human ac vi es
• Burning fossil fuels (coal, oil, and
natural gas)
• Deforesta on.
Deforesta on of the tropical rainforest is a
double blow – not only does it increase
atmospheric CO2 levels, it removes the
trees that convert CO2 into oxygen
Methane production
Methane is the second largest contributor to
global warming, and is increasing at a rate
of 1 per cent per annum.
• It is estimated that cattle convert up
to 10 per cent of the food they eat
into methane, and emit 100 million
tonnes of methane into the
atmosphere each year.
• Natural wetland and paddy fi elds are
another important source – paddy fi
elds emit up to 150 million tonnes of
methane annually.
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As global warming increases, bogs
trapped in permafrost will melt and
release vast quantities of methane
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Discuss qualitatively the potential
effects of increased mean global
temperature.
Increase in global temperatures,
sea level rise and changes in
precipita on pa erns could a ect
the quan ty and quality of water
available.
Reduced water could lead to:
• Lakes and river beds drying out,
adversely affecting the aquatic
ecosystems and biota such as fish.
• Increase in arid areas and
desertification.
• Loss of crops or reduction in yield.
• Loss of livestock due to lack of
sufficient fodder, pasture areas and
water to drink.
• Migration of wildlife in search of
water.
• Increase mortality of wildlife.
• Increased risk of wild fires due to
dry environmental conditions
resulting in loss of habitats and
biodiversity.
• Conflict between people over the
limited water resources.
• Migration of people to other areas
for employment and basic resources
(i.e. water and food).
• Reduced electricity generation from
hydroelectric power schemes.
Flooding
Increase in frequency and intensity of
precipitation is likely to increase the risk of
flooding in the middle and high latitude
regions. Floods can cause:
• Sewers to overflow.
• Contamination of drinking water
supplies and increase risk of disease.
• Landslides
• Injury or death by drowning.
• Damage to homes and possessions.
• Displacement of people
Fisheries
Higher water temperature can lead to:
•
Death of some species unable to
cope with higher temperature range
leading to loss of biodiversity.
•
Migration of some fish towards the
poles in search of cooler waters.
•
Increase in range of distribution of
fish adapted to warmer waters.
•
Change in spawning period,
potentially expanding the growth
season for some fish.
•
Coral bleaching in which the coral
expels zooxanthellae, a symbiotic
algae. Zooxanthellae live inside the
coral polyp and provide the polyp
with food
Impact on ecosystems and biodiversity
As a consequence of climate change,
ecosystems are under threat from:
•
Increase in temperature and change
in precipitation patterns.
•
Increase risk of flooding.
•
Drought conditions.
•
Increase risk of wild fires.
•
Increase spread of pests.
•
Ocean acidification.
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la tudes leading to increased
snowfall on the polar ice caps.
Impacts on human health
Insufficient water and food
resources.
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Degraded ecosystems reducing
goods and services.
•
Extreme weather such as heatwaves,
storms and floods.
Heatwaves
•
Heatwave episodes can result in
cardiovascular and respiratory
problems especially within the
elderly and urban poor.
•
The European heatwave in 2003 was
the hottest summer in 500 years and
contributed to about 35,000 deaths
across Europe. The extreme
conditions also exacerbated the
effects of air pollution.
Heatwave conditions can increase
occupational health risk. Working in
hot environments can lead to
heatstroke and death
Discuss the feedback mechanisms that
would be associated with an increase in
mean global temperature.
•
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The surface of snow and ice is very
re ec ve, so the albedo is increased.
Increased re ec vity reduces the
amount of solar radia on received
and so lowers temperatures.
Posi ve feedback
In contrast, posi ve feedback may involve
increased thawing of permafrost, leading to
an increase in methane gas levels, which
increases the mean global temperature.
As methane is a greenhouse gas, it has the
poten al to increase temperatures, thereby
reinforcing the rise in temperature.
Describe and evaluate pollu on
management strategies to address the issue
of global warming.
•
The Kyoto Protocol
The Kyoto Protocol (1997) encouraged most
MEDCs to take on legally binding targets for
cuts in greenhouse gas emissions from the
1990 level by 2012. The EU agreed to cut
emissions by 8 per cent and the USA by 6
per cent. Not all MEDCs signed up to the
Kyoto Protocol
•
Carbon taxes
Some countries have introduced carbon
taxes to encourage producers to reduce
emissions of carbon dioxide. These tax the
burning of fossil fuels in propor on to how
much carbon they contain.
•
Nega ve feedback
Nega ve feedback may involve
increased evapora on in tropical
•
Carbon trading
Carbon trading is an a empt to create a
market in which permits issued by
governments to emit carbon dioxide can be
traded. Governments set targets for the
amount of carbon dioxide that can be
emi ed by industries. Companies that go
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Carbon o set schemes
•
Carbon o set schemes are designed to
reduce the e ects of increased carbon
dioxide by inves ng in projects that cut
emissions elsewhere or trap carbon dioxide.
O set companies typically buy carbon
credits from projects that plant trees or
encourage a switch from fossil fuels to
renewable energy.
Alterna ve energy sources
•
The use of alterna ve energy sources would
reduce emissions of carbon dioxide. These
sources include hydroelectric power and
solar power. They do not produce carbon
dioxide when they are opera ng, although
carbon dioxide is released when building
the facili es. Alterna ve energy sources
cannot be built everywhere, but require the
right climate and topography
Individuals’ reduc ons in greenhouse
gases
•
Grow their own food and/or eat
locally produced foods
•
Choose energy-e cient products
(for example, energy-saving light
bulbs)
•
Reduce their hea ng – weatherproof their homes
•
Unplug appliances when not in use.
•
Turn o lights where electricity is
generated by fossil-fuel combus on
Reduce the use of air condi oning
and refrigerants
Use a manual lawnmower rather
than an electric or diesel one
•
•
Walk or ride a bike
•
Use public transport
•
Use biofuels (made from animal/
plant waste)
•
Eat lower down the food chain
(vegetables rather than meat)
•
Buy organic food (not produced
using harmful chemicals)
Outline the arguments surrounding global
warming.
There are natural causes of climate change
as well as those caused by humans. Just
because the natural ones exist does not
mean that there is no human impact on
climate change.
Global warming
Many people believe that scien c data
proves that the climate is warming. They
state that scien c data shows that carbon
dioxide levels and greenhouse gas levels are
increasing. Moreover, data from a wide
variety of sources and mes indicates
warming.
They stress that human ac vi es and/or
fossil fuel combus on are known to
increase carbon dioxide levels. The rapid
rate of increase in carbon dioxide since
industrializa on implies a human link. They
also argue that carbon dioxide and other
greenhouse gases are known to impact
global temperatures. Therefore it is likely
that human ac vi es are resul ng in global
climate change.
Global warming scep cs
Some people scep cally claim that natural
uctua ons occur so that the current
increase in temperature could be due to
short-term changes. They claim that the
only technologically veri able data we have
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over the limit are forced to buy permits
from others that do not. It is working, but
not very well. Cri cs argue that the targets
are too generous.
Global dimming
Global dimming refers to a reduc on in
global temperatures as a result of pollu on.
Aerosols are highly re ec ve and re ect
solar energy. This blocks some of the solar
energy from entering the lower
atmosphere, which has a cooling e ect. Air
pollu on has a similar impact. It is possible
that global dimming has slowed down
global warming. Scien sts showed that from
the 1950s to the early 1990s, the level of
solar energy reaching the Earth’s surface
had dropped due to high levels of pollu on
at that me.
Evaluate contras ng human percep ons of
the issue of global warming.
Your response to climate change and
global warming depends on your personal
viewpoint. One person may focus on the
posi ve bene ts associated with the
predicted changes in world climate.
Some parts of the world will experience
more rainfall, which will improve farming.
Trade may bene t from new routes opening
up as ice sheets melt, for example the
north-west passage between the Atlan c
and Paci c Oceans.
Tourist revenue from warmer loca ons may
increase. Most scien sts are now convinced
that there is a causal link between carbon
dioxide levels and global temperature
change.
Some s ll argue that rela onships are more
complex and that the e ects of global
warming remain unclear. Some claim that
current changes are part of wider pa erns
of natural uctua on.
Opinions of ordinary ci zens depend on
what scien c evidence they nd most
convincing. This depends on their level of
educa on and specialized knowledge of the
issues.
The growth of the environmental
movement has played a large role in raising
awareness of the issue.
Your cultural or religious group may play a
role in your views on climate change, and
where you live may a ect your views.
People who live close to the sea are more at
risk from coastal ooding. Socio-economic
status plays a role.
Extreme poverty leads to short-term views
and wealth leads to faith that money will
solve the problem.
Age may also be important. Young people
tend to be more concerned than the old.
Some ci zens feel they have a responsibility
to change the way in which they live to
reduce their emissions of greenhouse gases.
Environmental value systems
State what is meant by an environmental
value system.
An environmental value system can be
de ned as a par cular world view that
in uences the way an individual or group of
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49
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has been collected over a short period of
me. Moreover, they also state that other
aspects of climate change are not all fully
understood. Climate has changed in the
past due to due to natural uctua ons, such
as Milankovitch cycles. Current carbon
dioxide levels and global temperature
uctua ons are moderate compared to
geologic history. Therefore it is not
conclusive that humans are causing global
climate change.
people recognize and evaluate
environmental issues.
It is in uenced by cultural factors, economic
and socio-poli cal context, such as whether
the society is more economically developed
or less economically developed, or from a
democra c or authoritarian society.
EVS inputs are:
•
Educa on
•
Cultural in uences
•
Religious texts and doctrine
•
The media.
EVS outputs are:
•
Perspec ves
•
Decisions on how to act regarding
environmental issues
•
Courses of ac on.
Discuss how these philosophies in uence
the decision-making process with respect to
environmental issues covered in this course
There are problems associated with the use
of fossil fuels, such as global warming.
A technocentrist would:
•
Use science to nd a useful
alterna ve, such as hydrogen fuel
cells; technocentrists see this as a
good example of resource
replacement, where an
environmentally damaging industry
can be replaced by an alterna ve
one
•
Develop technology to reduce the
output of carbon dioxide from fuel
use rather than change lifestyles to
reduce the use of fuel say that
economic systems have a vested
interest in being e cient so the
exis ng problems will self-correct
given enough me
Outline the range of environmental
philosophies.
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Believe that new technological
developments would increase
standards of living thereby
increasing demands for a healthy
environment
•
•
Believe that scien c e orts should
be focused on removing carbon
dioxide from the atmosphere rather
than slowing economic growth
•
Believe that a technology-centred
environmental philosophy would
predict that market pressure would
eventually result in lowering of
carbon dioxide emission levels.
•
would support iceberg capture and
transport, where icebergs from
colder areas are used as a source of
fresh water
•
Encourage waste-water puri ca on
•
Support synthe c water produc on,
where water is made through
chemical reac ons. Cloud seeding
could be used.
An ecocentrist manager would:
•
Highlight the overuse and misuse of
water
•
Encourage the conserva on of water
and greater recycling
•
•
An ecocentrist’s approach to the
same problem would:
•
Say that water use should be within
sustainable levels
•
Call for the reduc on of greenhouse
gases through limi ng exis ng gasemi ng industry, even if this
restricts economic growth
•
Recommend monitoring to ensure
that water use remained within
sustainable limits
•
Encourage water use that had few
harmful impacts on habitat, wildlife,
and the environment.
Say that people should change their
lifestyle to reduce fossil fuel use;
reduc on in energy consump on
and lower consump on overall
would reduce fossil fuel use.
Demand for water resources
•
I will discuss how environmental
philosophies in uence the decisionmaking process with respect to the
increasing demand for water
resources.
•
A technocentrist manager would:
•
Suggest that future needs can be
met by technological innova on and
the ability to use reserves that have
yet to be used
•
Support desalina on ac vi es
where fresh water is extracted from
sea water
Outline key historical in uences on the
development of the modern environmental
movement.
Minamata
In 1956, a new disease was discovered in
Minamata City in Japan. It was named
Minamata disease and was found to be
linked to the release of methyl mercury into
the waste-water produced by the Chisso
Corpora on’s chemical factory. The mercury
accumulated in shell sh and sh along the
coast. The contaminated sh and shell sh
were eaten by the local popula on and
caused mercury poisoning. The symptoms
were numbness of the hands; damage to
hearing, speech, and vision; and muscle
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51
weakness. In extreme cases, Minamata
disease led to insanity, paralysis, and death.
Rachel Carson’s Silent Spring
In 1962 American biologist Rachel Carson’s
in uen al book Silent Spring was published.
Carson wrote about the harmful e ects of
pes cides and made a case against the
chemical pollu on of natural systems. The
book led to widespread concerns about the
use of pes cides in crop produc on and the
consequent pollu on of the natural
environment (mainly terrestrial systems).
James Lovelock’s Gaia
James Lovelock’s book Gaia, published in
1979, proposed the Gaia hypothesis – that
the Earth is a living organism with selfregulatory mechanisms that maintain its
clima c and biological condi ons. He saw
the ac ons of humanity upse ng this
balance with poten ally disastrous
outcomes. Later books, up to the present
day, have developed these ideas.
Bhopal
extensive area. Large areas of the Ukraine,
Belarus, and Russia were badly
contaminated. The disaster resulted in the
evacua on and rese lement of over 336
000 people. The fallout caused increased
incidence of cancers in the most exposed
areas. An area around the plant s ll remains
a no-entry area due to radia on. The
incident raised issues concerning the safety
of nuclear power sta ons
Pick any 3 you are familiar with from class
WITH PRECISE DETAILS.
The disaster, what happened and the
decisions made a er the disaster.
Compare and contrast the environmental
value systems of two named socie es.
Communist socie es have been cri cized
for their poor environmental record. For
example, between 1947 and 1991 the Buna
chemical works in East Germany dumped
ten mes more mercury into its
neighbouring river than chemical work
plants in West Germany.
Chernobyl
Cars in the East emi ed 100 mes more
carbon monoxide than those in the West,
because they did not have cataly c
converters Communist and capitalist
socie es to remove this toxic gas. East
German sulfur dioxide concentra ons were
also an environmental issue, and were the
highest in the world at the me. This was
due to the combus on of fossil fuels in
power plants and industries across the
country, and a failure to remove this gas
from emissions. Some people argue that the
economic principles of communism
inevitably lead to environmental disaster.
On 26 April 1986, a nuclear reactor at the
Chernobyl plant in the Ukraine exploded. A
cloud of highly radioac ve dust was sent
into the atmosphere and fell over an
In communist countries it is thought that
people see free natural resources as having
use-value to humans alone. The communist
idea of equal distribu on of resources with
On 3 December 1984, the Union Carbide
pes cide plant in the Indian city of Bhopal
released 42 tonnes of toxic methyl
isocyanate gas. The release was caused by
one of the tanks involved with processing
the gas overhea ng and burs ng. Some 500
000 people were exposed to the gas. It has
been es mated that between 8000 and 10
000 people died within the rst 72 hours
following the exposure, and that up to 25
000 have died since from gas-related
disease.
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52
no pro t mo ve means that energy,
materials, and natural resources can be
squandered without care.
In contrast, the capitalist model is seen by
some as being environmentally friendly.
People see in the capitalist model that the
free market imposes checks and balances to
ensure sound use of resources in order to
maximize pro ts. The actual story is more
complex.
Many of the cri cisms of the communist
environmental record stem from the period
of the Cold War. Such cri cism was used
against the communist states to jus fy the
Cold War. Capitalism itself has a mixed
record with regard to the environment. In
Germany, before reuni ca on, the
communist state (East Germany) had
protected the interests of farmers,
foresters, and shermen. The state
therefore uninten onally bene ted certain
sectors of the environment.
The rise of capitalism in the former
communist state led to polluters organizing
into powerful lobbies to protect their own
interests without considera on for the
environment. A state’s response to
environmental concerns is not just a ma er
of poli cal doctrine.
Many factors contribute, such as
technology, wealth, geography, economic
decision making, and democra c structures.
In capitalist socie es, civil liber es and the
role of democracy may have played a more
signi cant role in comba ng environmental
problems than the capitalist basis of the
system.
Jus fy your personal viewpoint on
environmental issues.
Introduce yourself and what you believe
in . e,g recycling, water etc and what lead
you to make those decisions(is it faith?
School? A movie etc)
Example approach to an environmental
issue.
I believe that rainforests should be
conserved and not be over-exploited.
Rainforests have an economic value to
humans as they may contain food,
medicines, and materials for human use.
Ecotourism can also provide income.
Rainforests are of more value to humans
intact than being exploited for mber or
cleared to produce land for agriculture.
Tropical rainforests also have an intrinsic
value and the organisms there have a right
to exist free from human exploita on.
Rainforests provide life-support func ons
such as water cycles, lock up carbon in
plants that would otherwise be in the
atmosphere, and provide oxygen for the
planet. There are high levels of biodiversity
in rainforests and many species are endemic
to the area in which they are found.
Rainforests provide a home to many
indigenous peoples. They also have an
aesthe c value and give pleasure to those
who visit them. Because the soil is poor and
thin, the regenera on rate of rainforests is
slow if it is cleared. Rainforests provide
spiritual, cultural, and religious value to
local communi es. I believe it is important
for humans to act as stewards for
rainforests so that they can be enjoyed by
future genera ons.
References
•
Environmental Systems and Socie es
- ESSENTIALS - Andrew Davis
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•
Environmental systems and socie es
2015 Edi on
•
Kognity
•
IB ESS GUIDE last assessment 2025
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