Systems and Models
1.1.1 Outline the concept and characteristics of Systems A
system is an assemblage of parts and the relationships between
them, which together constitute an entity or whole. The
interdependent components are connected through the transfer of
energy and matter. Four things can characterize systems:1. Storages
(of matter or energy)2. Flows (inputs and outputs)3. Processes
(transfers and transformations of matter and energy)4. Feedback
mechanisms (negative and positive feedback)
1.1.2 Apply the systems concept on a range of scalesThe systems
concept can be applied across a range of scales such as ecosystems
as small as a garden or as large as a biome, and even can be
applied to look at the entire world as a system.
1.1.3 Define the terms open system, closed system and isolated
systemOpen System: Both matter and energy is exchanged across the
boundaries of the system, open systems are organic and so must
interact with their environment
Closed System: Energy but not matter is exchanged across the
boundaries of the system. Matter is usually recycled within the
system.
Isolated System: Neither energy nor matter is exchanged across
the boundary of the system. These systems do not exist naturally,
although it is possible to think of the entire universe as an
isolated system
1.1.4 Describe how the first and second laws of thermodynamics
are relevant to environmental systemsThe first law of
thermodynamics states that energy can neither be created nor
destroyed, it can only change forms. This means that the total
energy in any system is constant and all that can happen is change
in the form that they energy takes. This law is also referred to as
the law of conservation of energy
The second law of thermodynamics states that the energy goes
from a concentrated form into a dispersed form and the availability
of energy to do work therefore diminishes and the system becomes
increasingly disordered. The transformation and transfer of energy
is not 100% efficient, in any energy conversion there is less
usable energy at the end of the process.
1.1.5 Explain the Nature of EquilibriumSteady State Equilibrium:
The common property of more open systems. There is a tendency in
natural systems for the equilibrium to return after a disturbance
such that fluctuations in the system are around a fixed path.
Static Equilibrium: There are no inputs or outputs of matter or
energy and no change in the system over time; therefore there are
no fluctuations and the system state remains constant.
Stable Equilibrium: If a system returns to the original
equilibrium after a disturbance it is said to be stable
Unstable Equilibrium: If a system does not return to the same
equilibrium but rather forms a new equilibrium are described as
unstable
1.1.6 Define and explain thee principles of positive and
negative feedbackPositive Feedback: occurs when a change in the
state of the system leads to an additional and increased change
Negative Feedback: work by reducing the effect of one of the
systems components. This is a self-regulating method of control
leading to the maintenance of a steady-state equilibrium
1.1.7 Describe transfer and transformaiton procesesTransfers:
normally flow through a system and involve a change of location or
state.1. movement of matierla through living organisms
(consumption)2. Movement of material in a non-living process
(percipitation)3. Movement of energy (energy re-radiating from
greenhouse gases)
Transformations: lead to an interaction within a system in the
formation of a new end product 1. Matter transformatons (amino
acids into protein chains)2. Energy transformations (photosynthesis
in plants converitng sunlight energy)3. Matter to energy
transformations (respiration breaking down glucose)
1.1.8 Evaluate the strengths and limitations of modelsStrengths:
They allow scientists to predict and simply large systemsInputs can
be changed and outcomes examined without having to wait for real
events
Disadvantages:They may not be accurate because of over
complexityThey rely on the expertise of the people making
themDifferent people may interpret them differently
Structure
2.1.1 Distinguish between biotic and abiotic components in an
ecosystemBiotic: refers to the living components within an
ecosystem (the community)Abiotic: refers to the non-living factors
of the ecosystem (the environment)
2.1.2 define the term trophic levelThe term trophic level refers
to the feeding level within a food chain. Food webs are made from
many interconnecting food chains.
2.1.3 Identify and explain trophic levels in food chains and
food websEcosystems contain many interconnected food chains.
Generally a food chain will start with the autotroph trophic level,
then to primary consumer, then to secondary consumer and so
forth.
2.1.4 explain the principles of pyramids of numbers, biomass and
productivityPyramid of Numbers:A number pyramid represents the
number of producers and consumers coexisting in an ecosystem can be
shown by counting the number of organisms in an ecosystem and
constructing a pyramid.
Pyramid of BiomassA biomass pyramid quantities the amount of
biomass present at each trophic level at a certain point in time
and represents the standing stock of each trophic level measured in
units such as grams of biomass per meter squared.
Pyramid of ProductivityA pyramid of productivity takes into
account of the rate of production over a period of time because
each level represents energy per unit area per unit time (rate of
change)
2.1.6 define the terms species, population, habitat, niche,
community and ecosystemSpecies: a group of organisms that
interbreed and produce fertile offspringPopulation: a group of
organisms of the same species living in the same area at the same
timeHabitat: refers to the environment in which a species normally
livesNiche: best described as where, when and how an organism
lives, essentially what defines the speciesCommunity: a group of
populations living and interacting with each other in a common
habitatEcosystem: a community of interdependent organisms (biotic)
and their physical environment (abiotic)
2.1.7 Describe and explain population interactionsIntraspecific
Competition: competition within a species (occupy the same
niche)Interspecific Competition: competition between species
(niches overlap)Predation: occurs when one animal hunts and kills
another animalParasitism: an organism (the parasite) benefits at
the expense of another (the host) from which it derives
foodMutualism: a relationship in which two organisms live together
and a symbiotic relationship in which both species benefit is
developed
Biomes
2.4.1 define the term biomeA biome is a collection of ecosystems
sharing similar climatic conditions. A biome has distinctive
abiotic factors and species that distinguish it from other
biomes.
2.4.2 explain the distribution, structure and relative
productivity of specific biomes
Tropical Rainforest BiomeConsistent high temperaturesHigh
rainfallLie in a band around the equator within the tropics of
Cancer and Capricorn, so they enjoy high light levels year
roundHigh biodiversityHigh productivity
Desert BiomeFound at latitudes of approximately 30 degrees north
and southHigh temperaturesLow precipitationLimited
productivitySpecies are highly adapted to reduce water loss during
dehydration
Tundra BiomeFound at high latitudes where insolation is
lowLimited levels of sunlight Low productivityTemperatures are
low
Temperate Forest BiomeLargely found between 40 and 60 degrees
north of the equatorWinters are cold and summers are warmCan
contain both evergreen and deciduous treesRainfall is
moderateBiodiversity is lower than in rainforest
Function
2.5.1 explain the role of producers, consumers and decomposers
in the ecosystemProducers: organisms that use sunlight energy to
create food are called photoautotrophs. Producers are the basis of
ecosystems, supporting them through constant input of energy
Consumers: consumers do not contain photosynthetic pigments.
They must obtain their energy and nutrients by eating other
organisms they are heterotrophs.
Decomposers: obtain their food and nutrients from the breakdown
of dead organic matter, and they break down tissue, they release
nutrients ready for reabsorption by producers
2.5.2 Describe photosynthesis and respiration in terms of
inputs, outputs and energy transformationsPhotosynthesis: the
process by which green plants convert light energy from the sun
into usable chemical energy stored in organic matter1. Inputs =
sunlight, carbon dioxide and water2. Processes = chlorophyll traps
sunlight, the energy is used to split water, hydrogen from water is
combined with CO2 to produce glucose3. Outputs = glucose used as an
energy source for the plant and oxygen is released into the
atmosphere4. Transformations = light energy is transformed to
stored chemical energy
Cellular Respiration: releases energy from glucose and other
organic molecules inside all living cells1. Inputs = glucose and
oxygen2. Processes = oxidation processes inside cells3. Outputs =
release of energy for work and heat4. Transformations = stored
chemical energy to kinetic energy and heat
2.5.3 Describe and explain the transfer and transformations of
energy as it flows through an ecosystemCARBON CYCLINGCarbon dioxide
is fixed by autotrophsThese organism respire and return some carbon
into the atmosphere or assimilate into into their bodes as
biomassWhen organisms die they are consumed by decomposers, which
return carbon to the atmosphere when they respireDeforestation
releases large amounts of carbon dioxide into the atmosphereOil and
gas were formed when marine organisms died and fell to the bottom
of the ocean, when these fuels are burned they release large amount
of carbon into the atmosphere
NITROGEN CYCLEThere is four types of bacteria that drive the
nitrogen cycle:1. Nitrogen-fixing bacteria are species in root
nodules derive the soars they need from plants, and the plants gain
useable nitrogen that has been fixed into nitrates2. Decomposers
produce ammonia and ammonium compounds which is then fixed by the
nitrogen-fixing bacteria3. Nitrifying bacteria found in the soil
oxidize the ammonia first into nitrites then into nitrates4.
Denitrifying bacteria return nitrogen to the atmosphere
2.5.5 define the terms gross productivity, net productivity,
primary productivity and secondary productivityPrimary
Productivity: the gain by producers in energy or biomass per unit
area per unit timeSecondary Productivity: the biomass gained by
heterotrophic organisms measured in units of mass or energy per
unit area per unit timeGross Productivity: the total gain in energy
or biomass per unit area per unit timeNet Productivity: the gain in
energy or biomass per unit area per unit time remaining after
losses (R)
2.5.6 define the terms and calculate the values of both gross
primary productivity and net primary productivity Gross Primary
Productivity (GPP): gained through photosynthesis in primary
producersNet Primary Productivity (NPP): the gain by producers
after respiratory losses (R)NPP = GPP - R2.5.7 define the terms and
calculate the values of both gross secondary productivity and net
secondary productivity Gross Secondary Productivity (GSP): gained
through consumption and absorption in consumersNet Secondary
Productivity (NSP): the gain by consumers after respiratory losses
(R)NSP = GSP - R
Changes
2.6.1 explain the concepts of limiting factors and carrying
capacityLimiting Factors include temperature, water and nutrient
availabilityCarrying Capacity is the maximum number of organisms
that an area or ecosystem can sustainably support over a long
period of time
2.6.2 Describe and explain S and J population curvesThe S Curve
has three stages:1. Exponential Growth stage in which the
population grows and an increasingly rapid rate because there are
no limiting factors, no competition and plentiful resources2.
Transitional phase where the population growth slows considerably
but it continues to grow because there is an increase in
competition and in predators3. Plateau Phase in which the number of
individuals stabilizes and the population growth stabilizes because
the available space and resources decrease
The J curve is a population growth curve, which shows only
exponential growth. Growth is initially slow and becomes
increasingly rapid and usually results in a population crash when
carrying capacity is reached.
2.6.3 describe the role of density dependent and independent
factors and internal and external factorsDensity Dependent Factors:
some limiting factors are related to population density such as
competition for resources, space and predation. As a population
grows in size, the availability of resources per organism
decreases.
Density Independent Factors: can operate alongside
density-dependent factors. These are generally abiotic such as
climate change or geophysical events such a volcanic eruptions.
These events increase death rate and reduce birth rate.
Internal and External Factors: internal factors include density
dependent fertility or size of breeding territory while external
factors include predation or disease
2.6.4 describe the principles associated with survivorship
curves including K and R strategistsK Strategists: Tend to be
limited by the carrying capacity of an environmentDominate
speciesSlow developmentDelayed reproductionLonger livingLarger
sizeLess productive
R Strategists: tend to have a fast rate of increaseInitial
colonizersLarge numbersRapid growth and developmentEarly
reproductionShort lifeVery productive
2.6.5 describe the process of succession and zonationSuccession:
the long term change in the composition of a community. They change
in communities from the earlier (pioneer) community to the final
community (climax community), each community is called a sere. 1.
Succession on a bare rock = lithosere2. Succession in freshwater =
hydrosere3. Succession in a dry habitat = xerosere
Succession occurring on a previously un-colonized substrate it
is called primary succession. Secondary Succession occurs in places
where a previous community has been destroyed.
Zonation: refers to changes in communities in relation to
spatial patterns and can be illustrated in the figure below.
Population Dynamics
3.1.1 Describe the nature and explain and implications of
exponential growth in human populationsThe worlds population is
growing very rapidly in an exponential manner. The impact of this
is that a huge amount of resources are needed to look after the
increasing number of people. Humans are K strategists, so
exponential growth does not match with our type of species, as we
will eventually reach carrying capacity
3.1.2 Calculate and explain the values of crude birth rate,
crude death rate, fertility, doubling time and natural increase
rate
Birth Rate:
Fertility:Changes in fertility are a combination of both
social-cultural and economic factors like level of education,
family planning and economic prosperity The age specific birth rate
shows the number of births per 1000 women of a specific age
Doubling Times:The doubling time refers to the length of time it
takes for a population to double in size assuming its natural
growth rate remains constant
Death Rate:Death rate can vary for many reasons such as age
structure, social class and occupations
3.1.3 Analyze age/sex pyramids and diagrams showing demographic
transition modelsPopulation pyramids represent any measurable
characteristic of the population. Population pyramids tell us a
great deal of information about the age and sex structure of a
population: A wide base indicates a high birth rate Narrowing base
suggests falling birth rate Straight sides reveal low death rates
Concave slops characterize high death rates
Energy Resources
3.3.1 Outline the range of energy resources available to
societyEnergy can be generated from both renewable and
non-renewable resources. Renewable energy resources are sustainable
because there is no depletion of natural capital. Some of these
include solar, hydroelectric, geothermal and biomassNon-renewable
energy supplies cannot be replenished at the same rat they are used
resulting in a depletion of the stock. Some of these include fossil
fuels and nuclear power.Only about 9% of the worlds energy supply
comes from renewable resources.
3.3.2 evaluate the advantages and disadvantages of two
contrasting energy sourcesFossil Fuels (nonrenewable)Advantages:
they are cheap and plentiful and technology has been developed to
allow for safe extraction and to control pollutionDisadvantages:
they are unsustainable because it implies liquidation of a limited
stock of the resource and they contribute to climate change by
adding carbon dioxide to the atmosphere
Wind Power (renewable)Advantages: there is no pollution, wind
energy is reliable and renewable and they do not contribute to
climate change at allDisadvantages: wind turbines require a large
amount of space and the placement is critical, as they require
consistent high wind since if there is no wind, there is no energy
generated
The Soil System
3.4.1 Outline how soil systems integrate aspects of living
systemsSoil Profiles: soil can be divided into horizons
(distinguishable layers). These layers have distinct qualities.
3.4.2 Compare and contrast the structure and properties of sand,
clay and loam soils including their effect on primary
productivity
CHARACTERISTICSANDY SOILLOAM SOILCLAY SOIL
Mineral contentHigh HighIntermediate
DrainageVery goodGoodPoor
Water holding capacityLowIntermediateHigh
Air SpacesLargeIntermediateSmall
Total to hold organic matterLowHighIntermediate
Primary ProductivityLowHighintermediate
3.4.3 Outline the processes and consequences of soil
degradationSoil degradation is the decline in quantity and quality
of soil. It includes:1. Erosion by wind and water2. Acidification
is change in the chemical composition of the soil, which may
trigger the circulation of toxic materials3. Atmospheric persistent
organic pollutants may render soils less suitable to sustain the
original land cover and use4. Can cause desertification (spread of
desert conditions into previously productive areas)5. Overgrazing
can severely reduce the vegetation cover and leave the surface
vulnerable to erosion
3.4.4 Outline Soil conservation measuresFarmers are encouraged
towards more extensive management practices Mechanical methods
include contour ploughing to prevent the movement of rainwater to
stop erosion Preventing erosion by different cropping techniques
such as maintaining a crop cover and planting grass for
protectionFor soils that have been affected by salt, farms can
flush the soil with water to leach the salt away, or apply
chemicals that replace the sodium ions
Water Resources
3.6.1 describe the Earths Water Budget
Only a small portion of the Earths water is fresh water and
around 70% of this is trapped in icecaps and glaciersThe different
forms of water are fully replenished during the hydrological cycle
but at very different rates called turnover timesPolar ice caps,
oceans, groundwater, lakes and glaciers have the largest turnover
times which is a problem since they make up a large portion of
available fresh waterThe degree to which water can be seen as
renewable or non-renewable depends on where it is found in the
hydrological cycle and how long it takes to replenishNature Of
Pollution
5.1.1 define the term pollutionPollution is defined as the
contamination of the Earth and atmosphere to such an extent that
normal environmental processes are adversely affected. Pollution
can be natural or anthropogenicIt can be deliberate or accidentalIt
includes the release of substances, which harm the sustainable
quality of air, water and soil
5.1.2 Distinguish between the terms point source pollution and
non-point source pollutionPoint Source Pollution: refers to
discrete sources of contaminants that can be represented by single
points and the source of the pollution can be tracked.
Non-Point Source Pollution: refers to more dispersed sources
from which pollutants originate and enter the natural
environment
Point-source pollution is generally more easily managed as it
can be localized and controlled
5.1.3 State the major sources of pollutantsMajor sources of
pollution include the combustion of fossil fuel, domestic and
industrial waste, manufacturing and agricultural systems. Some of
the more significant sources include:27% comes from mining and
quarrying20% comes from agriculture organic wastes17% comes from
industry
Approaches to Pollution Management
5.3.1 Outline Approaches to pollution management with respect to
the process of pollution and strategies for reducing impacts
Changing Human Activities Regulation can occur by altering human
activity through education, incentives and penalties to promote:The
development of alternative technologiesThe adoption of alternative
lifestylesReducing, reusing and recycling
The main advantage of changing human activities is that it may
prevent pollution from happening.
Regulating ActivitiesAn easy way to reduce pollution is to
reduce the amount of pollution at the point of emission by
regulating the activities that cause pollution. However such
treatments are expensive and it is difficult to enforce such
measures in an unregulated part of the economy. They may be able to
regulate activities by:Setting and imposing standardsIntroduction
measures for extracting the pollutant from waste emissions
Eutrophication
5.4.1 Outline the processes of eutrophication
1. Increased amount of nitrogen and phosphorus are carried into
streams, lakes and groundwater causing nutrient enrichment2. This
leads to an increase in algal blooms as plants respond to the
increased nutrient availability3. The increase in algae and
plankton shade the water below, cutting off the light supply for
submerged plants resulting in anoxia (oxygen deprivation) which
kills off the organisms living in the water
The main source of anthropogenic eutrophication is from nitrous
oxides from fossil fuel combustion and the percolation of nitrogen
fertilizers into the water
A number of changes may occur as a result of eutrophication:1.
Turbidity increases of the water2. Net primary productivity
increases3. Dissolved oxygen in water decreases
5.4.2 evaluate the impacts of eutrophicationLoss to farmers: an
economic loss for farms such that when farmers apply fertilizers to
stimulate crop growth and it runs off, it reduces these benefits to
the soilsHealth concerns: A concern for health related to increase
rates of stomach cancer caused by nitrates from drinking water and
blue baby syndrome caused by insufficient oxygen in the mothers
blood
5.4.3 Describe and evaluate pollution management strategies with
respect to eutrophicationAltering Human Activities1. Avoid using
nitrogen fertilizers when soils are wet2. Maintain crop cover to
conserve nitrogen3. Give preference to crops that conserve nitrogen
in the soil 4. Do not apply nitrogen to areas near water or sloped
areas
Clean Up Strategies1. Adding a chemical which causes phosphates
to precipitate and therefore allow for easy removal2. Remove
nutrient enriched sediments by mud pumping3. Remove biomassGlobal
Warming
6.1.1 describe the role of greenhouse gases in maintaining mean
global temperatureShort-wave ultraviolet light from the Sun is
reflected from the surface of the Earth as infrared light (which
has a longer wavelength)Atmospheric gases (greenhouse gases) are
transparent to short-wave radiation but they can trap or reflect
back outgoing long-wave radiationGreenhouse gases include water
vapor, carbon dioxide, nitrous oxide and ozone
6.1.2 describe how human activities add to greenhouse gasesHuman
activities have increased the level of greenhouse gases in the
atmosphere. Some of the activities include:1. Burning fossil fuels
and releasing carbon dioxide2. Deforestation removes a carbon sink
3. Increased cattle ranching had leas to increased methane levels4.
Rice farming in paddy fields creases anoxic conditions leading to
methane release
6.1.3 discussion qualitatively the potential effect of increased
mean global temperatureEnvironmental FeaturesIce and snow: retreat
of polar ice caps and glaciersCoastline: increase in sea level
causing floodingEcosystems: change in biome distribution and
species composition
Societal FeaturesWater resources: severe water shortagesCoastal
Occupation: relocation due to flooding and stormsHuman Health:
increased disease
6.1.4 discuss the feedback mechanisms that would be associated
with an increase in mean temperaturePositive feedback with regards
to climate change usually refers to one a change in one
environmental factor results in a successive change to stimulate
more climate change. Negative feedback however in the instance of
global warming usually signifies a dampening effect of global
warming, or something that is slightly reversing the effect of
global warming.
Positive Feedback ExampleTemperature increases leading to ice
caps meltingDecreases the Earths albedo, thus increasing
temperature Melting of polar ice caps
Negative Feedback Example
Surface temperature increases slightlyIncreased evaporation from
the oceansMore low clouds in the atmosphereReflects more light back
into spaceSurface temperature decreases slightly
6.1.5 describe and evaluate pollution management strategies to
address the issue of global warmingNational and International
MethodsControlling the amount of atmospheric pollutionStopping
forest clearanceDeveloping alternative renewable energy
sourcesImproving public transportSetting limits on carbon
emissions
Individual MethodsUse public transportationUse biofuelsUse
energy efficient productsEat locally produced foodsEnvironmental
Value Systems
7.1.1 state what is meant by an environmental value systemA
particular worldview or set of paradigms that shapes the way an
individual or group of people perceive and evaluate environmental
issues (EVS)EVS Inputs are:EducationCultural influenceThe mediaEVS
Outputs are:PerspectivesCourses of actionDecisions regarding how to
act
7.1.2 outline the range of environmental
philosophiesEcocentrism-Minimum disturbance of natural
processes-Sustainability for the whole Earth-Lack of faith in
modern large-scale technology-Intrinsic important of nature for the
humanity of man
Anthropocentrism-People as environmental managers of sustainable
global systems -Belief that economic growth and resource
exploitation can continue assuming that there is suitable economic
adjustments, improvements to legal rights regarding the environment
and compensation for those who experience adverse environmental
effects
Technocentrism-Technology can keep pace and provide solutions to
environmental problems-Belief that people can find a way out of any
difficulties-Faith that scientific and technological expertise
provides the basic foundation for advice on matter pertaining to
economics growth, public health and safety