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