Environmental Systems and Societies Student Guide

Mr. Vinlove

George Washington High School

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Aims:“The systems approach provides the core methodology of this course. It is amplified by other methodologies such as economic, historical, cultural, socio-political and scientific, to provide a holistic perspective on environmental issues.

The aims of this course are to:

1. Promote understanding of environmental processes at a variety of scales, from local to global2. Provide a body of knowledge, methodologies and skills which can be used in the analysis of

environmental issues at local and global levels3. Enable students to apply the knowledge, methodologies and skills gained4. Promote critical awareness of a diversity of cultural perspectives5. Recognize the extent to which technology plays a role in both causing and solving environmental

problems6. Appreciate the value of local as well as international collaboration in resolving environmental

problems7. Appreciate that environmental issues may be controversial, and may provoke a variety of

responses8. Appreciate that human society is both directly and indirectly linked to the environment at a number

of levels and at a variety of scales

Objectives: “The objectives reflect those parts of the aims that will be assessed. It is the intention of this course that students should achieve the following objectives:

1. Demonstrate an understanding of information, terminology, concepts, methodologies and skills with regard to environmental issues.

2. Apply and use information, terminology, concepts, methodologies and skills with regard to environmental issues.

3. Synthesize, analyze and evaluate research questions, hypotheses, methods and scientific explanations with regard to environmental issues.

4. Using a holistic approach, make reasoned and balanced judgments using appropriate economic, historical, cultural socio-political and scientific methodologies.

5. Articulate and justify a personal viewpoint on environmental issues with reasoned argument while appreciating alternative viewpoints, including the perceptions of different cultures.

6. Demonstrate the personal skills of cooperation, perseverance and responsibility appropriate for effective investigation and problem solving.

7. Select and demonstrate the appropriate practical and research skills necessary to carry out investigations with due regard to precision, ethics and safety.

ACKNOWLEDGEMENTS

IBO Environmental Systems and Societies Syllabus 2010 Exam questions from IBO Question Bank CD: ESS Stephen Taylor, Bandung International School, Indonesia 2007 published

on the Biology OCC.

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COMMAND TERMSThese command terms indicate the depth of treatment required for a given assessment statement. These

command terms will be used in examination questions, so it is important that students are familiar with the

following definitions. They are used throughout the syllabus to let you know what you are expected to do

with each piece of information. PLEASE learn them early and get a head-start!

EXAM TIPIf you know the meanings of all the command terms, then you know what the examiner expects you to do

– no more, no less. Pay attention to the number of marks available for that question and make at least that many relevant points (better to try to make >2 extra points)

Here are the ESS Command Terms.

Objective 1Define Give the precise meaning of a word, phrase, concept or physical quantity.Draw Represent by means of a labelled, accurate diagram or graph, using a pencil. A

ruler (straight edge) should be used for straight lines. Diagrams should be drawn to scale. Graphs should have points correctly plotted (if appropriate) and joined in a straight line or smooth curve.

Label Add labels to a diagram.List Give a sequence of brief answers with no explanation.Measure Obtain a value for a quantity.State Give a specific name, value or other brief answer without explanation or calculation.

Objective 2Annotate Add brief notes to a diagram or graph.Apply Use an idea, equation, principle, theory or law in relation to a given problem or issue.Calculate Obtain a numerical answer showing the relevant stages of working.Describe Give a detailed account.Distinguish Make clear the differences between two or more concepts or items.Estimate Obtain an approximate value.Identify Provide an answer from a number of possibilities.Outline Give a brief account or summary.

Objectives 3, 4 and 5Analyse Break down in order to bring out the essential elements or structure.Comment Give a judgment based on a given statement or result of a calculation.Compare and contrast Give an account of similarities and differences between two (or more) items or

situations, referring to both (all) of them throughout.Construct Display information in a diagrammatic or logical form.Deduce Reach a conclusion from the information given.Derive Manipulate a mathematical relationship to give a new equation or relationship.Design Produce a plan, simulation or model.Determine Obtain the only possible answer.Discuss Offer a considered and balanced review that includes a range of arguments,

factors or hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate evidence.

Evaluate Make an appraisal by weighing up the strengths and limitations.Explain Give a detailed account, including reasons or causes.Justify Give valid reasons or evidence to support an answer or conclusion.Predict Give an expected result.

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Solve Obtain the answer(s) using algebraic and/or numerical methods and/or graphicalmethods.Suggest Propose a solution, hypothesis or other possible answer.

NATURE OF THE SUBJECTAs a transdisciplinary subject, environmental systems and societies is designed to combine the techniques and knowledge associated with group 4 (the experimental sciences) with those associated with group 3 (individuals and societies). By choosing to study a transdisciplinary course such as this as part of their diploma, students are able to satisfy the requirements for both groups 3 and 4 of the hexagon, thus allowing them to choose another subject from any hexagon group (including another group 3 or 4 subject). Transdisciplinary subjects therefore introduce more flexibility into the IB Diploma Programme. The environmental systems and societies course is offered at SL only.The prime intent of this course is to provide students with a coherent perspective of the interrelationships between environmental systems and societies; one that enables them to adopt an informed personal response to the wide range of pressing environmental issues that they will inevitably come to face. Students’ attention can be constantly drawn to their own relationship with their environment and the significance of choices and decisions that they make in their own lives. It is intended that students develop a sound understanding of the interrelationships between environmental systems and societies, rather than a purely journalistic appreciation of environmental issues. The teaching approach therefore needs to be conducive to students evaluating the scientific, ethical and socio-political aspects of issues.

The international dimensionEnvironmental issues are both local and global in their extent. This course reflects the international element throughout but, where it may be drawn particularly to the attention of the students, this is highlighted alongside some assessment statements (Int).We all live on one planet Earth, yet use much more than one planet Earth’s worth of resources. This is obviously not sustainable and this course attempts to discuss the issues surrounding resource use at various scales—from that of the individual (for example, attitudes to recycling) to that of the global community (aims 1, 2, 6 and 8 in particular).Internationally, both governmental and non-governmental environmental organizations are considered in the course, from the United Nations Environment Programme (UNEP) to Greenpeace and the World Wide Fund for Nature (WWF).Environmental scientists work internationally at all levels. In this course, students may share data collected with those in other IB Diploma Programme schools on other continents just as professional scientists pool their data. Students taking this course should thus become more aware of the diversity of cultural perspectives on the environment (aim 4) and appreciate that environmental issues may be controversial as they cross geographical and cultural boundaries (aim 7).

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ASSESSMENT OUTLINEThe objectives reflect those parts of the aims that will be assessed. It is the intention of the environmental systems and societies course that students should achieve the following objectives.1. Demonstrate an understanding of information, terminology, concepts, methodologies and skills with regard to environmental issues.2. Apply and use information, terminology, concepts, methodologies and skills with regard to environmental issues.3. Synthesize, analyse and evaluate research questions, hypotheses, methods and scientific explanations with regard to environmental issues.4. Using a holistic approach, make reasoned and balanced judgments using appropriate economic, historical, cultural, socio-political and scientific sources.5. Articulate and justify a personal viewpoint on environmental issues with reasoned argument while appreciating alternative viewpoints, including the perceptions of different cultures.6. Demonstrate the personal skills of cooperation and responsibility appropriate for effective investigation and problem solving.7. Select and demonstrate the appropriate practical and research skills necessary to carry out investigations with due regard to precision.For a list of command terms for objectives 1–5, see the “Glossary of command terms” section.practiceAssessment statementsAssessment statements, which are numbered, are expressed in terms of the outcomes that are expected of students at the end of the course (for example, “2.1.1 Distinguish between biotic and abiotic (physical) components of an ecosystem”). These are intended to prescribe to examiners what can be assessed by means of the written examinations. Each one is classified as objective 1, 2 or 3 according to the command terms used (see the “Glossary of command terms” section). The objective levels are relevant for the examinations and for balance within the syllabus, while the command terms indicate the depth of treatment required for a given assessment statement.

SL ASSESSMENT SPECIFICATIONS

First examinations 2010

Assessment Component WeightingExternal assessment ( written papers, 3 hours

Paper 1 – 1hour45 marksPaper 1 is made up of short-answer and data-based questions.Paper 2 - 2 hours65 marksPaper 2 consists of two sections, A and B.In section A, students will be provided with a range of data in a variety of forms relating to a specific case study. Students are required to make reasoned and balanced judgments by analysing this data.In section B, students are required to answer two structured essay questions from a choice of four.

80%

30%

50%

Internal assessment – 30hours42 marks

20%

Note: Wherever possible, teachers should use, and encourage students to use, the Système

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International d’Unités (International System of Units—SI units).

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Top tips for Exam Success!1. Practice, practice, practice, practice, practice, practice,

practice, practice, practice, 2. Learn the Command Terms!3. Revise well ahead of time4. Check that you are happy with all the relevant sections in the

syllabus. Can you give them 5. Start your revision with the bits you DON’T like – then you can

fill in the gaps before you start going over all the stuff you already know

6. Practice some more. Ask for more practice. And then do more practice. There are only so many questions the examiners can think of, so if you master them all, you can’t go wrong!

In The Exam1. Read the paper through once completely before you even

write anything down. It will help you judge the time.2. Read every question carefully. Avoid silly mistakes3. Highlight the Command Terms as you go through – it will

help you focus on what the examiner wants to read4. If the question is worth one mark, write one point. If it is

worth five marks, they are looking for five bits of information. If possible write six or seven relevant points. Pay attention to the marks!

5. Of course, CHECK YOUR ANSWERS.

Strategies for Data-based Questions: Questions will ask you to read the data or draw conclusions

from it. Check the marks for each question. The examiner will

compare your answer to the accepted answer. You can write as much as you like as long as you don’t contradict yourself. If you write something wrong, no marks are deducted, BUT if you contradict yourself, you will receive no marks.

You are expected to use the data within the question Become familiar with units - kJm-2yr-1

If asked to calculate , you must show working Compare – clearly relate BOTH similarities and differences

between 2 sets of data, usually involves numeric data and MUST include units. Do a full comparison and be sure to state whether any difference is an increase or decrease.

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Use a RULER to draw lines on graph to help you increase your chance of being within the tolerance allowed by mark scheme.

Strategy for Open-ended Questions You MUST be familiar with Command terms. Discuss, explain,

describe and outline – give the facts, not an opinion or theory.

Explain – relate mechanism of how something works, usually requires a long response. There are no penalties for writing too much. Check the marks.

Discuss – make sure you present at least two alternate views. Eg. Imagine there is a discussion question on conserving the rainforest. You must give opposing views why the rain forest should and should not be conserved.

List – you must give the EXACT number of things asked. Eg. If asked to list 3 factors which affect distribution of plant species – only list 3. If you list 4, the fourth answer will not be marked.

TIPS TO REMEMBER1. The examiner does not know you. You must communicate

fully what you know and not expect the examiner to “fill in the blanks” for information that you do not relate.

2. State the obvious in your answers. Many of the items in the mark scheme will be information that is very basic in relation to the question.

3. Do not use abbreviations that may be unfamiliar to someone else. Be clear and concise with your choice of words

4. If you have handwriting which is very small or not clear, PRINT your response. If the examiner cannot read your writing, you will get NO MARKS

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INTERNAL ASSESSMENT

General informationFor internal assessment, a number of assessment criteria have been identified. Each assessment criterion has level descriptors describing specific levels of achievement together with an appropriate range of marks.The level descriptors concentrate on positive achievement, although for the lower levels failure to achieve may be included in the description.Criteria and aspectsThere are four assessment criteria that are used to assess the work of students.• Planning—Pl• Data collection and processing—DCP• Discussion, evaluation and conclusion—DEC• Personal skills—PSThe first three criteria—planning (Pl), data collection and processing (DCP), and discussion, evaluation and conclusion (DEC)—are each assessed at least twice.Personal skills (PS) is assessed summatively, once only, at the end of the course. It should not be the average achieved over the whole practical scheme of work but should reflect any sustained improvement in performance.Each of the assessment criteria can be separated into three aspects as shown in the following sections.Descriptions are provided to indicate what is expected in order to meet the requirements of a given aspect completely (c) and partially (p). A description is also given for circumstances in which the requirements are not satisfied, not at all (n).A “complete” is awarded 2 marks, a “partial” 1 mark and a “not at all” 0 marks.The maximum mark for each criterion is 6 (representing three “completes”).Pl × 2 = 12DCP × 2 = 12DEC × 2 = 12PS × 1 = 6This makes a total mark out of 42.The marks for each of the criteria are added together to determine the final mark out of 42 for the internal assessment component. This is then scaled by the IB to give a total out of 20%.

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Planning

Data collection and processing

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Discussion, Evaluation and Conclusion

Sample IAs are available on the learning place.

IB ESS- Learning Resources – Labs – IB Lab writing tips – marked examples.

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Write in your investigations here to keep track of your lab hours and progress.

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INTERNAL ASSESSMENT and PRACTICAL REPORTSWRITE UP GUIDE.

To make sure you get the best possible marks for an assessed criterion, you MUST make sure you have covered all of the ‘Aspects’ described – to the best of your ability.

Missing or incomplete aspects will result in reduced marks, so pay attention!

The easiest way to ensure you have covered everything is to lay out your write-up in a clear and logical order:

Start with ‘Planning’ and go through the aspects in order (easier for the moderator to find) Make sure everything has an appropriate title and is neatly presented Use tables to present information where possible – very helpful if you have difficulties with English or have terrible

handwriting!

The following is an exemplar write-up.See if you can spot where each aspect of each criterion is fulfilled.

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AIM (or RESEARCH QUESTION):

Make it absolutely clear what you are investigating (with a little ‘why’ and ‘how’). The reader should be able to deduce the point of the investigation from this sentence alone.E.g.“Osmosis: investigating the effect of solute concentration on the weight of potato discs, when submerged in a range of concentrations of salt solution for 2 hours.”

VARIABLES: Units RangeINDEPENDENT

VARIABLEDEPENDENT

VARIABLE

CONTROLLED VARIABLES Units Possible effect(s) on results

1.

2.

3.

4.

HYPOTHESIS (or BACKGROUND INFORMATION)

If you are testing a hypothesis, make your prediction and give full, supported reasons for it If you are carrying out another type of investigation, give some background information or theory on

the subject.

ACADEMIC HONESTY: Remember to cite your sources of information properly!

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METHOD FOR CONTROLLING VARIABLES:

Include details of equipment used to control each variable

CONTROLLED VARIABLES: Method for control:

1.

2.

3.

4.

METHOD FOR COLLECTING DATA:

Include details of how to measure your independent and dependent variables. Give precise details of values, units and equipment Make sure you collect enough data – how large does your sample size need to be? How many times will you REPEAT your investigation to ensure reliable results? SAMPLE SIZE ( > 10, preferably more) What will you do with your data? (Graph type/statistical test?) Take a digital photo of the set-up and label all of the equipment and materials used.

RECORDING RAW DATA:

Large, clear table for your raw (un-processed) results. Include possible errors/uncertainties in your measurement. Complete table as you go – don’t leave it on scraps of paper.

E.g. (columns 1-4)

SoluteConcentration(%) (+/-0.5%)

RE-PEAT

Weight of discsBEFORE(g) (+/-0.5g)

Weight of discsAFTER(g) (+/-0.5g)

WEIGHTCHANGE(g)

% CHANGE INWEIGHT (g)(+/- 1%)

MEAN%CHANGE(+/-1%)

0

1

2

3

3

1

2

3

6

1

2

3

PROCESSING RAW DATA (e.g. columns 5-7 above) How will you transform the data you have collected to make it useful? Include an example of any calculations performed. Check your calculations to avoid any silly mistakes.

Clear labelsunits

uncertainties

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PRESENTING PROCESSED DATA:

Present your processed data in the most appropriate form Tables, charts and graphs must be titled, labelled, large and clear Remove any confusing formatting from computer-generated chars or graphs

TIP: when plotting ‘best fit’ graphs using Excel, choose the ‘scatter’ option instead and complete the line of best fit by hand – it will look much better.

Don’t forget units and errors/uncertainties (e.g. error bars on a bar chart).

For more detailed help with using and choosing graphs, see the next section.

CONCLUDING: (you might not need to answer all of these questions)

Interpret your results, based on the data collected and with reference to your hypothesis or background information.

What (if any) general trends do you observe? What do they suggest? Are there any anomalous (unusual) results? What might be their significance? Do the data you collected support your hypothesis? Why / Why not? What do your data suggest about the outcome of your research question? Do other sources of information or investigations support your findings? (Cite your source!) How could you develop this investigation for further study?

EVALUATING PROCEDURE(s):

This must be a worthwhile evaluation of the method chosen, rather than a superficial commentary on poor lab techniques and sloppy work. “I should measure more accurately” is a problem with your practical skills, rather than the method of the investigation.

Did you record any anomalies in your practical work? How did they affect your results and what did you do to minimize their adverse effects?

What weaknesses were present in the method chosen for the investigation and how could they have affected the outcome?

Did anything occur during the investigation to compromise the reliability of your results?

IMPROVING THE INVESTIGATION:

For each of the weaknesses or limitations mentioned above, describe a workable, realistic method to remedy the problems caused.

REFERENCES (OR BIBLIOGRAPHY):

Using the Harvard method, cite all sources used in your research for this investigation. Be consistent in your method. For more information, see the section entitled ‘Academic Honesty’.

APPENDIX:

You may want to include:

raw data or lab notes Article/research cuttings Prac protocols from other sources (where ‘Planning’ is not being assessed)

It is a good idea to put the evaluation and improvements in a table so that for each part of the procedure that is mentioned, an improvement is also noted.

Check List for Internal Assessment- Practical Reports

Checklist for planning

Aspect 1: defining the problem and selecting variables

I have identified a focused problem or a specific research question. I have done this by, for example, stating a clear

aim, a clear hypothesis, and clearly defining the variables.

I have identified and stated the independent variable and the dependent variable, and I have listed the controlled

variables.

Aspect 2: controlling variables

I describe a method for the effective control of the variables. In particular, I describe how the independent variable is

manipulated and how the controlled variables are maintained at constant values

I list all the apparatus and materials used, including the volumes of tubes and cylinders, the concentrations of

solutions, the model and manufacturer of any complex apparatus, etc.

I state the level of precision of the values for the independent variable

Any standard methods that I use are fully referenced in a footnote

Aspect 3: developing a method for the collection of data

I describe a method that allows for the collection of sufficient relevant data

The data gathered enables the aim, the research question or the hypotheses to be adequately addressed

The data gathered enables an evaluation of the reliability of the data

The sample size should be adequate to allow a reasonable statistical analysis of the data (for calculating the standard

deviation, at least five items per treatment)

An adequately broad data range is considered

An adequate number of data values within this range are considered

Checklist for data collection and processing

Aspect 1: recording raw data

I have recorded my data independently

I have data which is quantitative (numerical) where possible.

I have chosen a suitable format in which to record the raw data

The variable that is measured or recorded is clearly state (e.g. in the column heading in a table)

The units are given for every variable (e.g. in any column headings)

An indication is given of the uncertainty of measurements (e.g. in any column headings

A complete and descriptive title is given to any table that is used

The same level of precision (number of decimal places) is used for all the items of a variable

Aspect 2: processing raw data/ secondary data

I have decided on a suitable manner in which to process the data, so that I may fully test the hypotheses or fulfil the

aim (this may involve a mathematical processing, statistical analysis, or transforming the data into a suitable graphical

representation

All of the data has been processed to a suitable extent

The data has been processed correctly

Any data plotted onto a graph includes a line of best-fit

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Aspect 3: presenting processed data

I have decided upon a suitable format in which to present the processed data

There are clear, unambiguous headings for calculations, tables or graphs

Any graphs have appropriate scales, labelled axes with units and accurately plotted data points with a suitable best-fit

line or curve

The data has been presented so that all the stages to the final result can be followed

Metric/SI units are included for the final results

The final results are shown expressed to the correct number of significant figures

The uncertainties and errors associated with the raw data have been taken into account and this is shown in some

manner (e.g. error bars may be used, as appropriate

Checklist for discussion conclusion and evaluation

Aspect 1: Discussing and reviewing

The discussion is clear and well reasoned

o I show a broad understanding of the context of the topic I am discussing

o The implications of my findings are fully discussed

o I have explained the significance of each graph and table in the results section and how this impacts on the findings

for this topic.

Aspect 2: evaluating procedures and suggesting improvements

I have commented on the design and method of the investigation

I have commented on the quality of the data

I have listed the weaknesses of the study

I have assessed the importance of each of these weaknesses

I have commented on the precision and accuracy of the measurements

In evaluating the procedure, I have specifically looked at the processes, the use of

equipment and the management of time

My suggestions for improvements are based on the weaknesses and limitations indentified in aspect 2

As appropriate, I address modifications to the experimental technique and the data range

The modifications that I propose are realistic and clearly specified

Aspect 3: Concluding

o I state a conclusion which is based on a reasonable interpretation of the data

If any hypotheses are being tested, I have sated whether the data supports these hypotheses

I give a justification for my conclusion in both the results I obtained and published information on the topic.

As appropriate, I compare different graphs, or describe the trends shown in my graphs

If I am measuring an already known and accepted value, I have compared my value with that in a textbook, in order to

assess the validity of the result

I fully reference any literature that is quoted

o I have used in text referencing throughout this report.

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CHOOSING AND USING GRAPHS

Graphs can help you to: Understand what is happening in your data (analysis). See trends in different variables (interpretation). See how one factor affects another (correlation). Communicate information to other people.

Basic TermsData – is information that you collect when you measure or count objects (e.g. lengths of antennae on grasshoppers).

Variable – is the aspect or fact that you are taking measurements or counts of (e.g. eye colours, heights of individuals).

Continuous data – this is data which is obtained by taking measurements (e.g.height, temperature, heart rate). Continuous data always has units (e.g. °C, mm, beats/minute).

Discrete data –n this is data which is collected by counting individual objects rather than by taking measurements. Discrete data has no units (e.g. number of each plant species in a lawn area).

Categories – are square classes into which individuals can be grouped (e.g. male/female).

Size categories – this is when data is obtained by measuring (e.g. heights) and then individuals are placed into class size intervals (e.g. 1 to 5 mm/6 to 10mm/11 to 15mm) and counted up.

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Always use a pencil and ruler to draw graphs.Some types of graph can have colour added after the basic graph is completed.

GRAPH CHECKLIST1. Use graph paper2. Use a pencil and ruler3. Make your graph a good size4. Draw in the two axes with a ruler5. Put the INDEPENDENT variable (if there is one) on the HORIZONTAL axis6. Scales on each axis should go up evenly (but not necessarily have to start at zero).7. Scales increase upwards and from left to right8. Adjust the scale to fit the range of data (so that it covers the highest and lowest values)9. Give your graph a title which explains what it is about (try to include the variables)10. Plot the points accurately with a small ‘x’11. Label both axes with the name of the variable and units (use abbreviations for scientific units)12. Use a key with plotting symbols if you plot several lines

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Constructing an Effective Graph

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Types of Graphs

Pie graphs are circles divided up into pieces or segments. The area of each segment represents the percentage of individuals which fall into a particular category.Pie graphs should only be used with discrete grouped in categories and then converted into percentages of the total number.

Bar graphs and column graphs have the data displayed in either vertical columns or horizontal bars.The height of the column or the length of the bar represents the number of individual objects in a particular category.Bar and column graphs should be used when the data is discrete and is grouped into separate categories (e.g. blood types).

A histogram has columns which touch each other. The width of each column represents a class size interval (e.g. 5 to 10 mm in length)./ The height usually indicates the number of individuals (or %) which fall into each class interval.Histograms should only be used with data grouped into class size intervals rather than data sorted into distinct categories.

A Line graph consists of a series of points plotted on the grid and then connected together by a line or curve.Line graphs are only used when both variables are continuous. They are very useful for showing how changing one variable (e.g. light intensity) affects another (e.g. rate of photosynthesis).

With a scatter graph the points are plotted on the grid but they are usually not joined with a line or curve.Scatter graphs are only used when both variables are continuous.These graphs are useful for showing if a relationship exists between two variables (e.g. a relationship between antennae length and number of body segments) especially when it is not possible to alter either of the variables involved.

In many scientific investigations you are trying to find out if there is any connection or relationship between two factors or variables. Interpreting graphs involves indentifying patterns and trends. If a trend is present then it suggests some kind of relationship or connection between the two variables; and there are a variety of different kinds of relationships possible.

EXAMPLES

Animal MetabolicHuman Weight/Height Rate and Weight Human IQ and Head Size

Height Metabolic I.Q.(cm) rate

Weight (kg) Animal weight (kg) Head circumference (cm)

There are also some statistical tests that can be done to determine the strength of correlation between two variables (e.g. the “Coefficient of linear Correlation” test).

Example: (for a line graph about photosynthesis with the variables being light intensity and the number of bubbles of oxygen given off per minute)

“As light intensity increased, the rate of photosynthesis (as shown by the oxygen given off) increased rapidly initially but then levelled off to a constant value”

Thanks to Rod Murphy from Bandung International School, Indonesia

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Interpreting Graphs

. : . . .

.. . .

. .

(a) Positive correlation – heavier people tend to be taller and lighter people tend to be shorter.

(b) Negative correlation – heavier animals have a lower metabolic rate.

(c) No correlation – people with larger heads do not necessarily have higher IQ.

Some terms and phrases that could be useful when describing trends in a line graph are :

rapidly slowly regularly unevenly erratically smoothly

became constant reached a peak fluctuated levelled off

REFERENCING: A QUICK GUIDEAcademic honesty has two main factors:

1. ‘In-text’ citationsYou let the reader know where you have used a piece of information in your work.

Name / date citations as part of your text.

2. BibliographySupply complete details of the sources you have used – so that the reader could find them easily to check them or learn more.

IN-TEXT CITATIONS

Name/date (Harvard method):“Monkeys prefer ripe bananas to unripe bananas (Taylor, 2006). According to Pugh (2007), this is due to the extra sugars present in ripe bananas. Murphy et al (2006) propose that monkeys may have a similar range of tastes to humans. It has yet been unproven whether or not monkeys find it funny when someone slips and falls on a discarded banana skin (Taylor, 2006).”

BIBLIOGRAPHY

If you are using the Harvard method (or another name/date method) to cite your source in-text, then you must present your bibliography in alphabetical order of the last names of the lead authors of the sources. All other formatting remains the same:

Murphy, R. et al. 2005. ‘A study into the taste pallet of primates’. Monkey Journal, vol 2, issue 12. Dec 2005. pp 12=15.

Pugh, D.2007 Banana Web – nutrition page. Association of Bananas. Retrieved June 13, 2007 from www.bananaweb.com/nutrition.htm

Taylor, S.2006. Monkey Nutrition Handbook, 2nd Edition. pp198-199. Primate Press, Bandung.

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ACADEMIC HONESTYIt is ESSENTIAL that you are honest in your research and you cite your sources. The penalties for plagiarism (passing another’s work off as your own) are severe.

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ICT in ESSBelow are a list of great web sites you should look up for good information relating to the syllabus.http://www.youtube.com/watch?v=O3CZFfyed3M – species to communityhttp://www.youtube.com/watch?v=TE6wqG4nb3M – food chain songhttp://www.youtube.com/watch?v=ag5ATGEplbU – biomeshttp://www.youtube.com/watch?v=taLr2pTlAEM – ecological pyramidhttp://www.enviroliteracy.org/article.php/580.html - labshttp://highered.mcgraw-hill.com/sites/0072315474/ http://www.youtube.com/watch?v=TGRuen6BMbw – population interactionshttp://www.youtube.com/watch?v=U3SZKJVKRxQ&feature=related – carbon cycle cartoonhttp://www.youtube.com/watch?v=1o4ODWMZq5U&feature=related – carbon cycle and global warminghttp://www.youtube.com/watch?v=pdY4I-EaqJA&feature=related – nitrogen cyclehttp://expert-eyes.org/shola.html - tropical montane forestshttp://www.wildvistas.com/nationalparks/kodaikanal/kodaikanal.html - kodaikanal sholahttp://www.youtube.com/watch?v=rFLssJ2n5FY&feature=related – successionhttp://www.youtube.com/watch?v=44HCCSq75o0&feature=related – secondary successionhttp://www.youtube.com/watch?v=j6UFRIAcWgY – soil formation during succession http://www.countrysideinfo.co.uk/successn/intro.htm - ecological successionhttp://www.youtube.com/watch?v=eEFwaQej_0E – sustainable developmenthttp://www.shell.com/home/content/media/news_and_library/speeches/2009/climate_change_podcasts.html - CCS - carbon capture and storagehttp://tonto.eia.doe.gov/kids/resources/teachers/pdfs/EIAScavengerHunt.pdf - energy huntinghttp://tonto.eia.doe.gov/kids/resources/teachers/pdfs/Activitybook_web.pdf - ENERGY ACTIVITYhttp://www.youtube.com/watch?v=xytSsbJusVg – soil erosion and conservationhttp://www.youtube.com/watch?v=D_GohbbmoKs - commercial agriculturehttp://www.youtube.com/watch?v=qXdEmQkYlek - subsistence to commercial farminghttp://media.ft.com/cms/s/2/f5bd920c-975b-11dc-9e08-0000779fd2ac.html?from=textlink - Food http://earthguide.ucsd.edu/earthguide/diagrams/watercycle/ - water cycle animationhttp://www.unesco.org/education/tlsf/TLSF/theme_b/mod09/uncom09t05.htm - footprinthttp://www.sciencebuddies.org/science-fair-projects/science_project_ideas.php - projectshttp://www.myfootprint.org/en/visitor_information/ - ecological footprint quizhttp://www.sciencebuddies.org/science-fair-projects/project_ideas/EnvEng_p026.shtml - roof top gardenhttp://www.bigpicture.tv/videos/watch/a5bfc9e07 - mackernagel’s view on ecological foorprinthttp://www.youtube.com/watch?v=MSNGp-3c5CE&feature=related – loss of biodiversityhttp://www.youtube.com/watch?v=VjbiNmLmQaU&feature=related – rain forestshttp://www2.ucar.edu/climate/faq - global warming UCARhttp://ei.cornell.edu/toxicology/bioassays/Duckweed/analysis.asp - bioassay analysishttp://www.teachertube.com/viewVideo.php?video_id=127021 – LEARNING ENVIRONMENThttp://www.youtube.com/watch?v=yT7ogH7B3_w – atmospherehttp://www.youtube.com/watch?v=p79g9_5IxgE&feature=related – earth’s surfacehttp://www.sciencebuddies.org/science-fair-projects/project_scientific_method.shtml - steps of scientific experimenthttp://www.saburchill.com/index.html -source for all sciencehttp://www.youtube.com/watch?v=nfziy_860GU – plate tectonicshttp://www.youtube.com/watch?v=XdtQhTV0J6g – non point source pollutionhttp://www.youtube.com/watch?v=dabPFNxo844&feature=related – water cycle 1http://www.youtube.com/watch?v=YswL4dIDQuk&feature=related – water cycle 2http://www.youtube.com/watch?v=nDALeYd9i2U – biotic indexhttp://www.youtube.com/watch?v=WczsDc1LiOI – lichen as http://www.aquatext.com/tables/bioticind.htm - biotic indexhttp://www.mbgnet.net – biomeshttp://www.youtube.com/watch?v=SA8tEUGVI_I - deep seahttp://www.youtube.com/watch?v=SyBO10VhVmc&feature=related – deep sea creatureshttp://www.youtube.com/watch?v=fN_NmCpry38 - el ninohttp://www.practicalbiology.org/areas/intermediate/environment/environmental-indicators/ - practicalshttp://www.tropical-biology.org/admin/documents/pdf_files/Kenyaabstracts/O'Moore%20Donohue%20&%20Meijer_2006.pf – lichen http://sciencebitz.com/ - resourcehttp://new.coolclassroom.org/img/adventures/plume/docs/Eutrophication_Teacher.pdf - eutrophicationhttp://www.youtube.com/watch?v=jBgDeG0kzCQ – eutrophication 1http://www.youtube.com/watch?v=JevA4C6Iwu8 – use of models

1. http://www.neok12.com/quiz/ECOSYS03 - ECOSYSTEM QUIZ 1 2. http://www.neok12.com/quiz/ECOSYS04 - ECOSYSTEM QUIZ 2

ESS EXTRA READING BOOK LIST

26

To increase higher-level thinking and environmental philosophy in this course, students are encouraged to read a novel or two from the list below.

They are encouraged to write a weekly journal reflection about their reading.

Reading List

Ishmael, by David QuinnBreakfast for Biodiversity, by John Vandermeer and Ivette PerfectoSong for the Blue Ocean, by Carl SafinaA Sand County Almanac, by Aldo LeopoldWalden Pond, by Henry ThoreauA Civil Action, by Jonathan HairEarth in Balance, by Al GoreDeception Point, by Dan BrownA Silent Spring, by Rachael Carson

Other choices are possible with instructor approval.

Television Documentaries and current affairs programs are informative and broaden our understanding and perspectives on environmental issues. Students should watch various programs, as appropriate, and are encouraged to journal their reflections about their viewing.

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SYLLABUS OVERVIEW

28

SYLLABUS DETAILS

THIS SECTION OUTLINES THE ASSESSMENT STATEMENTS SET BY THE IBO:

Work through the progress tracker to keep track on how you are going Make sure you are keeping up with your notes and cover any statements that may be

missing from your class or homework. KEEP ALL YOUR NOTES AND WORKSHEETS IN A FOLDER SO YOU KNOW WHERE

TO LOCATE ANY TOPIC AT ANY TIME. Pay attention to the command terms and the objectives in each statement. Often, the

exam question is identical to the assessment statement.

TRACK YOUR PROGESS THROUGH THE SYLLABUS:

As you cover an assessment statement in class or as part of an assignment, highlight it with a marker and tick the “class” box.

Once you have revised the work, put a tick under the “home” column. If you are 100% sure that you could walk into an exam and answer a question on that

statement (remember the command term and objective), stick a smiley face under “I’m confident”.

It’s a simple, visual way to track your progress, but it just might work for you. TRY IT....

Assessment statement Obj Class Home 2.1.1 Distinguish between biotic and

abiotic (physical) components of an ecosystem.

2 2.1.2 Define the term trophic level. 3

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Topic 1: Systems and models (5 hours)It is essential that the systems approach is used throughout this course. This approach identifies the elements of the systems, and examines the relationships and processes that link these elements into a functioning entity. This topic may be best viewed therefore as a theme to be used in the delivery of the other topics, rather than as an isolated teaching topic. The topic identifies some of the underlying principles that can be applied to living systems, from the level of the individual up to that of the whole biosphere. It would therefore be helpful to describe and analyse the systems addressed in the terms laid out in this topic (wherever possible). The systems approach also emphasizes the similarities between environmental systems, biological systems and artificial entities such as transport and communication systems. This approach stresses that there are concepts, techniques and terms that can be transferred from one discipline (such as ecology) to another (such as engineering). TOK: How does a systems approach compare to the reductionist approach of conventional science? How does methodology compare between these two approaches? What are the benefits of using an approach that is common to other disciplines such as economics and sociology?

Assessment Statement Obj

Notes Class Home 1.1.1

Outline the concept and characteristics of systems.

2 The emphasis will be on ecosystems but somemention should be made of economic, social and value systems.

1.1.2

The emphasis will be on ecosystems but some mention should be made of economic, social and value systems.

2 The range must include a small-scale local ecosystem, a large ecosystem such as a biome, and Gaia as an example of a global ecosystem.

1.1.3

Define the terms open system,closed system and isolated system.

1 These terms should be applied when characterizing real systems.• An open system exchanges matter and energy with its surroundings (for example, an ecosystem).• A closed system exchanges energy but not matter; the “Biosphere II” experiment wasan attempt to model this. 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).

1.1.4

Describe how the first and second laws of thermodynamics are relevant to environmental systems.

2 The first law concerns the conservation of energy.The second law explains the dissipation of energythat is then not available to do work, bringing about disorder. The second law is most simply stated as: “In any isolated system entropy tendsto increase spontaneously.” This means that energy and materials go from a concentrated into a dispersed form (the availability of energyto do work diminishes) and the system becomes increasingly disordered.Both laws should be examined in relation to the energy transformations and maintenance of order in living systems.

1. Explain the nature of 3 A steady-state equilibrium should be 30

1.5

equilibria. understood as the common property of most open systems in nature. A static equilibrium, in which there is no change, should be appreciated as a condition to which natural systems can be compared.(Since there is disagreement in the literature regarding the definition of dynamic equilibrium, this term should be avoided.) Students should appreciate, however, that some systems may undergo long-term changes to their equilibrium while retaining an integrity to the system (for example, succession). The relative stability of an equilibrium—the tendency of the system to return to that original equilibrium following disturbance, rather than adopting a new one -should also be understood.

1.1.6

Define and explain the principles of positive feedback and negative feedback.

3 The self-regulation of natural systems is achieved by the attainment of equilibrium through feedback systems.• 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.Feedback links involve time lags.

1.1.7

Describe transfer and transformation processes.

2 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.

1.1.8

Distinguish between flows (inputs and outputs) and storages (stock) in relation to systems.

2 Identify flows through systems and describe their direction and magnitude.

1.1.9

Construct and analyse quantitative models involving flows and storages in a system.

3 Storages, yields and outputs should be included in the form of clearly constructed diagrammatic and graphical models.

1.1.10

Evaluate the strengths and limitations of models.

3 A model is a simplified description designed to show the structure or workings of an object, system or concept. In practice, some models require approximation techniques to be used. For example, predictive models of climate change may give very different results. In contrast, an aquarium may be a relatively simple ecosystem but demonstrates many ecological concepts.

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PAST EXAM QUESTIONS TOPIC 1

1. Figure 1 shows a farming system and Figure 2 outlines the activities for the farm in areas A, B and C over a year.

Figure 1

seed b ed s fo r tob ac co a nd ric e

fru it tre e s:m an g o es , ja ck fru it , co co n u t p a lm an d b e te l n u t

k itc h e n g ard e n :v eg e tab le s , sp ice s,su g a r ca n e

w o rk in g an im a ls , m ain ly c a ttle , u se fo o d in w et sea so n ro u n d v illag e , b u t g ra ze s tu b b le a fte r ha rv e st

fam ily la bo u r, se a so n a l ro ta tio n o f c ro p s

h eav ie s t, p lou g h ed la nd foo d ed a n d ric e p a d d ie s . B as ic ir rig a tio n tech n o lo g y u sed in d ry sea son .

A rea Alig h te r so il b e tte r

d ra in ed ab o v e fo o d in g

A rea Bo p en fe ld s

A rea Cpo o rly d ra in e d lan d liab le to

fo o d in g

Figure 2

M o n th M a rch A p ril M a y S e p tem b e r M arch

S ea so n P re– m o n so o n Wet se aso n D ry sea so n

A rea A c a ttle in y a rd , m an g o es , v e g e tab le s

re p a irin g a n d th a tch in g , g re en c o co n u ts , b e te l n u ts

A rea B ju te w h ea t, to b ac c o , m u s ta rd

A rea C g ra z in g , r ice (fo o d in g ) g ra z in g

[Source: Adapted from M Carr, Patterns, Process and Change in Human Geography, Macmillan, (1987), page 142]

(a) State, giving two reasons, whether this system is more typical of farming in a more economically developed country (MEDC) or a less economically developed country (LEDC).

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................(2)

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(b) Complete the systems diagram below to show three inputs, processes and outputs for the farming system shown in Figure 1 and Figure 2.

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

In p u ts

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

O u tpu ts

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

P ro ce sses

FA R M

(3)

(c) With reference to Figure 1 and Figure 2, describe two ways in which the farming system has been developed in response to variations in the local environment.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(2)

Figure 3 below shows nutrient cycling in a terraced paddy.

d ecay o f r ice s tu b b le re le ase s n u tr ien ts

n itro g en fx a tio n b y b lu e -g ree n a lg ae

N O 3

r ice

w ate r

te rrac e

little so il e ro s io n

litt le le a ch in g

o x id ise d zo n ered u c ed z o n e ( lit tle O 2)

d e ad o rg a n ic m a te ria l

rap id b re ak d o w nslow b rea k d o w n

irrig a tio ncan a l r ice p ad d y

lo w er ric ep ad d y

(d) With reference to Figure 3 define

(i) leaching............................................................................................................................(1)

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(ii) nitrogen fixation............................................................................................................................(1)

(e) With reference to Figure 3 explain the following.

(i) There is very little soil erosion in this farming system.

...........................................................................................................................(1)

(ii) The dead organic material breaks down more rapidly in the oxidized zone.

...........................................................................................................................(1)(Total 11 marks)

2. Below is a diagram from UNESCO showing relationships between development, the environment and health.

Sustainable development spirals

T H E D E S C E N D IN G S P IR A L

In a p p ro p ria ted e v e lo p m e n t

Im p a cts

U n d e rm in es

D e v e lo p m e n tIn h ib its

E n v iro n m en t

H ea lth

D eg rad es

T H E A S C E N D IN G S P IR A L

S u sta in a b le d ev e lo p m e n t M ak e s p o ss ib le

In c reases H e a lth

D e v e lo p m en t

E n v iro n m en t

Im p ro v e s S u s ta in s

[Source: Sustainable development spirals, United Nations Environment Programme]

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(a) State, giving one reason, what kind of system feedback is illustrated by the descending spiral.

......................................................................................................................................

......................................................................................................................................(1)

(b) Discuss the meaning of the term sustainable development with reference to the diagram above.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(2)

(c) Evaluate the strengths and limitations of the models shown in the diagram above.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(2)(Total 5 marks)

3. (a) Define the term feedback.

......................................................................................................................................

......................................................................................................................................(1)(b) Explain, with the help of an example, the term negative feedback in relation to an ecosystem.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(3)(Total 4 marks) 4. The following is a schematic diagram of an “ecotron”. This is a walk-in chamber with computer controlled

climatic conditions for studying small communities representative of natural ecosystems.

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a irtig h t tran sp a ren t ce ilin g

irrig a tio n sy stem

p lan t, an im al an d d ec o m p o se r

co m m u n itie s

a ir p u m p

lig h tin g

a ir o u tle t

sen so rs

S ca le : 1 m

[Source: modified from NERC www.cpb.bio.ic.ac.uk/ecotron/ecotron.html]

(a) State whether this is an open, closed or isolated system. Give one reason for your answer.

......................................................................................................................................

......................................................................................................................................(1)

(b) Identify and explain two ways in which the inputs to the system would differ from the outputs while communities are growing within the ecotron.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (4)

(c) If a fall in temperature of the system is detected by the sensors, mechanisms will be automatically initiated to increase the temperature. State which kind of feedback this demonstrates.

......................................................................................................................................(1)

(d) (i) Outline how the second law of thermodynamics can explain the pyramid shape associated with most food chains including that found in the ecotron.

...........................................................................................................................

...........................................................................................................................(2)

(ii) In this context, explain why food chains studied in the ecotron are generally limited to no more than three trophic levels.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)(Total 10 marks)

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Topic 2: The ecosystem (31 hours)The techniques required in this topic may be exemplified through practical work in marine, terrestrial, freshwater or urban ecosystems, or any combination of these. The selection of environments can be made according to the local systems available to the students, and the most convenient systems for demonstrating the techniques in question. However, there is an advantage in using the various practical measurements to quantify different aspects of the same ecosystem, where possible. In this way, the techniques are not simply rehearsed in isolation, but can be used to build up a holistic model of that system.TOK: How does the role of instrumentation circumvent the limitations of perception? Can environmental investigations and measurements be as precise or reliable as those in the physical sciences? Why is this, and how does this affect the validity of the knowledge? Applying similarly rigorous standards as are used in physics, for example, would leave environmentalists with very little they could claim as knowledge. But, by insisting on high degrees of objectivity, would we miss out on a useful understanding of the environment?Is a pragmatic or correspondence test of truth most appropriate in this subject area?

2.1 Structure4 hours

Assessment Statement Obj

Notes Class Home 2.1.1

Distinguish between biotic and abiotic (physical) components of an ecosystem.

2

2.1.2

Define the term trophic level.

1

2.1.3

Identify and explain trophic levels in food chains and food webs selected from the local environment.

3 Relevant terms (for example, producers, consumers, decomposers, herbivores, carnivores, top carnivores) should be applied to local, named examples and other food chains and food webs.

2.1.4

Explain the principles of pyramids of numbers, pyramids of biomass, and pyramids of productivity, and construct such pyramids from given data.

3 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

37

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).A pyramid of energy may be represented either as the standing stock (biomass) measured in units of energy (J m–2) or as productivity measured in units of flow of energy (J m–2 yr–1), depending on the text consulted. As this is confusing, this syllabus avoids the term pyramid of energy.

2.1.5

Discuss how the pyramid structure affects the functioning of an ecosystem.

3 This should include concentration of non-biodegradable toxins in food chains, limited length of food chains, and vulnerability of top carnivores. Definitions of the terms biomagnification, bioaccumulation and bioconcentration are not required.

2.1.6

Define the terms species, population, habitat, niche, community and ecosystem with reference to local examples.

1

2.1.7

Describe and explain population interactions using examples of named species.

3 Include competition, parasitism, mutualism,predation and herbivory. Mutualism is an interaction in which both species derive benefit. Interactions should be understood in terms of the influences each species has on the population dynamics of others, and upon the carrying capacity of the others’ environment. Graphical representations of these influences should be interpreted.

2.2 Measuring abiotic components of the system1 hour

Assessment Statement Obj

Notes Class Home 2.2.1

List the significant abiotic (physical) factors of an ecosystem.

1

2.2.2.

Describe and evaluate methods for measuring at least three abiotic (physical) factors within an ecosystem.

3 Students should know methods for measuring any three significant abiotic factors and how these may vary in a given ecosystem with depth, time or distance. For example:• marine—salinity, pH, temperature, dissolved oxygen, wave action

38

• freshwater—turbidity, flow velocity, pH, temperature, dissolved oxygen• terrestrial—temperature, light intensity, wind speed, particle size, slope, soil moisture, drainage, mineral content.This activity may be carried out effectively in conjunction with an examination of related biotic components.

2.3 Measuring biotic components of the system4 hours

Assessment Statement Obj

Notes Class Home 2.3.1

Construct simple keys anduse published keys for theidentification of organisms.

3 Students could practise with keys supplied and then construct their own keys for up to eight species.

2.3.2

Describe and evaluate methods for estimating abundance of organisms.

3 Methods should include capture–mark–release–recapture (Lincoln index) and quadrats for measuring population density, percentage frequency and percentage cover.

2.3.3

Describe and evaluate methods for estimating the biomass of trophic levels in a community.

3 Dry weight measurements of quantitativesamples could be extrapolated to estimate total biomass.

2.3.4

Define the term diversity.

1 Diversity is often considered as a function of two components: the number of different species and the relative numbers of individuals of each species.

2.3.5

Apply Simpson’s diversity index and outline its significance.

2

Students are not required to memorize this formula but must know the meaning of the symbols:D = diversity indexN = total number of organisms of all species foundn = number of individuals of a particular speciesD 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.

2.4 Biomes3 hours

Assessment Statement Obj

Notes Class Home 2.4.1

Define the term biome. 1 Int: Biomes usually cross national boundaries (biomes do not stop at a border; for example, the

39

Sahara, tundra, tropical rainforests).Explain the distribution, structure and relative productivity of tropical rainforests, deserts, tundra and any other biome.

3 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.

2.5 Function7 hours

Assessment Statement Obj

Notes Class Home 2.5.1

Explain the role of producers, consumers and decomposers in the ecosystem.

3

2.5.2

Describe photosynthesis and respiration in terms of inputs, outputs and energy transformations.

2 Biochemical details are not required. Detailsof chloroplasts, light-dependent and light independent reactions, mitochondria, carrier systems, ATP and specific intermediate bio-chemicals are not expected.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.

2.5.3

Describe and explain the transfer and transformation of energy as it flows through an ecosystem.

3 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.Construct and analyse simple energy-flow diagrams illustrating the movement of energy through ecosystems, including the productivity of the various trophic levels.The distinction between storages of energy illustrated by boxes in energy-flow diagrams (representing the various trophic

40

levels), and the flows of energy or productivity often shown as arrows (sometimes of varying widths) needs to be emphasized. The former are measured as the amount of energy or biomass per unit area and the latter are given as rates, for example, J m–2 day–1.

2.5.4

Describe and explain the transfer and transformation of materials as they cycle within an ecosystem.

3 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 noted where appropriate.Construct and analyse flow diagrams of these cycles.

2.5.5

Define the terms gross productivity, net productivity, primary productivity and secondary productivity.

1 Productivity is production per unit time.

2.5.6

Define the terms and calculate the values of both gross primary productivity (GPP) and net primary productivity (NPP) from given data.

2 Use the equationNPP = GPP – R where R = respiratory loss

2.5.7

Define the terms and calculate the values of both gross secondary productivity (GSP) and net secondary productivity (NSP) from given data.

2 Use the equationsNSP = GSP – RGSP = food eaten – fecal losswhere R = respiratory lossThe term “assimilation” is sometimes used instead of “secondary productivity”.

2.6 Changes7 hours

Assessment Statement Obj

Notes Class Home 2.6.1

Explain the concepts of limiting factors and carrying capacity in the context of population growth.

3

2.6.2

Describe and explain S and J population curves.

3 Explain changes in both numbers and rates ofgrowth in standard S and J population growth curves.Population curves should be sketched, described, interpreted and constructed from given data.

41

2.6.3

Describe the role of density-dependent and density-independent factors, and internal and external factors, in the regulation of populations.

2 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 densityindependent 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.

2.6.4

Describe the principles associated with survivorship curves including, K- and r-strategists.

2 K- and r-strategists represent idealized categories and many organisms occupy a place on the continuum. Students should be familiar with interpreting features of survivorship curves including logarithmic scales.

2.6.5

Describe the concept and processes of succession in a named habitat.

2 Students should study named examples of organisms from a pioneer community, seral stages and climax community.The concept of succession, occurring over time, should be carefully distinguished from the concept of zonation, which refers to a spatial pattern.

2.6.6

Explain the changes in energy flow, gross and net productivity, diversity and mineral cycling in different stages of succession.

3 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.

2.6.7

Describe factors affecting the nature of climax communities.

2 Climatic and edaphic factors determine the nature of a climax community. Human factors frequently affect this process through, for example, fire, agriculture, grazing and/or habitat destruction.

42

2.7 Measuring changes in the system5 hours

Assessment Statement Obj

Notes Class Home 2.7.1

Describe and evaluate methods for measuring changes in abiotic and biotic components of an ecosystem along an environmental gradient.

3

2.7.2

Describe and evaluate methods for measuring changes in abiotic and biotic components of an ecosystem due to a specific human activity.

3 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.

2.7.3

Describe and evaluate the use of environmental impact assessments (EIAs).

3 Students should have the opportunity to see an actual EIA study. They 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.

43

PAST EXAM PAPER QUESTIONS

TOPIC 2

1. The figure below shows the range of tolerance to temperature for a fish population.

O p tim u m ra n g e

Z o n e o f p h y sio lo g ic a l

stress

Z o n e o f in to lera n c e

Z o n e o f in to lera n c e

Z o n e o f p h y sio lo g ic a l

stre ss

N o o rg a n ism s

F ew o rg a n ism s

F e w o rg a n ism s

N o o rg a n ism sA b u n d a n c e

o f o rg a n ism s

L o w er lim it o f to le ran ce

U p p e r l im it o f to leran ce

Tem p e ra tu re H ig hL o w

[MILLER, Living in the Environment, 7E. © 1992 Brooks/Cole, a part of Cengage Learning, Inc.Reproduced by permission. www.cengage.com/permissions]

(a) (i) Outline what the figure above shows about fish density and temperature.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(ii) Explain what is meant by a limiting factor in the context of the fish population in this lake.

...........................................................................................................................

...........................................................................................................................(1)

(iii) State, giving a reason, whether temperature is a density-dependent or density-independent factor in the

44

regulation of fish populations.

...........................................................................................................................

...........................................................................................................................(1)

(b) Temperature is an abiotic feature of an ecosystem. List four other abiotic factors of an ecosystem.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(2)

(c) With reference to one abiotic factor you have named in (b), outline and evaluate a method for measuring this factor.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(3)(Total 9 marks)

2. (a) A tree can be thought of as a system. Draw and label a systems diagram of a tree that shows inputs, outputs and storages of matter and energy.

(3)

(b) State two functions of producers in an ecosystem.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(2)

(c) For a named ecosystem, draw a food chain with named species showing three appropriately labelled trophic levels.

(3)

(d) Outline three reasons for the relative value of tropical rainforests in contributing to global biodiversity.

......................................................................................................................................

45

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(3)

(e) Explain the role of decomposers in an ecosystem.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(2)

(f) Suggest what effect a significant and prolonged decrease in the pH of rainfall would have on primary productivity in a terrestrial ecosystem. Explain your answer.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................(3)(Total 16 marks)

3. The figure below shows a simple aquatic food chain which has been exposed to a pesticide called DDT.

46

L an d p ro g re ss iv e seq u en ce A q u a tic p ro g ress iv e seq u en ce

H u m a n s, th e u ltim a te a ccu m u la to rs

T h ird ca rn iv o re(la rg e r fsh )

S eco n d ca rn ivo re(la rg e r fsh )

F irs t c a rn iv o re(la rg e r fsh )

H erb iv o re(sm a lle r fsh )

F irs t accu m u la to r(a lg ae , w ate r p lan ts )

P o llu tan t inm o lecu la r fo rm

M ilkM eat

G raz in g an im a ls

G rass

D D T sp ray

[Source: Adapted from Goudie, A (1993) The Human Impact on the Natural Environment, Blackwell, p.219]

(a) (i) State how many trophic levels are shown in the figure above.

...........................................................................................................................(1)

(ii) Identify which trophic level represents:

the producers .....................................................................................................

the top carnivores ..............................................................................................(1)

(iii) State and explain what may be happening to the concentration of pesticide in the food chain.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(b) An estimated 1000 kg of plant plankton are needed to produce 100 kg of animal plankton. The animal plankton is in turn consumed by 10 kg of fish, the amount needed by a person to gain 1 kg of body mass.

(i) Explain why the amount of biomass declines at each successive trophic level.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

47

(ii) Distinguish between a pyramid of biomass and a pyramid of productivity.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)(Total 8 marks)

4. The diagram below shows the carbon cycle.

m e d iu m

lo w

carb o n d io x id e (C O ) in a tm o sp h ere2

C in stem s,ro o ts an dle av e s o f p la n ts an im a ls

d ea th d ea th ,ex c re tio n

C in d e tritu s

d e tritiv o resd ec o m p o se rs

C in h u m u s

C O in w a te r 2(m a in ly a s h y d ro g enca rb o n ate , H C O )3

-

d e tritiv o re s an d d ec o m p o se rs

C in a lg ae

C in d e tritu s

d ea th

d ea th , ex c re tio n

C in an im a ls w a te r

fo ss il fu e ls (o il, c o a l, n a tu ra l g as , p e a t an d o il sh a le )

R e la tiv e flo w s o f ca rb o n (C ) p e r y ea r

K ey

la n d

(a) Describe and explain the processes by which carbon is added to, and lost from, the atmospheric storage. State

examples of the organisms involved in the processes. (8) (b) Human activities have changed the balance of carbon dioxide. How has this balance changed and what activities

have altered it? (4) (c) Suggest the effects these changes might have on the biosphere. (5)Expression of ideas (3)(Total 20 marks)

5. (a) Explain what is meant by the terms ecological succession, pioneer community and climax community. (6) (b) For a named ecosystem, describe how the abundance of the different species of organisms present changes during

the various stages of succession. (5) (c) Describe and explain how gross primary productivity changes during the stages of succession. (6)Expression of ideas (3)(Total 20 marks)

48

Topic 3: Human population, carrying capacity andresource use (39 hours)TOK: What do the models of “natural capital/income” and the “ecological footprint” add to the earlier concepts of “resources” and “carrying capacity”? Is one model any more objective than the other? Is this a good thing? With regard to the terms used, how does the language affect our understanding of the concepts? (For example, there is perhaps a sense that “natural capital” is something to be preserved, while “resources” are specifically there for human utilization. Similarly, “ecological footprint” conjures an image of environmental threat from any growing population, whereas “carrying capacity” focuses on the maximum number that a population can reach.)3.1 Population dynamics5 hours

Assessment Statement Obj

Notes Class Home 3.1.1

Describe the nature and explain the implications of exponential growth in human populations.

3

3.1.2

Calculate and explain, from given data, the values of crude birth rate, crude death rate, fertility, doubling time and natural increase rate.

3

3.1.3

Analyse age/sex pyramids and diagrams showing demographic transition models.

3 Int: While many of the more economically developed countries (MEDCs) have a declining population size, that of many of the less economically developed countries (LEDCs) is rising rapidly. The position of various countries on the demographic transition model reflects their development stages.

3.1.4

Discuss the use of models in predicting the growth of human populations.

3 This might include computer simulations, statistical and/or demographic tables for LEDCs and MEDCs, age/sex pyramids and graphical extrapolation of population curves.

3.2 Resources—natural capital8 hours

Assessment Statement Obj

Notes Class Home 3.2.1

Explain the concept of resources in terms of natural income.

3 Ecologically minded economists describe resources as “natural capital”. If properly managed, renewable and replenishable resources are forms of wealth that can produce “natural income” indefinitely in the form of valuable goods and services.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.

3. Define the terms renewable,

1 There are three broad classes of natural capital.

49

2.2

replenishable and non-renewable natural capital.

• Renewable natural capital, such as living species and ecosystems, is self-producing and self-maintaining 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.

3.2.3

Explain the dynamic nature of the concept of a resource.

3 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.

3.2.4

Discuss the view that the environment can have its own intrinsic value.

3 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.TOK: How can we quantify values such as aesthetic value, which are inherently qualitative?

3.2.5

Explain the concept of sustainability in terms of natural capital and natural income.

3 The term “sustainability” has been given a precise meaning in this syllabus. Students should understand that 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 longterm harvest (or pollution) rates should not exceed rates of capital renewal. Sustainability means living, within the means of nature, on the “interest” or sustainable income generated

50

by natural capital.3.2.6

Discuss the concept of sustainable development.

3 The term “sustainable development” was first used in 1987 in Our Common Future (The Brundtland Report) and 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 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.Int: 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.

3.2.7

Calculate and explain sustainable yield from given data.

3 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. See figures 1 and 2.

3.3 Energy resources4 hours

Assessment Statement Obj

Notes Class Home 3.3.1

Outline the range of energyresources available to society.

2

3.3.2

Evaluate the advantages anddisadvantages of two contrasting energy sources.

3 Consider one non-renewable (fossil fuels or nuclear) and one renewable energy source.

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3.3.3

Discuss the factors that affect the choice of energy sources adopted by different societies.

3 This may include availability, economic, cultural,environmental and technological factors.

3.4 The soil system4 hours

Assessment Statement Obj

Notes Class Home 3.4.1

Outline how soil systems integrate aspects of living systems.

2 Emphasize a systems approach. Students shoulddraw diagrams that show links between the soil,lithosphere, atmosphere and living organisms.The soil as a living system should be considered with reference to a generalized soil profile.Studies of specific soil profiles, for example, podsol, are not required.Transfers of material (including deposition) result in reorganization of the soil. There are inputs of organic and parent material, precipitation, infiltration and energy. Outputs include leaching, uptake by plants and mass movement.Transformations include decomposition, weathering and nutrient cycling.

3.4.2

Compare and contrast the structure and properties of sand, clay and loam soils, including their effect on primary productivity.

3 Consider mineral content, drainage, waterholding capacity, air spaces, biota and potential to hold organic matter, and link these to primary productivity.

3.4.3

Outline the processes and consequences of soil degradation.

2 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.

3.4.4

Outline soil conservation measures.

2 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.

3.4.5

Evaluate soil management strategies in a named commercial farming system and in a named subsistence farming system.

3.5 Food resources6 hours

Assessment Statement Obj

Notes Class Home 3. Outline the issues 2 Students should appreciate the differences

52

5.1

involved in the imbalance in global food supply.

in food production and distribution around the world, including the socio-political, economic and ecological influences on these.

3.5.2

Compare and contrast theefficiency of terrestrial and aquatic food production systems.

3 Compare and contrast these in terms of their trophic levels and efficiency of energy conversion. There is no need to consider individual production systems in detail. 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.

3.5.3

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 NorthAmerican cereal farming and subsistence farming in some parts of South-East Asia, intensive beef production in the developed world and the Maasai tribal use of livestock, or commercial salmon farming in Norway/Scotland and rice-fish farming in Thailand. Other local or global examples are equally valid. 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• socio-cultural—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• outputs—for example, food quality and quantity, pollutants, soil erosion.

3.5.4

Discuss the links that exist between social systems and food production systems.

3 This could be illustrated through the use of examples, such as:• 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 agro-ecosystems.

53

3.6 Water resources3 hours

Assessment Statement Obj

Notes Class Home 3.6.1

Describe the Earth’s water budget.

2 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. Precise figures are not required.

3.6.2

Describe and evaluate the sustainability of freshwater resource usage with reference to a case study.

3 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.

3.7 Limits to growth2.5 hours

Assessment Statement Obj

Notes Class Home 3.7.1

Explain the difficulties in applying the concept of carrying capacity to local human populations.

3 By examining carefully the requirements of a given species and the resources available, it might be possible to estimate the carrying capacity of that environment for the species. This is problematic in the case of human populations for a number of reasons. 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. All these variables make it practically impossible to make reliable estimates of carrying capacities for human

54

populations.3.7.2

Explain how absolute reductions in energy and material use, reuse and recycling can affect human carrying capacity.

3 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.

3.8 Environmental demands of human populations6.5 hours

Assessment Statement Obj

Notes Class Home 3.8.1

Explain the concept of an ecological footprint as a model for assessing the demands that human populations make on their environment.

3 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. 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.

3.8.2

Calculate from appropriate data the ecological footprint of a given population, stating the approximations and assumptions involved.

2 Although the accurate calculation of an ecological footprint might be very complex, an approximation can be achieved through the steps outlined in figures 3 and 4.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.

Assessment Statement Obj

Notes Class Home 3.8.

Describe and explain the differences between

3 Data for food consumption are often given in grain equivalents, so that a population

55

3 the ecological footprints of two human populations, one from an LEDC and one from an MEDC.

with a meat-rich diet would tend to consume a higher grain equivalent than a population that feeds directly on grain. Students should be aware that 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.

3.8.4

Discuss how national and international development policies and cultural influences can affect human population dynamics and growth.

3 Many policy factors influence human population growth. Domestic and international development policies (which target the death rate through agricultural development, improved public health and sanitation, and better 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.

3.8.5

Describe and explain the relationship between population, resource consumption and technological development, and their influence on carrying capacity and material economic growth.

3 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.

PAST EXAM PAPER EXAM QUESTIONS

TOPIC 3

1. A recent census indicated that India’s population of 855 million might double in 35 years unless the growth rate is soon lowered sharply. This increase would completely cancel out India’s recent social and economic

56

development.

It is said that educating women is the single most important step governments can take to improve the health of their citizens and their economies. There are an estimated 600 million illiterate women in the world. They outnumber illiterate men by nearly two to one.

[© [1996] WWF (panda.org). Some rights reserved.]

(a) Define natural capital and discuss the implications of the information above for its exploitation.(6)

(b) Discuss four reasons why educating women might reduce the birth rate in India.(8)

(c) Explain, with examples, how national policies could affect human population growth.(3)Expression of ideas (3)(Total 20 marks)

2. (a) As well as their direct impact on the atmosphere, the effects of fossil fuel use are widespread.Discuss the range of effects of fossil fuel use on the environment.

(8)

(b) What steps could be taken to reduce these effects?(5)

(c) The average cost of petrol (gasoline) for automobiles is four times higher in Europe than in the USA. Discuss the environmental implications of this difference.

(4)Expression of ideas (3)(Total 20 marks)

3. The following tables show predicted changes in the population between the years 2000 and 2050 for two different countries.

Ethiopia Population(in thousands)

Percentage of thepopulation in urban areas

Year 2000 65 590 14.9

Year 2050 170 987 28.4

Austria Population(in thousands)

Percentage of thepopulation in urban areas

Year 2000 8 102 65.8

Year 2050 7 376 72.3

(a) Using calculations and sketches where appropriate, compare the percentage growth, age/sex pyramids and position on the demographic transition model you would expect for these two populations over the period 2000-2050.

(7)

(b) For each country, suggest three factors that might affect their population size and outline how they could lead to the predicted changes between the years 2000 and 2050.

(6)

57

(c) Suggest two examples of natural capital that have “ecological value”, and describe how they might be affected by changes predicted in the urban populations of these countries.

(4)Expression of ideas (3)(Total 20 marks)

4. (a) In the context of human population growth, define the terms carrying capacity and ecological footprint. Suggest how the ecological footprints might differ between an economically more developed country and an economically less developed country.

(4)

(b) Suggest ways in which technological development may affect carrying capacity and the ecological footprint of human populations.

(5)

(c) It is often argued that the solution to the world’s resource management problems is population control. To what extent do you agree? Justify your views.

(8)

Expression of ideas(3)(Total 20 marks)

5. (a) Explain how a named organism can be used as an indirect measure of pollution levels within the environment.

(4)

(b) Describe the main stages in an environmental impact assessment (EIA).(7)

(c) Justify the importance of ecological monitoring and research for society.(6)Expression of ideas (3)(Total 20 marks)

6. The diagram below shows some of the environmental problems caused by a demand for greater agricultural

production.

red u c tio n o f lo n g-te rmp ro d u c tiv ity

in c rea se d so ile ro s io n

lo ss o f sp e c ie sd iv e rs i ty

d a n ge r toh u m an h ea lth

lo ss o f sp e c ie sd iv ers i ty

n a rro w in g o fg en e tic b a se

eu tro p h ica tio n h ig h n itra teco n c en tra tio n s in

d rin k in g w a te r

re s id u e s o n fo o d

h a rm to n o n -ta rg e t sp ec ie s

o rg an ic p o llu tio no f fre sh w a te r

an im a l an d p la n tb ree d in g

so ilco m p ac tio n m o n o c u ltu re s

m ec h an isa tio n

d em an d fo r g rea te r p ro d u c tio n

in c rea s in g u seo f fe r til ize r

in c re a s in g u seo f p e s tic id e s

in d o o r rea rin go f a n im a ls

* S ites o f S p ec ia l S c ie n tific In te re s t

h e dg e gro w slo ss o f

a n d w a llsd a m ag e

to S S S Is*

58

[Source: Kevin Byrne, Environmental Science, (Nelson Thornes Ltd., 1997) p. 167.Reproduced by permission of Nelson Thornes Ltd.]

(a) Explain why there has been a demand for greater food production in many societies around the world.(4)

(b) With reference to two specific problems from the diagram above, explain the environmental consequences of increasing agricultural production.

(8)

(c) Suggest ways in which agricultural productivity can be increased without detrimental effects on the environment.

(5)Expression of ideas (3)(Total 20 marks)

59

Topic 4: Conservation and biodiversity (15 hours)TOK: This topic raises some engaging issues of debate concerning the moral justification for exploiting species and the moral imperative for conserving them. Do other organisms have a right to moral consideration? How is this justified? Do panda bears have a greater right than lichens? What about the rights of “pest” or pathogenic organisms? To what extent are these arguments based upon emotion and to what extent upon reason? And how does this affect their validity?

4.1 Biodiversity in ecosystems3 hours

Assessment Statement Obj

Notes Class Home 4.1.1

Define the terms biodiversity,genetic diversity, species diversity and habitat diversity.

1

4.1.2

Outline the mechanism of natural selection as a possible driving force for speciation.

2 Speciation occurs as a result of the isolation (geographical or reproductive) of populations. The concept of fitness should be understood. The history of the development of the modern theory of evolution is not expected, nor is a detailed knowledge of genetics (including allele frequency).

4.1.3

State that isolation can lead to different species being produced that are unable to interbreed to yield fertile offspring.

1 Isolation of populations, behavioural differencesthat preclude reproduction and the inability to produce fertile offspring (leading to speciation) should all be examined, with examples.

4.1.4

Explain how plate activity has influenced evolution and biodiversity.

3 The consequences of plate tectonics on speciation should be understood (that is, the separation of gene pools, formation of physical barriers and land bridges) together with the implications these consequences have for evolution. The role of plate activity in generating new and diverse habitats, thus promoting biodiversity, should also be considered. Detailed understanding of the mechanism of plate tectonics is not required.

4.1.5

Explain the relationships among ecosystem stability, diversity, succession and habitat.

3 Consider how:• diversity changes through succession• greater habitat diversity leads to greater species and genetic diversity• a complex ecosystem, with its variety of nutrient and energy pathways, provides stability• human activities modify succession, for example, logging, grazing, burning• human activities often simplify ecosystems, rendering them unstable, for example, North America wheat farming versus tall grass prairie• an ecosystem’s capacity to survive changemay depend on diversity, resilience and inertia.

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4.2 Evaluating biodiversity and vulnerability6 hours

Assessment Statement Obj

Notes Class Home 4.2.1

Identify factors that lead to loss of diversity.

2 These include:• natural hazard events (for example, volcanoes, drought, ice age, meteor impact)• habitat degradation, fragmentation and loss• agricultural practices (for example, monoculture, use of pesticides, use of genetically modified species)• introduction and/or escape of non-native species• pollution• hunting, collecting and harvesting.Int: Rate of loss of biodiversity may vary from country to country depending on the ecosystemspresent, protection policies and monitoring, environmental viewpoints and stage of economic development.

4.2.2

Discuss the perceived vulnerability of tropical rainforests and their relative value in contributing to global biodiversity.

3 Consider:• the vulnerability of other systems• the regeneration rate of tropical rainforests• total area and species diversity• rainforest and “green politics”.

4.2.3

Discuss current estimates ofnumbers of species and past and present rates of species extinction.

3 Examine the fossil record for evidence of mass extinctions in the past, and compare and contrast the possible causes of these to present-day extinctions. The time frame of these periods of extinction should be considered.

4.2.4

Describe and explain the factors that may make species more or less prone to extinction.

3 The following factors (among others) will affect the risk of extinction: numbers, degree of specialization, distribution, reproductive potential and behaviour, and trophic level.

4.2.5

Outline the factors used to determine a species’ Red List conservation status.

2 Students should be aware of the factors used to determine a species’ conservation status, and that a sliding scale operates. Students should appreciate that a range of factors are used to determine conservation status, such as:• population size• reduction in population size• numbers of mature individuals• geographic range and degree of fragmentation• quality of habitat• area of occupancy• probability of extinction.Definitions of the conservation status categories are not required and the term “criteria” has been avoided due to the complexity of the Red List classification system.

4.2.

Describe the case histories of three

2 Students should know the ecological, socio-political and economic pressures that

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6 different species: one that has become extinct, another that is critically endangered, and a third species whose conservation status has been improved by intervention.

caused or are causing the chosen species’ extinction. The species’ ecological roles and the possible consequences of their disappearance should be understood.

4.2.7

Describe the case history of a natural area of biological significance that is threatened by human activities.

2 Students should know the ecological, sociopolitical and economic pressures that caused or are causing the degradation of the chosen area, and the consequent threat to biodiversity.

4.3 Conservation of biodiversity6 hours

Assessment Statement Obj

Notes Class Home 4.3.1

State the arguments for preserving species and habitats.

1 Students should appreciate arguments based on ethical, aesthetic, genetic resource and commercial (including opportunity cost) considerations. They should also appreciate life support and ecosystem-support functions.

4.3.2

Compare and contrast the role and activities of intergovernmental and non-governmental organizations in preserving and restoring ecosystems and biodiversity.

3 Consider the United Nations Environment Programme (UNEP) as an intergovernmental organization and the World Wide Fund for Nature (WWF) and Greenpeace as non-governmental organizations. Compare and contrast UNEP and WWF in terms of use of the media, speed of response, diplomatic constraints and political influence.Consider also recent international conventions on biodiversity (for example, conventions signed at the Rio Earth Summit (1992) and subsequent updates).

4.3.3

State and explain the criteria used to design protected areas.

3 In effect, protected areas may become “islands” within a country and will normally lose some of their diversity. The principles of island biogeography might be applied to the design of reserves. Appropriate criteria should include size, shape, edge effects, corridors and proximity.

4.3.4

Evaluate the success of a named protected area.

3 The granting of protected status to a species or ecosystem is no guarantee of protection without community support, adequate funding and proper research. Consider a specific local example.

4.3.5

Discuss and evaluate the strengths and weaknesses of the species based approach to conservation.

3 Students should consider the relative strengths and weaknesses of:• the Convention on International Trade in Endangered Species (CITES)• captive breeding and reintroduction programmes, and zoos• aesthetic versus ecological value.

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PAST EXAM QUESTIONS

TOPIC 4

1. Figure 1 shows two wildlife reserve models. Model A has two isolated reserves whilst Model B has a corridor connecting the reserves. Species X, Y and Z are found in all three reserves.

Figure 1

M od el A M od el B

R o a d

S p ec ie sX ,Y, Z

S p e c ie sX , Y, Z S p e c ie sX , Y, Z

S p e c ie sX ,Y, Z

1 k m 1 k m

(a) In Figure 1, state, giving a reason, whether Model A or Model B is better for the conservation of genetic diversity of species X.

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Figure 2

P rec ip ita tio n

L IT T E R

B IO M A S S

R u n o ff

L e ach in gWea th e rin g

S O IL

(b) Figure 2 is a nutrient model for a rainforest ecosystem. The size of the circles represents the amount of nutrients stored and the width of the arrows represents size of the flow of nutrients.

(i) Explain why the nutrient store for the biomass is so large.

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(ii) Explain why losses due to leaching are so large.

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(iii) State, giving a reason, whether the model in Figure 2 shows an open or closed system.

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(iv) Evaluate the strengths and limitations of the model shown in Figure 2.

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(c) Outline two reasons why tropical rainforests are vulnerable to habitat destruction.

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2. (a) Suggest why the size of a nature reserve is an important factor for the conservation of large animals.

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(b) Outline what is meant by the term species based conservation.

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(c) Outline two historic causes of mass extinction.

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(d) The table below shows reasons why some plant species have become endangered.

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Threat Number of endangered species

Collecting by gardeners/tourists 35

Overgrazing 33

Populations critically low for breeding 31

Clearance for agriculture 22

Industrial and urban growth 16

Logging in forests 12

Dams and flooding 8

Changes in farming practice 6

[Source:J L Chapman and M J Reiss, Ecology: Principles and Applications (1999). © Cambridge University Press]

Select two threats from the table above and suggest a conservation strategy for reducing each threat.

Name of threat: ............................................................................................................

Conservation strategy: .................................................................................................

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Name of threat: ............................................................................................................

Conservation strategy: .................................................................................................

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3. Below is an information poster designed to show how individual actions can help to promote sustainability.

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[Dave May, www.customcartoonart.com, Washington State Department of Ecology]

(a) Explain why the poster recommends that manure piles are kept away from streams.

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(b) (i) Identify, giving reasons, two actions from the poster which will promote species diversity.

Action 1: ...........................................................................................................

Reason: ..............................................................................................................

Action 2: ...........................................................................................................

Reason: ..............................................................................................................(2)

(ii) Explain why species diversity is considered to be an advantage to an ecosystem.

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(c) Suggest two reasons why grass cuttings and natural fertilizers are recommended as fertilizers rather than artificial fertilizers in the poster.

1 ...................................................................................................................................

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2 ...................................................................................................................................

......................................................................................................................................(2)(Total 7 marks) 4. The table below shows the approximate numbers of species that have become extinct since 1600 on continents,

on islands and in oceans, compared with the number of species alive today.

Biological groupTotal number of

living species

Number of extinct species (since 1600)

Continents Islands Oceans Total

Mammals 4 000 30 51 2 83

Birds 9 000 21 91 0 112

Reptiles 6 300 1 20 0 21

Fishes 19 100 22 1 0 23

Invertebrates >1 000 000 49 48 1 98

[Source: R B Pinnock, Essentials of Conservation, Sinauer Associates Inc, (1993)]

(a) Calculate the percentage of mammals that have become extinct since 1600.

......................................................................................................................................

......................................................................................................................................(1)

(b) Use the data in the table to determine which groups of organisms have had the highest and lowest total rates of extinction in relation to the number of living species.

(i) Highest total rate of extinction: ........................................................................

(ii) Lowest total rate of extinction: ........................................................................(1)

(c) Suggest two reasons for the difference in the rate of extinction between these two groups.

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(d) Explain the differences between the numbers of extinctions on islands and those on continents.

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Topic 5: Pollution management (18 hours)The purpose of this topic is to give a broad overview of pollution and its management with reference to examples from aquatic, terrestrial and atmospheric systems.TOK: Most cases of non-point source pollution exemplify well the intractable ethical problem of the “tragedy of the commons”. That is to say, an individual polluting a common resource suffers little themselves from their own pollution and yet may benefit considerably in other ways. Therefore, those that do not pollute are doubly penalized—they suffer the pollution, and yet gain no benefit from polluting the resource themselves.There is thus a net advantage for any individual who does pollute. Ultimately, as many individuals adopt the most advantageous attitude, this leads to a great deal of suffering for all. It is exactly this conundrum that underlies much of the difficulty in managing non-point source pollution of shared resources on both a local (for example, a river) and an international (for example, the atmosphere) scale. Indeed, that one nation may gain considerably from non-compliance, especially while others comply, underlies much of the hesitancy in reaching international agreements on pollution strategies. Consideration and comparison of how both deontological and utilitarian approaches to ethics address this issue may make for interesting debate.In addition, the role of international legislation compared to increasing public awareness in tackling the problem could arguably be seen as a directly parallel debate. That is, is a system of rules, or appealing to the general good, the most effective way forward?

5.1 Nature of pollution1 hour

Assessment Statement Obj

Notes Class Home 5.1.1

Define the term pollution.

1

5.1.2

Distinguish between the terms point source pollution and nonpoint source pollution, and outline the challenges they present for management.

2 Point source pollution is generally more easily managed because its impact is more localized, making it easier to control emission, attribute responsibility and take legal action.

5.1.3

State the major sources of pollutants.

1 Sources of pollutants are combustion of fossil fuels, domestic and industrial waste, manufacturing and agricultural systems.

5.2 Detection and monitoring of pollution3 hours

Assessment Statement Obj

Notes Class Home 5.2.1

Describe two direct methods of monitoring pollution.

2 Students should describe one method for air and one for soil or water.

5.2.2

Define the term biochemical oxygen demand (BOD) and explain how this indirect method is used to assess pollution levels in water.

3

5.2.3

Describe and explain an indirect method of measuring pollution levels using a biotic index.

3 This will involve levels of tolerance, diversity and abundance of organisms. The concept of indicator species should be understood. A polluted and an unpolluted site (for example, upstream and downstream of a point source) should be compared.

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5.3 Approaches to pollution management2 hours

Assessment Statement Obj

Notes Class Home 5.3.1

Outline approaches to pollution management with respect to figure 5.

2 Pollutants are produced through human activities and create long-term effects when released into ecosystems. Strategies for reducing these impacts can be directed at three different levels in the process: altering the human activity, regulating and reducing quantities of pollutant released at the point of emission, and cleaning up the pollutant and restoring ecosystems after pollution has occurred.Using figure 5, students should be able to show the value and limitations of each of the three different levels of intervention. In addition, students should appreciate the advantages of employing the earlier strategies over the later ones and the importance of collaboration in the effective management of pollution.

5.3.2

Discuss the human factors that affect the approaches to pollution management.

3 Cultural values, political systems and economic systems will influence the choice of pollution management strategies and their effective implementation. Real examples should be considered.

5.3.3

Evaluate the costs and benefits to society of the World Health Organization’s ban on the use of the pesticide DDT.

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5.4 Eutrophication3 hours

Assessment Statement Obj

Notes Class Home 5.4.1

Outline the processes ofeutrophication.

2 Include increase in nitrates and phosphates leading to rapid growth of algae, accumulation of dead organic matter, high rate of decomposition and lack of oxygen. The role of positive feedback should be noted in these processes.

5.4.2

Evaluate the impacts of eutrophication.

3 Include death of aerobic organisms, increased turbidity, loss of macrophytes, reduction in length of food chains and loss of species diversity.

5.4.3

Describe and evaluate pollution management strategies with respect

3 Students should apply the model in 5.3.1 in the evaluation of the strategies. For example:

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to eutrophication. • Altering the human activity producing pollution can be exemplified by alternative methods of enhancing crop growth, alternative detergents, and so on.• Regulating and reducing pollutants at the point of emission can be illustrated by sewage treatment processes that remove nitrates and phosphates from the waste.• Clean-up and restoration can beexemplified by pumping mud from eutrophic lakes and reintroducing plant and fish species.

5.5 Solid domestic waste2 hours

Assessment Statement Obj

Notes Class Home 5.5.1

Outline the types of solid domestic waste.

2 Students should consider their own and their community’s generation of waste. Consider the different types of material, for example, paper, glass, metal, plastics, organic waste (kitchen or garden), packaging, as well as their total volume.

5.5.2

Describe and evaluate pollution management strategies for solid domestic (municipal) waste.

3 Consider recycling, incineration, composting and landfill.

5.6 Depletion of stratospheric ozone3 hours

Assessment Statement Obj

Notes Class Home 5.6.1

Outline the overall structure and composition of the atmosphere.

2

5.6.2

Describe the role of ozone in the absorption of ultraviolet radiation.

2 Ultraviolet radiation is absorbed during the formation and destruction of ozone from oxygen.Memorization of chemical equations is not required.

5.6.3

Explain the interaction between ozone and halogenated organic gases.

3 Halogenated organic gases are very stable under normal conditions but can liberate halogen atoms when exposed to ultraviolet radiation in the stratosphere. These atoms react with monatomic oxygen and slow the rate of ozone re-formation. Pollutants enhance the destruction of ozone, thereby disturbing the equilibrium of the ozone production system (see 1.1.5).

5.6.4

State the effects of ultraviolet radiation on living tissues and biological productivity.

1 The effects include mutation and subsequent effects on health and damage to photosynthetic organisms, especially phytoplankton and their consumers such as zooplankton.

5.6.5

Describe three methods of reducing the manufacture and release of ozone-depleting

2 For example, recycling refrigerants, alternatives to gas-blown plastics, alternative propellants and alternatives to methyl bromide (bromomethane).

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substances.5.6.6

Describe and evaluate the role of national and international organizations in reducing the emissions of ozone-depleting substances.

3 Examine the role of the United Nations Environment Programme (UNEP) in forging international agreements (for example, the Montreal Protocol and subsequent updates) on the use of ozone-depleting substances, and study the relative effectiveness of these agreements and the difficulties in implementing and enforcing them. In addition, students should be familiar with what steps national governments are taking to comply with these agreements.

5.7 Urban air pollution2 hours

Assessment Statement Obj

Notes Class Home 5.7.1

State the source and outline the effect of tropospheric ozone.

2 When fossil fuels are burned, two of the pollutants emitted are hydrocarbons (from unburned fuel) and nitrogen monoxide (nitric oxide, NO). Nitrogen monoxide reacts with oxygen to form nitrogen dioxide (NO2), a brown gas that contributes to urban haze. Nitrogen dioxide can also absorb sunlight and break up to release oxygen atoms that combine with oxygen in the air to form ozone.Ozone is a toxic gas and an oxidizing agent. It damages crops and forests, irritates eyes, can cause breathing difficulties in humans and may increase susceptibility to infection. It is highlyreactive and can attack fabrics and rubber materials.

5.7.2

Outline the formation of photochemical smog.

2 Photochemical smog is a mixture of about one hundred primary and secondary pollutants formed under the influence of sunlight. Ozone is the main pollutant.The frequency and severity of photochemical smogs in an area depend on local topography, climate, population density and fossil fuel use. Precipitation cleans the air and winds disperse the smog. Thermal inversions trap the smogs in valleys (for example, Los Angeles, Santiago, Mexico City, Rio de Janeiro, São Paulo, Beijing) and concentrations of air pollutants can build to harmful and even lethal levels.

5.7.3

Describe and evaluate pollution management strategies for urban air pollution.

3 Measures to reduce fossil fuel combustion should be considered, for example, reducing demand for electricity and private cars and switching to renewable energy. Refer to clean-up measures, for example, catalytic converters.

5.8 Acid deposition2 hours

Assessment Statement Obj

Notes Class Home 5. Outline the chemistry 2 Refer to the conversion of sulfur dioxide

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8.1

leading to the formation of acidified precipitations.

and oxides of nitrogen (NOx) into the sulfates and nitrates of dry deposition and the sulfuric and nitric acids of wet deposition. Knowledge of chemical equations is not required.3

5.8.2

Describe three possible effects of acid deposition on soil, water and living organisms.

2 Include:• one direct effect, for example, acid on aquatic organisms and coniferous forests• one toxic effect, for example, aluminium ions on fish• one nutrient effect, for example, leaching of calcium.

5.8.3

Explain why the effect of acid deposition is regional rather than global.

3 Refer to areas downwind of major industrial regions that are adversely affected by acid rain and link them to sources of sulfur dioxide and nitrogen dioxide emissions. Consider the effect of geology (rocks and soils) on water acidity through buffering.

5.8.4

Describe and evaluate pollution management strategies for acid deposition.

3 Measures to reduce fossil fuel combustion should be considered, for example, reducing demand for electricity and private cars and switching to renewable energy. Refer to clean-up measures at “end of pipe” locations (points of emission).Consider the role of international agreements in effecting change. The cost-effectiveness of spreading ground limestone in Swedish lakes in the early 1980s provides a good case study.

PAST EXAM QUESTIONS

TOPIC 5

1. The graph below shows the pH and concentrations of lead (Pb) in the water of a lake for selected years between 1970 and 2000.

p H

1 9 7 0 1 9 7 5 1 9 8 0 1 98 5 1 9 9 0 1 9 9 5 2 0 0 03

4

5

6

7

3L ead / g d m

X p H

Lead

0

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

6 0 0

Years

(a) Identify the year in which

(i) the concentration of lead in the water was highest. ..........................................

(ii) the water was most acidic. ................................................................................(1)

(b) From the data in the graph, state whether the quality of the water in the lake has improved or deteriorated. Give a reason for your answer.

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(c) Explain the changes shown by the graph.

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(d) Outline one indirect method of measuring the pollution levels in a lake.

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(e) (i) Define the term eutrophication.

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(ii) State three environmental effects of eutrophication.

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(f) Describe a strategy for the cleaning up and restoration of a eutrophic lake.

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(g) State two advantages and two disadvantages of incineration as a method of disposal of domestic (municipal) waste.

(i) Advantages:

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(ii) Disadvantages:

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2. The following graph shows the annual percentage change in use of inorganic fertilizers in developing countries and western Europe between 1961 and 1999:

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Ann

ual c

hang

e/pe

rcen

t2 0

1

1 0

0

D ev e lo p in g c o u n trie s

We ste rn E u ro p e

1 9 7 0 1 9 8 0 1 9 9 0 2 0 0 0

Year

K ey :

5

– 5

Adapted from “Mineral Fertilizer Use and the Environment”, http://www.fertilizer.org/publish/pubenv/fertuse.htm.Reproduced by permission of the International Fertilizer Industry Association (IFA).

(a) Compare the changes in fertilizer use in developing countries with those in western Europe, as shown by this data.

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(b) If a typical developing country were using 40 000 tonnes of fertilizer in 1969, use the graph to estimate the quantity it might have used in 1970.

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(c) Explain how the use of inorganic fertilizers might be described as “pollution”.

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(d) Outline the processes and impacts of eutrophication in aquatic systems that may arise due to this use of

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inorganic fertilizers.

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(e) State the meaning of the term BOD, and explain how it is likely to be affected by eutrophication.

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3. (a) Explain, with the help of an example, the term non-point-source pollution.

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The table below gives the iron (Fe), and lead (Pb), concentrations (mg kg–1) in the atmospheric fallout (solid particles) at two sampling locations near a mining centre in Sweden.

April–May June–July Aug–Sep Oct–Nov Dec–Jan Feb–Mar

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Location 1 Pb 1.1 2.3 2.7 3.1 6.8 6.7

Pb 26.0 65.0 76.0 86.0 259.0 222.0

Location 2 Fe 45.3 10.0 10.9 10.4 11.0 8.0

Fe 640.0 104.0 105.0 123.0 131.0 216.0

[Reprinted from Zhixun Lin et al., "The source and fate of Pb in contaminated soils at the urban area of Falun in central Sweden ", Science of the Total Environment, Volume 209, Issue 1, 8 January 1998, Pages 47-58, © 1998, with permission from Elsevier]

(b) Calculate the mean value for the lead concentration for each of the two sampling locations.

(i) Location 1: .......................................................................................................

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(ii) Location 2: ........................................................................................................

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(c) The data show many differences in values (i) between the two pollutants (ii) at various times of the year, and (iii) between the locations. Identify one example of each and suggest an explanation for the difference.

(i) between the two pollutants: ..............................................................................

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(ii) at various times of the year: .............................................................................

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(iii) between the locations: ......................................................................................

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(d) The data in the table represent an example of the direct monitoring of pollution. Outline, with the help of an example, what is meant by indirect monitoring.

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(e) A company specialising in waste disposal proposes to establish a facility for the incineration of domestic (municipal) waste close to your school. Explain how you would assess the probable environmental effects of such a facility.

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(f) Outline three strategies for the management of a named example of industrial waste.

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4. The figure below shows the mean October ozone concentrations recorded at the Halley research station, Antarctica, over a 45 year period.

D o b so n u n its

1 9 5 0 1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0 2 0 0 0 2 0 1 0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

Year

[Source: J Shanklin, British Antarctic Survey, in Climate Change, 2001, Royal Society of Chemistry]

(a) (i) Describe the trend in ozone concentration in the figure above.

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(ii) Suggest reasons for the trend you have described in (a) (i).

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(b) Outline the role of ozone in the absorption of ultraviolet (UV) radiation.

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(c) State one negative consequence to humans of exposure to UV radiation and one negative consequence to plants.

Humans ...................................................................................................................

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Plants ...................................................................................................................

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(d) Outline three methods of reducing the quantity of ozone depleting substances in the environment.

1 ...................................................................................................................................

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2 ...................................................................................................................................

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3 ...................................................................................................................................

......................................................................................................................................(3)(Total 10 marks) 5. The diagram below shows amounts of waste being recycled or sent to landfill in Australia between 1993 and

2002.

K ey : Wa ste to lan d fill R ecy c le d m a te ria ls

M ass/× 1 0 ton n es

8

7

6

5

4

3

2

1

019 93 1 9 94 19 9 5 1 9 9 6 19 97 1 9 9 8 1 9 99 2 0 0 0 20 01 20 0 2

5

Ye ar

[Source: adapted from www.environmentcommissioner.act.gov.au/_data/assets/image/12231/graph2_03.jpg]

(a) (i) State, to the nearest hundred thousand tonnes, how much material was recycled in Australia during 2001.

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...........................................................................................................................(1)

(ii) Explain why the amount of waste sent to landfill in Australia has remained relatively constant since 1994

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despite the increase in recycling.

...........................................................................................................................

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...........................................................................................................................(2)

(b) (i) Outline two ways in which technology can reduce the amount of solid domestic waste that is sent to landfill within a country.

1 ........................................................................................................................

...........................................................................................................................

2 ........................................................................................................................

...........................................................................................................................(1)

(ii) Explain why the technological solutions you have described in part (b)(i) may still have negative environmental effects.

...........................................................................................................................

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...........................................................................................................................(2)(Total 6 marks)

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Topic 6: The issue of global warming (6 hours)This topic allows the study of a controversial global issue in more depth. Opinion within scientific and political communities is divided on this issue, and students should be encouraged to develop a personal viewpoint having considered the arguments.TOK: This topic directly and usefully challenges popular views of certainty within the sciences. If the scientific community has access to such certainty, how can it be as publicly divided as it has been in this case? What effect does a highly sensitive political context have on objectivity? Can politicians exploit the ambiguity of conclusions coming from the scientific community to their own ends?Int: This issue involves the international community working together to research and reduce the effects of global warming.

Assessment Statement Obj

Notes Class Home 6.1.1

Describe the role of greenhouse gases in maintaining mean global temperature.

2 The greenhouse effect is a normal and necessary condition for life on Earth. Consider carbon dioxide (CO2) levels in geological times.

6.1.2

Describe how human activities add to greenhouse gases.

2 Water, CO2, methane and chlorofluorocarbons (CFCs) are the main greenhouse gases. Human activities are increasing levels of CO2, methane and CFCs in the atmosphere, which may lead to global warming.

6.1.3

Discuss qualitatively the potential effects of increased mean global temperature.

3 Consider the potential effects on the distribution of biomes, global agriculture and human societies. Students should appreciate that effects might be adverse or beneficial, for example:• biomes shifting• change in location of crop growing areas• changed weather patterns• coastal inundation (due to thermal expansion of the oceans and melting of the polar ice caps)• human health (spread of tropical diseases).

6.1.4

Discuss the feedback mechanisms that would be associated with an increase in mean global temperature.

3 For example:• negative feedback—increased evaporation in tropical latitudes leading to increased snowfall on the polar ice caps, which reduces the mean global temperature• positive feedback—increased thawing of permafrost, leading to an increase in methane levels, which increases the mean global temperature.Any feedback mechanisms associated with global warming may involve very long time lags.

6.1.5

Describe and evaluate pollution management strategies to address the issue of global warming.

3 Students should consider the following strategies:• global—intergovernmental and international agreements (for example, Kyoto Agreement and subsequent updates), carbon tax and carbon trading, alternative energy sources• local—allow students to explore their own lifestyle in the context of local greenhouse gas emissions• preventive and reactive.Students should evaluate these strategies with regard to their effectiveness and the implications for MEDCs and LEDCs of reducing CO2 emissions in terms of

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economic growth and national development.

6.1.6

Outline the arguments surrounding global warming.

2 Students should appreciate the variety of sometimes conflicting arguments surrounding this issue. Note the complexity of the problem and the uncertainty of global climate models. Students should be aware of the concept of global dimming due to increased levels of atmospheric pollution.

6.1.7

Evaluate contrasting humanperceptions of the issue of global warming.

3 Students should explore different viewpoints in relation to their own.

PAST EXAM PAPER QUESTIONS

TOPIC 6

1. The graphs below show the top ten countries in terms of total carbon emissions and emissions per capita.

Graph A: Total carbon emissions from fossil fuel burning for the top ten emitting countries, in million tonnes (Mt).

C a rb o n em issio n s (M t)

US

Chi

na

Rus

sia

Japa

n

Ger

man

y

Indi

a

UK

Ukr

aine

Can

ada

Italy

0

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

1 2 0 0

1 4 0 0

Graph B: Total carbon emissions (tonnes) per capita for the top ten emitting countries.

C a rb o n em iss io n s ( to n n e s)per ca p ita

US

Chi

na

Rus

sia

Japa

n

Ger

man

y

Indi

a

UK

Ukr

aine

Can

ada

Italy

0

1

2

3

4

5

6

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[Source: Brown, L. R. et al, State of the World, 1996, Earthscan.]

(a) Comment on the significance of these data.(8)

(b) Describe the international agreements that aim to reduce the amount of carbon emissions.(4)

(c) What technologies and what policies might reduce the amount of carbon emissions?(5)Expression of ideas (3)(Total 20 marks)

2. The diagram below shows storages (in percentage of total water) and flows in the global water cycle. The rates of flow are given in 1015 kg yr–1.

C L O U D S0 .0 0 1 %

AT M O S P H E R ICWAT E R VA P O U R

0 .0 0 1 %

S U R FA C E WAT E R 0 .0 0 1 %IC E 2 % G R O U N D WAT E R 1 %

O C E A N9 7 %

C on d ensa tion4 0 0

P rec ip ita tio n 30 0

P rec ip ita tion 1 0 0

E v apora tio n 64 E v apo ra tion

33 6

R un -o ff/g ro u nd w a te r flo w

(a) (i) What is the source of energy which drives the water cycle? ........................ .(1)

(ii) In which of the processes given in the diagram does this energy enter the cycle?

...........................................................................................................................(1)

(b) (i) What percentage of all precipitation falls directly into the oceans?

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...........................................................................................................................(1)

(ii) What percentage of all evaporated water comes from the oceans?

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(c) (i) Assuming the cycle is in steady state, what mass of water flows into the oceans through run-off and groundwater flow per year?

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...........................................................................................................................(2)

(ii) Explain why this figure might increase in the future, as a result of burning fossil fuels.

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(d) Name a storage of water in the biosphere that is not shown in the diagram, and explain how water is transferred in and out of this storage.

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(e) (i) State briefly one way in which one of the other flows in the diagram might change if evaporation rates were to increase.

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(ii) Describe how two changes in the flows shown on the diagram could lead to a fall in global temperatures and reduce global warming.

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(iii) Name the type of feedback involved in this reduction in global warming.

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(f) Identify each of the different processes referred to on the diagram as either transfer or transformation processes.

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......................................................................................................................................(2)(Total 20 marks)

3. The diagram below shows the carbon cycle.

m e d iu m

lo w

carb o n d io x id e (C O ) in a tm o sp h ere2

C in stem s,ro o ts an dle av e s o f p la n ts an im a ls

d ea th d ea th ,ex c re tio n

C in d e tritu s

d e tritiv o resd ec o m p o se rs

C in h u m u s

C O in w a te r 2(m a in ly a s h y d ro g enca rb o n ate , H C O )3

-

d e tritiv o re s an d d ec o m p o se rs

C in a lg ae

C in d e tritu s

d ea th

d ea th , ex c re tio n

C in an im a ls w a te r

fo ss il fu e ls (o il, c o a l, n a tu ra l g as , p e a t an d o il sh a le )

R e la tiv e flo w s o f ca rb o n (C ) p e r y ea r

K ey

la n d

(a) Describe and explain the processes by which carbon is added to, and lost from, the atmospheric storage. State examples of the organisms involved in the processes.

(8)

(b) Human activities have changed the balance of carbon dioxide. How has this balance changed and what activities have altered it?

(4)

(c) Suggest the effects these changes might have on the biosphere.(5)Expression of ideas (3)(Total 20 marks)

4. The figure below shows a model of the climatic system.

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C L IM AT E

R ad ia tio n o u tp u ts fro mE arth -a tm o sp h ere

S o lar in p u ts toE arth -a tm o sp h ere

A tm o sp h eric c ircu la tio n an dco m p o sitio n

H u m anac tiv ity

E arth -a tm o sp h e re system

L an d an dte rres tria lfea tu re s

A tm o sp h ere

O ceanO cean icc ircu la tio n

Ice

E x te rn a l in p u ts a nd o u tp u ts o f th e c lim a tic sys tem

In tern a l in te rac tio n s o f th e c lim atic sys te m

[Source: O’Hare and Sweeney, The Atmospheric System, (1986), Oliver and Boyd, page 189]

(a) Define the term model.

......................................................................................................................................

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......................................................................................................................................(2)

(b) Identify two internal interactions in the figure above which affect the climate.

......................................................................................................................................

......................................................................................................................................(1)

(c) List four gases which are part of the atmosphere.

......................................................................................................................................

......................................................................................................................................(2)

(d) State how solar inputs and Earth outputs differ in their radiation wavelengths.

......................................................................................................................................

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......................................................................................................................................(1)

(e) Outline the ways in which human activity can have an impact on climate.

......................................................................................................................................

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(f) Evaluate the strengths and limitations of the model in the figure above for describing the atmospheric system.

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......................................................................................................................................(4)(Total 13 marks) 5. (a) Using the data in figure 1 below, calculate the percentage rise in global sea level by 2100 due to

thermal expansion of the ocean surface.

.....................................................................................................................................

.....................................................................................................................................

Figure 1. Sea level change prediction for 2100 based on present trends.

Contributing factor Sea level change / cmAntarctic ice sheetGreenland ice sheetAlpine glaciersThermal expansion

161628

91

Total 49[Source: P W French, Coastal and Estuarine Management (Routledge, 1997).

Reproduced by permission of Taylor & Francis (part of Cengage Learning)](1)

(b) Define what is meant by the term global warming.

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(c) (i) Outline the impact of global warming on society.

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(ii) State two possible effects of sea level change on a coastline.

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(d) List four methods of reducing global warming.

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Figure 2.

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4

3

2

1

0

– 1

– 2

– 3

– 4

– 5

Av e ra g e tem p era tu re o v er p a s t1 0 0 0 0 y ears = 1 5 °C

Tem p era tu re c h an g e / °C

A g ric u ltu ree s tab lish ed

IP C C p red ic tio n :+ 2 .7 °C w ith b ando f u n ce ra ta in ty

1 9 4 0 –1 9 7 0“L ittle Ic e A g e”

in E u ro p e

E n d o fla st

Ice A g e

2 0 00 0 1 0 0 0 0 2 0 00 1 0 00 2 0 0 1 0 0 N o w + 1 0 01 8 0 0 0 y ea rs 1 8 0 0 y ears 3 0 0 y ea rs

N u m b er o f y ears b e fo re p resen t

?

L on g term clim a te chang e

[Source: Physicians for Social Responsibilities, PSR Monitor, 1998](2)

(e) Using the data in figure 2, suggest why global warming may not be entirely caused by human activity.

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.....................................................................................................................................(2)(Total 11 marks)

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Topic 7: Environmental value systems (6 hours)Understanding environmental value systems is a central theme in this course. Therefore, this topic should be used in the analysis of environmental issues throughout the course, as well as being taught as a discrete unit.TOK: This topic, in its entirety, could be considered a component of a theory of knowledge course, and particularly directs students to evaluate their own personal standpoints. Any knowledge, including all that gained from this course, once it is put to use in either intellectual argument or practical application, tends to carry with it a value-laden context. Even where the data itself is highly objective, the selection of the data is rarely value-free. Besides, valuing objectivity over subjectivity can be seen as a value in itself.Int: There are frameworks of axioms and assumptions, values and beliefs, perspectives and world views that colour our knowledge. This topic explores a range of just such frameworks, and invites students to identify, evaluate and justify their own position within that spectrum.

Assessment Statement Obj

Notes Class Home 7.1.1

State what is meant by an environmental value system.

1 This is a particular world view or set of paradigms that shapes the way an individual or group of people perceive and evaluate environmental issues. This will be influenced by cultural (including religious), economic and socio-political context. An environmental value system is a system in the sense that it has inputs (for example, education, cultural influences, religious doctrine, media) and outputs (for example, decisions, perspectives, courses of action) determined by processing these inputs.Int: Ecosystems may often cross national boundaries and this may lead to conflict arising from the clash of different value systems about exploitation of resources (for example, ocean fishing and whaling).

7.1.2

Outline the range of environmental philosophies with reference to figure 6.

2

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Assessment Statement Obj

Notes Class Home 7.1.3

Discuss how these philosophies influence the decision-making process with respect to environmental issues covered in this course.

3

7.1.4

Outline key historical influences on the development of the modern environmental movement.

2 Consider major landmarks, for example, Minamata, Rachel Carson’s Silent Spring, Bhopal, whaling (Save the Whale), Chernobyl, leading to environmental pressure groups, both local and global, the concept of stewardship and increased media coverage raising public awareness.

7.1.5

Compare and contrast the environmental value systems of two named

3 The societies chosen should demonstrate significant differences, for example:• First Nation Americans and European

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societies. pioneers operating frontier economics, which involved exploitation of seemingly unlimited resources• Buddhist and Judaeo-Christian societies• Communist and capitalist societies.

7.1.6

Justify your personal viewpoint on environmental issues.

3 Students should be encouraged to reflect upon where they stand on the continuum of environmental philosophies with regard to specific issues arising throughout the syllabus, for example, population control, resource exploitation, sustainable development, and so on.Int: The environmental philosophy of an individual, as with that of a community (see 7.1.1), will inevitably be shaped by cultural, economic and socio-political context. Students should recognize this and appreciate that others may have equally valid viewpoints (aims 4 and 7).

Past Exam Paper Questions

Topic 7

1. The figure below contains an ancient Chinese proverb.

Proverb

If you are thinking a year ahead, sow seed

If you are thinking ten years ahead, plant a tree

If you are thinking a hundred years ahead, educate the people

Chinese poet Kuan Tzu 500 BC

(a) The poet Kuan Tzu could be seen as an ecocentrist or a technocentrist. Justify whether you think his views are ecocentric or technocentric.

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(b) Outline two factors which may affect someone’s environmental philosophy.

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2. The diagram below shows the effects of two different fishing policies on fish stocks over four years.

H ig h in ten s ity fish in g p o licy L o w in ten sity f ish in g p o licy

2 0 0

2 0 3 2

2 83 6

1 83 6

2 4

4 82 0

5 6

1 6

3 6

6

1 2 0

4 8

1 6 8

1 2 3 4 1 2 3 4Yea r Yea r

K ey : C a tc h S to ck o f f ish

2 0 0

Wei

ght o

f fis

h / t

onne

s

Wei

ght o

f fis

h / t

onne

s

(a) (i) Define the term sustainable yield.

...........................................................................................................................

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(ii) Calculate the total catch over four years in each fishing policy in the diagram above.

High intensity: ...................................................................................................

Low intensity: ...................................................................................................(1)

(iii) Calculate the percentage difference between the year 4 catch for the high intensity fishing policy and the year 4 catch for the low intensity fishing policy.

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(iv) Predict, giving two reasons, which fishing policy would probably give the greater profit over 20 years.

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(b) Outline two reasons why hunting and fishing may not be controlled by legislation.

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(c) Compare the energy efficiency of terrestrial and aquatic food production systems.

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(d) Suggest one possible solution that a technocentrist might give to the problem of overfishing.

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......................................................................................................................................(1)(Total 10 marks)

3. Figure 1 and Figure 2 below are cartoons which each express an environmental message.

Figure 1

[Source: Cummings, Winnipeg Free Press, CartoonArts International]

(a) Suggest what message the cartoonist is trying to depict about attitudes to environmental problems in Figure 1.

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Figure 2

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[Source: DeAngelis, Rome, Italy, CartoonArts International]

(b) Figure 2 is a cartoon which suggests that a conflict exists between resource use and the needs of indigenous people. Explain why such a conflict might exist in tropical rainforests.

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4. The pie charts below show the relative contributions of different sources of commercial energy for less economically developed countries (LEDCs) and more economically developed countries (MEDCs).

Commercial Energy Use by Source in LEDCs Commercial Energy Use by Source in MEDCs

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o il 3 7 %

nu c lea r p o w er 5 %

na tu ra l ga s 2 3 %

hyd ro p o w er,ge o the rm a l &

so lar 7 %

co al 2 5 %

b io m a ss 3 %o il 2 6 %

nu c lea r p o w er1 %

na tu ra l ga s 7 %

hyd ro p o w er,ge o the rm a l &

so lar 6 %

co al 2 5 %

b io m a ss 3 5 %

[MILLER, Living in the Environment, 15E. © 2007 Brooks/Cole, a part of Cengage Learning, Inc.Reproduced by permission. www.cengage.com/permissions]

(a) State and explain the differences shown in the two pie charts.(5)

(b) Compare the advantages and disadvantages of fossil fuels and solar energy with respect to efficiency and sustainability.

(6)

(c) Discuss the Cornucopian view of the environmental challenges posed by the extensive use of fossil fuels.

(6)Expression of ideas (3)(Total 20 marks) 5. Figure 1 below shows the estimated biochemical oxygen demand (BOD) for a series of point and non-point

sources along the river Mersey.

Figure 1. BOD values (pounds day–1) for the river Mersey in England.

W alla sey

C ru d e sew ag e fro mW alla sey 117 0 0

C ru d e sew ag e fro mB irk enh ead 24 1 5 0

C ru d e sew ag e fromB ebin g to n 90 0 0

C ru d e sew ag e fro mB o o tle 2 0 0 0 0

C ru d e sew ag e fro mL iv e rp oo l 14 6 0 00

Trad e efflu en tfro m W id n esarea 63 9 0 0

C rud e sew ag efrom W id n es1 2 00 0

W id n es

R un corn

C ru d e sew ag e fromR u n co rn 4 2 0 0

C ru d e sew ag e fromW arrin g to n 2 0 7 00

W arrin g to nTrad e efflu en t fromW arr in g ton a rea2 1 20 0

P o llu tio n lo ad fro mriv er u ps tream11 72 0 0

N o te : S e w a g e d isch a rg e d ep ic ted inn o rm a l ty p e , trade (co m m erc ia l)e ff lu en t in b o ld ty p eR ive r G o w y

p o llu tion lo ad2 0 00

Trad e efflu en t fromE lle sm ere P o r t an dS tan lo w a rea s10 30 00

M anch es te r S h ip C an a lP o llu tio n lo ad 10 0 0 0

B irk en h ead

P o rt S u n lig h t

B rom b o ro ug h

E lle sm ere P o rt

B oo tle

L ive rp oo l

Trad e efflu en t fro mB eb in g ton area17 7 0 0

Ir ishS ea

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[R B Clarke, Marine Pollution, (Oxford: Oxford University Press, 1994) page 17. By permission of Oxford University Press]

(a) (i) Define what is meant by the term biochemical oxygen demand.

...........................................................................................................................

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(ii) Using figure 1, complete the scatter graph below by adding data for trade effluent from Widnes and for trade effluent from Ellesmere Port and Stanlow.

Figure 2. Selected BOD values for the river Mersey.

1 2 0 00 0

1 0 0 00 0

8 0 0 00

6 0 0 00

4 0 0 00

2 0 0 00

0

B O D v a lu e /p o u n d s d ay –1

2 0 0 0 0 B o o tle

11 7 0 0 W alla se y

2 4 1 5 0 B irk e n h e ad

1 7 7 0 0 B e b in g to n2 0 7 0 0 W a rrin g to n

4 2 0 0 R u n c o rn

1 2 0 0 W id n e s1 0 0 0 0 M an c h es te rS h ip C a n a l

2 1 2 0 0W a rrin g to n

11 7 0 0 0 riv e ru p s tre am

1 61 41 21 086420

R e la tiv e d is tan ce u p strea m(2)

(iii) Suggest one reason why the BOD values for the Manchester Ship Canal and the “river upstream” are so different.

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(iv) Suggest why some sites contribute more pollution to the river Mersey than others.

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...........................................................................................................................(2)

(b) (i) Define what is meant by the term eutrophication.

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(ii) State one way in which humans can accelerate the process of eutrophication.

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(iii) Outline and evaluate how eutrophication can be controlled from

• an ecocentric perspective

• a technocentric perspective.

Ecocentric: ........................................................................................................

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Technocentric: ..................................................................................................

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MATHEMATICAL REQUIREMENTSAll Diploma Programme environmental systems and societies students should be able to:• perform the basic arithmetic functions: addition, subtraction, multiplication and division• use simple descriptive statistics: mean, median, mode, range, frequency, percentages, ratios, approximations and reciprocals• use standard notation (for example, 3.6 × 106)• use direct and inverse proportion• interpret frequency data in the form of bar charts, column graphs and histograms, and interpret pie charts• understand the significance of the standard deviation of a set of data• plot and sketch graphs (with suitable scales and axes)• interpret graphs, including the significance of gradients, changes in gradients, intercepts and areas• demonstrate sufficient knowledge of probability (for example, in assessing risks in environmental impact).

EXTENDED ESSAY The extended essay is an in-depth study of a focused topic chosen from the list of approved Diploma Programme subjects—normally one of the student’s six chosen subjects for the IB diploma. It is intended to promote high-level research and writing skills, intellectual discovery and creativity. It provides students with an opportunity to engage in personal research in a topic of their own choice, under the guidance of a supervisor (a teacher in the school). This leads to a major piece of formally presented, structured writing, in which ideas and findings are communicated in a reasoned and coherent manner, appropriate to the subject chosen. It is recommended that completion of the written essay is followed by a short, concluding interview, or viva voce, with the supervisor.

The extended essay is assessed against common criteria, interpreted in ways appropriate to each subject.

The extended essay is:

compulsory for all Diploma Programme students externally assessed and, in combination with the grade for theory of knowledge, contributes up to three points to the

total score for the IB diploma a piece of independent research/investigation on a topic chosen by the student in cooperation with a supervisor in the

school chosen from the list of approved Diploma Programme subjects, published in the Vade Mecum presented as a formal piece of scholarship containing no more than 4,000 words the result of approximately 40 hours of work by the student concluded with a short interview, or viva voce, with the supervising teacher (recommended).In the Diploma Programme, the extended essay is the prime example of a piece of work where the student has the opportunity to show knowledge, understanding and enthusiasm about a topic of his or her choice. In those countries where it is the norm for interviews to be required prior to acceptance for employment or for a place at university, the extended essay has often proved to be a valuable stimulus for discussion.

The extended essay and the IB learner profileThe learning involved in researching and writing the extended essay is closely aligned with the development of many of the characteristics described in the IB learner profile. Students are, to a large extent, responsible for their own independent learning, through which they acquire and communicate in-depth knowledge and understanding. The research process necessarily involves intellectual risk-taking and extensive reflection; open-mindedness, balance and fairness are key prerequisites for a good extended essay.

Relationship to theory of knowledgeWhichever subject is chosen, the extended essay shares with the theory of knowledge (TOK) course a concern with interpreting and evaluating evidence, and constructing reasoned arguments. Where the two differ is in the emphasis placed on the research process and its formal outcomes. These aspects are of primary importance in the extended essay but are given much less weight in TOK: in the Theory of knowledge guide (March 2006) the section describing the TOK assessment tasks states that “neither the [TOK] essay nor the presentation is primarily a research exercise”. At a more abstract level, both TOK and the extended essay promote reflection on the nature of knowledge and on how new knowledge is produced.

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International dimensionsSome extended essay subjects include cross-cultural questions within them. Others invite such an approach. Whatever the subject, the extended essay student should strive to find relevant information from a diverse range of sources.

AimsThe aims of the extended essay are to provide students with the opportunity to:

pursue independent research on a focused topic

develop research and communication skills

develop the skills of creative and critical thinking

engage in a systematic process of research appropriate to the subject

experience the excitement of intellectual discovery.

Assessment objective

In working on the extended essay, students are expected to:

1. plan and pursue a research project with intellectual initiative and insight

2. formulate a precise research question

3. gather and interpret material from sources appropriate to the research question

4. structure a reasoned argument in response to the research question on the basis of the material gathered

5. present their extended essay in a format appropriate to the subject, acknowledging sources in one of the established

academic ways

6. use the terminology and language appropriate to the subject with skill and understanding

7. apply analytical and evaluative skills appropriate to the subject, with an understanding of the implications and the

context of their research.

Extended Essay HintsCRITERION ADVICE

Research Question A good research question is essential to a good extended essay. It should be stated early in the introduction and should be the focused for a 4000 word essay.

Adequate time and thought must be spent in writing the research question.Introduction This should provide an explanation of the research question.

The Introduction should include discussion of the significant research question with reference to theory.

Investigation The procedure is the key:- Is it unique- Does it allow for adequate data collection- Are controls used?- Is the procedure truly biological nature- Is the procedure relevant to the research question?

Knowledge and understanding of the topic studied

Have you shown that you clearly understand all aspects of the essay? Do your analyses represent an obvious understanding?

Reasoned argument In your quest to confirm your hypothesis, are you logical and methodical in your approach and explanation.

Application of analytical and evaluative skills

Have all aspects of the experiment been evaluated for appropriateness? Is the presentation of the data logical? Has there been adequate data analysis?

Use of Language Is the language appropriate to the topic and is it correctly used?

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appropriate to the subject. Does the terminology represent understanding?

Conclusion Does the conclusion flow logically from the arguments in the essay? Is the conclusion relevant to the research question and does it support the

original hypothesis? Does the conclusion include unresolved questions and potential future

research?Formal Presentation This includes elements such as: Title page, table of contents, page

numbers, appropriate illustrations, proper citations and bibliography, and appropriate appendices if used.

Abstract This is written LAST and includes three elements:- research question- investigate approach- conclusion

Holistic Judgement This criterion is used to reward creative and unique approaches It also involves depth of understanding, insight, and apparent interest in

the topic.Damon, McGonegal, Tosta, Ward (2007) Standard level Biology Developed specifically for the IB Diploma, Heinemann International, Essex

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Environmental Systems and Societies Glossary

Abiotic factor A non-living, physical factor that may influence an organism or ecosystem; for example, temperature, sunlight, pH, salinity, precipitation.

Biochemical oxygen demand (BOD)A measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity.

Biodegradable Capable of being broken down by natural biological processes; for example, the activities of decomposer organisms.

Biodiversity The amount of biological or living diversity per unit area. It includes the concepts of species diversity, habitat diversity and genetic diversity.

Biomass The mass of organic material in organisms or ecosystems, usually per unit area. Sometimes the term “dry weight biomass” is used where mass is measured after the removal of water. Water is not organic material and inorganic material is usually relatively insignificant in terms of mass.

Biome A collection of ecosystems sharing similar climatic conditions; for example, tundra, tropical rainforest, desert.

Biosphere That part of the Earth inhabited by organisms, that is, the narrow zone (a few kilometres in thickness) in which plants and animals exist. It extends from the upper part of the atmosphere (where birds, insects and windblown pollen may be found) down to the deepest part of the Earth’s crust to which living organisms venture.

Biotic factor A living, biological factor that may influence an organism or ecosystem; for example, predation, parasitism, disease, competition.

Carrying capacity The maximum number of a species or “load” that can be sustainably supported by a given environment.

Climax community A community of organisms that is more or less stable, and that is in equilibrium with natural environmental conditions such as climate; the end point of ecological succession.

Community A group of populations living and interacting with each other in a common habitat.

Competition A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, mates, nesting sites. It may be intraspecific or interspecific.

Correlation A measure of the association between two variables. If two variables tend to move up or down together, they are said to be positively correlated. If they tend to move in opposite directions, they are said to be negatively correlated.

Crude birth rate The number of births per thousand individuals in a population per year.Crude death rate The number of deaths per thousand individuals in a population per

year.Demographic transition A general model describing the changing levels of fertility and mortality in a

human population over time. It was developed with reference to the transition experienced as developed countries (for example, those of North America, Europe, Australasia) passed through the processes of industrialization and urbanization.

Diversity A generic term for heterogeneity. The scientific meaning of diversity becomes clear from the context in which it is used; it may refer to heterogeneity of species or habitat, or to genetic heterogeneity.

Diversity, genetic The range of genetic material present in a gene pool or population of a species.

Diversity, habitat The range of different habitats or number of ecological niches per unit area in an ecosystem, community or biome. Conservation of habitat diversity usually leads to the conservation of species and genetic diversity.

Diversity index A numerical measure of species diversity that is derived from both the number of species (variety) and their proportional abundance.

Diversity, species The variety of species per unit area. This includes both the number of species present and their relative abundance.

Doubling time The number of years it would take a population to double its size at its

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current growth rate. A natural increase rate of 1% will enable a human population to double in 70 years. Other doubling times can then be calculated proportionately, that is, the doubling time for any human population is equal to 70 divided by the natural increase rate.

Ecological footprint The area of land and water required to support a defined human population at a given standard of living. The measure takes account of the area required to provide all the resources needed by the population, and the assimilation of all wastes. (A method of calculation is provided in 3.8.2.)

Ecosystem A community of interdependent organisms and the physical environment they inhabit.

Entropy A measure of the amount of disorder, chaos or randomness in a system; the greater the disorder, the higher the level of entropy.

Environmental impactassessment (EIA) A method of detailed survey required, in many countries, before a major

development. Ideally it should be independent of, but paid for by, the developer. Such a survey should include a baseline study to measure environmental conditions before development commences, and to identify areas and species of conservation importance. The report produced is known as an environmental impact statement (EIS) or environmental management review in some countries. The monitoring should continue for some time after the development.

Equilibrium A state of balance among the components of a system.Eutrophication The natural or artificial enrichment of a body of water, particularly with

respect to nitrates and phosphates, that results in depletion of the oxygen content of the water. Eutrophication is accelerated by human activities that add detergents, sewage or agricultural fertilizers to bodies of water.

Evolution The cumulative, gradual change in the genetic characteristics of successive generations of a species or race of an organism, ultimately giving rise to species or races different from the common ancestor. Evolution reflects changes in the genetic composition of a population over time.

Feedback The return of part of the output from a system as input, so as to affect succeeding outputs.

Feedback, negative Feedback that tends to damp down, neutralize or counteract any deviation from an equilibrium, and promotes stability.

Feedback, positive Feedback that amplifies or increases change; it leads to exponential deviation away from an equilibrium.

Fertility In the context of human populations, this refers to the potential for reproduction exhibited in a population. It may be measured as fertility rate, which is the number of births per thousand women of child-bearing age. Alternatively it may be measured as total fertility, which is simply the average number of children a woman has in her lifetime.

Gaia The Gaia hypothesis (developed by James Lovelock and named after an ancient Greek Earth goddess) compares the Earth to a living organism in which feedback mechanisms maintain equilibrium.

Global warming An increase in average temperature of the Earth’s atmosphere.GNP Gross National Product, the current value of all goods and services

produced in a country per year.Greenhouse gases Those atmospheric gases which absorb infrared radiation, causing world

temperatures to be warmer than they would otherwise be. This process is sometimes known as “radiation trapping”. The natural greenhouse effect is caused mainly by water and carbon dioxide. Human activities have led to an increase in the levels of carbon dioxide, methane and nitrous oxide (dinitrogen oxide, N2O) in the atmosphere, and there are fears that this may lead to global warming.

Habitat The environment in which a species normally lives.Halogenated organic gases Usually known as halocarbons and first identified as depleting the

ozone layer in the stratosphere. Now known to be potent greenhouse gases. The most well known are chlorofluorocarbons (CFCs).

Isolation The process by which two populations become separated by geographical, behavioural, genetic or reproductive factors. If gene flow between the two subpopulations is prevented, new species may evolve. See evolution.

K-strategist Species that usually concentrate their reproductive investment in a small number of offspring, thus increasing their survival rate and adapting them for living in long-term climax communities.

Latitude The angular distance from the equator (that is, north or south of it) as

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measured from the centre of the Earth (usually in degrees).LEDC Less economically developed country: a country with low to moderate

industrialization and low to moderate average GNP per capita.MEDC More economically developed country: a highly industrialized country with

high average GNP per capita.Model A simplified description designed to show the structure or workings of an

object, system or concept.Mutualism A relationship between individuals of two or more species in which all

benefit and none suffer. (The term symbiosis will not be used.)Natural capital A term sometimes used by economists for natural resources that, if

appropriately managed, can produce a “natural income” of goods and services. The natural capital of a forest might provide a continuing natural income of timber, game, water and recreation.

Natural capital,non-renewable Natural resources that cannot be replenished within a timescale of the

same order as that at which they are taken from the environment and used; for example, fossil fuels.

Natural capital, renewable Natural resources that have a sustainable yield or harvest equal to or less than their natural productivity; for example, food crops, timber.

Natural capital, replenishable Non-living natural resources that depend on the energy of the Sun fortheir replenishment; for example, groundwater.

Natural increase, rate of The form in which human population growth rates are usually expressed: Inward and outward migration is ignored.

Niche A species’ share of a habitat and the resources in it. An organism’s ecological niche depends not only on where it lives but also on what it does.

Parasitism A relationship between two species in which one species (the parasite) lives in or on another (the host), gaining all or much (in the case of partial parasite) of its food from it.

Plate tectonics The movement of the eight major and several minor internally rigid plates of the Earth’s lithosphere in relation to each other and to the partially mobile asthenosphere below.

Pollution The addition to an environment of a substance or an agent (such as heat) by human activity, at a rate greater than that at which it can be rendered harmless by the environment, and which has an appreciable effect on the organisms within it.

Pollution, non-point source The release of pollutants from numerous, widely dispersed origins; for example, gases from the exhaust systems of vehicles.

Pollution, point source The release of pollutants from a single, clearly identifiable site; for example, a factory chimney or the waste disposal pipe of a factory into a river.

Population A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding.

Productivity, gross (GP) The total gain in energy or biomass per unit area per unit time, which could be through photosynthesis in primary producers or absorption in consumers.

Productivity, gross primary(GPP) The total gain in energy or biomass per unit area per unit time fixed by

photosynthesis in green plants.Productivity, gross secondary(GSP) The total gain by consumers in energy or biomass per unit area per unit

time through absorption.Productivity, net (NP) The gain in energy or biomass per unit area per unit time remaining after

allowing for respiratory losses (R). Other metabolic losses may take place, but these may be ignored when calculating and defining net productivity for the purpose of this course.

Productivity, net primary(NPP) The gain by producers in energy or biomass per unit area per unit time

remaining after allowing for respiratory losses (R). This is potentially available to consumers in an ecosystem.

Productivity, net secondary(NSP) The gain by consumers in energy or biomass per unit area per unit time

remaining after allowing for respiratory losses (R).Productivity, primary The gain by producers in energy or biomass per unit area per unit time.

This term could refer to either gross or net primary productivity.Productivity, secondary The biomass gained by heterotrophic organisms, through feeding and

absorption, measured in units of mass or energy per unit area per unit time.

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r-strategist Species that tend to spread their reproductive investment among a large number of offspring so that they are well adapted to colonize new habitats rapidly and make opportunistic use of short-lived resources.

Sere The set of communities that succeed one another over the course of succession at a given location.

Smog The term now used for any haziness in the atmosphere caused by air pollutants. Photochemical smog is produced through the effect of ultraviolet light on the products of internal combustion engines. It may contain ozone and is damaging to the human respiratory system and eyes.

Society An arbitrary group of individuals who share some common characteristic such as geographical location, cultural background, historical timeframe, religious perspective, value system, and so on.

Soil A mixture of mineral particles and organic material that covers the land, and in which terrestrial plants grow.

Soil profile A vertical section through a soil, from the surface down to the parent material, revealing the soil layers or horizons.

Speciation The process through which new species form. See also evolution.Species A group of organisms that interbreed and produce fertile offspring.Stable equilibrium The condition of a system in which there is a tendency for it to return to

aprevious equilibrium condition following disturbance.Standing crop See biomass.Steady-state equilibrium The condition of an open system in which there are no changes over the

longer term, but in which there may be oscillations in the very short term. There are continuing inputs and outputs of matter and energy, but the system as a whole remains in a more or less constant state (for example, a climax ecosystem).

Succession The orderly process of change over time in a community. Changes in the community of organisms frequently cause changes in the physical environment that allow another community to become established and replace the former through competition. Often, but not inevitably, the later communities in such a sequence or sere are more complex than those that appear earlier.

Sustainability Use of global resources at a rate that allows natural regeneration and minimizes damage to the environment. For example, a system of harvesting renewable resources at a rate that will be replaced by natural growth might be considered to demonstrate sustainability.

System An assemblage of parts and the relationships between them, which together constitute an entity or whole.

System, closed A system in which energy, but not matter, is exchanged with its surroundings.

System, isolated A system that exchanges neither mat ter nor energy with it surroundings.System, open A system in which both matter and energy are exchanged with its

surroundings (for example, natural ecosystems).Trophic level The position that an organism occupies in a food chain, or a group of

organisms in a community that occupy the same position in food chains.Zonation The arrangement or patterning of plant communities or ecosystems into

parallel or sub-parallel bands in response to change, over a distance, in some environmental factor. The main biomes display zonation in relation to latitude and climate. Plant communities may also display zonation with altitude on a mountain, or around the edge of a pond in relation to soil moisture.

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ANSWERS TO QUESTIONS IN BOOKLETTopic 1

1. (a) LEDCbasic/lack of technology generally;rice farming is typical of LEDCs/where rice is often the staple crop;cash crops for export such as sugar cane, tobacco;houses look fairly simple and made from local/cheap materials/thatched roofs;dependence on working animals;labour intensive (family labour);mixed cropping on small scale; 2 maxLEDC but no reasons award [0].

(b) inputs: [1 max]water/technology/cattle (livestock)/sunlight/rain/manure/seed/labour/soil;Award [1] for any three of the above.

processes: [1 max]planting/ploughing/harvesting/irrigating/repair/respiration/run-off/labour;Award [1] for any three of the above.

outputs: [1 max]jute/vegetables/mangoes/Jack fruit/Palm/coconut/sugarcane/spices/crops/waste/income/energy/rice/food/Betel nuts/tobacco/cattle (livestock)/heat/oxygen/carbondioxide/wheat/mustard; 3 maxAward [1] for any three of the above.

(c) different crops planted at different levels;rotation of crops to match seasonal rainfall patterns;monsoonal climate so main crop is rice;irrigation technology used in dry season;livestock fed differently at different times of year;different jobs done at different times of year; 2 maxAccept other reasonable answers.Answers must be linked to variations in environment.

(d) (i) when nutrients, dissolved in water, wash down throughthe soil/paddy and are lost; 1

(ii) process by which nitrogen in atmosphere is fixed toform nitrate by blue-green algae (and converted into auseable form for plants); 1

(e) (i) because the terraces are level there is little run-off by waterso soil is not washed away/terraces prevent soil erosion/soil collects in paddies; 1

(ii) oxygen is required by decomposers to break downorganic matter (the oxidized zone is closer to the surfaceand richer in oxygen)/higher BOD in oxidized zone asmore decomposers, thus more decomposition; 1

[11]

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2. (a) positive feedback because the effects of the problem make theproblem worse; 1Award [0] if no reason is given for positive feedback.

(b) traditionally defined as development which meets the needs of thecurrent generation without compromising ability of future generationsto meet their own needs;but in this context it suggests development which has a positiverole in enhancing the environment;and is dependent in some way on a healthy population; 2 maxAccept any other reasonable responses.Award [1 max] if no reference is made implicitly or explicitly tofigure 2.

(c) simple, easy to see the connections;shows clearly how actions in one area can have a knock-on effecton the original development;can distinguish between positive and negative actions andconsequences;but far too simple, detail of what constitutes sustainable as opposedto inappropriate development is not clear;exact natures of the causal relationships are not explained; 2 maxAward [1] for a strength and [1] for a weakness.

[5]

3. (a) feedback:the return of part of an output of a system (or subsystem) as an input,so as to affect succeeding outputs/OWTTE; 1

(b) Answers must have a definition, some explanation of negativefeedback and an example (which need not be as detailed as thatbelow) to achieve full marks.

negative feedback:feedback that tends to damp down, neutralize or counteract anydeviation from an equilibrium and promotes stability/OWTTE;

example:increase in number of predators (e.g. owls) → decrease in smallmammals (e.g. mice, voles, shrews) → increase in smallmammals → increase in predators;

explanation:understanding of ecological relationships/processes; 3 max

For the final mark the answer must show some understanding ofecological relationships or processes, such as predation, disease,breeding success. This material may be incorporated in theexample. Some or all of the information may be given in theform of a diagram.

[4] 4. (a) open, due to inputs/outputs of matter/air/water (and energy); 1

(b) inputs would include more CO2 than outputs;due to net productivity/photosynthesis; (E)inputs would include less O2 than outputs;

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due to net productivity/photosynthesis; (E)inputs would include more liquid water than outputs;due to absorption by plants; (E)inputs would include less water vapour than outputs;due to evapotranspiration; (E)inputs would include more light energy/electricity;whereas outputs would include more heat energy;due to respiration; (E)due to conversion of light/electrical energy to heat; (E)inputs greater than outputs in early stages;due to growth occurring/biomass increasing; (E) 4 maxAny other appropriate differences[2 max] for differences[2 max] for appropriate explanation.

(c) negative (feedback); 1

(d) (i) in energy transformations (in food chains), not all energycan be converted to a useful form/some chemical energy(in food chains) is lost as heat energy;so not all energy is transferred from one trophic level to thenext;so the energy available to each successive trophic level decreases; 2 max

(ii) the size of the ecotron limits the size of the primary producercommunity;which limits the amount of energy that can be made availableat the bottom of the food chain;and since there are losses at each trophic level, this limits thenumber of trophic levels that can be supported; 2 max

[10]

Topic 2 MS

1. (a) (i) most fish will be found in places where temperatures aremoderate;normal distribution of fish;some fish will be able to survive at more extreme temperatures(but they will be in a state of physiological stress); 2 max

(ii) at low and high temperatures, only small populations offish are supported due to physiological stress 1

(iii) density independent because temperature is a factor whichaffects populations regardless of population size 1

(b) Accept any reasonable response. Answers could include:salinity/water pH/flow velocity/wave action/soil pH/light intensity/wind speed/soil moisture/drainage/slope/particle size/mineral content 2 max4 correct = [2], 2 or 3 correct = [1], 1 correct = [0]

(c) For example, flow velocity:use a flow meter;insert into water just below surface and take a number of readingsto ensure accuracy;results can be misleading if only one part of stream is measured;water flows can vary over time and with depth; 3 max

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[9]

2. (a) L i g h tH e a t

N u t r i e n t s W a t e r

T R E E

T i s s u e t o o t h e r t r o p h i c l e v e l s

L i t t e r t o s o i l

H e a t

2C O 2

2O

H O

3 maxAward [1] for tree in box, [1] for two matter flows and [1] for twoenergy flows.

(b) producers convert solar energy into chemical energy throughphotosynthesis;one of the main contributors to organic matter in soil;through symbiotic bacteria, producers are significant in fixingnitrogen;provide habitat for other organisms; 2 maxAccept other reasonable statements that show ecological knowledge.

(c) e.g. Chilean matorral 3 max

p ro d u c e r p rim ary co n su m er sec o n d a ry co n su m er

F e lis g u ig n a / C h ilean w ild ca t

O ctod o n d eg u /ro d en t

A ca cia ca ven sC h ile an th o rn

tree

Award [1] for appropriately labelled trophic levels, [2] for threeappropriate species or [1] for two appropriate species.Do not accept rabbit, fox etc., unless there is some identifyingfeature i.e. snowshoe hare and arctic fox.

(d) long-term stability leading to speciation/complexity;high species number per unit area (South America 0.125 species km–2

versus 0.0027 species km–2 in temperate forests in North America);high number of endemic species;limiting factors low and so high productivity leading to high diversity; 3 max

(e) decomposers break down tissue;release nutrients for reabsorption by producers;form basis of decomposer food chain (which may be energeticallymore important in some ecosystems than grazing food chains);as chemosynthetic autotrophs may form basis of food chain;through incomplete breakdown of organic material contributeto build up of humus and improve nutrient retention capacity in soil;

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are vital in nitrogen cycle; 2 max

(f) primary productivity would decrease;

Award [2 max] for the following.acid rain can damage foliage directly thus reducing photosynthesis;increase in solubility of nutrients facilitates leaching with consequentloss of productivity;increases susceptibility of trees to stresses such as disease/temperature/insects/fungal infection; 3 max

[16]

3. (a) (i) 6 1

(ii) producers = first accumulator/algae, plants/level 1top carnivores = ultimate accumulators/humans/level 6Both required for [1] 1

(iii) pesticide becomes increasingly concentrated as you go upthe food chain;because each successive trophic level supports fewerorganisms and so the pesticide becomes concentrated inthe tissues;a progressively longer life span – intake of many individualsof a lower level; 2 max

(b) (i) energy is used in respiratory processes at each trophic stageand is lost as heat;also lost as waste; 2

(ii) pyramid of biomass represents biomass at a given time;whereas pyramid of productivity represents rate at whichstocks are being generated;pyramid of biomass is measured in units of mass/energy/J m–2/g m–2 ;pyramid of productivity is measured in units of flow/J m–2 yr–1/g m–2 yr–1; 2

[8]

4. (a) Lost from atmospheric storage by fixation by photosynthesis [1];Photosynthesis by green plants/phytoplankton/producers/autotrophs [1];Takes carbon dioxide, water, chlorophyll and light energy to make organiccompounds/glucose and releases oxygen [1];Light energy is transformed to chemical energy [1];Release by respiration [1];By animals/heterotrophs/zooplankton/decomposers [1]; producersalso respire [1];Breakdown/oxidation of organic matter using oxygen to produce energy,carbon dioxide and water [1];Release by combustion – fast oxidation of organic matter [1];Release by diffusion of carbon dioxide from the water to theatmosphere [1]/dissolves in atmosphere (rain) [1](Award marks for reasonable points e.g. examples of the above.) 8 max

(b) More C in atmosphere as carbon dioxide [1]/less C in sink as organicmolecules [1];Due to: increased burning of fossil fuels [1]/increased use of cars [1]/

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increased industrialisation [1];deforestation [1];increased water temperature – gases less soluble [1](Accept any reasonable activity) 4 max

(c) Effects: global warming [1];Sea temperatures rise – plankton killed [1];Ice caps melting [1]/habitats destroyed [1];possible rise in sea levels due to thermal expansion [1]/low lyinglands flooded [1]/organisms displaced [1]/ecosystems destroyed [1];weather patterns changed [1]/crop growth patterns altered [1];(Award marks for any reasonable answers that relate changesto the biosphere.) 5 max

Expression of ideas [3 max][20] 5. (a) ecological succession [2 max]

the (orderly) process of change over time in a community/ecosystem/OWTTE;changes in organisms may be associated with changes inabiotic environment (e.g. soil, microclimate);successive communities displace each other through competition;e.g. volcanic island developing into tropical rainforest;

pioneer community [2 max]the first organisms to colonize a new environment;usually dominated by producers/plants;usually dominated by r-strategists;pioneer communities often very simple in structure/low diversity;tolerate harsh conditions e.g. strong light/low nutrient levels;e.g. community of lichens covering bare rock (lithosere);

climax community [2 max]the end-point of ecological succession;in equilibrium/relatively stable;may have a high level of complexity;usually dominated by K-strategists;characteristics of climax community determined by climate and soil;e.g. mature woodland/rainforest ecosystem;Any other reasonable points. 6 max

(b) name of ecosystem;e.g. sand dune succession on coast of Western AustraliaName must be reasonably detailed, e.g. “freshwater” is not insufficient.

pioneer species very low in number initially;but numbers increase rapidly with lack of competition;then decrease later as other species displace them;rarely reaching their full carrying capacity;changing abundance follows a J-curve;eventually climax species become established;their numbers increase slowly to maximum/carrying capacity;changing abundance follows an S-curve;examples of named species showing these changes; 5 maxAward [1] for each of the above [4 max].Any other reasonable points, but they must refer to relative

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abundance of species, not to diversity for award of credit.

(c) gross primary productivity (GPP) – the total amount of organicmatter produced/solar energy fixed by photosynthesizing plantsper unit area per unit time/OWTTE;gross productivity initially absent/very low;due to initial absence of photosynthesizing organisms;increases through pioneer stage as colonization byphotosynthesizing plants increases;and structural complexity/number of layers increases;as green plant biomass increases, gross primary productivityincreases;GPP usually at its maximum at climax;GPP is limited at climax by abiotic factors e.g. nutrients/sunlight/temperature/water;in some cases GPP declines slightly as older/more woodyplants dominate;productivity varies seasonally;productivity may be affected by human interference; 6 maxAny other reasonable points.Some of the points above may be scored by means of suitablylabelled graphs/diagrams.Do not accept references to secondary productivity or netprimary productivity.

Expression of ideas [3][20]

Topic 3 MS

1. (a) Define natural capital = resources that produce natural income [1];increase in population puts more pressure on natural capital [1];if this is not used sustainably, natural income is reduced or lost [1];as India becomes more industrialised, it uses more natural capitaland income [1];more people need more goods and services and as living standardsimprove, more is required [1];pricing of natural capital is only in terms of economics – conflictingvalues [1].or appropriate arguments. 6

(b) (Award [1 mark] for reasons and [1 mark] for discussion × 4).For example – educated women are more productive [1];Discussion [1]/e.g. data from 70 developing countries suggest thatincreasing girls’ secondary schooling from 4 to 16 % would increasethe women’s labour force by over 12 %. [1]/

– educated women are more confident [1];Discussion e.g. studies from India found literate women expectedand received better treatment at clinics and hospitals. Research inBangladesh found educated women communicated more with theirhusbands and have a greater say in family decisions than uneducatedwomen. [1]/

– educated women use family planning [1];Discussion e.g. it has been estimated that giving 1000 girls an extra

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year of education would avoid up to 500 births. [1]/

– educated women have healthier children [1];Discussion e.g. the mother is usually responsible for her family’s health.Data from 33 less-developed countries reveals that every additionalyear of a mother’s schooling is associated with an additional 7 to 9 %drop in child mortality. [1]or appropriate reasons and discussion [2].

(Expect to give credit for a variety of relevant responses.) 8

(c) (Award marks for detailed discussion of a named policy orappropriate discussions of several policies).For example, Indian policy of enforced sterilisation probably hadlittle effect on birth rate [1]/transistor radios and compulsionfailed in India [1]/but decreased rates of infant mortality due tobetter education and health care can reduce growth rate [1];free contraception can reduce growth rate [1]/In China the one child policy has led to female infanticide [1]/ 3

Expression of ideas [3 max][20]

2. (a) Effects due to: increased carbon dioxide levels/sulfur oxides/nitrogen oxides/unburned hydrocarbons/particulates/lead/carbon monoxide/mining/pollution of oceans.

Allow up to [2] for more than 3 effects and then up to [2] for eachcategory.Candidates are asked to review so there should be an overview ofmost effects not emphasis on one or two.

Carbon dioxide increases → global warming → climate change→ sea levels rise/disruption of ocean currents (e.g. in NorthAtlantic)/possible negative feedback effects from increased snowfall at poles/coral bleaching/ice caps melt/flooding of low-lyinglands/biomes shift/food production changes [2];sulfur dioxide → acid deposition → Al/cations leaching → treedeath/acidifies lakes/limestone buildings eroding [2];nitrogen oxides → also acid deposition/photochemical smog/CFC breakdown/pollution of oceans/effects of transportinglarge quantities of oil round the world e.g. oil spillages,Exxon Valdez (March 1989), oiling of seabirds [2].

Credit up to one specific health effect correctly attributed to fossilfuel induced pollution e.g. asthma.

(Give credit also for review of other impacts.) 8 max

(b) Award marks for up to 5 strategies (e.g. carbon taxes/alternativesources of energy/energy efficiencies/liming), provided somerelevant detail is given for each example. 5 max

(c) USA uses more [1]/larger and less efficient automobiles [1];→ more gases released [1]/In North America, petrol is cheaper soNorth Americans use more gasoline per capita [1]; ecologicalfootprint high [1]/new cars – more efficient technology innewer engines – cleaner emissions [2]/pollution effects lead to

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strong campaign for pollution controls [1]/more smog andother pollution effects (including lead in environment) [1]. 4 max

Candidates may approach problem from either European ‘direction’or North American ‘direction. e.g. expensive petrol in Europeencourages more use of public transport, leading to less pollution;cheap petrol in USA makes public transport unattractive and useof cars more likely, etc. Credit either approach.

Expression of ideas [3 max][20]

3. (a) Award [2 max] for comparisons and calculations of % growth

Ethiopia = 5906559065987170

× 100 = 161% (allow 160% to 161%);

Austria = 102810283767

× 100 = –9% (negative value) (allow –8% to –9%);

Ethiopia shows a high/positive growth rate whereas Austria shows alow/negative growth rate;

Award [2 max] for differences in pyramids (shown in diagram ordescribed in words)Ethiopian pyramid is shorter than Austrian pyramid (because ofhigher life expectancy in Austria);Ethiopian pyramid is triangular and Austrian pyramid isparallel-sided;Ethiopian pyramid widens towards base but Austrian pyramidbecomes narrower at base;Larger overall area for Ethiopian pyramid/smaller overall areafor Austrian pyramid.

E th io p ia A u stria

Award [2 max] for position in demographic transition model(shown on diagram or described in words)Ethiopia likely to be in stage 2 (or 3) Ethiopia is at an early stagewhere death rates are falling below birth rates;whereas Austria likely to be at the end of stage 4 (or in a possiblestage 5)/Austria is at a very late stage with birth rates fallingbelow death rates; 7 max

Award [1 mark] for clear and appropriate sketches of pyramidsand/or demographic transition model.

(b) Award [3 max] for each population:Ethiopia: (factors should account for the relatively high growth rate)Population largely rural/dependent on agriculture which providesincentive for large families leading to high birth rates;overseas aid may improve health/diet leading to reduced death

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rates;poor education/cultural values may limit use of birth controlleading to high birth rates;high infant mortality may encourage families to have morechildren to compensate, leading to high birth rates;Any other appropriate point.

Austria: (factors should account for the relatively low growth rate)policies that provide greater independence/education for womenmay lead to lower birth rate;competitive/expensive urban lifestyles may provide disincentivefor having many dependent offspring, leading to lower birth rate;government policies may provide disincentives for large familiesby taxation/benefits leading to reduced birth rates;education regarding/availability of birth control methods maylead to reduced birth rates; 6 maxAny other appropriate point.Factors should not just be stated without explanation of how theylead to the predicted change in the populations. For responsesthat lack explanation, award [1] per two factors but [2 max].

(c) Allow [2 max] for named examples and [2 max] for describingimpacts of urbanization.decomposer communities providing natural waste assimilation/decomposition;impact: urbanization may lead to overload of local naturalsystems of waste assimilation;

vegetation providing flood/erosion control;impact: urbanization may lead to loss of vegetation andincreased run-off.

photosynthesis maintaining balance in CO2 concentration;impact: deforestation/increased use of fossil fuels associated withurbanization may limit/overload the system;

hydrological cycle replenishing freshwater supplies;impact: concentration of population in urban areas may lead todepletion/contamination of local freshwater supplies. 4 maxAny other appropriate example with associated impact of urbanization.Example must be a resource of ecological value (not economic).

Expression of ideas [3 max][20]

4. (a) carrying capacity – the maximum number of people that can besustainably supported by a given environment;ecological footprint – the area of land and water required tosupport a defined human population at a given standard ofliving / the measure takes account of the area required toprovide all the resources needed by the population, and theassimilation of all wastes;the ecological footprint of an EMDC is likely to be larger thentheir land area;whereas the footprint of an ELDC is likely to be smaller

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than their land area; 4

(b) technology development give rise to continual changes in theresources required and available for consumption, making ithard to calculate the carrying capacity for human populations;improvements in transports have enabled humans to importresources from outside their immediate environment increasingtheir local carrying capacity;technological developments have enabled humans to substituteone resource for another if that resource becomes limiting(e.g. with alternative fuel resources);technological innovations, e.g. in the areas of recycling andremanufacturing, can increase carrying capacity;

thus many economists argue that human carrying capacitycan be expanded continuously without necessarily increasingthe impact (load) on the environment;increased levels of technological development (associated withMEDCs for example) tend to be associated with larger ecologicalfootprints; 5 max

Credit should be given for the use of specificexamples to support these statements.

(c) Clearly this question can be answered in a variety of ways.Credit should be given for answers which are balancedi.e. candidate cannot gain full marks if only oneside is argued.population pressure can be lead to resources being misused;e.g. soil being farmed too intensively / forests being cuttoo rapidly;in the sense that many resource management problems arethat there are insufficient resources for the available population,reducing total population size would therefore be a solution of sorts;however, resource management problems are often to do withdistribution of resources (e.g. water resources are not distributed evenlyacross the globe) and therefore more equitable distribution is arguablywhat is required rather than population control;

some resources are finite and therefore no amount of population controlwill make a difference ultimately to the availability of that resource;e.g. all use of oil is ultimately unsustainable no matter what size thepopulation is;excessive population growth arguably occurs as a result of poverty(associated with inadequate resources);a vicious cycle exists where population control will not be effectiveunless poverty and inequitable resource use is addresses first;the largest use of resources if found in the most economicallydeveloped countries of the world;these countries may not have the largest populations, or thefastest population growth rates; 8 max

Credit should be given if specific case studies are used to illustrate these points.[20]

5. (a) named organism (e.g. water flea, peppered moth, blood worm,rat tailed maggot, Asellus, Gammarus, stonefly larvae, etc.);organism can be used as an indicator;by abundance of organism (either high or lower levels than expected)/

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by colour of moths’ wings etc.;reference to the Trent biotic index or similar;polluted and unpolluted sites should be compared; 4 max

(b) baseline study - important to know what the physical and biologicalenvironment is like;there should be an understanding of the development in termsof impact;there should be an assessment of impacts during and afterdevelopment;there should be monitoring of environmental conditions duringand after development;should contain non-technical summary;should inform decision making;often difficult to put together a complete baseline study due tolack of data;often all impacts are not identified;information and suggestions in EIA are often not acted upon; 7 maxGive credit for references to actual EIA.

(c) research provides baseline data;monitoring enables changes as a result of e.g. pollution, to be detected;without research and monitoring it is difficult to argue objectivelyor legally that an environment is under threat;research provides an understanding of complex interrelationshipsin ecosystems and enables them to be managed more sustainably;research provides data as an educational tool making society awareof what is happening to the environment;monitoring can be used to “police” the system and ensurenon-infringement of standards; 6

Expression of ideas [3 max][20] 6. (a) increase in population growth as death rates lowered due to

better medical care;increased wealth means people are consuming more (sometimesmore than they need);economics of food production systems mean that food productionis a business and subsidies may guarantee prices no matter howmuch is produced;desire for food security in turbulent political times;as more and more land is used for settlement and industry,increasing need to intensify production on existing farm land;in LEDCs food production used as a way to generate foreign currency; 4 max

(b) Answer will, of course, depend on the problems chosen. [4] for eachproblem. Credit should be given for use of examples and case studies.

e.g. soil erosion:use of heavy machinery leads to compaction of soil, so soilstructure is lost;top soil is more easily removed by the agents of erosion(wind or water);even more erosion likely if wind breaks (hedgerows and walls)are removed;once top soil is lost, organic material is gone and the fertility of

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the soil is reduced;this occurred during the 1930s in the US due to intensive farmingon the prairies;leading to the dust bowl as vast quantities of soil were blown away;leads to lower yields and a vicious cycle as remaining soil may beeven more intensively farmed by farmers to compensate; 8 max

(c) Answers may be general, covering a variety of strategies or morespecific, addressing strategies related to a particular problem.Credit should be given for use of examples and case studies.

e.g. a general answer:use of natural fertilizers (e.g. manure) rather than chemical fertilizers;controlling the amount of fertilizers that are applied to ensure excessis not washed into water bodies;organic farming methods applied and marketed effectively to consumers tocompensate for higher production costs;biological pest control rather than chemical control;keeping stores of genetic material to ensure species diversity is not lost;encouraging polyculture to reduce vulnerability to disease;agro-forestry to reduce soil erosion;specific strategies to reduce soil erosion e.g. terracing; 5 max

Expression of ideas [3 max][20]

Topic 4 MS

1. (a) model Bcorridor allows organisms to migrate between reserves/greater numberof opportunities for mating with a wider population/greater geneticdiversity because more individuals can mix; 1No marks for stating model without reason.Accept Model A if valid reason is given. e.g. separate reserves meanthat if wildlife in one are wiped out/killed, others may survive.Reasons must relate to genetic diversity.

(b) (i) living mass is large in the rainforest/tall trees/many layersof vegetation/large amounts of nutrients stored as there isa lot of biomass per unit area; 1

(ii) high levels of rainfall washing nutrients out of the soil/leachingresults in infertile soil/loss of nutrients; 1

(iii) open because matter/nutrients (and energy) are freely exchangedoutside the system; 1

(iv) Strengths:simple to interpret/quantitative to some extent/pictorial soeasy to compare with others;Limitations:no indication of quantities as numeric values/simplistic; 2

(c) found in parts of the world with high population density so pressureon the land to remove forest and grow food;it takes a long time to recover from logging/destruction;have biological hotspots with high biodiversity so many speciesaffected;

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valuable timber is removed and so forest damaged; 2 maxDo not accept acid rain (Brazil is low for acid rain).Do not accept tourism/ecotourism unless tied to impacts on habitat(s).Credit answers which either address reasons why this ecosystem isintrinsically fragile or reasons why people might destroy the habitat.

[8]

2. (a) large animals require relatively large space for breeding/foraging/hunting/ territoriality;the area often needs to be large enough to limit disturbance/includebuffer zones;the area needs to be large enough to minimize the chance of animalswandering outside the reserve and becoming targets for hunters;if reserves are too small, viable populations of large animals arenot sustainable; 3 max

(b) conservation designed to conserve a particular species;may not require the preservation of the animal’s habitat;or the animal in the wild;usually associated with charismatic species, e.g. big cats, rhino; 2 max

(c) global volcanic eruption leading to rapid climate change/hostileenvironment;catastrophic events such as meteorite impact leading to rapidclimate change/hostile environment;over hunting of large mammals by man (in the Holocene) to theextent that populations became reproductively unviable/wiped out; 2 maxDo not accept Ice Age.

(d) collecting: [2 max]using legislation to prevent moving/import of endangered species;education about impact of collecting to change behaviour;encouraging non-destructive “collection” e.g. photography ratherthan digging up;

overgrazing: [2 max]fencing/cordoning off sensitive habitats/ biological hotspots;reducing herd sizes;providing alternative grazing;supplementing income through nature tourism; 4 maxAccept other choices of threat and reasonable strategies.

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3. (a) stops organic residues entering streams and causing pollution/eutrophication; 1

(b) (i) reducing lawn size – lawns are restricted to grass species andsuccession cannot occur as they are cut regularly;allowing plants and trees to grow alongside streams will increasethe range of habitats for insect/bird species;more food/nutrients provided for species; 2Accept any other reasonable responses.Award [0] if no reason given.

(ii) provides greater stability;more niches so more alternative food sources within the foodweb should anything happen to an individual species;greater genetic diversity so better able to withstanddiseases/change;

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aesthetic/potential economic value of greater diversity; 2 max

(c) removing grass cuttings takes nutrients away from the soil, sothere will be a net loss of nutrients;natural fertilizers less likely to contain harmful toxins whichmay build up in species (biomagnification);cheaper;a way of reducing overall waste/resources/energy used;a more sustainable strategy;less likely to cause eutophication than artificial fertilizers;artificial fertilizers lead to release of greenhouse gases as theyare produced;natural fertilizers may contribute positively to soil structure; 2 max

[7] 4. (a) 2.075 % (allow values between 2.0 and 2.1); 1

(b) (i) mammals;

(ii) invertebrates; 1Both answers needed for [1].

(c) Award [1] each for two of the following.mammals are often large/conspicuous;and sometimes of economic value (fur, meat, skins);large mammals require substantial area for their support;many mammals feed at high trophic levels/are k-strategists andhave low reproductive potential;and so are more vulnerable to extinction;mammal species number lower, so loss of a few species moresignificant;knowledge of mammals and their extinctions is reasonably complete;biodiversity of invertebrates is not well known;many species of invertebrates may have become extinct withoutbeing documented;most insects are small/inconspicuous;and are of little economic value; 2 maxAny other appropriate point.

(d) Award [1] each for five of the following.with the exception of fishes and invertebrates, many more islandspecies have been rendered extinct than continental species;island biotas are particularly vulnerable because of high degreeof endemism;small size of populations on islands;less genetic diversity in small island populations;absence of predators on islands and therefore vulnerability oforganisms when these are introduced;specialized nature of island forms;small number of fish extinctions on islands due to rarity of suitablehabitats;and small number of species originally; 5 maxAny other appropriate point.

[9]

Topic 5 MS

1. (a) Both must be correct for [1].125

(i) 1970

(ii) 1970 1 max

(b) Must have “improved” and a satisfactory reason for [1].

improved. Lead is toxic and concentrations have declinedsubstantially/water was very acidic and is, by 2000, approachingneutrality/acid water often has lower biodiversity; 1 max

(c) A mark for each of three valid points: don’t expect too much.No mark for simply saying there has been an improvement – alreadyrewarded;

water may have been very polluted;as the result of chemical or metallurgical industries/run-off fromroads;but there may have been improvement over 30 years through legalcontrols, regulations;extraction of pollutants before water released into lakes;high acidity might have been counteracted by adding alkali;as water becomes less acidic it leaches less lead out of environment;cessation of use of leaded petrol;any other reasonable alternative; 3 max

(d) measurement of species diversity;by collection under standard conditions for a set time;and comparing results at different sites/times;use of indicator organisms;any other reasonable alternative; 2 max

(e) (i) the natural or artificial enrichment of a body of water,particularly with respect to nitrates and phosphates/OWTTE; 1 max

(ii) rapid growth of algae;high rate of decomposition;low levels of oxygen;death of aerobic organisms;increased turbidity;loss of macrophytes;loss of species diversity;reduction in length of food chains;aesthetic deterioration (smell, etc.); 3 maxDo not allow a point already rewarded in (i).

(f) Responses may approach the question by mentioning “early” or“upstream” strategies or “later” or “downstream” ones.Reward understanding of principles and practical details.

altering activity producing pollution;by switching to slow-release fertilizers;other methods of encouraging crop growth;alternative (non-P) detergents;regulation and reduction at point of emissione.g. by sewage treatments that remove N and P;“post-pollution clean-up”;by pumping mud;chemical treatment;

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replanting vegetation indigenous to area;reintroducing fish/other organisms; 5 maxany other reasonable suggestions;

(g) (i) advantages:substantial reduction of waste volume;unsophisticated technology;energy released may be used as source of power;destroys pathogens;in some circumstances may be cost-effective; 2 max

(ii) disadvantages:disposal of ash;atmospheric pollution;CO2 produced;loss of material such as paper, cardboard, plastics that mightbe recycled;smoke;aesthetic, smell etc.;loss of organic material that might be composted;any other reasonable suggestion; 2 max

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2. (a) both show an annual increase in use throughout most of the periodshown;the annual increase is generally declining for both regions;(N.B. do not credit responses that claim the use of fertilizers isdecreasing)western Europe shows a decrease in use of fertilizers for a short timearound 1990;developing countries consistently show a greater annual increase;developing countries show greater fluctuations in their annualincrease/western Europe shows a steadier decline in annual increase; 2 max

(b) annual increase for 1970 is 12.5% (allow 12–13%);

1005.12

× 40000 = 5000;

Total used = 40000 + 5000 = 45000 tonnes(allow 44 800 – 45 200/4.5 × 104 tonnes/45 k tonnes);[1 mark] for correct percentage and [1 mark] for correct total. 2 max(There is no need to insist on evidence that the graph was used,e.g. by seeing a ruled line or similar.)

(c) inorganic fertilizers are released into environment through humanactivity;in quantities that would not naturally occur within the environment;in quantities greater than can be rendered harmless by the environment;and has an appreciable effect on the organisms within it;and cause disturbance to the equilibrium of systems;resulting in reduced/altered biodiversity; 2 max

(d) N and P drain into aquatic systems;promote rapid growth of phytoplankton/algae;death of these algae contributes to dead organic matter;leads to similar events with zooplankton;larger plants die from lack of light;

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increased dead organic matter speeds up decomposition;rapid increases in population of decomposer organism populations/bacteria;O2 used up by respiring decomposers;animals die due to lack of O2;diversity of the system is greatly reduced; 6 max

(e) BOD = Biochemical Oxygen Demand; (Allow Biological)BOD is the quantity of oxygen required by decomposers for thefull decomposition of organic matter within a sample;due to high inputs to storages of dead organic matter BOD islikely to be relatively high/will increase; 2 max

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3. (a) the release of pollution from numerous widely distributed origins(Glossary)/the contamination of a wide area by a pollutant whereno single source can be identified OWTTE;e.g. waste gases from the exhaust systems of vehicles/fertilizerleaching into groundwater from the lawns of a suburb; 2 maxAward [1] for any reasonable example.

(b) (i) 3.8 mg kg–1 (accept 3.78 mg kg–1) units required 1

(ii) 15.9 mg kg–1 (accept 15.93 mg kg–1) units required 1

(c) (i) at both locations and at all times Fe amounts are higher than Pb;Possible reasons:both locations are some distance from mine site and Pb,being the heavier material, is precipitated closer than eitherlocation 1 or 2;there is very little Pb in the ore mined/much more Fe thanPb mined and therefore emitted owtte;Pb is removed from the material emitted; 2 max

(ii) at location 2, precipitation is much higher in April–Maythan at other times of the year;Possible reasons:seasonal variation in wind direction;amount of mining activity varies over time; 2 max

(iii) average concentration of Pb is much higher at location 2than at location 1;Possible reason:location 2 is closer to mine site; 2

Accept any other reasonable points throughout.

(d) monitoring of the level of pollution using biotic index/monitoring using observations on the abundance and types oforganisms present;Example:monitoring air pollution by noting the number of lichens present;the more species and the more individuals the less pollution;i.e. very few species in the “lichen desert” of large cities;many dozens of species in uncontaminated area (e.g. Cornwall,SW Tasmania, Tierra del Fuego); 3 max

(e) Environmental Impact Statement (EIS)/Environmental Impact

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Assessment (EIA) approach;careful pre-development baseline measurements/environmental study;of abiotic factors, e.g. air quality;biotic factors, e.g. biodiversity/rare species;comparison with similar sites elsewhere;computer (or other) simulation;assessment of vulnerability to local impact;consideration of associated activities, e.g. traffic/transport, etc.socio-economic impacts; 4 maxAny other reasonable points.

(f) e.g. nuclear waste:incorporate in glass or artificial rock;deep burial in abandoned mines/caves;shallow burial in places where radiation can be monitored;surround by lead or similar material;transport to reprocessing plant; 3 maxAny other reasonable points.

Must give a reasonable example, “toxins” or “waste” are not sufficient.[20]

4. (a) (i) ozone concentration has declined; 1

(ii) increase of halogenated gases in the atmosphere;inhibiting the production of ozone; 2

(b) UV radiation passing through the Earth’s upper atmosphere is absorbedby the formation and destruction of ozone;amount of ozone present (and its chemical “availability” and temperature)control the amount of UV radiation absorbed; 2

(c) humans: genetic mutation/skin cancer/cataracts/impairedimmune system;plants: reduced photosynthesis/reduced crop yield due to cell damage; 2Accept other valid answers.

(d) use inert gases in refrigeration units;do not use halogenated organic gases to blow insulation foam;recycle harmful gases;dispose of appliances such as refrigerators safely (removing gas);setting national and international limits; 3 max

[10] 5. (a) (i) 400 000 (tonnes)/4 × 10 (s) ; 1

(ii) Allow [2] for explanation in which increase in waste is implicit.

total amount of waste produced has increased;but a larger proportion is now recycled;

explanation:as demand for goods increases people consume more;economic/industrial growth so more waste produced;increase in packaging over time;some products cannot be recycled so will still have to besent to landfill;new landfill sites may have been opened so little incentive

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to reduce waste;increase in population has lead to more consumption;some people simply do not bother to recycle; 2 max

(b) (i) Award [1] for two of the following.recyclable packaging (e.g. cartons/recycling bins/devices);transporting waste to other countries;incineration technology;use of computers/IT to reduce paper storage;manufacturing goods which can be recycled; 1 maxAccept other reasonable responses.

(ii) collecting recycling still uses petrol/energy;waste is sent elsewhere but still contributes to global economicfootprint;incineration produces atmospheric pollutants; 2 maxNegative environmental effects should relate to responsegiven in (b)(i).Award [1 max] if not.

[6]

TOPIC 6 MARK SCHEME

1. (a) C emissions increase carbon dioxide in the atmosphere which isa Greenhouse gas and leads to global warming [2];C emissions are from industry, transport and power stations [1];US has highest emissions by far – nearly double China [1];size of C emissions not related to size of population but to development [2];US also has most emissions per capita [1];as do other developed countries [1];Four of top ten are in Europe [1]. 8

(b) Agreements award up to [4 marks] but must have specific agreements.The material below is for information. 1990, Geneva: scientists onIntergovernmental Panel on Climate Change say 60 % reduction incurrent carbon dioxide levels required. [1];

1992, Rio de Janeiro Earth Summit: politicians from 150 countriessign Climate Change Convention. Its purpose is to slow down climatechange to a level at which people and ecosystems will be able to adapt.Politicians cannot agree on any cuts;instead industrialised countries agree to keep carbon dioxide levelsdown to 1990 levels by year 2000. Developing countries make nocommitments. [1];

March 1995, Berlin: politicians hold climate summit. Agree thatmeasures previously agreed to meet the Convention’s goals areinadequate, but defer action on cutting emissions. Agree that legallybinding reduction targets for the early 21st century should be readyfor signing by industrialised countries by 1997. There are to be nocommitments for the developing world. [1];

December 1995, Rome: scientists complete IntergovernmentalPanel on Climate Change second report. Agree for the first timethat humans are discernibly altering the climate. Again warn that50 to 70 % cuts in Greenhouse gases are required. [1];

October 1996, Paris: International Energy Agency says the great130

majority of developed countries will fail to keep Rio Earth Summitpromises to stabilise carbon dioxide emissions. [1];

December 1997, signing of Kyoto Protocol: make or break meetingfor Rio’s Climate Change Convention. New agreement needed toreduce greenhouse gas emissions from year 2000. [1];

2001: Intergovernmental Panel on Climate Change will reporton the latest state of science. By then climate change is expectedto be well established and measurable.

2020: if by this date the whole world is not locked into an agreementto combat climate change, the Intergovernmental Panel on ClimateChange say a series of catastrophes loom. 4

(c) Any that reduce burning of fossil fuels [1];technology: renewable energy sources for transport [1] and electricitygeneration [1]/e.g. solar HEP [1];

policy: laws to clean car engines – catalytic converters/lean burn [1]/reduce car use [1]/improve public transport [1]/energy tax [1] 5

Expression of ideas [3 max][20]

2. (a) (i) solar energy/the sun 1

(ii) evaporation 1

(b) (i)400300

× 100 = 75%

need correct answer for the mark, not necessarily working. 1

(ii)400336

× 100 = 84% 1

(c) (i) 100 – 64 or 336 – 300 = 36 × 1015 kg

Award [1] for correct answer (36) and [1] for units (1015 kg). 2

(ii) Burning fossil fuels releases more carbon dioxide/greenhousegases [1]; …which increases global temperatures [1]; … which melts ice [1];increased temp. → increased evaporation → increasedcloud cover [1]. max 3

(d) Vegetation/plants/animals/organisms/biomass/soil water [1];Appropriate mechanisms for transfer [2]/e.g. organisms – water enters by absorption through roots ordigestive system [1];water leaves by transpiration or excretion (sweating, urination) [1]. max 3

(e) (i) Condensation/precipitation/run off/groundwater flow wouldincrease (because of extra water in atmosphere) [1]

Or: run off/groundwater flow would decrease (because of

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extra evaporation from warmer surfaces) 1

(ii) (accept any two of)• increase in evaporation/condensation leads to increased

cloud cover [1]; leads to increased reflection of solarradiation/higher albedo [1];

• increase in precipitation leads to more snow [1]; leads toincreased reflection of radiation [1];

• decrease in the rate of evaporation decreases amount of watervapour entering the atmosphere [1]; water vapour is agreenhouse gas (so reducing it will reduce the greenhouseeffect) [1] and/or reducing atmospheric water vapour willreduce cloud cover [1]; and hence increase radiation loss tospace [1].

(One change in flow [3 max], two changes in flow [4 max]) 4

(iii) (Response must follow on from (e) (ii))

For increases in flow given above; feedback is negative [1]For decreases in flow given above; feedback is positive [1] 1

(If part (ii) is not answered or answer does not mention adirection of change in flow and its consequences, no creditcan be given here.)

(f) Transformation = condensation and evaporation [1];Transfer = precipitation and run off/groundwater flow [1]. 2

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3.(a) Lost from atmospheric storage by fixation by photosynthesis [1];Photosynthesis by green plants/phytoplankton/producers/autotrophs [1];Takes carbon dioxide, water, chlorophyll and light energy to make organiccompounds/glucose and releases oxygen [1];Light energy is transformed to chemical energy [1];Release by respiration [1];By animals/heterotrophs/zooplankton/decomposers [1]; producersalso respire [1];Breakdown/oxidation of organic matter using oxygen to produce energy,carbon dioxide and water [1];Release by combustion – fast oxidation of organic matter [1];Release by diffusion of carbon dioxide from the water to theatmosphere [1]/dissolves in atmosphere (rain) [1](Award marks for reasonable points e.g. examples of the above.) 8 max

(b) More C in atmosphere as carbon dioxide [1]/less C in sink as organicmolecules [1];Due to: increased burning of fossil fuels [1]/increased use of cars [1]/increased industrialisation [1];deforestation [1];increased water temperature – gases less soluble [1](Accept any reasonable activity) 4 max

(c) Effects: global warming [1];Sea temperatures rise – plankton killed [1];Ice caps melting [1]/habitats destroyed [1];possible rise in sea levels due to thermal expansion [1]/low lyinglands flooded [1]/organisms displaced [1]/ecosystems destroyed [1];

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weather patterns changed [1]/crop growth patterns altered [1];(Award marks for any reasonable answers that relate changesto the biosphere.) 5 max

Expression of ideas [3 max][20]

4. (a) a simplified description of reality;designed to show the structure or workings of an object, system or concept; 2

(b) oceanic circulation/ice/human activity/land and terrestrial features; 1[1] for any two correct.

(c) nitrogen/oxygen/carbon dioxide/water vapour/methane/ozone/other named trace gases; 2Four correct [2], three or two correct [1].

(d) solar inputs will be short wavelength, and radiation outputs will be longwavelength; 1

(e) pollutant emissions leading to photochemical smogs;increased global temperatures through burning fossil fuels;altering chemistry of precipitation through sulfur dioxide/SO2 andnitrogen oxide/NOx emissions; x depletion of stratospheric ozoneincreasing input of UV light;reducing rainfall through deforestation; 3 max

(f) strengths:it stresses the interactions (feedback) within the system;represents the complex atmosphere as a system with inputs, outputsand transfers;Accept other reasonable strengths.

limitations:nature of the interactions is not really shown;some categories are too broad to be helpful e.g. atmospheric circulation;some interactions are not shown;relative importance of different parts of the system not shown; 4 maxAnswer must refer to both strengths and limitations for full marks.

[13]

5. (a) 57 % 1

(b) the increase, or possible future increase in the average temperature of the earth’s atmosphere as the result of the build up of greenhouse gases (e.g. carbon dioxide, methane) / OWTTE; 1

(c) (i) the impact of global warming on society may be felt on a number ofscales, local, national and international. In addition the impact of globalwarming may be direct or indirect. Students should be given credit forany relevant answer demonstrating a link between global warming andsociety. Examples include: drought driven by climate change and socialstress, loss of resources, changing agricultural practice, loss of land,migration, political change and war; 3 max

(ii) sea level change will lead to coastal inundation;and perhaps coastal erosion; 2

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(d) Four correct [2], two or three correct [1].

afforestation, reducing emissions, reducing fossil fuel burning, reducing heatemissions, preventing desertification, controlling population; 2

(e) the global environment has experienced significant warming and coolingepisodes over last 20000 years;even though human industrialization occurred only in the last 200 years; 2

[11]

Topic 7 MS

1. (a) This can be argued either way, although it is more probable thatKuan Tzu was an ecocentrist. Give credit for strong justification.

Ecocentrist becausethe proverb seems to be advising taking a long-term view;clearly advocates education and ecocentrism stresses importanceof self-reliant communities;through education people will arguably learn to value theenvironment and use resources sustainably;refers to “the people” and this perhaps suggests a lack of faithin elites/authorities;

or technocentrist becauseeducation will help lead to technological development;through technology we will find longer term solutions toenvironmental problems;we need to understand natural processes in order to control them;faith in the ability of people to overcome obstacles; 4

(b) education – level and type will affect environmental awareness;economic conditions – will shape views towards environmente.g. short-term or long-term view;political context – will affect e.g. how groups in society areorganized/treated;cultural views – will affect predominant attitudes to theenvironment;religious view – holy texts/doctrine may dictate relationshipbetween people and creation/nature; 2 maxAccept other reasonable answers.

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2. (a) (i) Sustainable yield: rate of increase is natural capital/resourcethat can be exploited/taken/harvested without depleting theoriginal stock; 1OWTTE.

(ii) High: 106 tonnes and low: 106 tonnes (units required); 1Both correct values required for [1].

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(iii)

10024

2448 = 100% difference 1

(iv) low intensity;because more fish are left in the sea to breed and increase stocks/the trend in low intensity is to have larger catch in year 4compared with year 4 in high intensity; 2

(b) ignorance of how “in danger” a stock is;miscalculation of how many are available;short-term gain is more important than longer-term growth of theindustry;if starving will break the law to catch food/hard for law-keepersto monitor catch;oceans are huge/vast areas;international boundaries make legislation difficult; 2 maxAccept other reasonable responses.

(c) Terrestrial:most food harvested from lower trophic levels/as crops/plants/herbivores/ cattle etc. so less heat/respiratory losses/more efficientfixation of solar energy as does not have to get through water first/less efficient use of land area (efficiency in terms of space ratherthan energy);

Aquatic:most food from higher trophic levels/bigger fish/higher up foodchain so much energy has been lost/energy conversions moreefficient as fewer warm-blooded animals which use most energyto keep body temperature stable/more efficient use of land area(efficiency in terms of space rather than energy); 2

(d) fish farming/change fishing grounds/eat alternative food sources/new technologies to ensure immature fish not caught/less wastage/research into alternative fish species/monitoring populationnumbers carefully to check stocks/research in GM fish (suitablefor aquaculture); 1Accept other reasonable responses.

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3. (a) perhaps cartoonist is suggesting that politicians/society refuseto act because they claim that more research needs to be done first;despite the fact that evidence (falling birds) is in front of their eyes; 2Accept similar interpretations of cartoon, no need to mention acid rain.

(b) conflict might exist because different groups see the resource differently;economic value of timber/land is incompatible with leaving foreststanding for other uses (indigenous cultures);indigenous tribes need large amounts of space in which to livesustainably;reserves left for indigenous people may be too small to sustain them;forest is cut down by outsiders ignoring the needs of indigenouspeople;

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intrinsic value of forest (biorights) is ignored by exploitativeusers only interested in economic use;difference between sustainable use of forest (natural income)and users who exploit natural capital;conflict between short-term and long-term perspective(indigenous people); 3 max

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4. (a) Descriptions: [3 max]oil use in MEDCs is almost 50 % greater than in LEDCs;fossil fuels in MEDCs account for 85 % of energy use asopposed to 58 % in LEDCs;biomass use in LEDCs is more than ten times that of MEDCs;use of coal and hydro/geo/solar is the same for both;nuclear is five times more important in MEDCs than in LEDCsand is the smallest contributor in both;Accept other reasonable comparisons e.g. oil use in MEDCs is11 % more than LEDCs.

Explanations: [2 max]the relatively small contribution of nuclear power may be due tothe problems of disposing of nuclear fuel and the cost of nucleartechnology;biomass is far more important in LEDCs as fuel for cooking;automobiles are more prevalent in MEDCs thus explaining thedifference in oil use; 5 maxAccept other reasonable explanations.

(b) use of fossil fuels is unsustainable because it implies liquidation ofa limited stock of the resource;we can extend the lifetime of this resource, but it is ultimatelyunsustainable;solar energy is sustainable as the energy will be available to usfor any time frame that is reasonable to contemplate;solar energy is currently more expensive than fossil fuels;it is currently very expensive to turn solar energy into highquality energy for manufacturing;passive solar energy combined with insulation is much cheaperfor heating homes than fossil fuels;fossil fuels are the most important contributor to build up of CO2and consequently global warming;solar energy has the disadvantage that its usefulness is limitedin northern countries during winter months;oil has the advantage that it can be delivered for use far fromits source through pipelines; 6 maxAccept other reasonable answers.

(c) the Cornucopian belief in the resourcefulness of humans andtheir ability to control their environment is the chief elementin their optimism about the state of the world;fossil fuels have problems associated with their use (i.e. global warming);rely on science to find a useful alternative such as hydrogen fuel cells;good example of resource replacement;develop technology to reduce output of CO2 from fuel use rather thanchanging lifestyles to reduce use of fuel;economic systems have a vested interest in being efficient sothe existing problems will self correct given enough time;

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development (which requires energy) will increase standardsof living thus increasing demand for healthy environment;this will eventually result in lowering of CO2 emission levelsthrough market pressure;scientific efforts should be devoted to removing CO2 fromatmosphere rather than curtailing economic growth; 6 maxAccept other reasonable answers.

Expression of ideas [3 max][20] 5. (a) (i) the amount of dissolved oxygen required to break down

the organic material in a given volume of waterthrough aerobic activity; 1

(ii) [1] for each correct data point (Widnes 63 900, Ellesmere Port and Stanlow 103 000) 2

(iii) the river upstream has a much larger catchment;river upstream may flow through larger urbanareas (thus more pollution);Manchester Ship canal being a man-made structuremay be relatively closed system and not as open topollution inputs as a river network; 1

(iv) Variation could be explained by:size of urban populations;amount of industry in the area;local efforts to control population; 2 max

(b) (i) the enrichment of a body of water(normally by nitrates and phosphates)leading to a depletion in oxygen content; 1

(ii) adding detergents;sewage;agricultural fertilizers; 1

(iii) Ecocentric perspective:altering human activity producing the pollutione.g. switching to alternative fertilizers or minimizing waste;evaluation: more holistic;longer-term financial cost (paying for prevention);

Technocentric perspective:application of technology to solve probleme.g. changing treatment processes;evaluation: more specific;financial cost of technology (high initial outlay);[2 max] for ecocentric [2 max] for technocentric. 4 max

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