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Environmental systemsslp1
1. ENVIRONMENTAL SYSTEMS
STANDARD LEVEL
PAPER 1
Thursday 11 May 2000 (afternoon)
45 minutes
M00/460/S(1)INTERNATIONAL BACCALAUREATE
BACCALAURÉAT INTERNATIONAL
BACHILLERATO INTERNACIONAL
220-249 13 pages
INSTRUCTIONS TO CANDIDATES
! Do not open this examination paper until instructed to do so.
! Answer all the questions.
! For each question, choose the answer you consider to be the best and indicate your choice on the
answer sheet provided.
2. 1. Which of the following is a characteristic of K-selected organisms?
A. They are typical of pioneer communities.
B. Usually a very high percentage of young die during the early part of their life cycle.
C. Sexual maturity is reached early in the lifespan.
D. They usually have a high degree of parental care of young.
2. Leaching of soil nutrients is an example of
A. transfer of materials.
B. transformation of materials.
C. transfer of energy.
D. transformation of energy.
3. The Second Law of Thermodynamics states that in any
A. open system, entropy tends to increase spontaneously.
B. open system, entropy tends to decrease spontaneously.
C. isolated system, entropy tends to increase spontaneously.
D. isolated system, entropy tends to decrease spontaneously.
– 2 – M00/460/S(1)
220-249
3. Questions 4 to 5 refer to the diagram below which shows energy transfer in a cow.
energy
consumed
C
energy respired,
lost as heat R
energy
assimilated
secondary
productivity
SP
energy
consumed
C
energy lost
in urine U
energy lost
in faeces F
4. Secondary Productivity (SP) is
A. .C R+
B. .C (R U F)− + +
C. .C (U F)− +
D. .C + R U F+ +
5. If and , the efficiency of conversion isC kJ day= −
4000 1
SP kJ day= −
200 1
A. 50 %.
B. 10 %.
C. 5 %.
D. 2 %.
– 3 – M00/460/S(1)
220-249 Turn over
4. 6. Modern commercial agricultural practices tend to
A. lower species diversity in the community.
B. reproduce early stages of succession to maximise net productivity.
C. create conditions favourable for r-selected species.
D. do all the above.
7. Which is an example of negative feedback?
A. Loss of vegetation leading to soil erosion leading to further loss of vegetation.
B. A decline in a large predator population after they have eaten most of their prey population.
C. Melting of permafrost in the tundra due to climatic change leading to further release of methane,
causing further change.
D. Unsustainable slash and burn agriculture practices in tropical rain forests.
– 4 – M00/460/S(1)
220-249
5. 8. The graphs below show four different population growth curves.
Which best represents (i) the total human population;
(ii) a bacterial population in a laboratory;
(iii) a predator/prey relationship?
I II
population
time time
population
III IV
population
time
population
time
(i) (ii) (iii)
A. III I IV
B. III IV II
C. IV III II
D. I IV I
9. Ocean currents are an important mechanism for the transfer of energy from
A. the polar regions towards low latitudes.
B. the high latitudes towards the equator.
C. low latitudes towards high latitudes.
D. southern polar regions to northern polar regions.
– 5 – M00/460/S(1)
220-249 Turn over
6. 10. Which list below contains only components of renewable natural capital?
A. Fish, timber, cattle
B. Methane, the ozone layer, water vapour
C. Groundwater, hydroelectric power, solar energy
D. Rice, whales, diamonds
11. The Earth’s mantle is
A. beneath the crust and the core.
B. between the core and the crust.
C. above the crust but beneath the core.
D. above both the core and the crust.
– 6 – M00/460/S(1)
220-249
7. Question 12 and 13 refer to the graph below which shows human population projections by region.
(10 )9
Projected
population
0
2
8
6
4
10
12
1950 1975 2000 2025 2050 2075 21252100 2150
World total
Africa
other Asian countries
India
China
Latin America
Developed world
year
12. By approximately how many times is the world population in 2125 expected to exceed the population in
1950?
A. 5
B. 4
C. 3
D. 2
13. The projected populations from year 2000 to 2125 are:
StableFallingRisingRisingD.
FallingStableStableStableC.
FallingFallingStableRisingB.
RisingFallingRisingRisingA.
Latin AmericaDeveloped WorldChinaAfrica
14. Which interaction would benefit both organisms in a relationship?
A. Predation
B. Commensalism
C. Mutualism
D. Competition
– 7 – M00/460/S(1)
220-249 Turn over
8. Questions 15 and 16 refer to the models of population pyramids below.
IVIII
III
15. The correct labels for axes in population pyramids are
age rangepercentage of populationD.
population sizesurvival rateC.
survival ratepopulation sizeB.
percentage of populationage rangeA.
y-axisx-axis
16. Match each population pyramid with the appropriate description.
Expanding with
short-term interruption
Contracting
Expanding with
short-term interruption
ContractingD.
ExpandingContractingContractingStableC.
Expanding with
short-term interruption
StableExpandingContractingB.
ExpandingStableContractingExpandingA.
IVIIIIII
– 8 – M00/460/S(1)
220-249
9. 17. Overpopulation occurs when
A. the population level allows resources to be used sustainably, giving a good standard of living to all.
B. there are too few people in an area to use the resources.
C. resources are being used at a rate that allows them to be replaced for further harvesting.
D. the available resources cannot support the number of people in the area at a reasonable standard of
living.
18. In a survey of an antelope population, 80 antelope were marked and released. Two weeks later a second
sample was captured, of which 16 antelope were found unmarked and 4 were marked. What would be the
estimated population size?
A. 100
B. 200
C. 400
D. 1600
19. Which of the following statements is correct?
A. Ozone gas is increasing in the upper atmosphere through the action of CFCs
B. Ozone gas is increasing in the upper atmosphere because of global warming
C. Ozone gas is decreasing in the upper atmosphere because of the increase in the amount of nitrogen
oxides produced by the combustion of fossil fuels
D. None of the above statements is correct
20. Which of the following groups of organisms can convert ammonium and nitrate ions into amino acids?
A. Producers
B. Primary consumers
C. Decomposers
D. Top carnivores
– 9 – M00/460/S(1)
220-249 Turn over
10. Questions 21 and 22 refer to the data below.
Carbon dioxide Methane Nitrous oxide
0
20
40
60
80
100
120
140
160
Percent increase from 1750 to 1992
(Source: IPCC. Summary for policymakers of the contribution of working group I to the IPCC second assessment report, 1995. Intergovernmental
Panel on Climate Change. In WWF Data Bulletin on Climate Change.)
21. These gases cause the Greenhouse Effect because they are
A. more effective at absorbing long-wave radiation than other gases in the atmosphere.
B. more effective at absorbing short-wave radiation than other gases in the atmosphere.
C. produced by human activities.
D. not broken down in the atmosphere.
22. Greenhouse gases not listed above are
I. sulfur dioxide.
II. CFCs.
III. low level (tropospheric) ozone.
IV. water vapour.
A. II and III
B. II, III and IV
C. I, II and III
D. I, II, III and IV
– 10 – M00/460/S(1)
220-249
11. 23. Net Primary Production is the amount of energy
A. produced from ‘alternative’ sources in developing countries.
B. fixed in an ecosystem by photosynthesis.
C. fixed in an ecosystem by photosynthesis, minus the losses due to respiration by producer organisms.
D. fixed by the herbivores in an ecosystem.
24. Two ecosystems have the following abundance of species:
343333Ecosystem Y
2395Ecosystem X
Species RSpecies QSpecies P
Number of individuals
Which of the statements below is correct?
A. Ecosystem X has the highest species diversity as one species is more numerous than the other
B. Ecosystem Y has the highest species diversity because this is a measure of both the number of
species and their abundance
C. The species diversity of both ecosystems is equal as they both have three species
D. Ecosystem Y has the highest species diversity because there is no competition between species
25. Which of these statements is correct?
A. The formation of ozone involves the absorption of ultra-violet radiation
B. Ozone is destroyed by carbon dioxide released by burning fossil fuels
C. The type of ultra-violet radiation absorbed by the ozone layer does not affect living organisms
D. Chlorofluorocarbons in the stratosphere are rapidly broken down allowing them to escape into the
outer atmosphere
– 11 – M00/460/S(1)
220-249 Turn over
12. 26. A lake with a stream flowing into it, but with water lost only by evaporation, is an example of a system
which is
A. isolated.
B. stable and closed.
C. unstable and closed.
D. open.
27. Most food chains seldom have more than four trophic levels because
A. in most ecosystems, competition for food is very great.
B. the total biodiversity in any ecosystem is limited.
C. energy is lost as it moves along a food chain and little remains at the level of the top carnivore.
D. in many parts of the world, many species have become extinct and complex ecosystems are rare.
28. Natural Increase Rate of a human population is
A. number of immigrants per year.
B. .number of immigrants number of emigrants per year−
C. .
crude birth rate crude death rate−
10
D. .
crude birth rate crude death rate+
10
– 12 – M00/460/S(1)
220-249
13. Questions 29 and 30 refer to the graph below.
0
20
40
60
80
100
I
II
III
IV
Altitude
(km)
29. The highest concentration of ozone is between
A. 0–10 km.
B. 10–20 km.
C. 20–40 km.
D. 40–80 km.
30. The troposphere is
A. I.
B. II.
C. III.
D. IV.
– 13 – M00/460/S(1)
220-249
15. 1. D 16. B 31. - 46. -
2. A 17. D 32. - 47. -
3. C 18. C 33. - 48. -
4. B 19. D 34. - 49. -
5. C 20. A 35. - 50. -
6. D 21. A 36. - 51. -
7. B 22. B 37. - 52. -
8. B 23. C 38. - 53. -
9. C 24. B 39. - 54. -
10. A 25. A 40. - 55. -
11. B 26. D 41. - 56. -
12. B 27. C 42. - 57. -
13. A 28. C 43. - 58. -
14. C 29. C 44. - 59. -
15. D 30. A 45. - 60. -
– 2 – M00/460/S(1)M
16. ENVIRONMENTAL SYSTEMS
STANDARD LEVEL
PAPER 2
Thursday 11 May 2000 (afternoon)
1 hour
M00/460/S(2)INTERNATIONAL BACCALAUREATE
BACCALAURÉAT INTERNATIONAL
BACHILLERATO INTERNACIONAL
220-250 12 pages
INSTRUCTIONS TO CANDIDATES
! Write your candidate name and number in the boxes above.
! Do not open this examination paper until instructed to do so.
! Section A: Answer Section A in the spaces provided.
! Section B: Answer one question from Section B. You may use the lined pages at the end of
this paper or continue your answers in a continuation answer booklet, and indicate
the number of booklets used in the box below. Write your name and candidate
number on the front cover of the continuation answer booklets, and attach them to
this question paper using the tag provided.
! At the end of the examination, indicate the number of the Section B question answered in the
box below.
Number
Name
TOTAL
/40
TOTAL
/40
TOTAL
/40
NUMBER OF CONTINUATION
BOOKLETS USED . . . . . . . . .
/20/20/20SECTION B
. . . . . . . . .
/20/20/201SECTION A
IBCATEAM LEADEREXAMINERQUESTIONS ANSWERED
17. SECTION A
This question must be attempted by all candidates in the spaces provided.
1. The table below shows annual production and respiration in in five ecosystems.kcal m year− −2 1
020002100290014400
Net Community
Productivity (NCP)
13000680030004600800
Heterotrophic
Respiration (HR)
Net Primary
Productivity (NPP)
3200012000640047009200
Autotrophic Respiration
(AR)
4500020800115001220024400
Gross Primary
Productivity (GPP)
EDCBAEcosystem
Net Community Productivity Productivity (SP)( ) ( )NCP Net Primary Productivity NPP Secondary= +
Ecosystems:
A = Alfalfa grass field
B = young pine plantation
C = medium aged oak-pine forest
D = large river
E = mature tropical rainforest
[Adapted from Odum, E. P. (1975) Fundamentals in Ecology, Saunders & Co.]
[1](a) (i) Define the term community in ecology.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[2]
(ii) Identify the ecosystem above which is likely to have the greatest species diversity.
Give a reason for your answer.
Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(This question continues on the following page)
– 2 – M00/460/S(2)
220-250
20. SECTION B
Answer one question. You may use the lined pages at the end of this paper or continue your answers in a
continuation answer booklet. Write your name and candidate number on the front cover of the continuation
answer booklets, and attach them to this question paper using the tag provided.
Each essay question is marked out of a total of 20 marks of which 3 are for the expression and development of
ideas as follows:
0 No expression of relevant ideas.
1 Expression and development of relevant ideas is limited.
2 Ideas are relevant, satisfactorily expressed and reasonably well developed.
3 Ideas are relevant, very well expressed and well developed.
2. 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 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.
[Data from WWF bulletin, Population and Resources, 1996.]
[6]
(a) Define natural capital and discuss the implications of the information above for its
exploitation.
[8](b) Discuss four reasons why educating women might reduce the birth rate in India.
[3](c) Explain, with examples, how national policies could affect human population growth.
[3]Expression of ideas
– 5 – M00/460/S(2)
220-250 Turn over
21. 3. Below is a diagram of the nitrogen cycle.
atmosphere
water
soil organisms
plants and
animals
rock
agriculture and
land drainage
industry and
transport
aquatic
organisms
seabed
sediment
Each year about 175 million tonnes of nitrogen are biologically fixed and about 40 million tonnes of
nitrogen are produced artificially.
[7](a) Explain the roles of the biotic phases in this cycle.
[3](b) What is the role of energy in this cycle?
[7](c) What effects have human activities had on the nitrogen cycle?
[3]Expression of ideas
– 6 – M00/460/S(2)
220-250
22. 4. 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).
Carbon emissions (Mt)
US
China
Russia
Japan
Germany
India
UK
Ukraine
Canada
Italy
0
200
400
600
800
1000
1200
1400
Graph B: Total carbon emissions (tonnes) per capita for the top ten emitting countries.
Carbon emissions per capita (tonnes)
US
China
Russia
Japan
Germany
India
UK
Ukraine
Canada
Italy
0
1
2
3
4
5
6
[Source: Brown, L. R. et al, State of the World, 1996, Earthscan.]
[8](a) Comment on the significance of these data.
[4](b) Describe the international agreements that aim to reduce the amount of carbon emissions.
[5](c) What technologies and what policies might reduce the amount of carbon emissions?
[3]Expression of ideas
– 7 – M00/460/S(2)
220-250
29. SECTION A
[1]
[1]
[1]
1. (a) (i) A group of populations living and interacting with each other in a common
habitat (or any reasonable alternative).
(ii) Ecosystem E/mature tropical rain forest
Reason: any of
climax community/higher habitat diversity/higher production base
(or any reasonable alternative).
[1]
(b) Any three of: solar radiation or light/ precipitation or water/ temperature/ pH/ soil
type/ climate. (But do not allow climate and either precipitation or temperature or
both for the mark.)
[1](c) (i) 15200
(ii)
14400
24400
100 59× = %
[2]
[2]
[2]
correct answer [1]; correct working [1]
(iii) It is not a climax community [1]/ is a crop in a managed system [1];
has high inputs of fertiliser [1]/
and pesticides to eliminate food chains [1]/
energy subsidy [1]
(iv) high rate of respiration as temperature is high…[1]/
…. Production is lost in respiratory losses [1];
All NPP is used in HR [1]
or reasonable alternative explanation.
[3]
[3]
[3]
(d) (i) Increase in CFCs leads to loss of ozone layer [1];
more UV radiation damage to producers [1];
less photosynthesis so less GPP [1]
(ii) Acid deposition reduces tree growth [1]/
trees die back [1];
Al ions cause brittle stems [1];
increasing acidity of soil reduces NPP [1].
(iii) Global warming [1];
as increased levels in atmosphere [1];CO2
as reduced sink for carbon [1]
Total [20 marks]
– 6 – M00/460S(2)M
30. SECTION B
General Essay Markscheme
Each essay is marked out of 20 of which 3 are for expression and development of ideas (EDI).
0 No expression of relevant ideas.
1 Expression and development of relevant ideas is limited.
2 Ideas are relevant, satisfactorily expressed and reasonably well developed.
3 Ideas are relevant, very well expressed and well developed.
[6]
2. (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 capital and income [1];
more people need more goods and services and as living standards improve, more is
required [1];
pricing of natural capital is only in terms of economics – conflicting values [1].
or appropriate arguments.
[8]
(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 that increasing girls’
secondary schooling from 4 to 16 % would increase the women’s labour force by
over 12 %. [1]/
– educated women are more confident [1];
Discussion e.g. studies from India found literate women expected and received
better treatment at clinics and hospitals. Research in Bangladesh found educated
women communicated more with their husbands and have a greater say in family
decisions than uneducated women. [1]/
– educated women use family planning [1];
Discussion e.g. it has been estimated that giving 1000 girls an extra 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 additional year 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.)
continued…
– 7 – M00/460S(2)M
31. Question 2 continued
[3]
(c) (Award marks for detailed discussion of a named policy or appropriate discussions
of several policies).
For example, Indian policy of enforced sterilisation probably had little effect on
birth rate [1]/ transistor radios and compulsion failed in India [1]/but decreased rates
of infant mortality due to better 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]/
Expression of ideas max [3 marks]
Total [20 marks]
– 8 – M00/460S(2)M
32. [3]
Candidates may include human processes here instead of in part (c).
(Award marks if valid points but obviously do not award twice.)
(b) energy drives the cycle of materials [1];
is driven by energy ultimately from solar radiation [1];
and lightning [1]/
human input of energy from the Haber process and fertiliser manufacture [1].
[7]
3. (a) (Names of bacteria are not required to gain full marks).
Biotic = living, so bacteria, fungi, plants and animals [1];
N fixation by bacteria with nitrogenase enzyme either free-living (90 %)
(Azotobacter, Nostoc) or Rhizobium (symbiotic with roots of legumes) – fix
atmospheric nitrogen to ammonium ions [1];
Nitrification by bacteria if oxygen present:
ammonium ions (Nitrosomonas) to nitrite (Nitrobacter) to nitrate [1];
Plants take up N as ammonium and nitrate ions [1];
convert to proteins which make up the structure of the cell [1];
Plants eaten by animals and amino acids rearranged to form other proteins [1];
Putrefaction/decomposition – breakdown of dead organisms by bacteria and fungi
of nitrogen compounds back to ammonium ions [1];
Denitrification – (Pseudomonas denitrificans) converts nitrate to nitrogen [1];
biotic phases store N briefly [1];
Excretion by organisms [1].
[7]
(c) large scale use of ammonia fertilisers converts nitrogen gas to ammonia – alters
balance [1];
use of excess fertiliser on land leads to leaching loss – contamination of water
supplies and eutrophication [1];
nitrogen oxides from car exhausts – released from fossil fuels [1];
nitrogen oxides contribute to acid deposition – affects food chains [1] and solubility
of other minerals by change of pH [1];
high N levels increase NPP at first [1];
alter balance of ecosystems [1];
ammonia from animal urine [1];
increase in food production [1];
human activity speeds up the cycle [1]
Expression of ideas max [3 marks]
Total [20 marks]
– 9 – M00/460S(2)M
33. [8]
4. (a) C emissions increase carbon dioxide in the atmosphere which is a 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].
[4]
(b) Agreements award up to [4 marks] but must have specific agreements. The
material below is for information. 1990, Geneva: scientists on Intergovernmental
Panel on Climate Change say 60 % reduction in current carbon dioxide levels
required. [1];
1992, Rio de Janeiro Earth Summit: politicians from 150 countries sign Climate
Change Convention. Its purpose is to slow down climate change 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 levels down to 1990
levels by year 2000. Developing countries make no commitments. [1];
March 1995, Berlin: politicians hold climate summit. Agree that measures
previously agreed to meet the Convention’s goals are inadequate, but defer action
on cutting emissions. Agree that legally binding reduction targets for the early 21st
century should be ready for signing by industrialised countries by 1997. There are
to be no commitments for the developing world. [1];
December 1995, Rome: scientists complete Intergovernmental Panel on Climate
Change second report. Agree for the first time that humans are discernibly altering
the climate. Again warn that 50 to 70 % cuts in Greenhouse gases are required. [1];
October 1996, Paris: International Energy Agency says the great majority of
developed countries will fail to keep Rio Earth Summit promises to stabilise carbon
dioxide emissions. [1];
December 1997, signing of Kyoto Protocol: make or break meeting for Rio’s
Climate Change Convention. New agreement needed to reduce greenhouse gas
emissions from year 2000. [1];
2001: Intergovernmental Panel on Climate Change will report on the latest state of
science. By then climate change is expected to be well established and measurable.
2020: if by this date the whole world is not locked into an agreement to combat
climate change, the Intergovernmental Panel on Climate Change say a series of
catastrophes loom.
[5]
(c) Any that reduce burning of fossil fuels [1];
technology: renewable energy sources for transport [1] and electricity generation
[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]
Expression of ideas max [3 marks]
Total [20 marks]
– 10 – M00/460S(2)M
34. ENVIRONMENTAL SYSTEMS
STANDARD LEVEL
PAPER 3
Friday 12 May 2000 (morning)
1 hour 15 minutes
M00/460/S(3)INTERNATIONAL BACCALAUREATE
BACCALAURÉAT INTERNATIONAL
BACHILLERATO INTERNACIONAL
220-251 10 pages
INSTRUCTIONS TO CANDIDATES
! Write your candidate name and number in the boxes above.
! Do not open this examination paper until instructed to do so.
! Section I: Answer one Option from Section I in the spaces provided.
! Section II: Answer two Options from Section II in the spaces provided.
! You may continue your answers in a continuation answer booklet, and indicate the number of
booklets used in the box below. Write your name and candidate number on the front cover of
the continuation answer booklets, and attach them to this question paper using the tag provided.
! At the end of the examination, indicate the letters of the Options answered in the boxes below.
Number
Name
TOTAL
/45
TOTAL
/45
TOTAL
/45
NUMBER OF CONTINUATION
BOOKLETS USED . . . . . . . . .
/15/15/15SECTION II
. . . . . . . . .
/15/15/15SECTION II
. . . . . . . . .
/15/15/15SECTION I
. . . . . . . . .
IBCATEAM LEADEREXAMINEROPTIONS ANSWERED
35. SECTION I
Options on analysing ecosystems – Options A, B and C
The compulsory question below relates to the detailed study of an ecosystem in either a marine, terrestrial or
freshwater environment.
Select the ecosystem on which you will base your answers by marking (×) one box only.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
estuariesmarshesswampsbogsriverslakesFRESHWATERC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
tundradesert
temperate
grassland
tropical
grassland
temperate
forest
tropical
forest
TERRESTRIALB
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
coral reefsmangroveslittoralbathyalneriticpelagicMARINEA
– 2 – M00/460/S(3)
220-251
45. 1. Matrix should be ticked (checked) with the ecosystem that the candidate has studied. No
marks given for this (or removed if not completed), but candidates should answer in
relation to system indicated. If no system indicated, make very sure answers are
consistent.
Also no mark awarded for naming an organism but answers must follow on.
[5]
(a) Up to [3] for: names of predators [1]/ herbivores [1]/ food sources [1] (note a plant
obtains nutrients from soil, etc.)/ disease organisms [1]/competitors [1];
Up to [2] for: interrelationships such as that between disease and predation;
predation and food supply [2];
Not all links need to be discussed; full marks could be obtained with detailed
discussion of one or two.
[4]
(b) identification of trophic levels [1]; arrows correctly shown [1]; names of six
organisms [1]; clear diagram [1]. (Marks for six organisms - i.e. five plus the “named”
organism - allowed.) Note: Sunlight is not an organism.
[3]
(c) measure out area [1]/ harvest method [1]; collect and weigh material [1]/ air dry
where appropriate [1]/ allowances for underground material etc. [1]; for certain
organisms collect and weigh sample and determine number per unit area [1]/
calculation of result [1].
In the case of an animal: catch and count [1]/ weigh organisms [1]/ kill organisms
and dry tissues [1]/ or (with ethical considerations in view) obtain values for water
content from published source [1].
[3]
(d) measure out area [1] collect and weigh at start… and end of season [1]; allowances
for respiration/predation/herbivory/underground material [1];
dark and light bottle method where appropriate [2]; calculation of result [1].
In the case of an animal: weigh amount of food eaten by animals [1]/ weigh amount
of faeces produced [1]/ obtain caloric value for tissues [1]/ by experiment (calorimeter)
or from published source [1].
– 6 – M00/460/S(3)M
46. [4]
2. (a) Up to [2] for: Describe: steady increase from zero in 1916 to peak in
approx. 1935 [1]; thereafter decline to 1963 [1]/.
Intermediate short-term declines [1]/ very approx. ‘J’ curve [1];
Up to [2] for: Explain: rapid increase in exploitation of new resource [1]../… or
possible increase in population [1]; decline due to unsustainable
harvesting [1]/intermittent short-term declines due to WWI [1]/Depression of
1930s [1] WWII [1] stock almost exhausted by 1960s [1].
[2]
(b) One of each for both marks.
Advantages: source of protein [1]/ source of oils and vitamins [1]/ waste materials
can be used for fertilisers or feedstock for animals [1]/ some kinds of fish (at least
formerly) relatively cheap [1].
Disadvantages: overfishing depletes resources [1] (e.g. North Sea)/ interferes with
natural food-chains [1] (reduction of albatrosses)/ many non-target organisms killed
[1] (seabirds, dolphins)/ other interference in marine environment [1]/ uses a lot of
energy in relation to food obtained (i.e. high level of energy subsidy) [1]/ now quite
expensive in some cases [1].
[6]
(c) Systems – e.g. prairie cereal farming and subsistence cereal growing in SE Asia;
salmon farms and subsistence fishing; or any comparable alternatives [1];
Efficiency in terms of costs/ energy/ other inputs [1];
Inputs of energy (electricity, fuels, chemicals, feedstock – ‘energy subsidy’) [1];
Outputs of energy (heat, crops, reusable materials) [1];
Relationship of length of food-chain to energy-flow [1];
Impacts on environment: pollution/ nutrient build-up/eutrophication/ waste
production/ use of land/ amenity (smells etc.) [1];
Allow for reasonable alternatives.
[3]
(d) Represents possible cheap source of protein [1];
Extra link in food-chain so wasteful [1]/ loss with each trophic level [1]/ “10% transfer
rule” [1]/ better to use the fish protein directly [1]/ energy required in processing [1];
may be non-sustainable [1].
– 7 – M00/460/S(3)M
47. [1]3. (a) (i) Northern Andes
[1](ii) Amazon Basin
[2]
(iii) Overall figures are high [1]/ high productivity [1]…/… and structural
complexity of tropical ecosystems [1];
Northern Andes high biodiversity due to genetic isolation on mountain
summits and in remote valleys [1]/ range of environments due to altitudinal
variation [1]/ Amazon Basin a relatively homogeneous environment [1];
Any reasonable alternative. [Must have something more than ‘tropical forest
ecosystems are complex’ for both marks.]
[2]
(b) (i) A species of organism, of which numbers are so low that there is a likelihood
of its becoming extinct in the near future/owtte [1]; named species [1];
[IUCN definition = taxa in danger of extinction and whose survival is unlikely
if causal factors continue operating. Includes taxa with numbers at a critical
level; those with drastically reduced habitats; and those not seen in the wild in
the past 50 years.]
[3]
(ii) Any three of: small numbers [1]/ restricted distribution [1]/ complex
migration patterns [1]/ complex breeding cycle [1]/ reduced habitat [1]/ low
rate of reproduction [1]/ hunting pressure [1]/ economic value [1]/ or
reasonable alternatives.
[3]
(c) Any 3 ways with examples [1] each, e.g.
Protective legislation (koala in Australia in early 20th century) [1];
International treaty (CITES) (Green Amazon parrots) [1];
Breeding programmes (numbats in Australia/pandas) [1]/ protection of habitats
(whooping crane in USA) [1];
Any reasonable alternative
(2 ways, but no examples = [1])
[3]
(d) Natural selection = a mechanism of evolution [1]/ caused by removal of ill-adapted
individuals and survival of those adapted to the environment [1]; evolution in long
term → biodiversity by filling available niches [1]; isolation (cutting off islands/
formation of mountains etc.) separates populations [1]/ changing environment may
create isolated populations [1]/ climatic change may trigger adaptation to new
conditions [1].
– 8 – M00/460/S(3)M
48. [1]
4. (a) (i) measuring something affected by pollution rather than measuring the
pollution itself [1] owtte.
[4]
(ii) Site A has almost no organisms associated with well oxygenated water, but
very large numbers of chironomids/tubificid worms able to tolerate low
oxygen levels [1];
Site B has good numbers of mayfly, caddis larvae, beetles, and even a few
fish, associated with high oxygen levels [1];
max [2] for descriptions;
Input of sewage (or similar waste) near site A causes abundance of nutrients
(especially N and P)/ … → eutrophication [1]/ → oxygen depletion [1];
turbulence of stream/ dilution by incoming tributaries… allows
oxygenation [1]/ .. so site B has higher oxygen levels/
The few chironomids/tubificids at site B may be brought downstream by
current [1].
[1]
(iii) Any 3 of: N/ P/ pH/ turbidity/ temperature/ current speed / sunlight / salinity /
any reasonable alternative, not oxygen.
[4]
(b) Allow [1] each for 3 measures and extra [1] for more details.
remove heavy metals [1]/ separation of slurry [1]/ oxygenate artificially [1]…/ .. by
pumping in air [1]/ separate out industrial waste at source [1]/ pump effluent
elsewhere – into sea or underground [1]/ regular monitoring [1]/ any reasonable
suggestion.
[5]
(c) Allow [1] for mention of baseline study and for consideration of use of×[2 2]
glasses and ceramic mugs versus plastic cups.
Baseline: evaluation of present situation. [1];
costs of washing and drying [1]/ energy costs of washing and drying [1]/
replacement costs of items stolen or broken [1]/ amount of detergent used in
washing [1]/ environmental impact of detergent in effluent [1]/ quantity of water
used [1]/ energy costs in manufacturing [1];
Alternative: financial cost of plastic cups [1]/ how many? [1]/ energy cost of
manufacturing cups [1]/ and of transport from factory to school [1]/ use of
non-renewable resources in manufacture [1]/ disposal of plastic cups/ if burnt → air
pollution, dioxins [1]/ are they biodegradable? [1].
Or alternative valid points. Note: this is a techniques question and a simple account of
the advantages and disadvantages of plastic cups is not what is required.
– 9 – M00/460/S(3)M
