Download TOPIC 2 - MARKING SCHEME - International School Bangkok

TOPIC 2 – ALL QUESTIONS MARKING SCHEME
(a)
(b)
(i)
Northern Andes
1
(ii)
Amazon Basin
1
(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
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.]
2
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
(i)
(ii)
(c)
(d)
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
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].
3
[15]
(a)
(b)
Population B: as ecological footprint is smaller than population [1]/
are living sustainably [1].
1 max
Award [1] for each two correct items.
Per capita CO2 production/per capita land requirement for
absorbing waste CO2 from fossil fuels/rate of absorption of
CO2 by local vegetation per unit area/per capita food
consumption/rate of food production locally per unit area/
population number.
(If candidate states total population CO2 production and food
consumption, then population number is superfluous.)
Other correct answers are acceptable but those above are on syllabus.
(c)
(d)
(e)
Any two of: lower latitudes – higher net productivity in local
vegetation – so smaller ecological footprint for the same CO2
output [1]/low latitudes may provide better conditions for
food production – so smaller ecological footprint to supply
same food production [1]/higher latitudes have lower
temperatures – greater need for energy sources – greater CO2
wastes – larger ecological footprint [1].
2
Population A [1];
because it takes a greater area than that available to sustainably
supply its resources [1].
2
(i)
(ii)
(f)
2 max
Allow any two of:
one population might use intensive farming techniques [1]/
monoculture [1]/use of fertilizers [1]/pesticides [1].
Allow for ECF from (a) and (d).
2 max
intensive farming techniques would lead to greater food
production per unit area [1]; so smaller footprint [1]/
eating more food or more meat would require more
agricultural production [1]; so larger footprint [1] OWTTE.
2 max
Sustainability up to [2]
fossil fuel use is unsustainable as a non-renewable resource [1]/
as rate of consumption > rate of renewal [1];
hydroelectricity – sustainable as replenishable [1]/water cycle
continues through input of solar energy [1];
Impacts up to [2]
fossil fuels – CO2 release increases global warming [1]/SOx
and NOx causing acid rain [1]/NOx causing ozone depletion [1];
hydroelectricity – building of dams floods and destroys
ecosystems [1]/reduces downstream flow rates [1]/reduces
downstream flood plains [1]/blocks fish migration [1].
4 max
[15]
(a)
(b)
(c)
Biodiversity is the variety of forms of life on earth [1];
encompasses species, habitat and genetic diversity [1]/generic
term for the abundance of and number of species on earth.
2 max
Habitat diversity – if the habitat is destroyed, there is nowhere
for the species to live [1]/conservation of habitats leads to
conservation of species and genetic diversity [1].
1 max
(i)
(ii)
Disturbance by humans reduces habitat diversity [1]/habitats
lost as humans clear vegetation/build cities [1];
most live in temperate forest zone so most disturbed here [1]/
most disturbed is temperate forests [1]; – logged and cleared
by humans for last few thousand years [1]/most converted
to crop land [1];
diversity much reduced as habitats lost [1];
tropical rainforest highest diversity [1]; as least limiting factors [1];
most threatened at present [1];
desert and tundra have lower diversity as conditions more
limiting [1];
tundra least threatened at present [1]; desert nearly half disturbed.
Accept any appropriate argument for any of the four ecosystems.
e.g. tropical rainforest – under most pressure from humans in
clearing and burning the forest [1]; highest species diversity/
many ecological niches [1];
e.g. desert - productivity easily damaged [1];
long recovery time [1]/more disturbed areas [1].
(d)
(e)
6 max
2 max
For named example award no marks, but award [1] for each
valid reason up to [2].
e.g. Dodo – ground-living/tame so vulnerable/small total
population/hunted by sailors as food.
2 max
e.g. World Heritage sites to protect habitats such as south-west
Tasmania/coastline of north-east England [1]; education of the
public by conservation organisations – WWF publicising pandas [1]/
any valid example [1].
2 max
[15]
(a)
(b)
Description [1]; explanation [2]. Number of species inversely
proportional to altitude [1]/Lower the altitude, more bird species [1];
at higher altitudes, temperature decreases so less NPP and so less
food for birds [1]; less species at 3000 m and over as there is less
land at these heights [1]/less ecological niches at altitude so less
diversity [1]/low biological productivity of high altitude
ecosystems [1] 0–500 m may include sea birds [1]/any
reasonable explanation [1]
Habitat diversity – the range of different habitats per unit area [1];
Species diversity – the heterogeneity of species in a given area [1]
3 max
2
(c)
(d)
(e)
Award [1] for each of two reasons.
e.g. because it is morally right to do so/aesthetic reasons/because
humans use other species for medicine/crops/food/drugs/
resources/because the gene pool is reduced if species become
extinct/some uses of species not yet discovered
2 max
Award [1] for each of three reasonable characteristics.
e.g. large enough area for a viable population of top carnivores [1]/
in one block of land/water that is not spread out but compact in
shape [1]/minimise edge:area ratio [1]/corridors between smaller
areas [1]/legislation/purchase of land to protect it [1]/agreement
of humans living in or around the area [1]/minimise harmful
edge effects [1]/variety of habitats [1]
3 max
Award marks for any reasonable changes described (positive
or negative).
e.g. increase in landscape variation to increase range of habitats [1]/
planting of more trees/bushes [1]/digging of ponds [1]/active
management to prevent deterioration [1]/education of humans
living nearby [1]
or
spreading of exotic species from cultivated areas/towns
nearby (e.g. weeds, feral cats) [1]/farm land runoff causing water
pollution [1]/disturbance of wildlife by humans [1]/contamination
of forest ecosystems by pesticide [1]/burning and development
of fire-tolerant species and ecosystems [1].
(f)
Award [1] for brief description of named area and up to [2] for
management strategies.
2 max
3
[15]
(a)
(b)
(c)
(d)
a general term for diversity;
which includes species, habitat and genetic diversity;
per unit area;
2 max
Allow [1] for each two arguments e.g.
ethical/aesthetic/genetic resource for humans/commercial
resources/life-support functions/maintain ecosystem stability/
conserve rare habitats;
2 max
Allow any three of the following.
isolation – geographic or reproductive;
changing environments;
variation in populations;
mutation in populations;
natural selection;
survival of the fittest;
competition;
3 max
advantages
easier to involve humans in identification of attractive species/
e.g. WWF and pandas;
breeding programmes in zoos → increasing population numbers;
possible to control international trade/CITES;
disadvantages not protecting habitats;
organisms cannot survive if not in habitat;
only focuses on endangered/conspicuous/attractive species;
led by public opinion;
(e)
4 max
Allow [1] for each pair considered. Allow for any reasoned argument.
might support greater species diversity/higher population numbers
of each species/greater productivity at each trophic level → longer
food chains;
edge effect increased in B → risk of disturbance/drift of pollutants/
greater productivity → more top carnivores in A/territory greater for
top carnivores in A/smaller units in B cannot support as high
biodiversity as A;
gene flow between reserves easier in A/movement of species
easier – top carnivores/can move between reserves in A;
edge effect lower in A/perimeter : area ratio lower in A (see also (2)
above)/smaller units in B cannot support as high diversity as A;
4
[15]
(a)
(b)
(c)
(d)
the mass (or weight) of organic material in organisms or ecosystems,
usually per unit area (glossary definition)/OWTTE;
organisms vary enormously in the proportion of water they contain,
so the biomass less water is usually given/OWTTE;
to facilitate comparison of data from different sources;
Award [1] each for three of the following.
curve fluctuates seasonally;
high values (approximately 2.2–2.6) in April–May and
September–October;
i.e. in southern hemisphere spring and autumn;
low value in January;
in southern hot summer;
other low points May–August;
i.e. in southern winter;
fluctuations may reflect life-cycles of insects;
and/or variations in plant productivity;
peaks may represent carrying capacity;
troughs may be result of predation;
Any other reasonable points.
Award [1] each for four of the following.
If there is no evaluation, award [3 max].
select random quadrats using random number tables/computer;
collect plant material from quadrat;
dry material in an oven;
1
1 max
3 max
or use tables to extrapolate dry weight values;
repeat at regular intervals through year;
ideally take several samples each time and calculate mean;
problems with very large plants (trees);
problems with roots and underground biomass;
Any other reasonable points.
4 max
[9]
(a)
Allow any reasonable method.
description of method for non-motile organism (plants, mussels):
measure area;
use of quadrats;
count organisms within area;
calculate number per unit area;
evaluation:
problems such as organisms part-in/part-out of quadrat;
difficulties of very large organisms (e.g. trees);
problem of organisms where it is impossible to clearly distinguish
individuals (e.g. some plants);
for motile organisms:
measure out area/use naturally limited area such as small pond;
use Lincoln index;
trap organisms and mark;
release and allow to mix with population;
retrap, counting number of marked individuals;
use formula to calculate number
no. marked at t1  no. captured at t 2
population =
;
no. marked organisms caught at t 2
use aerial photos for large organisms (trees; possibly waterfowl);
evaluation:
e.g. for Lincoln index method: problem of births and deaths
between trappings;
inward or outward migration;
some organisms become habituated to trapping/“trapshy”;
5 max
Generally [3] for description and [2] for evaluation unless
account of method is very detailed; in which case up to [4]
may be awarded for method and [1] for evaluation.
No mark for organism’s name; it is intended simply to focus
attention. However, responses must apply to organism selected
– if not mark out of [3].
(b)
(c)
some indices of diversity/e.g. Simpson’s index;
take account of both the abundance of species in an ecosystem
and the number of different species present;
carefully observe/measure specimen (colour, length, number
of limbs) etc.;
2
use key/by working through logically comparing characteristics
of specimen with those in key;
compare specimen with illustrations in field guide/reference
collection or herbarium;
characteristics such as sound (birds, insects)/distribution/
time of year;
good practice recommends that as far as possible identification
should be done in the field and removing/killing/picking
specimens should be avoided;
any other reasonable answers;
(d)
(i)
name of ecosystem and brief description
Must be reasonably specific: “lake” is insufficient; “Lake
Neerabup, north of Perth, Western Australia” gets the mark.
(ii)
(iii)
(iv)
(v)
(e)
(i)
(ii)
2 max
description of human activity;
must be appropriate to example: for above, “cultivation of
peat surrounding lake for vegetable-growing”;
1
1 max
abiotic factors: e.g. temperature/turbidity/pH/salinity
Must be appropriate.
1
must establish clear link between activity and factor;
and indicate direction or nature of change (e.g. increase
or decrease);
2
for above lake example: test pH by noting colour
change using pH-testing kit;
perform a number of tests and take mean;
ideally test before and after change and note difference;
and at different sites;
Method must be appropriate to example.
Any reasonable example allowable. No marks if response
gives a biotic factor.
2 max
the change in some factor or factors (biotic or abiotic) over
a distance/OWTTE;
such as the change in the amount of time organisms are
exposed to air across the distance from high tide mark to
the extremes of low tides on a seashore;
any other reasonable example;
2 max
mark out transect across gradient using tape or similar;
establish quadrats at appropriate distances apart along transect;
apply (Simpson’s) diversity index to each quadrat;
N ( N  1)
D=
;
n(n  1)
where D = diversity index, N = total number of organisms
of all species n = number of individuals of a particular species;
2 max
Allow [1] if diversity index is well explained, even if the
concept of environmental gradient is misunderstood
Responses need not have formula completely accurate for
full marks, providing method is clearly understood.
[20]
(a)
(b)
(c)
(d)
describe:
very low numbers of extinctions before 1650;
slightly higher number 1651 to 1850/approximately 0.5 species
per year;
rapid increase 1851 to 1950/approximately 2.5 per year;
decrease in extinction rate since 1951 to approximately one
species per annum;
2 max
explain:
extinction rate before 1850 low as human effect on biodiversity low
as population pressure on environment relatively low;
extinctions before 1850 not fully recorded;
extinction rate 1851 to 1950 much higher due to rapid human
population increase;
and rapid rate of habitat loss;
decrease in extinction rate since 1951 due to greater efforts to
protect endangered species and ecosystems;
or many vulnerable species already extinct;
any other reasonable points;
3 max
low total numbers/long or complex migration route/specialised
habitat/specialised food sources/widely hunted or otherwise
used by humans/low reproduction rate/large number of
predators/susceptibility to disease/limited distribution/
catastrophe such as flooding or meteor impact;
any other reasonable points;
Responses need two factors per mark.
Factors must be specific to extinction of organisms. No credit for
vague answers such as “global warming” or “degradation of
environment”.
2 max
endangered:
species in danger of becoming extinct in the immediate future
because their numbers have declined to a critical level;
extinct:
species believed to no longer exist alive;
2 max
Any reasonable example: reasons must be appropriate to example.
[1] for name and [2] for reasons e.g.
name: Dodo;
reasons: confined to small island (Mauritius);
extreme tameness;
hunting as a source of food by visiting sailors;
destruction of forest habitats;
competition with introduced organisms, e.g. pigs;
3 max
Note: recent research has suggested that dodos were not very tame
and that the flesh was unpleasant to taste; thus habitat
destruction and introduction of pigs (and rats) were
probably most significant factors. However, the points
given above are widely mentioned in the literature and
may be considered acceptable responses.
(e)
(i)
(ii)
(f)
[1] for name, [1] for brief description e.g.
Kakadu National Park, Northern Territory, Australia;
tropical savanna with extensive wetlands;
2 max
Any reasonable examples, but must have some evaluation
for full [5] marks.
For above example:
measures:
designation as World Heritage Area by UNESCO;
involvement of Aboriginal people in management;
concentration of visitor pressure, campsites, into limited areas;
strict protection of flora and fauna by law;
international agreements with Japan, China to protect migratory
birds;
attempts to eliminate introduced species;
3 max
evaluation:
considerable success, as measured by visitor numbers;
and protection of habitats and biodiversity;
success due to use of modern scientific techniques and
traditional land management;
and due to use of local, national and international measures;
2 max
genetic diversity represents the variety of genetic material in a gene
pool or population, habitat diversity is the range of different habitats
or ecological niches in an ecosystem, community or biome/OWTTE
1 max
[20]
(a)
Answers must mention both organisms and their environment for [2].
a community of interdependent organisms;
and the physical environment they inhabit;
or
segment of nature with its included organisms;
in their abiotic environment;
Any other reasonable definition.
(b)
Answers must mention the idea of a grouping/collection of
ecosystems, and similarity of climate/environment to achieve [2].
a collection of ecosystems;
sharing similar climatic conditions;
or
a major grouping of communities/ecosystems;
with similarities of structure and environment/climate;
Any other reasonable definition.
2 max
2 max
(c)
name: desert/semi-desert;
Award [1] each for any two of the following.
vegetation generally low/stunted;
plants capable of storing water;
cacti;
xerophytes;
absence of tall trees;
animals adapted to desert conditions;
absence of visible water;
extensive areas of bare ground;
low precipitation;
high mean temperature range;
high rates of insolation;
Any other reasonable suggestions.
(d)
(i)
low
(ii)
Points, e.g. relating to climate, which have already been
awarded credit in (c), should not be credited again.
High/low or equivalent must also be given e.g. “temperature”
alone is insufficient for credit.
precipitation/rainfall very low;
high daytime temperatures (so evaporation/transpiration/
evapo-transpiration high);
low plant biomass for photosynthesis;
low water-holding capacity of soil;
low soil fertility (allow, although fertility of some desert
soils may be quite high);
Any other reasonable point.
3 max
1
2 max
[10]
(a)
Clear use of characteristics (only accept characteristics visible
in the figure) [3 max] e.g.
presence or absence of legs;
horn on head;
shape;
shell;
tail;
dark ring on neck;
Any other valid suggestions.
appropriate key structure; (either of the two formats shown below)
Do not accept a table or list that simply describes the organisms.
4 max
Presence of legs?
Yes
No
Presence of shell?
D
Yes
No
C
Presence of tail?
No
Yes
E
Horn like structure on head?
No
Yes
Dark ring on neck?
Yes
No
A
B
F
————————————————————————
1. Presence of legs? If no → D, if yes → 2
2. Presence of shell? If no → 3, if yes → C
3. Presence of tail? If no → E, if yes → 4
4. Presence of horn on head? If no → 5, if yes → F
5. Dark ring on neck? If no → B, if yes → A
(b)
(c)
field guide;
compare specimen with illustration;
take sample for lab identification;
photography;
reference collection or herbarium;
characteristics such as behaviour/sound/distribution/time of the year;
compare with known species;
consider habitat;
genetic analysis/DNA;
Any other suitable suggestions.
(i)
pH;
temperature;
light;
soil;
salinity;
1 max
nutrients (in the case of a plant species);
water;
Any other relevant factor appropriate to the selected organism.
Award [0] for stating the organism’s name.
Do not be too strict on the name of the organism – candidates
are not asked for a species name, fish and crab are acceptable.
(ii)
(iii)
The method has to be appropriate to the named factor.
e.g. temperature.
use thermometer;
repeat measurements regularly over 24 hours;
take several measurements and calculate the mean;
repeat measurements at different times of year;
If organism is paired with an inappropriate factor in (c)(i),
allow credit for outlining the factor in (c)(ii) - error carried
forward (ECF).
1 max
2 max
Award [1] for name of activity e.g.
farming/hunting/agriculture/urbanization/introduction
of alien species/tree felling/use of pesticides;
Do not accept “pollution” - too vague.
Award [2] for effect on organism.
e.g. if organism is an insectivorous bird;
insecticides used to control insects accumulates in predators;
so number of predators would decrease leading to an increase
in insect numbers;
3
[11]
(a)
Description:
simple count at ground level;
tag/mark counted individuals;
use of aircraft/count from air;
count individuals in a known area and extrapolate for the area
of the whole park;
use information from previous census/survey;
capture – mark – release – recapture/Lincoln index;
Evaluation:
problems due to very large areas;
capture – mark – release – recapture method possibly inappropriate
for large mammals;
density of population in different habitats might vary;
some individuals might be concealed by vegetation;
seasonal variations/migration habits of elephants;
problem of replicating sampling;
high cost of some methods;
To receive full marks, answers must have at least one evaluation,
i.e. award only [3 max] for describing method.
(b)
count and identify organisms;
in a specified period of time;
defined number of collectors;
4 max
calculate relative abundance of organisms;
use of Simpson’s diversity index;
N ( N  1)
D=
;
n(n  1)
other appropriate diversity index;
higher index value implies greater diversity/OWTTE;
sample areas/quadrant;
replicate countings in both ecosystems under similar conditions;
compare values;
replicate countings in both ecosystems under similar conditions;
compare values;
Any other reasonable points.
5 max
[9]
(a)
(b)
non-point;
Award [1] for explanation, e.g.
because involves large area and cannot be traced back to a single,
treatable source;
Award [1] for method and [1] for a brief description e.g.
air:
air-filter pumps;
water: collect water – filter – measure pH/chemical analysis;
soil: collect soil – granulometry (particle size measurement)
– determine pesticides;
biota: measure concentration of pesticides in tissues;
repeat measurements several times and calculate mean;
repeat measurements different distances from contamination and
over a period of time;
(c)
2
2 max
Strategies:
introduce incentives for alternatives to pesticides/penalties/
legislation;
use of alternative pest controls/biological control;
setting and imposing standards;
ban the use of most toxic chemicals (e.g. DDT, Dieldrin);
use of certain pesticides only in specialized circumstances
(e.g. not entering the food chain);
compare effectiveness, i.e., rate of beetle infection with different
levels of pesticide use and alternative strategies;
regular monitoring prior and following changes in procedure;
Evaluation:
difficulty in enforcing penalties;
economic benefits/costs;
health considerations;
national/international differences (e.g. legislation);
3 max
Any other reasonable point. Award [2 max] if no evaluation is
provided.
(d)
(i)
(ii)
the potato and tomato have very low residues;
lettuce has a very high initial concentration of residue
(after 3 days);
amount of pesticide in lettuce after 14 days is low/similar
to potato and tomato;
behaviour of residues varies (in some crops increasing,
some decreasing over time);
residue levels vary from crop to crop;
Any other reasonable suggestion.
all crops provide some risk of contamination;
lettuce should not be consumed within three days of
pesticide application;
pepper retains high levels of pesticides and probably
should not be sprayed;
Any other reasonable point.
3 max
1
[11]
(a)
(b)
(c)
positive relationship/species diversity increases as island area
increases;
as island size increases, rate of increase in number of plant
species decreases/steepness of curve decreases;
number of habitats increases with island area/larger islands more
complex ecosystems;
larger islands have longer shores, therefore more likely to receive
drifting seeds, fruits, etc.;
larger islands more likely to be nesting sites for seabirds and
therefore to have seeds,
fruits brought from mainland;
larger islands more likely to be conserved;
larger islands can support larger populations of a given organism
and so extinction is less likely;
Any reasonable alternative explanation.
reduction in plant biomass;
reduction in number of plant species;
increase in very low “ground-living” plant species;
competition with and decline of any other herbivorous species;
trampling and soil erosion;
accelerated turnover of nutrients (especially N, P) though herbivore
excretion;
Any reasonable alternative explanation.
2 max
1 max
2 max
Do not expect sophisticated ideas on island biogeography in this
question, but reward appropriately if they appear.
[5]
(a)
tropical rainforest/tropical forest;
Also accept the abbreviation TRF.
(b)
describe:
several layers in canopy/trees, shrubs and herbs;
abundance of plant material/biomass;
multi-layered complex ecosystem;
indicative of high productivity;
presence of climbing plants;
tall trees with straight trunks;
explain:
the result of high precipitation amounts (rainfall);
high rates of insolation (sunlight input);
due to low latitude (tropical) location;
high temperatures;
If no “explain” points, [3 max].
If there is an incorrect answer for (a) allow error carried
forward (ECF) in (b).
(c)
low latitude (tropical) regions close to equator (do not give
mark if already rewarded above);
approximately 15 degrees north and south (do not expect
complete accuracy);
examples: Amazon basin/Congo basin/central America/
South-east Asia/far-north Australia;
Accept other reasonable examples.
absent where high altitude modifies climate (East Africa/Andes);
distribution has been much reduced over last 100 years by clearance;
Allow up to [2] for a good sketch-map.
1
4 max
2 max
[7]
(a)
(i)
(ii)
name and brief description (e.g. intertidal rock pool
at Tagus river, Portugal);
Candidates must state two abiotic factors appropriate
to ecosystem to receive [1].
e.g.
salinity;
pH;
temperature;
dissolved oxygen;
wave action;
turbidity;
flow velocity;
light intensity;
wind speed;
particle size;
slope;
soil moisture;
1
drainage;
mineral content;
(iii)
1 max
e.g.:
freshwater ecosystem, abiotic factor – temperature
use thermometer;
take account of: temperature may change with depth of the lake;
temperature may change at different hours of the day/seasons;
so need to take several observations to calculate mean;
aquatic ecosystem, abiotic factor – pH
use pH meter/pH paper;
take account of: pH is a logarithmic scale (increase of
1 point on the scale represents 10 times);
pH may change with depth of water column;
so need to take several observations to calculate mean;
terrestrial ecosystem, abiotic factor – soil texture
use of sieves;
use of triangular graph with proportions of sand, silt and clay;
take account of: field sample may be wet, so must be
dried before testing;
sample must be well shaken to separate particles;
soil may vary within profile/locally;
so need to take several samples;
presence of living organisms;
presence of organic matter;
(b)
3 max
appropriate example (name of organism);
Award [1] for appropriate method.
e.g. non-motile animal or plant by quadrat;
transect sampling;
by capture-mark-recapture if motile animal;
Method must be appropriate for the species named.
Award [1] for description.
repeat sampling procedure (time);
ensure sampling is consistent and replicated;
calibration of instrument;
location of sampling;
Award [1] for evaluation of method. Take account of e.g.:
birth;
death;
immigration;
emigration;
(c)
(i)
(ii)
50  49
;
(25  24)  (25  24)
= 2.04;
4 max
D=
there is a difference between the (relative) abundance of
organisms;
one area has been disturbed by human activities;
2
two areas are at different seral stages;
Any other reasonable suggestion.
1 max
[12]
(a)
(b)
(c)
(d)
presence/absence of legs;
number of legs;
presence/absence of tentacles;
number of tentacles;
shape;
visible eyes;
bristles;
Any other reasonable suggestion, but not size, colour, habitat.
size;
colour;
habitat;
behaviour;
organism not in key;
difficult terminology;
no key available for organisms under investigation;
may require dissection/chemical tests or other techniques;
Any other reasonable suggestion.
hard to collect;
difficult to determine dry weight;
difficulty of estimating area of irregularly shaped habitat;
seasonal variations in abundance;
Any other reasonable suggestion.
3 max
2 max
1 max
2 max
[8]
The organism chosen must be a consumer. If a producer is chosen, award [2 max].
Description: [3 max]
weigh the organism and place it into an enclosure;
each day weigh the food provided;
collect leftover food and feces (the wastes) and weigh them;
after a given period of time e.g. 1 month, reweigh the organism;
gross productivity is food eaten minus the wastes;
net productivity is the increase in animal biomass;
productivity must be given as mass (g or kg) per unit time;
Description of biomass alone award [2 max].
Evaluation: [2 max]
the animal must be provided with an ample amount of food;
it may be difficult to determine an appropriate diet for the animal;
the animal may become stressed and unwell in captivity;
water must be provided to keep the animal alive and may increase the
mass of the wastes being weighed;
it is very difficult to collect all leftover food and feces (particularly
for aquatic animals);
a number of animals should be involved in the testing and averages taken;
the artificial environment may contribute to errors as the animal
will have unusually low levels of activity;
problem of moving some organisms (e.g. limpets, barnacles) from
their habitat;
Any other reasonable points.
5 max
[5]
(a)
(b)
(i)
amphibians 16.7 %; (accept 16 to 17 %)
Both required for the mark.
1
(ii)
freshwater fish 4.9 %; (accept 4 to 5 %)
Both required for the mark.
1
(i)
facing a very high risk of extinction in the wild in the near future;
1
(ii)
example of currently endangered species e.g. giant panda/blue whale;
1
(iii)
Reasons: [3 max]
small population;
extremely specialized/specialized habitat;
restricted food source;
low reproductive potential;
accumulation of toxins;
a prominent predator, so killed by farmers protecting their stock;
migrates long distances;
Consequences: [2 max]
loss of species diversity;
loss of aesthetic value;
loss of habitat;
may be crucial to its food web/keystone species;
may have contributed to mankind as a medical, or other,
resource in the future;
Reasons must be appropriate for the species selected in (b)(ii).
5 max
[9]
(a)
counting from aircraft/helicopter;
counting in sample areas/quadrats/transects;
and multiplying to calculate numbers in total area;
repetition of count over a number of years;
under similar conditions;
and at same time of year;
allow for animals not seen (e.g. young kangaroos in pouch);
The above is how this type of data are actually collected, but
allow any reasonable suggestions, e.g. aerial photos, capture
– mark – release – recapture (Lincoln Index), hunting/shooting
records, population modelling.
4 max
(b)
the number of different species present;
the relative abundance of each species;
2
[6]
(a)
(i)
species diversity [1 max]:
the variety of species per unit area (this includes both the
number of species present and their relative abundance)/
OWTTE; (Glossary definition)
The response must have concept of unit area and/or
relative abundance for the mark. “Number of species”
is insufficient.
habitat diversity:
the range of different habitats in an ecosystem;
often associated with the variety of ecological niches/OWTTE;
(ii)
2 max
description [1 max]:
city has by far the highest biomass per square km;
city has highest density of population;
city has lowest biodiversity as absolute number of species
and expressed as index;
i.e. a small number of common species are very abundant;
forest has lowest biomass;
and population;
forest biodiversity is high, but not as high as farmland;
i.e. a wide variety of species, none of which is very abundant;
farmland has much lower biomass than city, higher than forest;
farmland has lower population than city, higher than forest;
explanation:
city is a specialized environment that a few species can
exploit very well;
food from gardens, rubbish (garbage) etc. may be available
to support some species;
city has low habitat diversity/low number of ecological
niches;
forest is a multi-layered habitat, with a variety of plant
species, so habitat diversity is high;
farmland may have highest habitat diversity of all,
having both natural and artificial habitats;
some food from human sources may be available in
farmland (crops);
the diversity index of the three environments takes account
of the species diversity and the relative abundance of the
species, hence farmland highest;
Any other appropriate point.
At least two “explain” points needed to achieve full marks.
4 max
(b)
(i)
(ii)
(iii)
the process through which new species form/OWTTE
(Glossary)/the process by which change in the frequency
of genetic trait occurs (in response to environmental pressures);
individual organisms in a population vary;
natural selection = the tendency of those organisms most
adapted to/fittest for environment to survive;
and therefore to pass their characteristics to their progeny;
thus organisms become increasingly adapted to their environment;
a changing environment may affect speciation/evolution;
mutations may affect rate of speciation;
appropriate example;
Reward any two of the above points or any other reasonable
points.
isolation of a small sub-group of the original population may
encourage/accelerate speciation;
through impossibility of interbreeding/exchange of genetic
material with original population;
and adaptations to new environment;
entirely new endemic species/unique species not found
elsewhere may appear;
e.g. unique finches/tortoises/iguanas on Galapagos Islands;
Any other reasonable point.
1
2 max
2 max
[11]
(a)
(b)
first part of graph resembles ‘j’ curve;
typical “boom and bust”/”increase and crash” graph;
initial low population;
period of exponential increase;
as population increases with few limiting factors (E);
e.g. with minimum effects of predators (E);
perhaps because predators killed off by humans (E);
population peaks in about 1924;
eventually population falls rapidly/crash occurs;
decline might be due to hunting pressure, owtte (E);
in due course control factor(s) take(s) effect (E);
e.g. as food supplies exhausted (E);
as population exceeds carrying capacity;
and/or disease/starvation occurs (E);
as death rate > birth rate (E);
population eventually approaches stability;
possibility that there may be an effect of severe weather (E);
Any other reasonable points.
At least two explanation (E) points are required for full marks.
“catch and release” method;
sample number of deer caught and marked/tagged without
harming them;
released and allowed to mix with population;
4 max
recaptured and checked for marks;
use of Lincoln index to calculate number;
use of aerial photos/satellite images;
photos/images could be divided into quadrats;
select sample quadrats using random number tables or similar;
multiply to obtain value for whole region;
use of hunting records;
use of tracks/scats (dung)/fallen antlers to estimate numbers;
statistical/computer modelling;
obtain separate estimates for areas of each distinctive habitat;
Any other reasonable points elaborating methods. Any points
addressing difficulties with methods should not be credited here
but may gain credit under (c).
(c)
(d)
possibility that marking might interfere with ability to move/
feed/reproduce;
some animals may become “capture-prone” or “capture shy”;
possibility of immigration/emigration/births/deaths within
census period;
hunting records can be unreliable (poaching/illegal shooting etc.);
some animals may be hidden from aerial surveillance beneath cover;
if sample quadrat system is used, sample area may not be typical;
deer are social animals and move in herds/groups – leads to underor over-recording;
indirect method (tracks, scats etc.) notoriously unreliable;
Any other reasonable points. Points mentioning difficulties under
(b) may be credited here.
Do not credit the same point in (b) and (c).
3 max
3 max
The methodology must be appropriate for the selected ecosystem.
(Terrestrial or aquatic)
NPP = GPP – R;
NPP measured by selection of typical quadrat/appropriate
ecosystem sample;
collection of biomass at start of growing period;
air-drying of organic material;
careful weighing to obtain value for dry-weight biomass per
unit area/sample;
collection of biomass from an identical quadrat/sample at end
of growing period;
drying and weighing of new sample;
obtain caloric value from tables;
or use bomb calorimeter;
difference related to time gives productivity;
allowance needs to be made for underground material, roots etc./
special efforts must be made to obtain this;
and material consumed by herbivores;
repetition of studies and taking of mean for greater accuracy;
Any other reasonable points.
N.B. Do not award a mark for naming an ecosystem, but mark out
of [3] if no ecosystem is mentioned. Do not credit details of
4 max
calculation of secondary productivity (e.g. measure mass of
animals, amount of feces produced, etc.).
(e)
(i)
The abiotic factor must be appropriate to ecosystem specified
in (d) and must change over time. The link with a biotic factor
(i.e. living organisms) must be reasonable. If no ecosystem
is named in (d), allow ECF.
E.g. for a freshwater system:
temperature varies both on a daily and a seasonal basis;
as photosynthesis varies with temperature, the abundance
of producers (e.g. phytoplankton) and consumers (e.g.
water fleas) varies seasonally with temperature;
(ii)
2
Method will depend on factor selected. E.g. for temperature
and number of water fleas in freshwater:
Method [2 max]
use thermometer/thermograph;
repeat at regular intervals;
e.g. at different times of day/times of year;
under identical conditions;
count number of water fleas in a scoop (with net) of water;
preferably at same time as temperature measurements;
under identical conditions each time;
Evaluation [2 max]
Should address issues of:
subjectivity of observation (different people observe/record
in different ways);
standardization of procedures;
“generalizability” (avoidance of atypical conditions
e.g. a shaded area);
difficulties in qualitative measurements (e.g. poor light
conditions);
correlation not necessarily indicative of causality;
Any other reasonable points;
4 max
Do not allow full marks for a detailed description of the
method, plus evaluation of that method, of a single factor,
however detailed. For the full [4] the candidate must
emphasize the relationship with the second factor. Thus
a very full account of the measurement of soil pH, even
if some evaluation is included, cannot obtain full marks
if there is no comment about the factor supposedly influenced
by it.
[20]
(a)
number of native species in Continental Europe/Africa/Australia
is high because of large area;
number of native species is high in Continental Europe/Africa/
Australia because of wider range of habitats;
number of native species is high in Continental Europe/Africa/
Australia because of wider range of climate;
(Converse: NZ and Hawaii – smaller range of species because
of smaller area/range of habitats/climate)
number of native species high in Australia because of isolation
throughout evolutionary history;
number of native species low in NZ/Hawaii as few species can
colonise remote islands;
islands more liable to be colonised by introduced species;
high proportion/percentage of total species in NZ and Hawaii
are introduced;
because native species may be adapted to specialized environments
and are less resistant to competition;
Any other reasonable points
(b)
(i)
(ii)
(c)
habitat diversity = the number of habitats/ecological niches
per unit area/in a certain area;
species diversity = the number of species of organism per
unit area/in a certain area;
habitat diversity is an indication of the ecological variety
of an ecosystem;
and therefore the number of species it can accommodate;
complex habitats provide more ecological niches for organisms;
habitat diversity may cause isolation of populations;
natural selection ensures organisms are adapted to
environment and way of life;
as environmental pressures influence frequency of genetic
traits in populations;
reproductive barriers may arise through (divergent) evolution;
so the more environments an ecosystem represents, the
greater the possibility of speciation;
e.g. an ecosystem with several layers such as tropical
forest is likely to have a higher diversity than single
layered ecosystems such as temperate scrub/heathland;
Any other reasonable points.
2
5 max
name of species, e.g. dodo;
Factors will depend on example selected. E.g. for the dodo:
confined to small island/limited distribution (Mauritius);
small population;
useful source of food for visiting sailors;
extreme tameness;
large and conspicuous;
slow rate of reproduction;
habitat destruction;
competition with introduced organisms (e.g. pigs);
Any other reasonable points. Award [1] for two factors.
Note date (1600); be tolerant here. However, dinosaurs are not
acceptable.
(d)
4 max
(i)
name of area, e.g. Uluru (Ayers Rock, Northern Territory, Australia)
Always allow benefit of the doubt if you have not heard of the
2 max
1
protected area.
Google may be helpful.
(ii)
(iii)
Reasons will depend on area. For example, with respect to Uluru:
spectacular nature/aesthetic appeal of isolated monolith;
geological importance;
relatively undisturbed nature of surrounding habitats (at least
by western/European influences);
archaeological importance;
variety of organisms (plants, reptiles);
significance to indigenous peoples;
possibility of taking large areas into management without
disturbing longestablished ownerships;
3 max
Evaluation of success again will depend on area chosen.
E.g., with respect to Uluru:
designation as a World Heritage Site;
therefore international recognition of its importance;
freehold of land transferred to indigenous (Aboriginal) people;
Aboriginal people involved in management of the area;
recreational pressure/accommodation concentrated in
limited locations;
plants/animals/landforms protected;
well drafted protective legislation;
funds from entry fees from visitors used for maintenance
of area;
some conflict between western/recreational/tourist values
and Aboriginal sacred site values;
thus climbing of Rock still allowed, contrary to Aboriginal
preference;
and has resulted in a number of casualties (some fatal);
A simple description of management does not answer the
question.
Candidates must evaluate the success, this implies at least
some comment on the management practise used.
Example: “Burning and grazing by sheep are used on
some of the heathland nature reserves of the East Suffolk
Sandlings” is not sufficient.
“Burning and sheep grazing are sometimes successfully
used to maintain the traditional ‘open landscape’ character
of the heather-dominated plant communities on some of the
East Suffolk Sandlings nature reserves, and to maintain
their characteristic biota, some species of which are
locally endangered” – full marks.
3 max
[20]
(a)
the orderly process of community change over time in an
ecosystem/community (based on subject guide Glossary)/OWTTE;
1
(b)
(c)
the mass/weight of organic material in ecosystems or organisms,
usually per unit area/OWTTE;
description:
“S” shaped curve;
origin at zero;
initial exponential increase;
starts to level-off at about 120 years;
very slight long-term decline;
explanation:
very low initial value as there is no productivity on bare, recently
exposed rocky surface;
biomass increases rapidly as productivity increases;
levels-off as equilibrium reached;
Any other valid points.
Must have at least one valid “explain” point to achieve [4].
(d)
1
4 max
spruce;
hemlock;
Both needed for [1].
1
(e)
alder;
1
(f)
305 tonnes ha–1 (accept 300–320 1 tonnes ha–1);
1
[9]
(a)
(b)
(c)
27  26
;
108
= 6.5;
Award [1] if the correct answer is given but no workings are shown.
D=
presence of legs;
number of legs;
presence of antennae/feelers;
tail presence/absence;
body shape;
colour;
size;
Any other appropriate suggestions.
(i)
(ii)
name of appropriate abiotic factor;
Accept either terrestrial or aquatic factors, e.g.
air/soil/water temperature;
aspect;
salinity;
dissolved oxygen;
pH;
Reward responses which indicate that factors affecting
diversity are understood and which relate to the chosen
abiotic factor.
2
2 max
1 max
e.g. dissolved oxygen:
some organisms can only live in water with high levels of
dissolved oxygen;
in a highly oxygenated environment, the number of species
(species richness) will be higher and hence the diversity
will be greater;
or
in water with low levels of dissolved oxygen, only a
few specially adapted organisms can survive;
a few species tend to be dominant (and a few others may
exist in small numbers), so diversity is low;
(iii)
name/description of measuring instrument/procedures
appropriate to abiotic factor;
Award [2 max] for:
repeated measurements to check validity;
measurements at both sites at same time/same day;
other appropriate comments on ensuring a fair test;
(d)
1
2 max
(i)
mark and recapture technique/Lincoln index;
1
(ii)
 20 
 8  = 32;
 5

1
(iii)
(e)
2 max
emigration/immigration;
birth/death;
predation;
very small sample size;
may interfere with relationships of other individuals in
population;
Any other valid suggestions.
Do not accept human error and equivalent generalities.
1 max
(iv)
increased chance of predation/possible toxicity of paint;
1
(i)
need to know inputs of energy;
not all food is absorbed/feces is an output;
2
water is not organic matter/moisture content is variable/
comparisons of wet weights not fair test/so that results
can be extrapolated for remainder of batch/OWTTE;
1
energy absorbed = food eaten – feces;
burn food/feces to measure energy content/use conversion
tables to convert mass to energy equivalent;
2
net productivity = animal mass at end – animal mass at start;
1
(ii)
(iii)
(iv)
[20]
(a)
open, due to inputs/outputs of matter/air/water (and energy);
(b)
inputs would include more CO2 than outputs;
due to net productivity/photosynthesis; (E)
1
inputs would include less O2 than outputs;
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)
Any other appropriate differences
[2 max] for differences
[2 max] for appropriate explanation.
(c)
negative (feedback);
(d)
(i)
(ii)
4 max
1
in energy transformations (in food chains), not all energy
can 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 the
next;
so the energy available to each successive trophic level decreases;
2 max
the size of the ecotron limits the size of the primary producer
community;
which limits the amount of energy that can be made available
at the bottom of the food chain;
and since there are losses at each trophic level, this limits the
number of trophic levels that can be supported;
2 max
[10]
(a)
(i)
between 80 and 120 yrs =
allow 5.3 – 5.7t ha–1 yr–1
(ii)
between 220 and 240 yrs =
225  5 220
= 5.5 t ha–1 yr–1;

40
40
1
0
= 0 (t ha–1 yr–1);
40
allow ± 0.1 t ha–1 yr–1 [1]
units required for values other than zero
(b)
initially growth rate increases due to more favourable habitat created
by pioneer species;
low intraspecific competition for light/nutrients;
reducing interspecific competition with alder/dryas;
few herbivores/parasites, etc;
in pioneer phase, GP substantially exceeds R because of high ratio
of photosynthetic to non-photosynthetic tissue;
towards end of period, growth rate decreases due to reaching
1
carrying capacity;
high intraspecific competition for light/nutrients;
interspecific competition with hemlock;
limited resources;
more herbivores/parasites;
at climax, energy inputs and outputs (GP and R) are equal so no net
productivity;
Any other reasonable points
(c)
(d)
it is likely to be an r-strategist;
with a high specific growth rate;
producing large numbers of offspring;
with small parental investment (food store) per individual;
all these strategies contribute to more effective dispersal;
Any other reasonable points
conversion of gaseous/atmospheric nitrogen into nitrates/proteins/
assimilation of atmospheric nitrogen;
Accept any one of the following for the second mark
produces nitrates which are essential for plant growth/makes soil
more fertile;
when there would otherwise be few available from the bare rock/
poor soils;
water-logged/anaerobic soils (common in post-glacial conditions)
favour denitrifying bacteria so tend to be low in nitrogen;
2 max
2 max
2 max
[8]
(a)
(i)
the weight/mass of (organic) material, after the removal of water;
(ii)
Methodology will vary slightly with ecosystem chosen.
Award [1] for each of the following up to [4 max]. Award [3 max]
if no evaluation of (E) points given.
mark out measured area;
select quadrats using an appropriate method;
harvest all plant material within sample area;
air dry/oven dry;
Do not accept ‘burn’
weigh;
ideally take several samples and obtain mean;
problems with very large trees/difficult to harvest/destruction
of ecosystem (E);
problems with estimation of subterranean biomass (especially
in forest ecosystems) (E);
Any other reasonable point
Points of methodology inappropriate to selected ecosystem should
not be credited.
Reject any discussion of animals/secondary productivity
(iii)
Methodology will depend on abiotic factor chosen and must
be appropriate to the selected ecosystem.
name of factor (e.g. temperature, rainfall);
1
4 max
Do not accept a biotic factor
brief methodology (e.g. use thermometer/thermograph/rain
gauge);
repeat observation under similar conditions regularly over
period/day/year;
(b)
(i)
(ii)
(c)
(i)
(ii)
(iii)
20 19
380
= 4.4

12  20  42  12 86
20 19
380
area B:
= 2.9

0  56  72  2 130
Accept more but not less significant figures than above.
therefore, area A is the most diverse area;
[1] for correct method, [1] for correct answers. Award [1] for
identifying area A.
Allow ECF for final point, but no mark if no working shown
at all
3
area A:
Award [1] for any reasonable factor e.g.
succession;
soil texture;
moisture;
pH of soil;
logging/burning;
light intensity;
Reject a statement about number of species and abundance
of species.
Award [1] for two of the following and [2] for three
presence of wings;
presence of pincers;
steeply curved antennae/feelers;
abdomen more than twice the size of head and thorax/
relative size of head, thorax, abdomen;
horn-like structure on head;
absolute size;
Any other reasonable suggestion
Reject number of legs. All the specimens shown have six,
as do almost all (adult) insects.
Award [1] for each of the following:
use field guide/illustrated textbook;
compare with museum specimen;
internet resources, OWTTE;
consult expert on the group;
distribution;
DNA testing;
behaviour (including sound);
habitat;
time of day or year;
Any other reasonable points
Award [3 max] for method and [1 max] for evaluation.
methods:
3 max
1 max
2 max
2 max
simple numerical count of termite mounds;
sample area might be taken and result multiplied to give total
figure;
mean of several samples might be taken;
use aerial photos to count mounds;
(Reject use of satellite images: scale probably too small).
use catch – release – recapture/Lincoln index method to
estimate number of termites in a colony;
multiply estimate of numbers in colony by number of colonies;
evaluation:
problems of dealing with very large numbers;
difficulty of access to interior of termite mound;
problems of variation in numbers with season;
difficulty of estimated numbers outside mound foraging;
Lincoln index method may not be appropriate for termite
community if organisms do not move around randomly between
marking and recapture;
problems of recruitment to population and deaths between
marking and recapture;
Any other reasonable suggestions for method or evaluation
4 max
When marking be tolerant: reward adequate understanding
of methods or concepts. However, award [3 max] if mounds
are not mentioned at all or if an account focuses solely on
mounds to the exclusion of actual insects.
[20]
(a)
(i)
(ii)
(iii)
genetic diversity represents the range of genetic material/
variability in a gene pool/population;
whereas habitat diversity represents the range of different
habitats/ecological niches in an ecosystem or biome
(based on glossary);
2 max
diversity at initial stage is low;
species diversity increases with colonisation through pioneer
stages and later stages of succession;
as plants grow, habitat diversity increases;
as habitat diversity increases, species diversity increases;
as productivity increases;
and food chains lengthen and insects and vertebrates colonise;
so a positive feedback link exists between habitat and species
diversity;
rise in populations and immigration may increase genetic diversity;
Any other reasonable point
4 max
islands represent isolated ecosystems;
and therefore support isolated populations;
immigration/incoming gene-flow is rare;
population of goats likely to be based on a small original
or “founder” population;
with very small genetic variety;
mixing of limited gene pool may have led to common
intermediate characteristics;
limited gene pool may have resulted in a population which was
very similar/homogenous;
natural selection;
may have caused adaptation;
to the characteristics of the island environment (e.g. camouflage);
Any other reasonable point
(iv)
(v)
(b)
the higher the area of the reserve, the higher the population;
the higher the population the higher the genetic index;
with one slight exception (Addo);
because a large population can generally “hold” a greater variety
of genes/variation than a small one;
the density of population varies from 6 ha per animal to over
200 ha per animal;
the density may vary with habitat/vegetation/climate;
might reflect difference in wildlife management/conservation/
hunting;
Any other reasonable point
small, isolated populations contain a very limited range of genes;
and therefore cannot vary or evolve very much;
this increases the possibility that they will become extinct;
a larger area can contain larger, and therefore more stable
population;
other factors include the greater habitat and species diversity
that can be held in larger areas;
however, some argue that a number of small reserves are
preferable to a few large ones;
as the package of genes/habitats/species will be different;
and if one reserve is destroyed, others may survive;
Any other reasonable points Be tolerant, reward understanding
of ecological and conservation principles.
Award [1] for each factor plus example.
volcanic eruption (e.g. Mount St Helens/Krakatoa);
glaciations (quaternary ice advances in northwest Europe);
meteorite impact (mesozoic impact in the Americas held by some
to be responsible for a major extinction event);
deforestation (northwest highlands of Scotland: “The Great Wood
of Caledon”);
monoculture (West Australian wheat belt/North American prairies);
introduction/escape of non-native species (New Zealand);
pollution (River Thames/reduction of predators through use of
pesticides in 1960s);
over-hunting/collecting (extinction of passenger pigeon in North
America/thyracine in Tasmania);
Any other reasonable suggestion
When marking be tolerant. Give benefit of the doubt to any apparently
3 max
5 max
2 max
4 max
reasonable examples.
Allow [2 max] for appropriate factors but without named examples.
[20]
(a)
Award [1] for each pair of valid advantage and disadvantage up to [4 max].
advantages
use very small volume of fuel;
once constructed, cheap to run;
can be constructed away from source of coal etc;
can be a source of other radioactive materials for industry/medicine;
little/no CO2 produced;
can be a source of military plutonium;
could be considered a disadvantage - do not allow both.
causes relatively little atmospheric pollution;
creates (high level) jobs/employment;
disadvantages very expensive to construct;
problems of decommissioning at end of useful life;
strict health and safety requirements/risk of leakages, etc;
risk of theft/ hijacking of radioactive materials;
so civil liberties implications for protection of plant/ fuel;
problems of disposal of spent fuel/ very long half-life of fuel;
require large amounts of cooling water;
require a technically advanced/ educated labour force;
Any other reasonable points
(b)
(i)
(ii)
(iii)
Western Europe and
Australasia;
Candidates must have both of these, and in the right order
for the mark.
504  40
× 100;
40
= 1160%;
Four of the following points:
output in all regions has steadily increased;
with increases in population (E);
and improvements in agricultural technology (E);
signs of slow-down in rate of increase in Africa;
and actual reversal in Europe;
because of overproduction/set-aside (E);
because of pollution/eutrophication (E);
consumption in Europe much higher than Australasia/Africa;
because of large area of arid/semi-arid land unsuitable for
agriculture (E);
because of lower level of technology/subsistence agriculture
in Africa (E):
high subsidies for fertilizer in Australia and Europe (E);
4 max
1 max
2
4 max
Any other reasonable suggestions
Must have at least one “explain” point for [4 max].
(c)
(d)
Award [1] for each of the following.
increase in crop production;
increase in N loss through soil leaching;
increase in loss of heat (through use of fuel in spreading, increased
growth);
increase in CO2 production (through use of fuel in spreading);
Any other reasonable suggestions
Reject increase in farm income as this is an input.
Reject ‘pollution’ (too vague).
(i)
(ii)
the area of land/land and water required;
to (sustainably) support a defined human population (at a
given standard of living) (glossary). OWTTE;
Award [1] for each of the following.
footprint of DC commercial farmer will be much larger;
will use more chemicals;
which will need a larger area to absorb;
will use more fossil fuels/energy subsidy;
and so produce more CO2;
which will need a larger area to absorb;
DC farmer will use more water for irrigation etc.;
Any other reasonable point
Converse statements equally acceptable e.g. “footprints of
LDC farmer will be much smaller” or “LDC subsistence
farmer will use less chemicals”, but same point cannot
be rewarded twice.
2 max
2
5 max
[20]
(a)
(b)
Award marks for 4 flows and 1 storage as shown on diagram.
Flows must be linked to an arrow in the correct direction and
include both number and process to gain the mark.
3.1 × 109/3 100 000 000/3.1 billion tonnes/3.1 Gigatonnes/3.1 Gt
Powers of ten and units must be correct for credit.
5
1
(c)
(i)
Photosynthesis;
1
Allow as alternatives to “light”: sunlight, solar energy, insolation.
3
(ii)
(d)
(i)
(ii)
carbon dioxide is a greenhouse gas/causes the greenhouse effect;
increasing levels of carbon dioxide may cause global warming/
melting of ice caps/rising sea levels/shifting of biomes/
changes in weather patterns/disruption of ocean currents/
increased rates of extinction/reduction in crop yields;
Allow any other reasonable points
some countries co-operate with other nations to agree limits
to global carbon emissions;
e.g. recent ratification of Kyoto Protocol (Treaty) by many
countries;
specific details about which countries have agreed to/rejected
controls on their carbon emissions;
specific details about actions agreed to by specific countries;
e.g. use of carbon or energy taxes;
developed countries assist less developed countries to install
cleaner technology;
trading in carbon credits/exchanges;
Allow other relevant points, provided they relate to
international cooperation
2 max
3 max
[15]
(a)
a parasite lives in or on another (host) organism/species and gains all
or much of its food from that organism (usually without killing it)
OWTTE;
a predator is an animal that hunts another animal and kills it for
food OWTTE;
2
(b)
(c)
(i)
pyramid of numbers;
“pyramid” alone is insufficient; allow Eltonian pyramid.
Do not allow: biomass pyramid, food-chain, food-web.
(ii)
parasites are usually much smaller than their host;
so many of them can feed on a single organism at a time;
more than one species of parasite may live on a single host;
parasites can breed more quickly than herbivores;
energy available higher up a food chain is limited by energy fixed
by producers;
losses due to respiration reduce available energy/much energy
(about 90%) is converted to heat at each level of the food chain;
because all organisms must transform some energy to heat to
carry out their metabolic functions;
as implied by the Second Law of thermodynamics;
predators are always near the top of food chain/at third trophic
level or above;
so much of the available energy/production from producers is
converted to heat and lost from the system before it reaches the
predators;
1
2
3 max
[8]
(a)
the heterogeneity/variety of life in an area/OWTTE;
(b)
(i)
1
site A
40 40  1
;
10 10  1  5 5  1  15 15  1  10 10  1
40  39
=
90  20  210  90
1560
=
= 3.80; (Allow 4/4.0/3.8)
410
Award [1] for correct answer and [1] for working.
D=
(ii)
2 max
site B
40 40  1
;
20 20  1  10 10  1  8 8  1  2 2  1
40  39

380  90  56  2
1560
= 2.95; (Allow 3/3.0)

528
Award [1] for correct answer and [1] for working.
D=
(iii)
site A
and one cause from the following
differences in: microclimate (temperature/humidity);
habitat differences;
soil;
pollution levels;
2 max
predation levels;
competition;
microhabitat required for some species very restricted (carrion,
dung);
Any other reasonable suggestion
Both correct site and cause needed for mark
Allow ECF
Do not credit an answer that just refers to numbers or variety
of organisms
(c)
(i)
(ii)
(d)
(e)
capture–mark–release–recapture method/use Lincoln index method;
mark out area of 0.1 ha;
capture sample of beetles using traps/nets/searching in
appropriate places e.g. dung/carrion/dead wood according
to species;
mark with non-toxic paint or some other appropriate method;
allow interval and recapture similar number;
n n2
P= 1
;
n3
Any other reasonable points
immigration;
emigration;
deaths;
births/hatching from pupae;
patchy distribution;
difficulty of finding adequate sample;
Any other reasonable points
use dichotomous key;
use field guide/illustrated book/internet resources;
refer to expert on the group;
DNA testing;
use factors such as sound/habitat/distribution/time of year/
time of day;
Any other reasonable points
(i)
(ii)
Award [1 max] for abiotic factor and named ecosystem.
Ecosystem must not be too vague. Do not credit biotic factors.
Example: sunlight intensity in eucalypt forest in south-west Australia;
Method will depend on the ecosystem selected.
For the above example:
light intensity varies with height;
measure light intensity with light meter;
measure at regular intervals (2m, 5m) from ground level to
top of canopy;
using ladders/extending poles/climbing trees or similar
method;
as far as possible under similar conditions each time;
as far as possible repeat several times and take mean;
Any other reasonable points
1
4 max
2 max
1 max
1
4 max
(iii)
Example: clearance of forest/cutting of trees
would allow sunlight to reach ground level;
light intensity would increase;
however, eventually thick successional community might
exclude sunlight;
and light intensity would decrease;
No mark is awarded for name of ecosystem, but if no name
is given, award [1 max]
2 max
[14]
(a)
(i)
(ii)
(iii)
(iv)
(b)
there may be more grassland habitat in total in the region;
commercial value of rainforests may be a disincentive for
protecting them;
grasslands may be easier to police than forests (e.g. against
poachers);
greater areas of forest may have already been destroyed
before protection programmes began;
grasslands may have more popular/“high status” organisms
(e.g. zebra, giraffe, large carnivores, etc.);
therefore may generate more tourist income per unit area;
Any other reasonable suggestions.
Calculations:
150 km 2
Grassland:
× 100 = 50% (allow 45–55 %);
300 km 2
50 km 2
Rainforest:
× 100 = 100% (allow 95–105 %);
50 km 2
2 max
2 max
percentage increase in rainforest greater because:
it began with a smaller area (so a small increase represents a
larger percentage increase);
increased interest in ecotourism for rainforests;
pressure from environmental groups to “save the rainforest”;
1 max
rainforests contain high diversity of species;
these species are unique to the habitat;
and represent a high proportion of the total world biodiversity;
biodiversity of tropical rainforests less well-documented than
other ecosystems;
rainforests have significant effect on wider climate;
which affects the survival of many other species;
rainforests are diminishing globally at a considerable rate;
source of useful products/genes;
2 max
Transition zone:
permanent settlements cause high impact;
by limiting their size, impact on boundary of buffer zone is reduced;
reduces impacts of pollution/disturbance on margins of buffer zone;
Buffer zone:
allowing research increases knowledge of species and ecosystems;
which can be used for better conservation;
tourism can provide revenue/raise public interest;
which can aid in further conservation;
sustainable exploitation by locals encourages their support for the project;
Core zone:
minimal immediate human activity protects the most vulnerable
species (even the most intensively conserved areas may need
occasional management e.g. control of bush fires, elimination
of exotic species);
maintains an untouched deposit of diversity that can feed into
buffer zone;
some ecological studies require natural/ near-natural environments;
At least one point from each zone to gain full marks.
4 max
[11]
(a)
(i)
the mass of organic material in organisms or ecosystems,
usually per unit area;
1
dry weight measurements are taken;
these figures are then extrapolated to estimate total biomass;
2
(i)
tropical rainforest;
1
(ii)
ideal growing conditions due to high temperatures (typically 28 °C);
and high rates of precipitation (typically over 2000 mm p.a.);
continuous growing season;
due to geographical location in equatorial area with sun
directly overhead;
for much of the year and energy of sun therefore concentrated
in this zone;
3
biomass is per unit area, productivity is production per unit time;
NPP is the quantity of biomass potentially available to
consumers in an ecosystem;
2
(i)
temperature deciduous woodland;
1
(ii)
deep humus means lots of organic matter and this leads to greater
fertility than acid humus (due to pine needles), therefore
coniferous is less fertile;
this soil has less leaching than the temperate coniferous
– i.e. fewer minerals washed out;
and parent material not as weathered as in tropical rainforest;
therefore likely to be contributing more minerals;
(ii)
(b)
(iii)
(c)
3 max
[13]
(a)
(i)
mangrove tree / coral / sea grass;
1
(ii)
crab / fish / shrimp / lobster / coral;
1
(b)
succession;
(c)
sunlight … converted by mangrove and coral provides food for primary
consumer e.g. shrimp … provides food for secondary consumers large
fish etc … eventually die and broken down by decomposers;
[1] for diagram, [2] for information.
(d)
(i)
(ii)
1
nurseries for young sea creatures lost so fewer survive
into adulthood;
coral becomes swamped with sediment as mangrove roots
no longer filter it out;
more sediment in water means water is less clear / more
turbid and coral productivity declines;
loss of income from fishing and tourism as coral
dies and fewer fish in this area;
more coastal erosion as protection from storms is lost;
3 max
2 max
2
[10]
(a)
6
Insolation
1972000
Insolation
185000
Open sea
Fjord
3470 Phytoplankton
Farmed shrimp
847
461
Kawai
Salmon
26
4.3
410
6.2
572
Inuit
12.5 Other human activities
Fishing for
kawai 6.7
Award [1] for each two correct labels.
14 Managing shrimp farm
4.1 Managing salmon
(b)
(i)
(ii)
(iii)
(c)
the quantity of organic matter produced or solar energy
fixed, by photosynthesis in green plants per unit area
per unit time;
1
net primary productivity is GPP less the biomass / energy
lost by plants through respiration;
1
nutrient and mineral availability;
temperauture;
2
kaway
847 – 572
× 100 = 32.5% ;
847
461 – 410
× 100 = 11.1% ;
461
kaway is more efficient;
salmon
(d)
3 max
in terrestrial systems most food is harvested from relatively
low tropic levels, but in aquatic systems most food is
harvested from higher trophic levels;
energy conversions along the food chain may be more
efficient in aquatic systems;
initial fixing or available solar energy by primary producers
tend to be less efficient due to the absorption and reflection
of light by water;
3
(e)
salmon is a source of income as well as a food source;
1
(f)
technology likely to be simpler;
methods likely to be more traditional;
environmental impact will probably be smaller;
more likely to be sustainable in the long term;
3 max
[20]
(a)
a group of organisms that interbreed and produce fertile offspring;
1
(b)
(i)
succession;
1
(ii)
a community of plants that has reached a steady state/
equilibrium within a particular habitat/environment/the
end point in an ecological plant succession;
area C;
2
(iii)
A range of answers are possible e.g.
agriculture;
hunting;
clearance/burning;
grazing;
all create a plagioclimax by arresting succession;
2 max
(c)
(i)
S curve
Population
J curve
Population
Time
(ii)
(d)
(i)
(ii)
Time
[1] for each curve and [1] for labelling the axes.
2
S curve area A;
J curve area C;
2
small number of offspring, large amount of parental care;
elephants/apes/humans;
Accept other suitable examples.
2
large number of offspring, small amount of parental care;
frogs/salmon/house flies;
Accept other suitable examples.
2
[14]
(a)
(i)
(ii)
(iii)
(b)
(i)
MEDCs 44.4 % (accept 44 %);
LEDCs 15.9 % (accept 16 %);
2
MEDCs: eat more calories/energy intake higher than they need;
LEDCs: do not eat enough calories/energy intake too low;
MEDCs: eat a lot of protein;
high % of protein from animals;
LEDCs: not enough protein;
protein mainly non-meat;
3 max
greater wealth in MEDCs enables people to buy enough food,
especially more expensive food, e.g. meat;
soil fertility for farming may be better in MEDCs so yields
higher;
better distribution systems in MEDCs so people have access
to fresh food;
religious restrictions (e.g. no beef or pork) less likely to be
an issue in MEDCs;
social expectations in MEDCs that meat will be an integral
part of the diet;
many families in LEDCs are subsistence farmers, and may
use animals for milk but not meat;
3 max
the biomass in Figure 3 is all the living material in the ecosystem;
1
(ii)
(iii)
biomass store is larger in the woodland;
litter store is larger in the woodland;
large output in mixed farming as harvested crops/livestock;
legumes and fertilizers are additional inputs in mixed farming;
input dissolved in rain is not shown for mixed farming;
additional nutrients are added directly to the soil through fertilizers;
and indirectly through the nitrogen fixing action of leguminous crops;
3 max
2
[14]
(a)
(b)
(c)
(d)
diversity: early = low, late = high;
size of organisms: early = small, late = large;
2
r-species – produce large numbers of offspring, opportunistic,
pioneer species/first to colonise an area;
K-species – produce a small number of offspring and are suited
to long-term climax communities;
2
as pioneer species die out their remains contribute to organic matter
in the soil;
this makes it easier for other species to colonise and over time litter
from the biomass will lead to a build up in organic matter;
soil organisms will move in and break down litter;
pioneer species will help to weather parent rock;
(i)
how well an ecosystem is able to cope with changes;
(ii)
food webs are more complex (high species diversity) so
species can turn to alternative food sources if one species
is reduced;
nutrient cycles are closed and therefore self sustaining/
not dependent on external influences;
large amounts of organic matter = good source of nutrients;
2 max
1
2 max
[9]
(a)
(i)
(ii)
(iii)
population numbers decrease from October until June;
mean mass increases (exponentially) from September until
March and then slows down/OWTTE;
Accept other valid answers.
Answer should make reference to the data in figures 1 and 2.
stream A demonstrates a slow decline in population size whereas
stream B shows a dramatic exponential decline/OWTTE;
the maxima for population size and mean mass are higher
for stream A;
Accept other valid answers.
Answer should make reference to the data in figures 1 and 2.
6350  44
× 100 = 99.3%;
6350
2
2
1
(b)
(i)
the mass of organic material in organisms or ecosystems
(usually per unit area);
1
(ii)
20
18
16
Stream A
14
Mean biomass
/ g m2
12
10
8
6
4
2
Stream B
0
Sept
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Month
(c)
(i)
(ii)
(d)
(i)
(ii)
Award [1] for each line.
2
a major pollution incident is the most likely;
whereby water quality has been severely affected in stream B
causing the mayfly population to crash;
Accept other reasonable answers e.g. eutrophication,
disease (endemic).
2
populations of predator species may crash if mayfly are the
only food;
mayfly prey numbers may increase as mayfly numbers fall;
populations of other prey species may also suffer if mayfly
disappear and predators switch prey;
e.g. using electro-fishing techniques/netting a significant
number of trout could be caught, tagged and released;
important to ensure that the capture and tagging does not
stress/harm the fish;
later (next day) the capture exercise would be repeated
using the same effort and time as before;
the fish caught would be noted as tagged or untagged
and the Lincoln index applied;
Award [1] for concept of capture—mark—release—recapture
without giving an outline of the method.
Award [1] for each factor with an explanation, e.g.
oxygen content – the amount of oxygen in the water will
influence the ability of organisms to respire/high levels of
oxygen – high respiration potential;
2 max
3 max
Jun
pH – the pH of the water will affect the stream chemistry
which in turn will affect the plants and animals/extremes
of acid and alkaline conditions will stress both plants and
animals/pH will influence the species types present;
temperature – water temperature affects both plant and animal
biochemistry/warmer water suits some species and not
others/extreme temperatures may alter water chemistry
and oxygen content;
Accept other reasonable answers.
(iii)
r-strategists produce a large number of offspring from which
few reach reproductive age;
exhibit little or no parental care;
well adapted to colonize new habitats rapidly/make
opportunistic use of short-lived resources;
less subject to feedback control;
3 max
2 max
[20]
(a)
(i)
(ii)
(iii)
(b)
(c)
most fish will be found in places where temperatures are
moderate;
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
at low and high temperatures, only small populations of
fish are supported due to physiological stress
1
density independent because temperature is a factor which
affects populations regardless of population size
1
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
4 correct = [2], 2 or 3 correct = [1], 1 correct = [0]
For example, flow velocity:
use a flow meter;
insert into water just below surface and take a number of readings
to ensure accuracy;
results can be misleading if only one part of stream is measured;
water flows can vary over time and with depth;
2 max
3 max
[9]
(a)
(i)
20.6 (accept 21)
1
(ii)
50 × 50 cm quadrat = 0.25 m2;
therefore 20.6 × 4 = 82.4 primroses m–2; (accept 82)
21 × 4 = 84
2
or
(b)
(iii)
e.g. light levels would decrease with distance into wood
1
(iv)
along a profile or transect;
take reading at regular intervals;
enough to be statistically significant;
take samples using relevant equipment;
2
28  32
;
10
N = 89.6;
2
(i)
(ii)
(c)
(d)
N=
make sure all traps were working properly;
ensure all traps were equally baited;
ensure all animals were handled humanely and not hurt;
ensure all traps were in similar locations (e.g. all at the base
of a tree, all on a defined animal track);
traps checked at same time each day;
mark in a way that will not rub off;
mark in a way that does not compromise survival;
Accept other reasonable answers.
randomly place a series of quadrats in the meadow/grassland;
remove all vegetation from each quadrat;
dry the vegetation in an oven to remove water and measure the
dry mass;
work out the average dry biomass per quadrat and multiply by
total area of meadow;
(i)
(ii)
(iii)
51(51  1)
;
n(n  1)
2550
D=
;
596
D = 4.28;
2 max
3 max
D =
low diversity index suggests that a habitat is newly colonised;
a monoculture dominated by a single species;
abundance is a measure of the number of organisms per
unit area;
diversity is the number of different species and the relative
number of individuals within a species;
3
2 max
2
[20]
(a)
(b)
energy is dissipated/lost along the food chain/converted to
less useful form;
this is because species at each trophic level are using some of
the energy for respiration, and some is lost as heat/waste to the
environment;
photosynthesis/primary production is the process by which
green plants convert light energy into a usable form/chemical
energy/food/organic matter;
2
requires carbon dioxide, water, chlorophyll and light;
involves production of oxygen;
Give credit for chemical equation.
(c)
coal/oil/natural gas;
Award [1] for any two of the above.
(d)
Accept any reasonable environmental problem.
e.g. noise pollution/air pollution/global warming/acid rain;
e.g. urban air pollution caused by release of hydrocarbons
(from unburned fuel) and nitrogen oxide;
nitrogen oxide reacts with oxygen to form nitrogen dioxide,
a brown gas that contributes to urban haze;
Award [1 max] for problem and [2 max] for explanation.
(e)
zone D;
(f)
primary productivity is the gain in energy/biomass by
producers/autotrophs whereas secondary is gain by
heterotrophic organisms;
primary productivity is the conversion of solar energy
whereas secondary involves feeding/absorption;
(g)
availability of light e.g. deep oceans dark below surface limits
productivity of plants;
availability of water e.g. tropical rainforests receive lots of
rainfall each year whereas deserts have little rain which is
limiting to plant growth;
temperature e.g. rainforests warm throughout the year so have
a constant growing season and higher productivity;
nutrient availability e.g. estuaries receive lots of sediment from rivers;
Award [1 max] for no reference to the biomes in figure 3.
2 max
1
3 max
1
1 max
2 max
[12]
(a)
(b)
population A;
the population pyramid demonstrates a large juvenile element,
i.e. there appears to be many offspring;
and high mortality rate;
Award [0] if population identified without reason.
60  50
;
15
= 200;
2 max
2
Density per 500 m 2 / density per unit
(c)
Jan
Feb Mar Apr May Jun
Jul Aug Sep Oct Nov Dec
months / time
Award [2 max] for the plot and [1] for the labels.
(d)
(e)
population is low in spring and winter months/November to March;
the population rises (dramatically) in summer;
1 max
low numbers in winter due to naturally high mortality rates caused
by extreme conditions/lack of food;
predation;
numbers increase dramatically in summer as females produce
numerous offspring;
r-strategy;
2 max
[10]
(a)
a community of interdependent organisms and the physical environment
they inhabit/OWTTE;
1
(b)
e.g. water flow through a river ecosystem;
Accept any reasonable answer that identifies a flow and an ecosystem.
Award [0] if no named ecosystem.
1
(c)
biomass within trees and plants/nutrient within soil;
Do not accept for example “trees” or “soil”. The item stored must
be identified.
1
(d)
0.04;
1
(e)
e.g. tropical rainforest and tundra;
mean NPP tropical rainforest greater than tundra/mean biomass
tropical rainforest far greater than tundra;
NPP per kg biomass of tropical rainforest is far lower than tundra;
Candidates may give figures from the table but they need to make
comparative statements.
tropical rainforest hot and wet so greater opportunity to develop
large biomass/high rate of photosynthesis and high rate of
respiration so NPP/per kg biomass/per year is low;
tundra cold and dry so low rates of photosynthesis and respiration/
plants slow growing, slow accumulation of biomass, relatively large
growth in biomass per year;
Award up to [2 max] for comparison and up to [2 max] for
explanation. Award any other combination of two ecosystems.
(f)
4 max
name of primary producer: e.g. grassland;
method: [2 max]
collect all the vegetation (including roots, stems, leaves) within a
series of quadrats;
weigh vegetation;
dry the vegetation until no further weight loss is encountered/dry
weight represents biomass;
Award [2 max] if no named primary producer.
3 max
[11]
(a)
(i)
(ii)
second law – since energy for work is dissipated there needs
to be an input of energy hence system cannot be isolated;
e.g.
Award [2] for a clearly labelled model demonstrating negative
feedback. Award [1 max] for a poor diagram or labelling.
There are many other possible models, however, they must
demonstrate a return to an equilibrium position to award full
marks.
(b)
(i)
1
2 max
(ii)
bar graph/histogram; (not line graph)
appropriate axes; (either as above or two separate vertical axes)
accuracy of plotting;
clear distinction between biomass and productivity data e.g. a key;
4
there is an initial rapid increase in percentage cover followed
by a gradual decline;
this is due to rapid initial growth in the pioneer stage due
to low competition;
but eventually heather is outcompeted/displaced by other
species within the succession sequence/later seral stages/
heather is not the climax vegetation for this system;
3
[10]
(a)
(i)
(ii)
(iii)
(iv)
(b)
Sustainable yield: rate of increase is natural capital/resource
that can be exploited/taken/harvested without depleting the
original stock;
OWTTE.
High: 106 tonnes and low: 106 tonnes (units required);
Both correct values required for [1].
 48  24

100  = 100% difference

 24

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 4
compared with year 4 in high intensity;
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 the
industry;
if starving will break the law to catch food/hard for law-keepers
to monitor catch;
oceans are huge/vast areas;
international boundaries make legislation difficult;
Accept other reasonable responses.
1
1
1
2
2 max
(c)
Terrestrial:
most food harvested from lower trophic levels/as crops/plants/
herbivores/ cattle etc. so less heat/respiratory losses/more efficient
fixation of solar energy as does not have to get through water first/
less efficient use of land area (efficiency in terms of space rather
than energy);
Aquatic:
most food from higher trophic levels/bigger fish/higher up food
chain so much energy has been lost/energy conversions more
efficient as fewer warm-blooded animals which use most energy
to keep body temperature stable/more efficient use of land area
(efficiency in terms of space rather than energy);
(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 population
numbers carefully to check stocks/research in GM fish (suitable
for aquaculture);
Accept other reasonable responses.
2
1
[10]