OFFICE OF TASMANIAN
ASSESSMENT, STANDARDS
& CERTIFICATION
2015 ASSESSMENT REPORT
Environmental Science and Society
Course Code: ESS315114
The written examination was well received by candidates and teachers, with teachers expressing broad approval
of the paper in allowing ample scope for candidates to demonstrate their knowledge.
Part 3, assessing criterion 6, is only the second year for external assessment in this newer section of the syllabus
and revealed a better understanding of what is expected. Part 5, assessing criterion 8, proved challenging for
some students as they struggled to express adequate depth in a response expected of longer questions. This is
reflected in the minimum score required to receive a C rating, which was 10 marks. Longer mark questions
should be restricted to one per section or scaffolded at least to allow students to demonstrate a broader
understanding of the content examined.
Candidates are again reminded that the Information Sheet be used as a reference to assist them in constructing
their responses. Responses that are written word-for-word from the sheet reveal little understanding of the
required knowledge, and often yield little if any credit. Candidates should use the information and apply it to the
question.
Written Examination
The following section specifically comments on candidates’ performance. Marking examiners have offered
suggested answers to each question, followed by specific comment on aspects such as how the question was
assessed, where candidates gained or lost marks, where they had difficulty in interpreting the question, or where
candidates failed to comprehend what was required to successfully answer the question. The suggested answers
are by no means prescriptive. Candidates providing different but valid answers were rewarded accordingly as
noted by the examiners.
Suggested answers and comments
Part 1 – Criterion 2
Question 1
(a) “Native species can avoid feral cats if there is better ground cover.”
(b) Many difficulties with this ten-year research project. Possible difficulties include:
•
There is a need for a baseline study as a control to refer back to before providing better ground cover.
This baseline study would be lengthy as population numbers of both cats and native species would
need to be established and interactions between cats and native species observed.
Difficulty in monitoring/recording interactions between feral cats and native animals especially due to
nocturnal/shy nature of many native species. Substantial use of cameras would be required but may still be not
that effective in recorded interactions.
•
It will be difficult to establish population numbers of feral cats and native species. Capture/recapture
method will be difficult to apply as there may be migration of cats and native species, species may be
territorial and not mix adequately before recapture or simply the number of native species in this area is
low.
•
A field environment involves many uncontrolled variables that may impact on species interactions and
populations, i.e. disease in native species, seasonal and climatic variations and therefore it would be difficult
to show that reduced interactions between feral cats and native species or increases in native species
populations are due to better ground cover.
2015 Assessment Report
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Comments
(a) Generally done well. Many variations on the hypothesis gained full marks as long as there was an
independent variable (1 mark), dependent variable (1 mark) and an appropriate outcome (1 mark).
(b) Although there are lots of difficulties researchers would encounter, this part of the question was, on the
whole, not done well. Candidates generally did not discuss in sufficient detail the difficulties researchers
would encounter. Each of the three difficulties was given a maximum of two marks.
Question 2
(a)
(i) Crop productivity
(ii) Type of fertiliser
(b) ½ mark for each variable stated:
1.
Amount/type of irrigation
2. Soil type/growing medium
3. Sunlight exposure/intensity
4. Temperature
Other possible answers include but are not limited to humidity, soil salinity levels, planting density, run-off,
rainfall, wind and aspect.
(c) Sample answers include:
• Soil type: if soil type in different test groups have different in-situ nutrient concentration and water
holding capability. High in-situ nutrient levels are likely to lead to increased crop productivity and water
is a limiting factor in photosynthesis.
• Sunlight exposure: those test groups that have greater sunlight exposure are able to photosynthesise
more than test groups that don’t. More photosynthesis generally implies greater plant growth and
greater crop productivity.
(d) Since the hypothesis involves a comparison between fertiliser types one set of results for a treatment can
act as a control for a different fertiliser treatment.
(e) Support: some fertilisers result in a greater crop productivity than other treatments
Negate: all fertiliser treatments result in the same/similar crop productivity.
(f)
Possible answers include, but are not limited to:
• Investigate new genetic strains of potatoes – give the same treatment of fertiliser and measure
productivity
• Investigate ways to eliminate/control any disease in potatoes
• Trial different amounts of fertiliser, irrigation types and amounts, pH levels, plant density, aspects, soil
types, timing of planting.
Comments
(a) Only a few candidates got the dependent and independent variables around the wrong way. Students were
required to state “crop productivity” rather than “growth of potatoes” to gain full marks for (i).
(b) Many possible answers and, on the whole, an easy two marks for most candidates
(c) Many possible answers, depending on which variable was selected. Generally done poorly. Many students
poorly outlined how the results would be altered and simply stated that they would be altered.
(d) This question was done well by most candidates.
(e) This question was done well by most candidates.
(f) Marks were allocation as follows: 2 marks for a detailed explanation of one additional feature researchers
could do. 1 mark each for two shorter descriptions of additional feature or ½ mark each if list provided.
Question 3
Advantages of using Lidar include, but are not limited to:
•
Easier access to remotely located trees especially where there is no road or walking track access.
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•
•
•
•
•
•
•
•
•
Does not harm the ecosystems near the tree or on the tree access route due to the movement of people
on the ground.
Clearer view to the tree top – undergrowth and tree foliage can obscure the view to the treetops from the
ground making it more difficult to measure.
Time efficient way of measuring tree height compared to on the ground measurement where it can take
time to establish a viewpoint and take measurements.
Cost effective since it eliminates both the time and personnel required to measure tree heights from the
ground.
More accurate results as the laser is able to measure the height to the top of the tree with more certainty
and at the same time measures the distance to the ground.
More accurate results as it is difficult to measure the distance from the base of the tree to the measuring
point in uneven ground.
Reduces chance of human error as the process is undertaken with proven laser technology and not
dependent on the human eye.
More trees can be measured in a much shorter time-frame.
Is possibly safer as there are many potential hazards in undertaking on-ground measurements such as
traversing difficult terrain, falling tree limbs, etc.
Comments
Generally well done by most candidates. There seemed to be a lack of knowledge about how tree heights are
measured with many candidates thinking that trees were climbed to measure their height rather than the use of
a clinometer and trigonometric calculations.
Question 4
Substance 1: Phosphates
Excess phosphates can lead to eutrophication of waterways which can lead to algal blooms. Algal blooms lead to
increased BOD which causes dissolved oxygen levels to decrease placing strain on aquatic organisms.
Substance 2: Lead
Lead is toxic to aquatic consumers. Lead also bioaccumulates in organisms and biomagnification up the food
chain occurs.
Substance 3: Suspended solids
Higher levels of suspended solids can lead to increased turbidity of the aquatic environment and therefore
decreased sunlight penetration. This reduces the photosynthetic rate of aquatic plants (and therefore the energy
available to the ecosystem).
Substance 4: Organic Matter
Increased organic matter leads to increased BOD and therefore lower dissolved oxygen levels which can place
stress on the aquatic species present in the area.
Other appropriate substances are nitrates, e-coli (or other bacteria), antibiotics, relevant heavy metals, chlorine,
salts, hormones.
Comments
Mark allocation: ½ for appropriate substance and 1 ½ for explaining why the substance is a problem. This
question was not answered well by most candidates. Despite the detail provided in the question, many
candidates seemed to be unware that the question was referring to effluent from sewerage treatment plants or
did not know what effluent was. There was also some confusion over what a substance is. Candidates are
reminded that pH, salinity and temperature are not substances. A common incorrect answer was dissolved
oxygen or lack thereof. This is not in the effluent but rather a result of other substances in the effluent. Other
common responses that were not awarded any marks included DDT (which has been banned in Tasmania for a
long time) and carbon dioxide. Many students suggested agricultural run-off, industrial run-off and mining waste
as substances. Wherever possible, some marks were awarded in these answers. Plastics were not awarded may
marks unless candidates referred to micro-plastics. Oil/grease were awarded some marks depending on the
explanation provided. Some candidates explained why the substance was in the effluent rather than explaining
why the substance was a problem.
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Part 2 – Criterion 5
Question 5
a)
b)
c)
d)
e)
Sunlight
2nd
Predatory nematode worms, spiders, birds, ants, echidnas
(Any 3 for 1 mark; ½ mark if only 1 or 2 animals were correct)
No (1 mark)
OR
The fungi (½) if the organic matter contains plants and animals (½)
Examples:
• Plantsà fungià smooth nematode wormsà predatory nematode wormsà antsà echidnas
• Organic matterà bacteria à protozoa à predatory nematode wormsà antsà echidnas
(1 mark for 6 organisms, 1 mark for correct use of arrows)
f)
C5
C4
C3
C2
Primary Consumers
(C1)
Producers or Autotrophs
g)
h)
i)
j)
(Must have 6 trophic levels, each labelled correctly and show only 10% of previous level. 1 mark taken off
for not enough levels shown, ½ mark taken off for incorrect labelling, and ½ mark removed for insufficient
loss at each level.)
It would be a similar shape as an energy pyramid cannot be inverted. Only 10% of energy is passed from
one trophic level to the next; the rest is lost as heat from respiration.
(1 mark for describing the 10% energy passed on, 1 mark for stating the loss is due to heat and respiration.
½ mark for stating the shape would be similar or that energy pyramids cannot be inverted)
In this food web the fungi and bacteria are acting as a food source for higher trophic levels. Normally they
act as decomposers and convert organic matter from dead and waste material into inorganic nutrients
which can then be absorbed by producers.
(1 mark for describing the role in this food web, 1 mark for describing the role in general food webs)
Examples:
• Mangroves
• Compost
• A decaying log
• Benthic ocean
Atmospheric carbon dioxide is fixed by producers through the process of photosynthesis. When producers
are consumed the carbon is passed on to the tissues of the consumers. This movement of carbon continues
each time an organism is consumed, up to the top level consumers. At each level carbon can be lost to the
atmosphere through respiration. When an organism dies, decomposition converts carbon into carbon
dioxide.
(½ mark for naming each process and ½ mark for the details of the process. Full marks could not be
obtained unless the movement of carbon up to the top level consumers was mentioned, as this was part of
the question. Extra credit given for additional relevant details, for example carbon is stored in plant tissues
OR respiration occurs at each level of the food web).
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Comments
(a) A significant number of students identified either plants or organic matter (sometimes both) as the ultimate
source of energy for this food web. Candidates should be reminded that the ultimate source is always the
sun.
(b) A number of students were not awarded marks for this question, either because they stated the wrong
trophic level (3 was a common answer) or because they wrote ‘1st order consumer’.
(c) This was done extremely well. Very few candidates received less than full marks for this question
(d) This question was difficult for many. Few wrote that there was no omnivore and fewer were able to explain
how fungi could be considered an omnivore.
(e) This was generally done well, although it was disappointing to note the number of students who lost marks
because they didn’t include enough organisms or because they used dashes or commas instead of arrows.
(f) The pyramid could be based on the food chain in d) or on the food web as a whole. Either way, six trophic
levels should have been included. Labelling either had to include individual organisms or the standard
convention of P, C1, C2 etc. Simply writing Trophic Level 1, Trophic Level 2 etc. was only awarded ½ mark.
Candidates are strongly reminded that biomass pyramids generally follow the 10% rule so there must be a
significant difference shown from one trophic level to the next. Rulers are not necessary but each trophic
level should be substantially less than level before it.
(g) This was generally done well, although not many students had a detailed enough explanation to gain full
marks- many received 1 ½ marks. It is worth noting that some students didn’t seem to understand what
was meant by the term ‘inverted’. Candidates are reminded that English dictionaries are permitted in the
examination.
(h) A number of students commented that fungi was consuming plants. As the question referred to both
bacteria and fungi, this observation was not relevant. Candidates are reminded that being a food source is
not the same as being ‘prey’-some described the fungi and bacteria in this manner.
(i) The community identified here had to be one where the decomposers were a source of food (as in the soil
community food web). Many students just named ecosystems such as a rainforest or a river; these were not
awarded marks.
(j) There were many things that could be awarded marks in this question, so many students did well (although
a significant minority did not attempt the question). Some students interpreted this as a biomagnification
question. A surprising number of students stated that plants absorb carbon from the soil.
Question 6
There are a number of factors that contribute to Tasmania’s slow growth rate. The aging population means that
many people are past reproductive age, so the birth rate is low. However the death rate is also low so growth
may still be positive. Emigration from the state is high, as people leave mainly to find work, but this is almost
balanced by people immigrating here to start families or to retire. As the population of Tasmania is small, growth
by reproduction must also be small.
Comments
Candidates were not sure how to respond to this question and the majority of them received 2 marks or less.
Many candidates only described the social or economic reasons for a low growth rate (the availability of
contraception, lack of housing infrastructure, cold weather) but these were not awarded credit unless they were
used in the context of four variables that influence growth: birth rate, death rate, emigration or immigration.
Some students referred to the factors that would impact on the growth of non-human populations, such as
carrying capacity or environmental resistance, but these are not relevant to people.
Of those students who did address the question in terms of human births, deaths, immigration and emigration,
the following errors were common:
•
Stating that an elderly population means that the death rate is high, when the opposite is true
•
Describing the death rate as greater than birth rate, and emigration greater than immigration (the growth
rate is slow, but not negative)
•
Simply restating the formula for population growth- this can be found in the information sheet so was not
awarded any marks.
•
Only discussing births and deaths or immigration and emigration
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•
Not demonstrating the immigration means entering the population and emigration means leaving the
population
To gain full marks in this question candidates had to clearly outline how the four factors could work together to
cause slow population growth.
Question 7
Biotic factors include lack of predators, an abundant source of prey and a lack of competition with other
organisms.
Abiotic factors could include cool water temperatures and high dissolved oxygen levels, which may be similar to
conditions in Scotland and England.
(1 mark for each factor, provided that it was clear how that factor was beneficial to the trout.)
Comments
This was a straightforward question and a good opportunity for students to pick up marks. 5 factors needed to
be mentioned, with at least 2 biotic and 2 abiotic. It wasn’t necessary to list the factors as biotic and abiotic,
however if candidates did do this but listed them incorrectly, marks were deducted. Some students copied down
the list of abiotic factors that were found in the information sheet, which included irrelevant factors such as
humidity. Students cannot show the extent of their understanding by simply copying from the information sheet.
Other examples of factors:
•
A broad niche/ large zone of tolerance
•
Fast breeding rate
•
Good plant growth, providing food or habitat (trout are carnivores but students were not penalised if they
didn’t know this)
•
Low pollution levels
•
Low salinity
•
pH that is similar to that in Scottish and English lakes
Question 8
a)
b)
The spotted pardalote and the yellow thornbill feed in different locations; in leafy foliage and on ground,
respectively.
They do not occupy the same niche as they move in different directions on the tree. The tree creeper is
also a specialist, preferring ants, while the varied sittella is a generalist. (1 mark for the different directions, 1
mark for the difference in their diets)
Comments:
Both these questions were done well, with almost all candidates receiving full marks for 8a. Most candidates
identified that the birds moved in different directions but not as many clearly described the difference in their
diets. Credit was also given for those who identified that no two organisms could occupy the same niche.
Question 9
In the Early DFTD region, where there are fewer devils, the cats are most active at night, In the Mid DFTD
region, the cats are least active at night and most active in the afternoon. This is because Tasmanian Devils and
feral cats are in competition over food, so when Devils are abundant, the cats have a different realised niche. (2
marks for describing the relationships shown in the graph, 2 marks for explaining the change)
Comments
This question proved difficult for many students and very few earned full marks. Common errors were:
2015 Assessment Report
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•
•
•
•
•
Describing changes in the feral cat population. The data given is for cat activity, not numbers
Stating that in the mid DFTD region, feral cat activity was reduced. The activity was only reduced at night
and in fact the activity during the day was quite high (candidates who identified this were given credit).
Stating that numbers of Devils were high in the early DFTD region but low in the mid DFTD region
Failing to mention the name of the animal when describing changes, so it was unclear whether the
statements related to Devils or cats
Incorrectly identifying the relationship between cats and Devils as predator-prey
Part 3 – Criterion 6
Question 10
a)
b)
Introduced species like Ragwort, are able to grow aggressively, outcompeting native plants for space,
nutrients, light and water. They produce an abundance of easily dispersible seeds and can reproduce in
several ways (roots, stems and seeds). They are very adaptable to a variety of habitats and climates, having
high genetic variation. In new environments, they have few herbivores that consume them.
Introduced animals like rabbits, have high reproductive rates, becoming sexually active early and produce
large numbers of young. They are also selective breeders, so can slow down reproduction when food is
scarce and increase it when resources are more available. Their high genetic variability make them resistant
to diseases and biological control methods. They are often generalist species, so can outcompete native
species for food and space and live in a variety of climates and habitats. Initially, they can have few
predators.
Comments
Most students answered both parts well, being able to identify 3 solid factors for 3 marks for each part. Most
students were able to identify high reproductive rates, being adaptable to a variety of habitats and conditions and
having high genetic variability. Some students talked about introduced plants as being generalists, this earned no
marks. 3 factors were needed for each part.
Question 11
(a) (i)
In wet sclerophyll forests, fires initially reduce competition for light as the canopy is opened up. This
enables eucalypt seedlings and other understorey plants to germinate and grow. Dry sclerophyll
forests also require fire for regeneration as shrub layer and ground cover species are burnt. In both
forest types, controlled fires help to reduce the flammable fuel load on the forest floor, which
reduces the risk of more intense, out of control fires. Fires are a natural part of the eucalypt forest
cycle and these and other trees (wattles), are well adapted for regenerating after fires. The resulting
ash bed and opening of the canopy provides ideal conditions and nutrients (potash and nitrogen) for
seedlings to grow.
(ii)
The ecological cost of frequent fires includes excess CO₂ emissions into the atmosphere, adding to
greenhouse gases and a reduction in trees can lead to a reduction in the amount of CO₂ that is taken
up from the atmosphere. Too frequent fires destroys sensitive habitat that is not fire tolerant, which
can cause a loss of plant biodiversity (reducing species richness) and can promote the growth of
pyrophytic plants species (grasses). Fires open up the canopy and change the prevailing abiotic factors
of the forest, sometimes destroying decomposers. Smoke can affect water quality in catchments also.
(b) Slow growing cool-temperate rainforest plant species do not require fire to regenerate and do not have
adaptations to cope with fires (such as a thick bark layer). An intense fire, which is more than likely to occur
from lightning strikes, will kill sensitive rainforest trees, such as our endemic pines (King Billy, Pencil Pine) that
will not regenerate. It will open up the canopy and allow sunlight to enter and dry out the forest floor. This
wipes out shade loving ferns, mosses, laurels etc. and provides conditions for wet sclerophyll species such as
wattles and eucalypts to grow. The forest, over 50 to 150 years will change from rainforest, to a wet
sclerophyll forest. It is only if the forest has no further fire for at least 400 years, and sclerophyll species die
out, that rainforest species may return.
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Comments
a) (i)
Students were able to explain the benefits of having a controlled fire regime. Most answered that
fires were a part of the sclerophyll forest cycle and that controlled fires reduced the risk of bushfires.
Many talked in detail about the ways eucalypts can regenerate. Better students were able to cite the
reduced competition for sunlight and water allowing new growth and a few mentioned regular fires
controlled the structure and composition of the forest. Very few mentioned the return of nutrients
back to the forest soil is also important. 3 good factors gave 3 marks, but 2 factors in detail was
accepted.
(ii)
This question provided students with an easy 2 marks, as it was mostly well answered. However,
some students interpreted the question as financial costs and went on to explain about the cost to
stage the burns or the costs of houses and infrastructure being burnt. Most could state that CO₂
emissions would increase adding to global warming and the loss of habitat and biodiversity. Very few
mentioned the loss of CO₂ uptake. 2 marks for 2 well explained points or 3 brief points. At least
two factors needed to be mentioned.
(b) This question proved to be fairly difficult for some students. Most could identify that rainforest communities
would not survive an intense fire and used the information booklet on forest structures to their advantage
when discussing time frames and forest composition. However, many simply stated that rainforests would
not survive and would need 400+ years to regenerate, which only awarded 2-3 marks. Those that went on
to describe why rainforests would be initially wiped out and then the progression through the different
forest types were awarded the 4 full marks.
Question 12
Three impacts specific to Tasmania’s coastlines could include:
•
•
•
•
Increasing sea temperatures impacting on our fisheries (salmon, oyster, abalone, crayfish), causing species to
die out or migrate to cooler waters. Movement of invasive species could occur into our waters (North
Pacific Sea Star and other pests) through warmer ocean currents. This would impact on people’s livelihoods,
on our aquaculture industry, our State economy and our endemic aquatic species. Cold water kelp forests
could be wiped out, so a loss of tourism (diving ventures) could occur.
Rise in sea levels would impact low lying coasts and townships (Lauderdale, Cremorne) and those living
along estuaries and inlets (Huon Channel). Beaches, houses, camping spots and infrastructure (boat ramps,
roads, and seawalls) would become inundated or damaged during storm surges. People may need to
relocate, so there would be stress and costs involved. It would also impact aquaculture in our inlets around
Strahan/Dover, so financial losses. Erosion associated with surges could destroy or wash away pristine
beaches on the East Coast, so a loss in tourism and loss to the State economy. With increased sea levels,
there is increased salinity into estuaries, impacting on this delicate environment, and into groundwater which
can impact coastal farmland and drinking water.
An increase in ocean acidification would lower pH levels in the water and impact our shell fish industry
(oysters, mussels and scallops) causing weakening/softening of shells. This would impact on our aquaculture
industry and cause financial loss to people’s livelihoods and our State economy.
Increased summer temperatures and U.V. radiation can impact the number of people visiting the beach,
either increasing, and putting pressure on fragile coastal reserves, or decreasing which impacts tourism and
places financial strain on livelihoods that rely on summer trade.
Factors not impacting the actual coast, but adjoining land areas, could include: increased risks of bushfires,
flooding and erosion, more severe storms, winds and droughts which will impact farming communities and
townships.
Comments
This question provided many answers that were in many cases, not applicable to Tasmania or Tasmanian
coastlines. Students were able to supply many impacts of climate change, but better students could relate these
to specific examples of impacts on Tasmanian coastlines. Some students talked about coral bleaching, which is
not relevant to Tasmania. Many related impacts to broader areas, not necessarily coastal areas, such as increased
bushfires, floods and droughts affecting farming and towns. (This was deemed as acceptable, as much farming
land and many townships occur on the coast).
2015 Assessment Report
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The breakdown of the marking was: 2 marks for each factor, comprising: ½ mark for naming each of the three
impacts that were relevant to Tasmania and then 1½ marks for a detailed discussion of the impact and how it
effects Tasmania’s coastline with specific examples. Half points deducted if the impact was not specific to
Tasmania’s coastline, but could still be applied to areas inland. Half a mark only awarded to impacts that related
to climate change but were not relevant to Tasmania at all, such as coral bleaching.
Question 13
Millions of years ago, Antarctica was part of the large landmass Gondwana, which included Australia, New
Zealand and South America. This landmass was much further north, with a mild and wet climate throughout and
was able to support the growth of Nothofagus sp. Over time, this landmass broke up into separate continents
and Antarctica moved further south. The climate began to cool down and permanent ice covered the continent.
The abiotic factors, such as temperature, water, light and nutrients were not suitable for Nothofagus to grow and
eventually it died out in Antarctica, leaving only fossil remains in the rocks. Currently, remnant species of
Nothofagus exist only in those areas that were part of Gondwana that still have suitable climates.
Comments
This question was answered quite poorly. Students were able to say that today Antarctica’s climate is too cold.
In many cases students said that because of global warming the species could no longer survive there. Some said
the species was found in Antarctica because seeds were spread there from birds/winds. Neither answers were
awarded any marks. Some students did talk about the continents being joined and then separating, but did not
go on to explain that the climate at this stage was suitable for Nothofagus growth. Only 3 marks were awarded
in this case.
For the full 4 marks: 1 mark: Nothofagus once grew when the continents were joined further north and the
climate was cool temperate. 1 mark: The continents drifted apart and the abiotic factors changed, restricting
Nothofagus. growth. 1 mark: Today, Antarctica’s climate and other abiotic factors are no longer suitable for
Nothofagus. growth, being too cold, dry, & dark for part of the year, with no soil. 1 mark: Fossil remains of
Nothofagus. are found in Antarctica as evidence it once grew there when the climate was suitable.
Question 14
(a) The overall trend shown in the graph is the area of Arctic ice shelf is decreasing over time.
(b) The area of Arctic ice shelf is first predicted to be ‘nearly ice free’ in about the year 2045.
(c) Main causes for the loss of the size of the Arctic ice shelf are global warming increasing the temperature of
the ocean and the atmosphere. As oceans warm, thermal expansion increases sea levels, which can cover
the ice shelf melting it quicker. Warming ocean currents increase the air temperatures, with increased rainfall
over the Arctic, adding to the melting. Anthropogenic causes, (increased greenhouse gases), are
exacerbating the melting. Increases in CO₂ and CFC’s are contributing to a thinning of the ozone layer,
allowing more solar radiation in. As the ice shelf thins and shrinks, its albedo is reduced, causing an increase
in temperatures over the polar regions, which leads to further melting.
(d) Some of the likely impacts would include reduced habitat for those that live on the sea ice or use it to give
birth or to rest. Polar bears hunt on the ice, so they may have to swim further or hunt on the land and/or
scavenge around human habitation which can result in conflicts. This would put pressure on females when
breeding and raising/feeding cubs. There may be increased competition for food from polar bears and arctic
foxes. Those species that seek refuge under the ice for protection from predators, (such seals and fish), may
decrease in numbers or move elsewhere. There may be increased predation from killer whales when seals
have less ice to escape the water. Walruses can give birth on the ice, so they will need to seek areas on the
land to breed. This could cause increased competition for space. Sea bird habitats may be reduced also.
(e) Numbers of species that inhabit the ice would generally be reduced and species may need to migrate to
other areas. In extreme cases, some species may die out.
Comments
a) This question was answered well by students. Nearly all students could interpret the decreasing area of the
ice shelf over time.
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b)
c)
d)
Reading off this graph to find the year that the area of ice shelf was first predicted to become nearly ice free
proved confusing for some students. Some said after 2060 or in 2050 and were not given any credit.
Answers that said ‘just after 2040’ were accepted. Those that said 2040 were given half a mark only, as it is
clearly a little after this time.
For 3 marks students needed to mention a minimum of two factors, giving an explanation about each, or
give three brief factors. Most students answered with global warming being the main cause for loss of ice
shelf size, with increases in air and sea temp’s from GHG’s being most common answers. Only a few added
the thinning of the ozone layer was also a cause.
This question was answered well and gave students, in some cases, 3 or 4 much needed marks. Most
students could mention at least three impacts. Four impacts with detail of how these will affect the ice shelf
communities were needed for full marks. Some students made very definitive predictions like extinction of
species and drowning of polar bears and left answers at that, which was awarded 2 marks only.
Part 4 – Criterion 7
Question 15
(a) i) halibut about 0.23 ppm ii) tilefish about 1.43 ppm.
(b) Scallops and oysters are filter feeders so they are low on the trophic level. They feed on phytoplankton and
zooplankton so could be considered level 2 consumers. They do bio-accumulate Mercury (Hg) from the
water into their tissues but the concentration in their flesh is many 100 times less than the top order
consumers due to bio-magnification.
(c) Mercury bio-accumulates in all organisms as it is a persistent toxin, does not degrade, cannot be excreted by
organisms and is stored in fat cells for the organism’s life. Each heterotroph stores all the toxin from its prey
in its own fat cells for the duration of its life. So the concentration of Hg increases up the trophic levels so
that swordfish and shark have the highest concentration as they are at the top of the food web.
(d) Any two well-described points were awarded full marks:
• There is a recommended limit of the amount of fish that are contaminated with Hg that the public
should not exceed each week. (e.g. Fish from the Derwent River should not be eaten more twice per
week. People that are pregnant and breastfeeding & children under six should further limit their
consumption. One portion is 150g and 75g for children. It is also recommended that no Bream or
shellfish be consumed from the Derwent)
• Periodic testing of shark flesh so that the recommended levels of Hg consumption is not exceeded.
• Limit the size and age of shark that are consumed. Older and larger fish would have bio-accumulated
more Hg during their life, so smaller and younger fish should be consumed.
• Consume lower level trophic fish as an alternative to top-order consumers, for example sardines,
octopus and cuttlefish are all short-lived so less contaminated, lower on the trophic level than sharks and
reproduce much faster than sharks.
• Limit the total allowable catch (TAC) of higher trophic level fish that are consumed as these fish will be
more contaminated and tend to reproduce slowly and we need to limit their catch to be sustainable for
the future.
Comments
(a) This question was very well answered but ½ a mark was deducted if the units (ppm) were not included.
(b) This was often a poorly answered question as many students guessed that they ‘filtered out the Hg’ and
thus were awarded no marks. It should be noted that the Hg concentration in the water is very, very low
but it still bio-accumulates and bio-magnifies starting at the producer level (phytoplankton). A few students
that stated that the oysters and scallops did not accumulate much Hg as the Hg was in the sediment and
they did not feed on sediment were awarded part marks as this is partially correct. Hg does attach to
sediment but it is usually consumed by bacteria in low oxygen conditions (in the sediment). The bacteria in
the sediment convert Hg to the soluble and deadly form of methyl-mercury. Methyl-mercury is the toxic
form of Hg that bio-accumulates and bio-magnifies in food webs.
(c) Students answered this well but often omitted to say why Hg bio-accumulates (persistent, not
biodegradable, not excreted and stored in fat cells) and did not use the terms ‘bio-accumulation’ or ‘bio-
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magnification’ which were required for full marks. If they omitted either term and did not explain bioaccumulation 2 marks were deducted.
(d) This was generally well answered although some student were very creative but did not notice that the
question asked for ‘employed strategies’ so were awarded no marks for answers that are not currently
occurring. For example sharks are currently not being farmed so limiting their diet with Hg-free fish food
was awarded no marks.
Question 16
(a) Less ozone in the stratosphere means that more ultra violet radiation is travelling through the atmosphere
to Earth. UV radiation is responsible for increases to cancers in organisms, cataracts and genetic mutations.
At very high levels plants are harmed especially phytoplankton, which may lead to lower marine ecosystem
productivity and food shortages for humans.
(b) All CFCs are very persistent chemicals and last in the atmosphere for up to 80 years. It also takes many
years to reach the stratosphere so this lag time means that some CFCs released before the Montreal
Protocol are still destroying the ozone above Antarctica. The following points were also given full marks;
•
Some refrigeration units may not have been properly disposed and may still be off-gassing (leaking)
CFCs from landfills
•
Nitrous oxide is a weak ozone depleting substance (ODS), but its quantity is large and expected to
increase and this ODS is not included in the Montreal Protocol
•
Not all countries have ratified the Montreal Protocol so some countries have been still using and
releasing CFCs in the last 30 years
•
Recent research has found that changes in atmospheric circulation have increased the HCl
concentrations in the stratosphere which further depletes the ozone.
Comments
(a) This question was surprisingly poorly answered as there is a lot of detail about ozone in the information
booklet. Unfortunately many students could not delineate between climate change and ozone or between
‘good’ vs. ‘bad’ ozone. Many students’ answers included all ozone and clearly copied from the information
booklet about increasing GHGs, tropospheric ozone and photochemical smog. As the question asked about
decreasing ozone this was awarded no marks unless the student clearly stated that this would lead to less
secondary pollution, less photochemical smog and its impacts.
More delineation between ozone and climate change clearly needs to be emphasized. They are generally
considered separate processes although as we learn more about climate change more links between the
two are being discovered, for example while greenhouse gases absorb heat in the troposphere and warm
the earth’s surface, the stratosphere is cooling. The chlorine gas in the ozone depleting substances (ODS) is
the problem as each molecule of chlorine acts as a catalyst and destroys thousands of ozone molecules. This
chlorine gases from ODS interacts and become active with tiny cloud particles that form only in extremely
cold temperatures; below -80° C. So this cooling of the stratosphere around Antarctica (as a result of
climate change) results in an increase in polar stratospheric clouds which create more chlorine thus
contributing to more ozone depletion
(b) This question was poorly answered with many students confusing ozone in the troposphere and no marks
were awarded. Full marks were given to answers stating that not all countries have ratified the protocol,
even though this is not entirely true. By 2015 all 197 countries of the world have ratified the Montreal
Protocol making it the first universally ratified Protocol ever; however as there have been several
amendments to the list of banned ODS and not all countries have ratified all these amendments, full marks
were awarded.
Question 17
(a) Four of any of the following (for full marks):
•
Less mixing or wave action
•
Increasing water temperature
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•
Less photosynthesis by phytoplankton or other water plants
•
Seasonal changes in temperature (less DO generally in summer)
•
Increasing sunlight (warms water)
•
Less freshwater or rainfall
•
La Nina (warmer sea in Australia so lower DO)
•
More salinity
•
Greater respiration from fauna and decomposers
•
Less atmospheric pressure
•
Lower pH
(b) One well described point (or two brief ones) was awarded full marks. The most common answers was
Eutrophication. Eutrophication needed to be explained for full marks; increased nutrients from feed &
faeces when decomposed by bacteria and fungi at the bottom of the ocean under the pens resulted in
hypoxic or anoxic conditions (also an increase in BOD) and often a dead zone. The great number of fish at
a high density would lower the DO due to their respiration and result in a high BOD.
(c) Full marks were awarded for two brief points from the following:
•
Chemicals and excess nutrients from food and faeces associated with salmon farms can reduce benthic
(ocean bottom) biodiversity of the flora and fauna
•
Excessive use of chemicals - such as antibiotics, anti-foulants and pesticides may impact upon wild
species and human health
•
Diseases, viruses and parasites can transfer between farmed and wild fish, as well as among farms
•
Escaped farmed salmon can compete with wild fish and interbreed with local wild stocks of the same
population, altering the overall pool of genetic diversity
•
A growing salmon farming business must control and reduce its dependency upon fishmeal and krill oil
so it does not put additional pressure on the world's fisheries. Fish caught to make fishmeal and krill oil
currently represent one-third of the global fish harvest
•
Nutrient loading and carrying capacity: Excess food and fish waste in the water have the potential to
increase the levels of nutrients in the water. This can cause the growth of algae in waters surrounding
the pen and its decomposition consumes oxygen thereby lowering its carrying capacity and biodiversity
•
Social issues for example salmon farming often has light and noise pollution and there may be conflicts
between users of the shared coastal environment.
Comments
(a) This was generally easily answered although many students did not read ‘naturally’ and included human
activities and were awarded no marks. More astute students included a quantity with each factor, for
example DO decreases with ‘more’ salinity. As each factor was only worth ½ a mark, answers without a
quantity were not penalised.
(b) This question was well answered although it should be noted that decreases in dissolved oxygen are largely
a result of very high nutrient load below the salmon pens, rather than due to the respiration of the fish. The
density or stocking numbers of a salmon pen is carefully controlled and currents and water quality flowing
through the pens is considered so that low DO does not impact upon the fish (very costly when the final
product dies). The water quality and currents are often the reason that many locations are not suitable for
salmon farms. A number of students did not explain how salmon would lower DO (through the respiration
of the great number and density of fish), and as a result were awarded ½ a mark.
(c) This question was well answered as long as the students read ‘other possible impacts’. If students used the
same answer for b) and c) no points were awarded in c).
Question 18
(a) The commons are resources or areas that are shared or common to all and owned by none. The marine
environment is where all plastic debris collects. As all countries pollute this environment the
harm/degradation is shared by all. The only benefit is to the polluters as there is no full cost pricing (the
polluters don’t pay for plastic disposal).
(b) Finland and Greece
(c) Germany and Belgium
(d) China and Indonesia
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(e) China and India are increasing their standard of living and becoming more affluent so the demand for
plastics is expected to increase, whilst these countries have poor recycling and waste disposal, so will have
the greatest increase in proportional plastic pollution.
(f) Two well-described points (not limited to the following):
•
Replacing disposable plastic with other materials such as calico, hessian or paper
•
Banning the sales of plastic bags from cities or states
•
Disincentives to purchase plastic bags by raising the cost to the consumers
•
Incentives to purchase alternative bags that are longer lasting and re-useable (an introductory or
transition phase where calico bags are cheap)
•
Enforcing the polluter pays principle so that plastic bag manufactures are forced to pass this extra cost
onto the consumer and this reduces demand
•
Legislation and education to ‘stow not throw’ plastics and other debris at sea.
Comments
(a) This was either very clearly answered or very poorly answered. Answers that were awarded full marks had
to include the ideas that the resource is common or owned by no one, and no one takes responsibility, and
that only the polluters benefit whilst the degradation is shared by all. Wording straight from the information
booklet without references to marine debris, was awarded no marks.
Questions 18 b), c), and d) were well answered with almost all students gaining full marks. The only
difficulty was with 18c) as Belgium was often incorrectly replaced with Netherlands for a deduction of ½ a
mark.
(e) This was generally well answered. Students that stated the increase was only due to increasing population
growth were given only ½ a mark. Even though these two countries are expected to have very high
population growth rates this does not account for the ‘proportional’ increase in pollution.
(f) Almost all students were awarded full marks as this was an easy two marks. The only problem was were
students did not describe their development, or did not notice ‘apart from recycling’ and answered with
recycling programs.
Question 19
Full marks were given to four well-described points (not limited to the following):
•
The large thermal mass of the ocean means that a great deal of the heat from climate change is being
absorbed in the ocean thus regulating the climate and reducing the heat entering the atmosphere.
•
Currents in the ocean have a great effect upon the climate, for example the Gulf Stream brings warm water
and moderates Europe’s climate.
•
Large surface of the ocean absorbs CO2 into the water thus reducing the amount of this GHG and lowering
the greenhouse effect which lowers the temperature of the atmosphere.
•
Currents, trade-winds and large area areas of warm/cool water move back and forth between South
America and Australia leading to alternating El Nino and La Nina weather events.
•
Evaporation of water over the ocean travels as water vapour in atmosphere and falls as precipitation (water
cycle) to greatly affect the Earth’s climate.
•
Warm water and winds over the ocean form into severe weather such as cyclones/hurricanes/typhoons
that make their way toward land.
Comments
Students generally answered this very well although many did not attempt this question - indicating that they ran
out of time. Using the reading time to plan which questions to attempt first and which questions are easier
should be emphasised. It should be also noted that those students using highlighters generally gave more astute
answers and this simple technique may help to focus on important words.
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Part 5 – Criterion 8
Question 20
(a) Installation of solar (photovoltaic) panels on the roofs of houses (½). Electrical energy may be either used
directly by the house or fed into the grid (1), thus reducing the amount of energy consumed that originates
from a coal fired power station (½).
Installation of solar (passive) hot water systems on the roofs of houses (½). Heat energy may be used
directly to heat up water rather than relying on an electric hot water cylinder (1), thus reducing the amount
of energy consumed that originates from a coal fired power station (½).
(b) Economic incentives such as rebates or subsidies, where people installing solar panels or insulation get a part
of the purchase price returned or the overall cost reduced (1)
Economic disincentives such as raising the price of electricity or a carbon/consumption tax in order to make
it more costly to consumers (1).
Comments
a) A large variety of answers were also awarded marks when in similar detail to the above example discussing
wind energy, LED lighting and energy efficient appliances. Solar (passive or photovoltaic panels) was the
most commonly given response. Many candidates did not give any detail in their answer as to how the
alternatives reduced reliance on coal fired power stations or cut domestic power consumption, but
concentrated on how the alternative worked, eg wind energy turns the blades of a turbine to convert
kinetic to electrical energy.
b) This question was well answered by many candidates. Marks were also awarded for answers discussing
education and marketing as a management strategy promoting alternatives.
Question 21
Arguments for reclassifying parts of the TWWHA will allow greater access via boat/plane to areas once
inaccessible to most people, so more people can experience and enjoy these areas (1). This will enhance the
region as an adventure recreation destination, which will boost visitor numbers (1) increasing the flow on effects
of tourism to hoteliers, transport, accommodation and recreational activities in the region (1). This in turn will
provide economic benefits to the region through the creation of jobs needed in construction of accommodation,
infrastructure (eg roads), hospitality, specialty timber products and ongoing management and maintenance (1) in
the region, which will have also social benefits for isolated communities in the region due to higher employment
(1).
Arguments against reclassifying are that increased visitor numbers may cause more land clearing for roads,
parking and accommodation, disturbing local communities of organisms (1). This, and the clearing of trees for the
speciality timber industries may disrupt highly specialised and sensitive organisms which may currently inhabit
these remote areas (1), causing them to be displaced due to the destruction of their habitat or other
requirements of their niche, such as nesting sites or tree hollows (1). Tourists may also introduce many weeds or
diseases to the area, which will also impact negatively on biodiversity (1). The presence of increased vehicles
during construction and maintenance may result in increased deaths of organisms due to road traffic (1). A
decline in water quality may occur due to more effluent from kitchens and accommodation having to be
discharged locally (1). There may be political tension or backlash from groups opposing the reclassification by the
government, which is also not desirable (1).
Other relevant points discussing the arguments for or against the reclassification were also awarded marks, such
as flow on effects to retail outlets through more specialty timber products available for purchase .
Comments
This section was generally well answered by most candidates and very few candidates did not attempt this
question. There were a broad range of answers awarded marks concerning the enhancement, or loss, of social,
economic, political, ecological, aesthetic and scientific values of the area. Some candidates failed to address both
sides of the argument and some students misinterpreted the ‘air and water access’ to mean that more air and
water storages would be available, rather than greater access to the reclassified areas by air and water.
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Question 22
Intergenerational equity has not been upheld (1) as the Ugandan villagers are being evicted from their lands, so
the next generation cannot enjoy the same land access rights as their parents. It may be upheld to some degree
through carbon offsets, as global CO2 levels are trying to be reduced to mitigate further climate change due to
rising average global temperatures for future generations (1).
Intragenerational equity has not been upheld as the Ugandan villagers are being denied access to basic rights such
as land, food and water in order to support themselves and their community (1). With forced evictions, they
may also be homeless/displaced and become refugees (1).
Precautionary and anticipatory principle has been upheld to some degree as the carbon offset project aims to
reduce global CO2 in anticipation of future temperature rises (1), but clearing of any land and evicting present
landholders would see this principle not being upheld (1).
Conservation of biodiversity and ecological integrity may or may not be upheld, depending if the 10,000 hectares
of land is cleared for tree farms through the carbon offset project, or left as it is, acting as a carbon store. If it is
left intact, then yes, the principal has been upheld as the biodiversity and integrity of the ecosystem is still intact
(1); if cleared, then it has not been upheld as biodiversity will be replaced with a monoculture in the tree farm
(1).
Pricing of environmental values and natural resources has been upheld to some degree in that carbon emissions
are being paid for by off sets, but not upheld as the villagers’ rights to live in their area are being completely
overlooked (1). If the land remains uncleared, it is being upheld as natural resources and biological integrity of
the area is being preserved (1).
Marks were also awarded for answers discussing how the principal of efficiency of resource use was upheld (or
not).
Comments
This question was attempted and generally answered well by most candidates. Most candidates were able to
understand what the fundamental concept of the six ecologically sustainable development (ESD) principles listed
were and were also able to apply whether or not the principles were being upheld or not in the context of the
question. Many candidates did not explicitly state whether the principle was upheld or not in their response,
which cost them marks. Students were not awarded marks for referring to other ESD principles that were not
being asked to be considered in the question, such as the polluter pays concept, or full cost pricing.
Question 23
Stakeholders should be identified and consulted on the new plan (eg local council, Mt Wellington trust, residents,
local users of the mountain) (1) A description and map of the area, including current and proposed access
points and buildings, such as huts, shelters and new cafe, should be included (1). A vision statement, identifying
potential threats and amenities (such as carparks, toilet blocks) and what the area should look like after a period
of time should be prepared (1). The values of the area (ecological, aesthetic, social, scientific) should be noted
and included in the statement (1). A list of management objectives should be included, such as not impinging on
areas of delicate vegetation, making the buildings blend in to the environment (1). Information on the legal status
of the area (building codes, EPBC act, threatened or endangered species) potential infringements should be
sought (1). A baseline study of all of the relevant biotic and abiotic factors should be prepared, so it can be
compared to follow up studies done in the management plan evaluation. Species numbers and diversity,
especially locally threatened or endangered sub-alpine plant species, should be carefully monitored (1).Various
options should be included for the new cable car, such as height, length of the cable car, location on the
mountain, materials used in construction and appropriate technology used in the project (1) .
Marks were also awarded for other parts of a management plan that were specific to this project, such as the
establishment of a management committee made from the various stakeholder groups eg Mt Wellington trust,
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proponents of the cable car plan, local council, recreational walkers in the area to plan for ongoing management
and monitoring.
Comments
This question was the last question on the paper and if students were time poor, this section, and particularly this
question, suffered as a result. Too many students listed/copied the dot points on how management plans are
developed straight off page 27 of the information sheet, without any reference whatsoever to the context of the
question, rather than describing what should be included in the management plan specifically for Mt Wellington,
as supplied in the suggested answer above.
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