STANSW Meet the Markers
2008 HSC Notes from
the Marking Centre
Earth and Environmental
Science
David Tweed, Penrith Anglican College d.tweed@pac.nsw.edu.au
General Comments
• 1240 candidates attempted the Earth and
Environmental Science examination.
• The most popular electives were
Introduced Species and the Australian
Environment (78%) and Oceanography
(8%).
Content
• examiners may write questions that address the
syllabus outcomes in a manner that requires
candidates to respond by integrating their
knowledge, understanding and skills developed
through studying the course, including the
Prescribed Focus Areas.
• It is important to understand that the Preliminary
HSC course is assumed knowledge for the HSC
course.
Depth of treatment
• Candidates need to be reminded that the answer space provided
and the marks allocated are guides to the maximum length of
response required.
• Candidates should use examination time to analyse the question
and plan responses carefully, working within that framework to
produce clear and concise responses.
– dot points,
– diagrams and/or
– tables,
• holistic questions which need to be logical and well structured.
• confused the terms and concepts of
– global warming and ozone depletion
– the Cambrian Explosion with a mass extinction event.
Better Responses
• Better responses indicate that candidates are following
the instructions provided on the examination paper. In
these responses, candidates:
• show all working where required by the question
• do not repeat the question as part of the response
• look at the structure of the whole question and note that
in some questions the parts follow from each other, ie
responses in part (a) lead to the required response in
part (b) etc
• use appropriate equipment, for example, pencils and a
ruler to draw diagrams and graphs. (A clear plastic ruler
would aid candidates to plot points that are further from
the axes and rule straight lines of best fit.)
Option Answers
•
In Section II, the option question is divided into a number of parts.
Candidates should clearly label each part of the question when writing in
their answer booklets.
• In part (e) of the 2008 option questions, the best responses
presented ideas coherently and included the correct use of scientific
principles and ideas.
• Many candidates wrote a lot of information that was not relevant to
the question.
• Some responses showed evidence of rote learning an anticipated
answer. These responses did not address the syllabus content
and/or outcomes being assessed and hence did not score full
marks.
• Candidates are required to attempt one question only in Section II,
but some candidates responded to more than one option question.
• Candidates are strongly advised to answer the option they have
studied in class.
2008 Scaling of EES
http://www.uac.edu.au/pubs/pdf/2008_table_A3.pdf
Zone C
b) There are several current mechanisms used to
explain plate motion.
i) Slab Pull- the colder, denser plates subduct (sink),
as in 'Area A' pulled downwards by gravity, which in
tum pulls the rest of the plate.
ii) Ridge Push - the mid-ocean ridge, as in 'Area C'
pushes oceanic plates out by forcing part of the
mantle up between them.
iii) Convection Currents - the heat in the mantle
causes the molten material to circulate pushing the
plates in the direction shown.
The medium risk along the NW region of Australia is caused by the
convergence of the 'Australian Pacific Plate' with that of the'
Indonesian Plate'. Convergent plate boundaries are more likely to
have deep focus earthquakes (caused by the pressure build up) and
explosive volcanic eruptions which may lead to a Tsunami. The
southern margin of Australia is at low risk due to reduced activity
upon the plate boundaries. A divergent plate boundary only creates
shallow focus earthquakes which are less likely to create Tsunami's.
Basalt
(igneous)
Andesite
(igneous)
Mid-Ocean
Ridge
Subduction Zone causing deep ocean
trenches ie: oceancont convergence
Non-Explosive/
Explosive
Passive
Large scale volcanic eruptions have many long and short term effects,
especially on the. climate. In the short-term, rainfall can increase due to fine
ash particles. There may also be a decrease in temperature due to ash
particles blocking sunlight. However, the long term effects can be much
more detrimental. The combination of ash and sulphur dioxide aerosols
reduces sunlight penetration for extended periods of time, causing a
possible global cooling effect. Other gases such as may create acid rain
impacting on water quality and vegetation.
Waxy Cuticles, Root Systems
The exposure to air resulted in the risk of plants drying out so
plants with an adaptation like a waxy cuticle on the surface (to
prevent fluid loss and retain moisture) ,had an advantage for
survival in a terrestrial environment.
(a) A sedimentary deposit consisting of Alternating Layers of iron rich
and iron poor sediment formed in the Archaean Eon
(b) During the Archaean Eon there was no O2 in the Atmosphere (anoxic)
however the levels of O2 begin to rise in the Proterozoic as the formation
of the BIFs declines and then ceases. Following this 02 levels continue to
increase in both the Atmosphere and the Hydrosphere until they level off
more recently.
(c) Photosynthetic organisms like Cyanobacteria in the ocean were
photosynthesising producing O2 as a waste product. The ocean at this
time had high levels of Iron salts possibly from fumaroles or weathering
and erosion. The O2 reacted with the Iron Salts dissolved in the ocean
and formed Iron Oxide which sinks to the ocean floor to create an iron
rich layer. Once the Iron Oxide was deposited the oxygen may have risen
to toxic levels in the ocean which killed most of the cyanobacteria. This
would then mean that cyanobacteria and Iron salts would take a while to
increase thus making an iron poor layer with natural sedimentation. When
the Iron levels and the oxygen levels were high enough again, the cycle of
iron oxide deposition would begin again.
Approximately 3.8 billion years ago in the Archaean Eon
Living things absorb more of the stable isotope carbon 12 than the
stable isotope carbon 13 from the environment during normal life
processes. If an ancient deposit has a higher ratio of C 12:C 13 than
occurs in the environment then it may indicate the presence ofliving
things at that time. One example of this is the graphite crystals found
in highly metamorphosed sediments in Isua, Greenland. The rocks, if
containing ratios indicative of life, can be dated using normal
techniques to determine the age of the deposit.
One hypothesis for the extinction of the megafauna is the arrival of people on
the Australian continent. Evidence suggests that the arrival of people and the
extinction of the megafauna overlap from 50000 to 42000 years before the
present. It has been argued by scientists (Flannery, Johnson etc) that because
megafauna were a good source of meat and had a slow reproductive rate then it
was possible for the first Australians to eventually hunt them to extinction over
a few generations as their population continued to decline.
Another Hypothesis is that of climate change. As the Australian continent
moved northward from Antarctica the climate would have shifted from cool and
wet to cool and dry to finally hot and dry. The lush forests of Gondwana would
have changed to the Arid saltbush plains of most of Australia today. With
ihcreased drying many Megafauna would have found themselves isolated
around inland lakes that continued to dry out. Eventually the lake would form a
salt pan and the ,:niegafauna would have had to migrate or die out. If it was too
far the species would have died of thirst or starvation along the way. Geniornis
was a large flightless bird for which fossils have been found at Lake Mungo, a
fossil lake in Western NSW.
Both hypotheses are plausible but the hunting hypothesis has the strongest
support.
a) Plant deep rooted native plants in order to lower the water
table.
b) Water tables rise because of land clearing and/or inefficient
irrigation. This mobilizes salt within bedrock and brings it
to the surface. By planting deep rooted plants which take
in a lot of the infiltrating water, water tables do not rise,
thus prevent upward salt movement.
a) i) Anywhere on the
impermeable shale.
ii) The impermeable
horizontally bedded shale will
minimize the leakage of
leachate.
X
b) An environmental scientist would
recommend against the mine site
as it sits within granite with
vertical fractures as well as
cavernous limestone. Both of
these rocks would allow any
leachate produced to move off
site and possibly reach the town
and or river which would cause
hazardous contamination. The
mine also sits on a fault which
would also make the site
unsuitable as it could be
tectonically unstable and cause
contamination by mobilisation of
leachate.
Australia is a very old continent. Its great age means that is has been
weathered and eroded extensively which has resulted in low relief and
nutrient depleted soil. The low relief can also been attributed to the lack of
recent tectonic processes such as mountain building or volcanism.
Mountains tend to erode to produce new nutrient enriched soil as do
volcanoes. The fact that Australia has missed out on the replenishment of
nutrients by these processes means that our soils are thin, nutrient poor
and cannot sustain extensive cropping which cause our farms to be very
vulnerable to other small environmental changes.
Australia's climate is one of harsh contradictions, some parts can be very
cold and some very hot. Rainfall is minimal mostly due to the flatness of
the continent and lack of orographic rainfall which means Australia's native
flora and fauna are very specialized to these conditions. This specialization
is enhanced by the fact Australia has been isolated as an island for so long,
thus very unique flora and fauna have evolved. Because they are so
specialized they can also be exceedingly vulnerable when exposed to
changed conditions such as an introduced species or diseases.
a i) An introduced species is one that is not indigenous to a particular
locality.
a ii) Modern quarantine is designed to stop the introduction and spread of
new species, disease and pests into the Australian environment.
a iii) AQIS X-ray and physically search all luggage/ packages/ cargo coming
in from overseas for signs of introduced species
a iv) Some forms of organisms, such as bacteria, can live in mud. A
tourist may visit an area where the disease originates and walk
through the mud. On arrival home the organism will be introduced
because of the mud on the shoes.
a v) An organism may be introduced for the purpose of food, for example beef cattle.
The 'cane toad' has poison glands on its back and it can breed
prolifically. The poison can kill any native species that consumes the
toad. Also due to the high reproductive rate/capacity of the cane
toads their population continues to grow, dominating native species
(frogs/toads) ultimately causing a loss of biodiversity.
1840 - Prickly Pear introduced into NSW
1915 - Prickly Pear spreads in QLD and across NSW taking over
large amounts of farmland making it unusable
Government committee formed to investigate control methods
including pesticides, burning and mechanical removal. All were
unsuccessful
'Cactoblastis cactorum' (a moth from Sth America) was tested as a
biological control in a limited release. It was successful and only
affected Prickly Pear. The moth larvae ate the inside of the cactus
causing collapse
1930 - widescale release of Cactoblastis eggs
Within 3 years, population of Prickly Pear had been dramatically reduced
Prickly Pear was now considered to be controlled and kept in check by
natural populations of Cactoblastis
(d) (i) Light intensity, soil pH.
(ii) To determine soil pH
Put a sample of soil from an area affected by introduced species onto a
watch glass
Sprinkle barium sulfate on the soil
Add a few drops of universal indicator
Compare the colour produced with the pH chart
Repeat the experiment with soil from an area not affected by introduced species
(iii) The reliability of data obtained could be assessed by repeating the
experiment a number of times and comparing results to see if the data
collected in each case was similar. The more repetition the greater the
reliability of the data.
European Carp
A fish farmer introduced a hybrid variety of carp into his ponds in Boolarra, Victoria, in
the early 1960s. The carp were introduced into farm dams and waterways and so they
became established in natural waterways in the Gippsland region of Victoria. They
escaped and lor were released into the Murray River between 1964 and 1968 and have
since then spread throughout the Murray-Darling River system into Queensland, South
Australia and NSW. Their spread has been assisted by floods such as those in 1974/1975.
~ Increase the turbidity of water and damage aquatic vegetation by their method of
feeding. They suck up mud from the bottom and "strain" food particles - mostly small
invertebrates - out with their gillrakers. The sediment is injected back into the water, thus
increasing turbidity. The diminished light penetration that results also reduces
photosynthesis and thus can affect most members of aquatic food chains, including
plants, molluscs, detritus feeders and other fish species. Aquatic plants also playa vital
role in most freshwater ecosystems as they provide cover and spawning sites for native
fish.
Carp compete with native fish for food and space. Young carp feed on zooplankton. As
adults, they compete for food directly with detrital feeders, such as the freshwater catfish
and bony bream, and utilize a large percentage of the total food resource because of their
size and rapid growth rates. They also eat the eggs and fry of other species and act as
carriers of the parasitic anchor worm that affects native fish, like the Murray Cod.
OR
Rabbits
In 1859, Thomas Austin brought 24 rabbits to his property in Victoria and set them free
with the intention of hunting them. The European rabbit spread during the following 60
years across the southern half of the continent to occupy an area of 4 million sq km,
and it continues to increase its range today. They were successful in Australia because
they were adapted to the climate; they breed prolifically; they had few natural
predators; they had a readily available food supply. They rarely needed to visit water as
they obtained enough moisture through their food
>- Rabbits ate everything before them: not only grasses, but also shrubs, bushes and
bark off larger trees. Its feeding habits have led to changes in the composition of plant
communities. Under dry conditions, the rabbit will strip bark off shrubs and eat the
shrub's roots and seeds in order to obtain moisture. This may kill the shrub. This
causes a change in the species composition within a habitat, resulting in a change
from woodland to grassland.
>- Competition with native grazers is thought to be responsible for the extinction, or
severe decline of a number of species of native mammals and birds, including the
bilby, several wallaby species and mallee fowls. Birds were unable to feed on grass
seeds and had nowhere to shelter or nest as the rabbits had eaten all the
shrubs and bushes.
>- Rabbits have severe impacts on soil by overgrazing and burrowing which destroys
vegetation cover and exposes areas of soil to erosion. Some semi-arid parts of S.A. are
believed to have reverted to desert due to rabbits causing permanent changes to the
environment
Note- only 2 impacts of the rabbit required.
(a)
(i) Bass Strait
(ii) Carbon
(iii) A fuel that is derived form preserved
plant/animal remains
(iv) A resource that is used up at a faster rate
than in can be formed or replaced.
(v) Anaerobic conditions
Drilling is a technique where a core is drilled in a suspected basin and
the material is removed and analysed for the presence of hydrocarbons
or coal. This technique gives direct information regarding the depth of
the overburden, thickness of reserve and the quality of the reserve.
Drilling as an exploration technique is costly on a regional scale due to
the large set up cost per bore hole.
In comparison seismic surveying is a cheap regional exploration tool as
it allows rapid identification of basin structures and lithological sequence
and extent. It does not however, provide any information on the grade of
the reserve or the overlying material.
Anticline/Dome Trap
Anticline/Do
me Trap
A correctly labelled diagram of a trap such as an anticline. The diagram
should have the impermeable cap layer labelled correctly for the sequence
(i.e. Shale) and the reservoir rock labelled (i.e. sandstone). Geological
sequence should match the stratigraphic column and the location of gas, oil
and water trapped in the sequence should be clearly marked.
(d) (i) Carbon Dioxide (C02) and Water Vapour (H20)
(ii) 1. Set up a Bunsen burner with hole open to allow complete combustion
Secure a filter funnel in an inverted position over the flame.
Using a delivery tube, bubble the gas given off by the combustion through
limewater to test for the presence of carbon dioxide gas.
4. Test the inside of the filter funnel for water which has condensed on the
surface. This test should be performed with cobalt chloride paper which
changes colour from blue to pink in the presence of water.
Check for soot in the inside of the filter funnel.
Repeat with hole closed to give an incomplete combustion reaction.
(iii) Repeat the experiment a number oftimes and compare the results.
Alternatively you could compare your results with data from a reputable
published source.
A fossil fuel that is used for the generation of electricity is petroleum. Petroleum comes from
marine plants and animals that are subjected to heat and pressure over time. As well being used for
electricity generation, petroleum can also be used as a fuel in transportation and as a lubricant
such as oil.
Another fossil fuel that is used for electricity generation is coal. Coal comes from plant material
that has been preserved in a low oxygen environment. Coal can be burnt to produce heat to
generate electricity; this produces the majority of our household electricity in Australia.
An alternate way of generating electricity is solar power. It involves the use of a solar cell or cells
that use the radiation from the sun to produce heat or electricity. Solar cells on the roof of a house
can be used to generate electricity for lighting or to power the hot water system.
Another way of generating electricity is wind power. Places where wind is strong and occurs
regularly would be ideal for establishing a wind farm. Air movement causes the blades of a wind
turbine to move around and this kinetic energy is transformed into electrical energy which may be
used to power a household or a larger commercial area.
The burning of fossil fuels such as coal and petroleum produces gases such as carbon dioxide and
water vapour. These are known as greenhouse gases. The collection ofthese gases in the
atmosphere has the negative effect of warming the planet. Replacing the fossil fuels with alternative
sources of energy will have the positive effect of reducing the harmful greenhouse gas emissions
and hence reduce the damaging effects of global warming such as rising sea levels and the melting
of the polar ice caps. Whilst being non-polluting there are possible negative effects of replacing
fossil fuels with alternate energy. Due to the size of a wind turbine and the expansiveness of a wind
farm they can be noisy, and also require a large area of land to be cleared. Also, because the sun is
only out during the day, the production of electricity by this source is limited - it can be also costly
to manufacture on a large scale.
(a)
(i) A rock that contains minerals which can be mined to gain a profit.
(ii) Cadia
(iii) Mabo
(iv) A measure of how much valuable ore is present in a sample.
(v) A resource that can be replaced at a rate greater than or equal to
the rate at which it is used.
(b) An ore contains at least one mineral that can be processed into a
commodity and other minerals (gangue) that have no (or little)
economic value at the present time. Gangue minerals can become ore
minerals if: the price of a commodity increases making the gangue
mineral now economic or a new commodity is used and can be
processed from a previous gangue mineral or an existing ore mineral is
exhausted (if the gangue mineral contains the same elements in a lower
proportion) or a new use is found for the gangue mineral.
(d) (i) Specific Gravity I Magnetic properties I chemical analysis I visual
identification of minerals (c)
(ii)
Copper Ore:
l.Take a piece ofrock that contains a copper mineral (such as malachite)
2.Crush the rock to separate the various component mineral and place in a
beaker
3.Carefully add dilute sulfuric acid to the beaker (use safety goggles and
take care when handling the acid)
4.Separate and filter the solid residue from the solution
5.Place some iron in the solution and identify copper as a pink coating on
the iron
(iii)
Repeat the experiment a number oftimes and compare the results.
Alternatively you could compare your results with data from a reputable
published source.
( e) A policy that covers mining practices is the requirement of an
Environmental Impact Statement. This describes the current state of the mine,
the change or impact that the mining process will cause and how it will be
returned to its original state. Prior to the requirement of an EIS, mining
practices often caused pollution from dust; toxic waste contaminated water
courses and soil; ecosystems were destroyed and there was extensive noise
pollution from machinery. EIS's have affected mining practices by making them
more environmentally friendly and ensuring that full rehabilitation takes place.
This includes practices such as stabilizing the ground to prevent subsidence,
revegetation of native plants as well as treating and removing wastes.
Another policy is the Native Title Act. This allows indigenous people the right to
negotiations over the use of their land. Prior to-this act, mining practices went
ahead without the approval of the traditional land owners consent and may have
damaged sacred sites. This act ensures that mining practices now involve
consultation and negotiations with the indigenous people who own the land.
(a)
(i)
Currents
(ii)
71 %
(iii)
Brines
(iv)
Manganese nodules
(v)
Organisms that are interdependent on
each other for things such as food
and shelter.
(b)
Calcareous ooze accounts for up to 36% of ocean floor sediment
and is composed of precipitated calcium carbonate (calcite) and/or
shell/skeleton material (e.g. foraminifera). It is formed in shallow warm
water (i.e. equatorial) where upwelling ocean currents carry nutrients. Due
to the solubility of CaC03 under high pressure, calcareous oozes are not
found in deeper waters.
Siliceous ooze account for about15% of the ocean floor sediment and is
composed of precipitated quartz or skeletal remains from Protozoa
(radiolarians) and diatoms. Formed in both polar and equatorial areas
where nutrients are supplied to surface waters by currents. Due to its low
solubility, Si02 rich ooze is formed in deeper, colder water than calcareous
ooze.
Environment
Pelagic Surface Waters
Benthic Hydrothermal
vent
Energy Source
Sunlight
Heat and Minerals from
HTV
Producer
Algae (Photosynthetic
Plants)
Chemosynthetic
Bacteria
1st Order
Herbivore eg parrot
fish
Tube worm
2nd Order
Small predator eg
larger fish
Small predator eg crab
Complexity
High
low
(d) (i)Surface area/Temperature difference between the solid and the water I volume of
solid
(ii) 1. Obtain different sized cubes made from the same type of metal.
Determine the surface area and volume of each cube
Put on safety goggles
Place the cubes into beaker of continually boiling water ensuring they are completely
submerged
4. Transfer one cube into a beaker of cool tap water of known temperature and
volume. Use metal tongs for the transfer to avoid burns to the skin
5. Monitor the temperature change of the water in the beaker using a data logger and
temperature probe or a hand-held thermometer until the temperature ceases to
rise
6. Repeat using the other cubes and same volume and temperature of cool water
Compare the results gained with other student groups in the class
Record the trend in the data
(iii) Repeat the experiment a number of times and compare the results.
Alternatively you could compare your results with data from a reputable published
(e) A technology used to study ocean environments is an echo sounder or more
recently a multi beam echo sounder. It works by emitting high frequency sounds
and measuring how long it takes for the sound to travel to the sea floor and
back to the surface. Prior to this technology, the depth of the ocean was
measured by throwing a weighted line over the side of a boat until it hit the
bottom. The echo sounder technology has enabled scientists to accurately map
the topography of the sea floor and discover that it has great variances in depth,
it has ridges, valleys, volcanically active areas, cliffs, boulders and varying
sediment sizes. It has had a positive impact by broadening our knowledge of the
sea floor
Another technology that is used to study ocean environments is submersible
robots (such as Alvin) that are fitted with cameras. Previous to the use of these
technologies scientists had little knowledge of deep water sea life and weren't
aware of the communities around hydrothermal vents. These technologies have
a positive impact on our understanding of ocean environments by enabling
scientists to see and study for the first time, communities around black
smokers/hydrothennal vents consisting of chemosynthetic bacteria, mussels,
crabs, giant worms and sea anemones.