STANSW Meet the Markers 2008 HSC Notes from

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_A 3. 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 O 2 in the Atmosphere (anoxic) however the levels of O 2 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 O 2 as a waste product. The ocean at this time had high levels of Iron salts possibly from fumaroles or weathering and erosion. The O 2 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. b) X ii) The impermeable horizontally bedded shale will minimize the leakage of leachate. 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 p. H. (ii) To determine soil p. H 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 p. H 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 1960 s. 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 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 (C 02) and Water Vapour (H 20) (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 Ca. C 03 under high pressure, calcareous oozes are not found in deeper waters. Siliceous ooze account for about 15% 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, Si 02 rich ooze is formed in deeper, colder water than calcareous ooze.

Environment Pelagic Surface Benthic Waters Hydrotherm al vent Energy Source Sunlight Producer Algae Chemosyntheti (Photosynth c Bacteria etic Plants) 1 st Order Herbivore eg parrot fish Tube worm 2 nd Order Small predator eg larger fish Small predator eg crab Complexity High low Heat and Minerals from HTV

(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.