2006 HSC Notes from the Marking Centre Earth and Environmental Science

1. STANSW Meet the Markers 2006 HSC Notes fromthe Marking CentreEarth and Environmental Science David Tweed, Penrith Anglican College d.tweed@pac.nsw.edu.au

2. General Comments • 1138candidates attempted the Earth and Environmental Science examination. • The most popular electives were Introduced Species and the Australian Environment (78%) and Others (10%).

3. 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.

4. Depth of treatment • Overall, the level of understanding of Earth and Environmental Science concepts indicated by the responses was appropriate for most HSC candidates. • Candidates need to be reminded that the answer space provided and the marks allocated are guides to the maximum length of response required. • Similarly, the key word used in the question gives an indication of the depth of the required response. • Candidates should use examination time to analyse the question and plan responses carefully, working within that framework to produce clear and concise responses. • This may include the use of dot points, diagrams and/or tables, and avoids internal contradictions. This is particularly so in holistic questions which need to be logical and well structured. • There was evidence that some candidates had a very poor knowledge of basic definitions specific to terminology associated with the course. Of particular concern in 2006 was that many candidates confused the terms and concepts of global warming and ozone depletion.

5. 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.)

6. 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 (c) of the 2006 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 based on a single source. 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.

7. 2005 Scaling of EES http://www.uac.edu.au/pubs/pdf/2005-Table-A3.pdf

24. The global Mean sea level rises between 1890 and 2000 • Each eruption happens just before a drop in the GMSL . This indicates a cooling effect as more water would get locked up as ice and also due to thermal contraction of the sea caused by global cooling.

25. X

28. Divergence: Plate margins and rifting of the continents allowing them to split into smaller pieces eg the splitting of Australia and Antarctica Africa ad South America • Convergence: of some continents, the joining together of some landmasses eg India with Eurasia; North and South America • b) The plate tectonic super cycle suggests that the continents will join back together and split apart again. It is possible that in 100 million years Australia and PNG will have joined to South East Asia as the current plate motion is North, the African rift will have caused a movement away from Eurasia as it is moving East-West

31. The 2004 Boxing day Tsunami was a result of tectonic activity causing an earthquake and resulting tsunami. The subduction of the Indian plate beneath the Burma plate an approximate 1200 km fault slipped an estimated 15 m resulting in an earthquake 9.1- 9.3 on the Richter scale. The resulting Tsunamis disrupted natural landforms and swamped costal communities with saline water, killed hundreds of thousands of people and dragged lots of pollutants into the nearby oceans as the waves receded.

32. Water proof covering to prevent desiccation, hard skeleton for locomotion and support, internal reproduction, Eyes with eyelid, changes in ear structure and lungs to breathe air.

34. b) i) Fossils found in a variety of places and very widespread. ii) Distribution change caused by changing environments (ie plate tects) and predator evolution over a period of time. Abundance change caused mostly by evolution of predators and now only found in areas where predators cannot survive.

36. Climate change as Australia moved north and came out of an Ice Age, temperature increased and organisms couldn’t evolve fast enough so died out. Humans – hunting chose the large slow organisms targeting the megafauna which died out • Mass Volcanism – this hypothesis suggests that a mass volcanism event caused an abrupt climate change (cooling then warming) which caused 90% of organisms to die out. This hypothesis is generally supported due to the presence of the Siberian traps which are huge outpourings of lava.

37. a) Canowindra mass fish Kill – the deposit contains 8 different species – some endemic and 1000’s of individual specimens preserved in sedimentary rock.

38. X X X X X X

39. An alternative management practice to the use of pesticides is Biological Control. Biological control is the use of a predator to lower the number of pests. The predator must be able to survive the same conditions as the pests and not become a pest itself. It must also have a high rate of reproduction and only target the pest so it does not damage the ecosystem. Introduction requires research which s costly and slow, however if the correct predator is chosen it would be effective.

41. Artificial wetlands – stormwater runoff is channelled into man made lakes, which contain reeds. Having a Lake causes the water velocity to drop, which allows the sediments to settle. The plants then filter the nutrients from the water. The water that leaves the wetlands is lower in sediment and nutrients than when it entered.This is effective in reducing sedimentation and algal blooms in natural waterways.

43. The earth’s original atmosphere consisted of carbon dioxide and there was no ozone layer to prevent radiation this was changed as cyanobacteria absorbed carbon dioxide and produce oxygen.if allowed a diversity of genera to appear as the ozone layer formed and oxygen allowed for respiration. Humans however have been releasing CFC’s and greenhouse gases into our atmosphere. CFC ‘s destroy the ozone by a chemical reaction. This will allow more fatal UV radiation to hit the earth leading to abnormalities of cells. Greenhouse gas to increase global temperatures which caused the sea level to rise. The changes of sea level and temperature will alter fragile ecosystems leading to the extinction of many species.

46. Land clearing has • Increased runoff • Decreased Evapotranspiration from trees • Caused he water table to rise • After the removal of trees transpiration decreases resulting in the movement of the water table close to the surface. As groundwater is salty, it’s rising increases the salinity of surface waters. • Removal of trees and other vegetation increases runoff as there is now little cover to slow down water and allow infiltration

48. 27 a i) the process of gathering information included researching information on the internet by looking at sites suggested by search engines (eg Google) as well as using an online encyclopaedia. Another site that was used was the Australian Government’s Quarantine website which had current and relevant information. We also used science texts and using all these sources we summarised and put the information into our own words. 27 a ii) We were able to assess the reliability of sources by comparing the information amongst the sources to make sure it was all the same.We were able to assess that information against our textbooks (deemed to be the most reliable because of the authors academic standing). With internet sites we checked which organisation published it and if it was .edu or .gov it indicated an educational or government site and that the information would be reliable.. Checking the currency of the information and the author’s credentials helped to assess the reliability.

50. Identify Affected regions and areas that are relatively undisturbed Selectively weed infestations ensuring that the rate of weed removal matches the revegetation rate Do not overclear s this will become overrun by denser weed infestations Mimimise disturbance to both the soil and the surrounding environment Monitor and manage as required