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2012 HSC Notes from the Marking Centre — Earth and Environmental Science

2012 HSC Notes from the Marking Centre – Earth and Environmental Science

Introduction
Section I – Core
Section II – Options

Introduction

This document has been produced for the teachers and candidates of the Stage 6 course in Earth and Environmental Science. It contains comments on candidate responses to the 2012 Higher School Certificate examination, indicating the quality of the responses and highlighting their relative strengths and weaknesses.

This document should be read along with the relevant syllabus, the 2012 Higher School Certificate examination, the marking guidelines and other support documents developed by the Board of Studies to assist in the teaching and learning of Earth and Environmental Science.

General comments

Teachers and candidates should be aware that examiners may ask 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 focused areas. It is important to understand that the Preliminary course is assumed knowledge for the HSC course.

Candidates need to be aware that the marks allocated to the question and the answer space (where this is provided on the examination paper) are guides to the length of the required response. A longer response will not in itself lead to higher marks. Writing far beyond the space allocated may reduce the time available for answering other questions.

Candidates need to be familiar with the Board’s Glossary of Key Words, which contains some terms commonly used in examination questions. However, candidates should also be aware that not all questions will start with or contain one of the key words from the glossary. Questions such as ‘how?’, ‘why?’ or ‘to what extent?’ may be asked, or verbs that are not included in the glossary may be used, such as ‘design’, ‘translate’ or ‘list’.

Teachers and candidates should also be aware that questions may be asked that focus on the mandatory skills content in Module 9.1.

Candidates should use examination time to analyse the question and plan responses carefully, working within that framework to produce clear and concise responses that avoid internal contradictions. This is particularly so in holistic questions, which need to be logical and well structured.

In the best responses, candidates:

showed all working where required by the question
did not repeat the question as part of the response
used 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.)

Candidates are reminded to attempt one question only in Section II. Candidates are also strongly advised to answer the option they have studied in class.

Section I – Core

Part B

Question 21

In better responses, candidates correctly identified the faults, plate boundaries, direction of the forces using either arrows or words and provided correct localities.

In weaker responses, candidates confused the types of interactions of the two mountain belts.

Question 22

In better responses, candidates indicated repetitive movement at pre-existing intra-plate faults.

A significant number of candidates incorrectly linked the earthquakes to a hotspot volcano. In other weaker responses, candidates placed Western Australia closest to a subduction zone or linked it to the process of mining.

In better responses, candidates established a link between depth of focus and high magnitude earthquakes/increasing fatalities. These candidates also provided examples of the types of disaster, such as a tsunami, and the dangers, such as the collapse of buildings.

In weaker responses, candidates disregarded the data differences in the tables and supplied general information.

Few candidates identified the importance of Australian scientific research within Australia or supplying of data to other countries.

In better responses, candidates identified the importance of research into prediction, building design and the mapping of seismic risk areas.

Question 23

Many candidates correctly and accurately plotted the positions on the graph.

In some responses, candidates included a ‘Line of Best Fit’, which was not required.

In better responses, candidates drew the diagram to scale, placed the Tonga Trench within 1 cm of the correct position (173^o W) and labelled the diagram with great detail.

In weaker responses, candidates did not pay attention to scale, place importance on the thickness of crust or label the diagram.

In some cases, the diagram was not drawn to scale, but was well drawn and labelled.

Question 24

In the best responses, candidates named an appropriate event and gave detailed features that matched that event. They gave a clear and explicit difference between the two hypotheses.

In weaker responses, candidates gave general information about the time period, referring to the process of evolution and natural selection, or only referred to the evidence for the hypothesis without reference to the features that explained the event.

Some candidates wrote about the effects of a hypothesis, such as climate change or sea level changes (transgression/regression cycle), formation of Pangea or continental drift without attributing a cause or giving detailed features of these processes.

Question 25

In general, candidates identified a specific fossil site. In better responses, candidates provided details on the overall number of specimens found and gave some examples about the types of fossils found at a specific, well-known site.

In weaker responses, candidates made generalisations about localities, fossil numbers or diversity.

In better responses, candidates referred to the same fossil site as used in part (a) to explain the nature of their site at the time of fossil formation and supplied characteristics of the environment and the events leading to fossilisation.

Question 26

This question was answered correctly by the majority of candidates.

The majority of candidates linked the reduction in both distribution and abundance of modern stromatolites compared to ancient stromatolites with changes in the environment, the evolution of predators or both. In better responses, candidates also linked the highly saline nature of their current habitat with the restriction of predator numbers.

Question 27

The majority of candidates identified an early advancement, such as spores, vascular tissue, waxy cuticle and stomata for plants to move into the terrestrial environment and explained a feature of this advancement. In better responses, candidates clearly linked the relationship between the advancement and the plant’s ability to colonise the land.

Question 28

In better responses, candidates identified an agricultural practice such as land clearing, over-irrigation or over-ploughing as a cause of land degradation. These candidates explained the practice and clearly linked this to a suitable effect.

Most candidates listed a series of strategies to overcome the issue and outlined how they would work, or they outlined a plan and listed features of the plan. In better responses, candidates developed a relationship between their plan or strategies and how it would reduce the damage caused to the area.

Question 29

In the best responses, candidates designed an integrated pest-management strategy that eliminated all pests while including the use of only one pesticide. They indicated the pests that each of the management practices affected and the rating scale. These candidates made clear statements about how the management practice reduced the effect of pesticides on the environment.

In weaker responses, candidates failed to use the stimulus material in the table when designing an integrated pest-management strategy.

Question 30

This question was well answered by the majority of candidates.

Most candidates identified both trends. In better responses, candidates provided clear reasons for both trends. Some candidates neglected to supply a reason for the increase in carbon dioxide emissions from forestry use.

Question 31

In better responses, candidates clearly related their knowledge of the evolution of the Australian continent to issues facing Australia in using its resources sustainably, eg soil fertility. These candidates described at least two examples of advances in knowledge and their relevant application in the field of earth and environmental science. In the best responses, candidates provided a clear judgement that indicated the value of management practices and advances in knowledge.

In weaker responses, candidates only described sustainability issues without relating them to the evolution of the Australian continent or they discussed at length the development of the Australian continent without relating it to resource sustainability. Clear judgements on the value of these issues were also not provided.

Section II – Options

Question 32 – Introduced Species and the Australian Environment

1. In better responses, candidates clearly stated the definition as given in the syllabus.
  
  In the weaker responses, candidates gave an alternative name for an introduced species only.
2. In better responses, candidates provided an appropriate reason for each viewpoint.
  
  Weaker responses were generic in nature.
In better responses, candidates described trends for each strategy and linked these to observable changes in the prickly pear population. They also provided specific data from the graph to justify their responses.

In weaker responses, candidates only assessed the strategies without addressing the data specifically as required or showed confusion in identifying correct trends or data references.

In the majority of responses, candidates outlined or explained at least one trend, typically that between the moth and the prickly pear.
1. In better responses, candidates provided specific characteristics that enable the animal to be a successful pest or cause damage to environment.
  
  In weaker responses, candidates provided generic information, background or irrelevant detail on a named animal species. In some weaker responses, candidates provided specific characteristics on a named plant species instead of an animal.
2. In better responses, candidates gave features and characteristics of two valid strategies and provided similarities and/or differences. The control strategies needed to be relevant for the named animal species.
  
  In weaker responses, candidates either outlined strategies only or named strategies and provided similarities and/or differences without comparing on the same factor.
1. In better responses, candidates clearly identified a feature and briefly described how it affected distribution.
  
  In weaker responses, candidates identified a feature but did not outline how it may have had an effect.
2. In better responses, the candidates displayed their understanding of validity versus reliability. Candidates either outlined what additional data needed to be collected to enable the effect of the introduced species on the native species to be determined, referred to the need of accessing historical data on the abundance and distribution of introduced species over time to compare to their data or referred to the need of more transect data over a prolonged period of time to allow for comparison.
  
  In weaker responses, candidates identified ways of making the conclusion more reliable, misinterpreted the species increasing or simply described data given in the question.
3. In better responses, candidates outlined aspects of the Bradley method and explained how these aspects were applied specifically to the reserve. Specific reference to the data was provided.
  
  In weaker responses, candidates outlined features of the Bradley method with no link to the reserve or the data provided. Alternatively, they discussed other strategies for regeneration.
In better responses, candidates demonstrated a depth or breadth of understanding and knowledge of introduced species and quarantine procedures, with the specific effect that these have had on the unique and fragile Australian environment clearly described. Specific examples of both introduced species and quarantine procedures were used. A clear judgement was made and correct scientific terminology and principles were used. Lantana, salvinia and prickly pear were the examples predominantly used as introduced species.

In weaker responses, candidates recalled either effects of introduced species or quarantine procedures with either no examples or only an example outlined in general terms. Detail and specific links to examples were missing. Many candidates did not mention quarantine regulations specifically.

Question 33 – Option – Organic Geology

1. Most candidates described coal as a fossilised form of organic matter, but did not relate this to a use of coal (ie burned for energy).
  
  In weaker responses, candidates only defined the fossil part of the question.
2. In better responses, candidates identified and outlined two or more changes that occur to coal as the rank increases. The candidates also identified that the energy yield also increases as the rank of the coal increases.
  
  In weaker responses, candidates only identified one change to coal composition or identified a change in energy yield.
In better responses, candidates accounted for the differences between the use of, or need for, solar and wind energy into the future compared to that for coal. Candidates made reference to the data and used the graph scales to determine overall use of energy sources and account for the increase in both coal and solar/wind. They also justified why we only have limited amounts of energy production from solar and wind.

In many cases, candidates confused the scale or scope of the graph and did not correctly compare the increase in coal (1000 petajoules over 40 years) with that of solar/wind (45 petajoules over the same period).

In weaker responses, candidates did not use the data provided or refer to the graph to write the response. They did, however explain why changes in energy consumption from different sources occurred in the 40 years.
1. In better responses, candidates made clear links between using the specific geological information from current fossil fuel deposits and applying these rules to predict where deposits might be found.
  
  In weaker responses, candidates only identified the fact that geological sites contained fossil fuels. The candidates also neglected to link why using the same geological features may help mining companies. Many candidates rewrote the question, and used the term ‘geological features’, but failed to identify specific geological features (such as basins or traps).
2. Many candidates were familiar with the processes used to discover new coal and oil reserves. However, some did not clearly identify the similarities or differences.
  
  In better responses, candidates made very clear distinctions between the two processes, naming the processes and outlining how the processes worked. They also made direct reference to the similarities (identification of site, testing of the site) and the differences (core drilling versus slant drilling).
  
  In weaker responses, candidates wrote about one process only or outlined how the processes worked, without to linking the processes.
1. Most candidates correctly responded to this question.
2. In better responses, candidates recognised Experiment 2 as incomplete combustion and identified air (oxygen) as the requirement to bring about complete combustion.
  
  In weaker responses, candidates could identify Experiment 2, but did not give a condition to increase combustion.
3. In better responses, candidates used the pie charts to identify the products of incomplete combustion and described the effects these have on the environment. These candidates then made an overall judgement of the effects of by-products of burning fossil fuels.
  
  In weaker responses, candidates identified the by-products of burning methane, but did not outline the effects of the product and link these to the environment. Some candidates only made reference to a general or incorrect effect on the environment without naming a particular product.
In better responses, candidates identified at least two alternative energies, other than solar or wind, and proposed reasoned arguments supporting their increased use.

Most candidates recognised several alternatives to coal, petroleum, solar and wind, the most common being nuclear, tidal, wave and hydroelectric.

In weaker responses, candidates referred to solar and wind in spite of the direction in the question not to do so.

Question 34 – Option – Mining in the Australian Environment

1. Generally, candidates named both renewable and non-renewable resources.
2. In better responses, candidates identified and outlined a technology, outlined how it worked and linked this to efficient mining exploration.
  
  In weaker responses, candidates did not link a technology with the correct processes. Some candidates did not identify any technology used.
Candidates were generally able to read the graph and recognise that for most of the time, the price of nickel was below $40/kg.

In better responses, candidates described techniques the mining company could use to modify its operations to save money while the ore price was below profitable. In many of the better responses, candidates used data from the graph.

In many cases, candidates did not refer to the graph, but explained the practices that needed to be modified to keep the mine viable.
1. In better responses, candidates made clear links between a named mine, the ore and techniques used to discover the size and grade of the ore.
  
  In weaker responses, candidates made a general statement about the techniques used to identify grade and size, and did not name a site.
2. In better responses, candidates made use of the same mine (named in (c) (i)), named the mining processes and described how the processing influences the mining operations.
  
  In weaker responses, candidates wrote about either mining or refining and did not link the processes to the size and grade of the deposit.
1. Many candidates correctly responded to this question.
2. In better responses, candidates clearly outlined the procedure in step form and referred to laboratory equipment.
  
  In weaker responses, candidates did not test a quantitative property or outline the steps of an experiment to determine the property. A few candidates only identified an experiment.
3. In better responses, candidates used the table to correctly identify all of the ore minerals and the gangue minerals, and justified their choices by using the properties. The most common choices for the ore metals were hardness and a high density. Most common choices for gangue metals were a low density and a non-metallic lustre.
  
  Some candidates were able to distinguish metal ore minerals from gangue minerals, but did not justify their choice with more than one criterion.
  
  In weaker responses, candidates did not identify all of the ore minerals or all of the gangue minerals. Some candidates failed to use the table.
In better responses, candidates included specific policies and stated how these policies affected the day-to-day operations and long-term environmental sustainability of the mine.

Some of the candidates did not assess the effectiveness of these policies.

Question 35 – Option – Oceanography

1. In better responses, candidates correctly identified two technologies.
  
  In weaker responses, candidates either named oceanic technologies used to study aspects other than the sea floor or did not name any relevant technologies.
2. Generally candidates named siliceous or calcareous oozes as their sediment. In the stronger responses, candidates provided an outline of both the origin and the distribution.
  
  In weaker responses, candidates did not outline both the origin and distribution.
In better responses, candidates outlined the oceanic or terrestrial processes that affect salinity. They specifically identified the appropriate region on the map and used the diagram to support their argument.

Many candidates struggled with providing an accurate reference to the map.

In weaker responses, candidates did not link the processes to the salinity levels; identifying only a salinity level change or identifying a process.
1. In better responses, candidates linked the understanding of the processes of sea floor formation with that of knowledge of plate tectonics. Often a range of tectonic processes and a range of ocean floor environments were identified.
  
  Some candidates outlined tectonic processes but did not link these to the sea floor.
2. In some responses, candidates supplied very detailed diagrams to support the written material. In the better responses, candidates made direct comparisons of photosynthesis and chemosynthesis. These candidates also included names of the organisms and outlined of the relationships between these organisms.
1. In better responses, candidates specifically identified two characteristics that make brine shrimp suitable for breeding at home or school.
  
  In many responses, candidates generalised that brine shrimp were ‘easy’ to look after.
2. In better responses, candidates referred to controlling variables, repeating the experiment and then comparing the results against research.
  
  Many candidates suggested repeating the experiment, but neglected to justify why this was an important step in validating the experiment.
  
  In weaker responses, candidates did not identify any techniques that could validate an experiment.
3. Overall, responses for this question were strong. In the majority of responses, candidates used the data to determine optimal hatching rates for brine shrimp by referring to both temperature and salinity.
  
  In better responses, candidates then compared the data and made a general comment about the shrimp’s low tolerance to temperature, but high tolerance to salinity.
  
  In weaker responses, candidates did not link salinity and temperature.
In better responses, candidates showed a good understanding of ocean currents and human activities that use the oceans resources. These candidates clearly linked the circulation of the ocean to the availability of its resources and also gave specific examples of these currents, activities and resources.

In weaker responses, candidates identified features of the ocean, but these were either irrelevant or not related to the action of currents.