STANSW Meet the Markers
2006 HSC Notes from
the Marking Centre
Earth and Environmental
Science
David Tweed, Penrith Anglican College d.tweed@pac.nsw.edu.au
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%).
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
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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.
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 (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.
2005 Scaling of EES
http://www.uac.edu.au/pubs/pdf/2005-Table-A3.pdf
a) The global Mean sea level rises between 1890 and 2000
b) 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.
X
a) 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
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.
a) 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.
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.
a) 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
b) 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.
a) Canowindra mass fish Kill – the deposit contains 8 different species –
some endemic and 1000’s of individual specimens preserved in sedimentary
rock.
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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.
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.
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.
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
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.
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
27b)ii) 1)Abiotic factors
Temperature Gully 18C ; Slope 28C
Humidity 70% (Gully) ; Humidity 10% (slope)
Light Intensity in gully 50 lux
Soil moisture (slope) 1g/kg
Soil moisture (gully) 30g/kg
From the data provided it can be concluded that the introduced
species in this ecosystem (lantana and Bitou bush ) are
predominantly in the gully and are less successful on the slope
This can be seen through the ratios of gully:slope for lantana
150:10 and Bitou bush 25:5 (5:1)
Thus the introduced species thrive in lower temperatures with
higher humidity, they also benefit from higher soil moisture
content and whether by invasion or otherwise have less
competition in the gully
There are many different methods that can be used to control the spread of
different species in Australia.These tend to be more suited to each
particular species whereas Quarantine methods are more specific. This
specificity makes them unable to control certain plants and animals that are
able to distribute themselves across long distances and not pass through
quarantine stations. This justifies specific methods of controlling
introduced species.
Invasive introduced species must be controlled in Australia as they
threaten the unique fauna flora of the continent. Baits are used to poison
introduced species such as the fox. Baits containing 1080 are buried in
areas that foxes inhabit in order to control numbers. Although some native
species are carnivores, burying the baits tends to ensure that they are
found by foxes (whose scavenging behaviour suits digging up some food).
Death is generally quick. The fox contributes to the decline in numbers of
many species and baits are the most effective method of control. Shooting
can be effective on a local level however it is difficult to access all areas
and to hunt from dusk to dawn and is therefore a less effective method.
Diseases have proven to be an effective control method for introduced
species such as rabbits. Rabbits are herbivores which reproduce rapidly
causing desertification as plague number build. This leads to erosion and
competition with native herbivores for food.
The myxomatosis disease was researched by the CSIRO before it was released
into the rabbit population. It has managed to control rabbit numbers for many
years but gradually becomes ineffective as the surviving rabbits pass on their
natural resistance to the disease.
This method is justified as it is cost effective, quick and only targets the
intended species. Although a specific strain of the disease is not effective in the
long run, the method of biological control using a disease is effective in
managing to keep rabbit numbers under control.
Sniffer dogs are used to sniff luggage and in the harbour, ballast water from
ships is treated by heating.
27 d ii)Sniffer dogs are trained to identify organic matter passengers
luggage. All bags are checked by the dog as passengers arrive. If the dog
locates organic matter it will indicate this to the handler by sitting or
scratching. Types of organics include fruit, plants, and meat which may
contain insects or diseases
27 d iii) Sniffer dogs have been very successful in reducing the
introduction of introduced species.This is due to their ability to
detect a variety of organic matter such as fruit plants and meat.
Their keen sense of smell and their high level of training makes this
method very effective. However not all bags are checked at all
terminals meaning some exotic species may miss detection. Overall
the speed of operation of the dogs and their accuracy makes this
method successful.
2- Ballast Water – The heat treatment of ballast water has been very
effective in reducing the introduction of species . The heating of the
water kills the eggs and young of many forms of sea creatures
(pacific sea star, zebra mussel, dinoflagellates ) before it is dumped
into the harbour.
Due to the cost and complex infrastructure required to perform this
process, not all boats can complete this process thus making total
protection impossible. Where it is done, the heating of ballast water
is successful.