2006 HSC Notes from the Marking Centre Earth and Environmental Science

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

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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.

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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.

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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.)

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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.

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2005 Scaling of EES
http//www.uac.edu.au/pubs/pdf/2005-Table-A3.pdf
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1. The global Mean sea level rises between 1890 and
   2000
2. 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.

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• 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

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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.
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1. 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.

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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.
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1. Climate change as Australia moved north and came
   out of an Ice Age, temperature increased and
   organisms couldnt evolve fast enough so died
   out. Humans hunting chose the large slow
   organisms targeting the megafauna which died out
2. 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.

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a) Canowindra mass fish Kill the deposit
contains 8 different species some endemic and
1000s 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.
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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.
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The earths 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
CFCs 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.
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• 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, its 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

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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 Governments 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 authors
credentials helped to assess the reliability.
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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
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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
gullyslope for lantana 15010 and Bitou bush
255 (51) 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
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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.
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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.
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Sniffer dogs are used to sniff luggage and in the
harbour, ballast water from ships is treated by
heating.
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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
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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.