Transcript Year12 2007 Exam & Marking notes

STANSW Meet the Markers
2007 HSC Notes from
the Marking Centre
Earth and Environmental
Science
David Tweed, Penrith Anglican College [email protected]
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 (d) of the 2007 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.
2007 Scaling of EES
http://www.uac.edu.au/pubs/pdf/2007_table_A3.pdf
Part B
Question 16
(a) Most responses correctly identified a modern technology. Weaker responses did not address the
term ‘technology’.
16 (a) Laser reflection devices across fault lines
Question 16
(b) Better responses described a modern technology such as lasers placed
across a fault line such as the San Andreas Fault. Some better responses
answered the question with a labelled scientific diagram. Weaker responses
lacked details of how devices worked to measure relative motion, particularly
those regarding GPS and other satellite technologies. Weaker responses did
not address time, distance and/or repeated measurements.
(b) This piece of technology uses lasers in the aid of comparing the past with the present
measurements. The two ends of the geodimeter are located either side of a transform
fault plate boundary and as the plates move relative to each other the laser measures
the relative movement.
Question 17 (a) In better responses, candidates constructed a table and
correctly identified the required three properties of the respective lithospheric
plates. The best responses used terminology such as mafic/felsic in
reference to mineralogy, and density rather than referring to weight. Weaker
responses confused tectonic processes with properties.
17(a) Comparing lithospheric
plates
Continental Crust
Oceanic Crust
-Lighter
-Thick ~ 75 km
-Felsic and intermediate
composition
-Rhyolite granite dolerite
andesite
-Older
-Dense
-Thin ~5-8 km
-Mafic composition
-Basalt Gabbro
-Younger destroyed more
rapidly
(b) Better responses described the role of density and gravity as key features
of the slab pull hypothesis, and correctly used these features to explain the
continued motion of the lithospheric plates.
(b) Slab Pull at subduction zones the heavier
(denser) plate subducts under the lighter plate. As
the plate subducts it pulls the remainder of the
plate with it due to gravity (weight) forces. The
plate continues to pull itself under moving the
entire plate and helping to drive the plate motion.
Question 18
(a)(i) The majority of responses correctly identified either a specific disaster such as the
eruption of Mt St Helens in 1980 or a general disaster such as an earthquake, tsunami
or volcanic eruption. Weaker responses named a place such as Mt Pinatubo or
Newcastle but did not associate it with an actual disastrous event.
18 (a)(i)Tsunamis – Boxing day Tsunami 2005 caused by
massive Earthquake
(ii) Better responses concentrated on specific tectonic processes such as plate
subduction with partial melting of the subducting plate, leading to volcanic eruptions.
Earthquakes were associated with a build up of stress due to plate interaction with
sudden release of energy at the fault line, generating an earthquake. In many of the
better responses, actual plates were named. Labelled scientific diagrams were often
included as part of the better responses. Weaker responses simply described the
hazards associated with the disaster rather than explaining the causes of them.
(a) (ii) At the subducting boundary between the indo Australian plate and the Eurasian
plate the tip of the over riding plate was displaced by the forces of subduction and was
then suddenly released back displacing a massive amount of ocean causing the
Tsunami.
(b) Better responses linked the production and weathering of igneous material to
increased soil fertility. This was then directly associated with increased crop yields.
Many responses mentioned mineral ions such as iron and magnesium as important
contributors to soil fertility. There was evidence that some candidates misinterpreted
the question and referred to the hazards of farming in volcanic areas instead of the
advantages. Weaker responses discussed only cultural or aesthetic reasons for
farming in these regions and did not address the scientific focus of the question.
(b) people risk farming in active volcanic
areas because of the rich fertile soils
resulting from the volcanic ash and
weathered volcanic rock. The rich fertile
soils increases crop yields and increases
productivity so it is more profitable farming
near volcanoes. The height of the volcano
can also increase the local rainfall.
Question 19
A variety of appropriate scale diagrams were used, eg pie charts, timelines
and histograms. The best responses correctly identified the eons, their
relative sizes and the scale used and/or the duration of the eons. In the
better responses, candidates referred to the geological timescale provided.
In better responses, candidates used a ruler and a calculator where
appropriate to accurately construct their diagram.
(a) Many of the weaker responses incorrectly included CFCs, methane and acids.
20 (a) Carbon Dioxide, Sulfur Dioxide
Question 20 (b)The best responses demonstrated that the fuel was combusted with
oxygen to produce the exhaust emission. In weaker responses, there was
evidence of confusion between the equation for combustion and those for
respiration, photosynthesis and acid rain formation.
(b) Hydrocarbon + Oxygen → Carbon Dioxide + Water
Question 21
(a) The better responses demonstrated an understanding of increased diversity in a
short period of time, while the weaker responses misunderstood the word explosion,
taking it to mean the meteorite collision with the Earth at the end of the Permian.
(b) Better responses gave two examples of differences between the
groups but weaker responses only identified the presence or lack of hard
parts as a feature of difference.
21(a) The fossil record displays a sudden radiation of
new species, particularly those with hard
shells(exoskeletons). There was great abundance
diversity of new organisms.
(b) (1) Ediacaran metazoans were soft bodied whilst the organisms of the
Cambrian had a hard exoskeleton, some armour or shell protection and
generally some protective mechanism(eg trilobite)
(2) Ediacarans seemed to float or drift with the ocean currents whilst the
Cambrian fauna possessed new mechanisms to enable faster movement
including muscle attachments meaning faster movement.
21 (c) 1 Hard shell allowed for protection against the elements (such
as the prevention of dessication as it held the soft organs within).
2 Hard shell also enabled the Cambrian fauna to defend against
predators.
3 Spines act as deterants to attackers
4 Allowed for easier predation of others as they had muscle
attachment to the exoskeleton for faster movement and Attacking parts
like jaws and teeth
Question 22
Better responses presented an analysis of the data. Better responses directly
referred to the information in the stem of the question but weaker candidates
failed to recognise the significance of this information. Weaker responses
demonstrated knowledge of the theories for the Permian Mass Extinction but
failed to apply that knowledge to the data. Many responses focused on
describing the depositional environment of the rock layers rather than the
processes and events which caused the changes in fossil numbers, diversity
and dominant types.
22 The sequence of rocks shows the fossil abundance and number
dropping dramatically From the Permian limestone to the Early
Triassic shale following two volcanic ash layers.
If this occurred globally it is likely to be the mass extinction separating
the palaeozoic from the Mesozoic era. This was thought to occur due
to the reforming of a super continent. The convergence of
Ocean/Ocean and oceanic continental plates led to the formation of a
large number of volcanoes on earth. The eruption of many of thes
around the same time would account for the layers of volcanic ash
found in the rock sequence.
The presence of rock and ash particles in the atmosphere is thought
to have blocked the suns rays from reaching the earth causing a
period of global cooling and subsequent sea level drops as the poles
froze over. This reduces the habitat areas of many organisms and
combined with being unable to withstand the cooler temperature a
huge number and range of organisms became extinct as evidenced in
the decrease of the numbers of fossils found. The increase in fossil
species and abundance in the middle Triassic shale rock layer and the
change in dominant fossil groupings displays the explosive
adaptation that occurs following a mass extinction.
Question 23
Better responses demonstrated an understanding of the term technology and gave
multiple examples of how technology had improved our understanding of fossil life
forms. They referred to specific technologies and described how these have enabled
us to improve our understanding.
23 Exponential advancements in technology have improved
our understanding of fossils, their formation and
background. Using computer analysis we can create
images of fossils digitally giving us a better understanding
of their form such as shape size transport and respiratory
systems. Advancements in submarine transport such as
sending unmanned submarines into deep ocean
environments allows us to uncover new types of fossils
which give us a better understanding of their evolution.
Using technology we can simulate past environments and
analyse the environment that the fossilised life forms lived
in. We can use more accurate absolute dating to determine
when the life form existed and place it in the evolutionary
tree. An example of this would be the use of technology in
the current analysis of ice cores analyse the atmospheric
composition of the early earth and therefore the
environment the life forms existed in and ultimately how
they were fossilised.
Question 24
(a) In the better responses, candidates clearly labelled the inputs and outputs in their
diagrams. In weaker responses, flowcharts of an industrial process were drawn
rather than a classroom simulation of a process.
24 (a) DIAGRAM
Filtration
Water and Dirt
mix
Filter paper
Retort
stand
and
clamp
Filter
Funnel
Beaker
The dirt and
water mix
was filtered
by the filter
paper and
the “clean”
water was
found in the
beaker
Question 24
(b)Better responses included reference to the results of their simulation as well as
referring to successes and limitations of the simulation.
(b) For a simple filtration experiment I feel
it was an effective experiment as it
successfully displayed how solids were
removed via a filtration process . It was
limited in its success of filtering the water
(it did still possess a brown tinge from the
dirt).as well as its scale.
This simulation could not for example treat
large scale amounts of water and the filter
paper would need to be continually
cleaned as build up of particles would stop
the process.
Question 25a)
Use of the pest's natural predators (biological
control)
Question 25b )
The ozone layer protects organisms by
filtering UV radiation which can damage
DNA.
(c) Better responses used diagrams and word equations to explain all the necessary
steps leading to the depletion of ozone. Weaker responses outlined only some of the
steps. Some responses showed that candidates were not aware that halides include
CFCs.
Question 25c )
-CFC (or other complex molecule) + UV light = free
radical (halide ion)
-free radical + ozone = oxygen gas + chloride
monoxide
-chlorine monoxide + free oxygen radical = oxygen
gas = chlorine radical
The halide is freed from the complex molecule by
UV light. This reacts with the
ozone molecule to produce chlorine monoxide and
oxygen gas. Chlorine monoxide
can react with a free oxygen radical/atom to
produce oxygen gas. The chlorine
atom/ion if left to repeat the process.
(d) Better responses named an existing scientist and/or organisation and outlined
current research rather than research from the 1990s. Weaker responses made general
responses about Australia’s role in ozone research and restated the question.
Question 25d)
CSIRO in Antarctica are using weather balloons and satellites images are
continually
monitoring the thickness of the ozone layer and the amount of pollutants.
Question 26 Better responses discussed multiple issues, providing arguments for
and/or against each. They also related each issue to the long-term use of a chemical
and its consequences.
Weaker responses listed the issues (such as bioaccumulation and biomagnification in
food chains/webs) and provided arguments for and/or against them. They used specific
examples of pesticides to argue the issues, including the impact on non-target species.
However, they gave minimal detail, only mentioning ‘harm’ or ‘suffer’ in their negative
arguments instead of more specific effects on the environment.
26 Exemplar Response
Note: any two of the following issues and their arguments and any one consequence.
When new pesticides are continually introduced into the environment, the potential
for non-target species to be eliminated from the food chain increases. This disruption
to the food chain leads to a decrease in the biodiversity of an ecosystem.
A pest species may develop multiple resistances to multiple pesticides over many
generations. This immunity ultimately leads to the formation of 'Super-Pests' which
are unable to be controlled through conventional pesticide use, alternatively, stronger
pesticides are needed.
Bioaccumulation/Biomagnification in a non-target species, ultimately leading to death
or deformities in the offspring, interrupts the food chain, leading to a decrease in the
ecosystems biodiversity.
Pesticides linked to the depletion of ozone in the atmosphere can increase the
amount
Of UV radiation penetrating the Earths atmosphere can increase global temperatures
therefore adding to the greenhouse effect, changing global climate.
Persistence of the pesticide in soil affecting future generations and maintaining
Bioaccumulation/ Biomagnification issues well into the future even after the use of
the
pesticide has ceased.
Question 27
Better responses assessed the recency of the article, the support provided by
other scientific studies and the validity of the source of the data and its author.
These could be stated in general terms without reference to the stimulus
provided.
Weaker responses included only one or two features of assessment and tried to
summarise the article rather than to actually assess its value as a piece of
science reporting.
Many candidates focused on the ‘assess’ part of the question rather than the
more general ‘how’ to assess the reliability.
27
Articles such as this would generally be
unreliable. Even though it may have been
written recently it appears in a daily
newspaper which may lack credibility in
scientific circles. Many of the statements
made in the article are not supported by
scientific studies and further research
would be needed.
Question 28
(a) (i) Better responses acknowledged that biological controls were used to reduce the
numbers of another species. Weaker responses confused biological control with control
by pesticides while others simply re-stated the question in definition form.
28 a(i) Biological control is the introduction of
a species to reduce the numbers of a pest
species. examples could be predator/prey,
disease/host or even release of sterilised
males.
Question 28
(a) (ii) Better responses named an appropriate type of control, used a current Australian
example and clearly identified the effect of the control agent on the target species. They
also tended to use a well-documented biological control such as the cactoblastis moth
and Prickly Pear.
a (ii) One example is the Cactoblastis moth
which was introduced to control the
numbers of prickly pear cactus. The moth
lays its eggs in the cactus and when the
caterpillars hatch they eat the fleshy
leaves of the plant and kill it. This has
been a successful control as the moth only
attacks the prickly pear.
Question 28
(b) (i) Better responses indicated the trend as a rapid increase between 1800 and 1860
and then related this increase to the increasing colonisation of Australia and the
deliberate or accidental importation of mammals for a range of appropriate reasons.
Weaker responses failed to explain the causes of the trend.
b(i) There is a dramatic increase in
numbers of mammals introduced from
1800-1860. This is most likely due to
the rapid population growth of
Australia at the time. The use of
mammals as food and transport as
well as for hunting was so important to
the Europeans that they brought many
of these species with them.
Question 28
(b) (ii) The best responses clearly stated two mechanisms for accidental introduction
and, for each mechanism, gave detailed characteristics and named examples. The best
responses clearly explained how the organisms arrived in Australia.
b(ii) Many species have accidentally been
introduced through ballast water from ships being
released into Australian harbours. Empty boats take
on water as ballast in foreign ports to stabilise the
ship. When they arrive in Australia they take on
cargo and release the ballast water which may
contain eggs of possible pest species. One example
is the North Pacific sea star which has become a
pest in Tasmanian waters.
Another method of accidental introduction can
be the introduction of plant material on the soles of
travellers shoes. Mud on the soles of peoples shoes
may contain seeds or spores which can be brought
into the country and then released into the
environment as the mud on the shoe falls off.
Question 28
(c) (i) The best responses provided easily testable hypotheses. In doing this, candidates
avoided subjective terms such as ‘overpower’ or ‘effect’ and chose terms that related
directly to measurable characteristics.
c
(i) There will be fewer introduced plant
species within natural (undisturbed)
temperate rainforest than adjacent to
areas disturbed by urban development in
Kiama.
Question 28
(c) (ii) The best responses clearly reflected a thorough first-hand investigation where
measurement and identification tools were used and comparisons of data or conditions
were made.
(ii)The % cover of each introduced and each
endemic plant species was researched within
1m x 1m quadrants placed every 10m along a
50m transect running from the urban margin
into undisturbed temperate rainforest.
1 A reference key was used to identify flora.
2 Transects were replicated by class groups.
3 Percentage cover of species was recorded in
a spreadsheet and populations of introduced
species in disturbed and undisturbed areas
were compared.
Question 28
(c) (iii) The best responses identified the risk and then the prevention method to
reduce/eliminate it.
(iii)For working outdoors in strong
sunlight, sunscreen and hats were
required to stop sun burn.
Question 28
(d) Better responses clearly distinguished between the biotic and abiotic components
and related these back to the species and its effects on the environment. The best
responses demonstrated a logical structure. Better responses chose an appropriate
example of an introduced species, such as rabbits, salvinia or lantana, which allowed
candidates to discuss both biotic and abiotic effects.
d Introduced species: Salvinia invades bodies of water
Effect on the Abiotic : salvinia can double in size rapidly
and so can cover large bodies of water quickly. Salvinia
creates a barrier that prevents the sunlight reaching the
aquatic plants and thus reduces the levels of oxygen in
the water body as these plants then cannot
photosynthesise properly. Salvinia also creates a problem
when it dies as it sinks to the bottom of the water body
and as it does so, increases the turbidity of the water.
Effect on the Biotic: Because of decreased sunlight
in the water body there is a lack of oxygen as plants
cannot photosynthesise as well. These plants eventually
die . Aquatic animals also die as a result of the decreased
oxygen and reduced food source(plants). The
introduction of salvinia thus greatly affects(reduces) the
biodiversity of an area and can lead to conditions which
favour the spread of the introduced species.
Question 28
(e) (i) The best responses used two different scales to plot rabbits and native plant
seedlings. They also chose a line graph.
Question 28
(e) (ii) The best responses addressed the relationship between both factors when they
were both high and low.
ii There is an inverse correlation between
rabbits and native plants seedlings. When the
rabbit numbers increase the number of native
plant seedlings decrease and visa versa.
Question 28
(e) (iii) The best responses sketched the condition in general terms rather than just
identifying a condition.
iii For an introduced animal to become or be perceived as
a pest it must reproduce rapidly and in large numbers such
that the pest out competes native flora and fauna and
depletes available resources. Another condition which
would enable these numbers to survive to become
abundant and aid depletion is a lack of predators.
Question 29
(a) (i) The best responses identified two renewable resources. Weaker responses
included nuclear energy which is not a renewable resource.
(ii) The best responses outlined a specific use for their identified renewable resource
and then gave a reason as to why this resource would or wouldn’t be used in the future.
29
(a) (i) Ethanol and Solar Power
(a) (ii) Ethanol: Current limitations on the
cost of producing ethanol prevent its
widespread use as an alternative fuel.
However as fossil fuels decline ethanol will
be seen as a clean energy efficient source
of fuel that can be produced from organic
matter mostly cellulose.
Question 29
(b) (i) The best responses described a trend as well as identifying a cause for the trend.
Weaker responses only described the trend.
(ii) The best responses described two advantages of petrol over coal as a transport fuel.
Advantages include petrol having a higher energy yield and being easier to use in
transport due to its state as a liquid.
(b) (i)The graph shows that as carbon content increases
so does the
energy yield.
AND
This is due to the fact that carbon contains more energy
than the water which
is removed from the coal as its carbon content increases
(b) (ii) Advantage 1 Petrol puts out more energy than coal
per kilogram this means it is lighter to transport for the
same delivery of energy.
Advantage 2 As petrol is already a liquid it is easier
to ignite the petrol vapours. This makes it more
appropriate for use in transport as it is easier to light than
a piece of coal. Petrol requires a spark whereas coal
requires a flame.
Question 29
(c) (i) The best responses included a hypothesis that stated which of two or more nonfossil fuels was most efficient. Weaker responses either compared the energy efficiency
of a fossil fuel to a non-fossil fuel, or failed to mention two non-fossil fuels. Weaker
responses showed confusion between an aim and a hypothesis.
(c) (i) The fuel with the higher carbon
content will produce more heat/energy
when combusted.
Question 29
(c) (ii) The best responses compared the energy given out by non-fossil fuels such as
methanol, ethanol or propanol when used to heat a specific quantity of water to a set
temperature. Weaker responses only mentioned heating one non-fossil fuel or
generalised about non-fossil fuels with no clear procedure. Alternatively, they mentioned
only fossil fuels.
(c) (ii) 1Collect equipment and set out as shown below
2 record the temperature of the water initially and the mass of the spirit
burner.
3 Light the spirit burner with matches and place under a beaker of
water. Cover with cardboard to prevent heat loss.
4Time for one minute and record the temperature of water again
5 Calculate the energy released by the fuel using the formula Heat = mc
6 Repeat the experiment again with different fuels. ie ethanol propanol
etc
Question 29
(c) (iii) Better responses outlined a risk and identified a safe work practice which
minimised that risk.
(c) (iii) Tie long hair back to keep it
away from the flame.
Question 29
(d) The best responses applied scientific principles in their description of methods of
conserving energy through architectural design. They detailed how these methods
specifically benefited both the individual and the environment.
DESCRIPTION OF
ARCHITECTURAL
DESIGN
BENEFIT FOR
INDIVIDUAL
BENEFIT FOR
ENVIRONMENT
Double glazing on
Lower energy costs
window can halve heat
loss for winter and
keep house cool in
summer by reflecting
heat
Lower production of
carbon dioxide
Deciduous trees to
shade in summer and
thus cool house but
allow in sun in winter
to warm house
Lower production of
carbon dioxide
Problem with raking
leaves Or Cheap &
aesthetically pleasing
Design plays a major role in conserving energy when designing a house one
method of conserving energy is to utilize the available sunlight to light the house
in favour of electrical lighting
These may include an extensive use of glass or a sun roof to allow light into the
house. This method is highly beneficial to both the individual and the
environment. the use of natural light removes the need for artificially produced
light reducing consumed energy and benefiting the environment by reducing
greenhouse gas emissions. For the individual natural light makes a building far
more welcoming .Although perhaps trivial this is still an important element. This
practice of architectural design is indeed beneficial to both the environment and
the individual
Another design method aimed at conserving energy is the practice of using
specific materials as thermal regulators to build the design. Some materials like
bricks absorb heat during the day and release it slowly at night reducing the need
for heating systems. In areas with hot days and cool nights this method of energy
conservation is extremely effective. The benefits to the environment are as
before. The reduction in the need for heating systems conserves energy and
reduces the need to burn fossil fuels (which releases greenhouse gases
adversely warming the earth and affecting the environment). To the individual it
also removes the need for often expensive and complicated (still inefficient)
temperature regulation systems. This is both broadly beneficial to the individual
and the environment removing the need for an energy consuming appliance. This
architectural design method is highly useful in benefiting the environment and the
individual.
Question 29
(e) (i) The best responses used two different scales on the graph for temperature and
rock density, their graph used the full grid and they provided a key. Weaker responses
used awkward scales which led to poor plotting of points.
29 (e) (i)
Question 29
(e) (ii) Better responses indicated that temperature increased with depth.
(e)(ii)As depth increases so does temperature
Question 29
(e) (iii) The strongest responses clearly outlined how higher temperatures reduce the
viscosity of oil thus helping its migration, while lower rock densities increase
permeability, which allows oil to migrate more easily. Weaker responses indicated how
oil and gas were generated at varying temperatures but did not relate their answer to oil
migration, or confused the density of oil with that of the rocks.
29 (e) (iii)
Higher temperatures reduced viscosity of
the oil thus helping migration.
Lower rock density usually increases
permeability which increases the rate of
migration
At greater temperatures oil is less viscous
allowing easier migration. the greater the
rock density the more difficult it is for oil
to move through rock layers
Question 30
(a) (ii) The best responses established a link between a valid government policy and the
sustainability of mining operations.
30(a) an ore is a mineral which can be refined and
processed so that a valuable metal can be extracted
from it.
(a)(ii) The Australian government’s policy is very strict
in relation to mining. The legislation regarding mining
means that before the mining company can begin they
must submit a very rigorous environmental impact
statement (EIS).
This affects the sustainability of mining operations
because it means that the company must allow enough
money to complete the regeneration of the area to its
original state. In this way the mining company may
have to stop mining earlier so as to be able to fulfill
their EIS requirements
(b) (i) The best responses described a trend as well as identifying a cause for the trend.
Weaker responses only described the trend. (ii) The strongest responses identified two
factors, such as grade, tonnage or market prices, and described how each factor would
influence production and income.
b(i) it starts off with a steady rise
probably as the mine is made bigger
then by year 4 has reached 2 million
tones. As they continue extracting
ore there is a gap ( one GB and
have some of the more money to
purchase more capital for more than
a proximity
(ii) Better responses outlined the procedure and equipment required in a first-hand
investigation that modelled the methods used to test for the presence of ore minerals,
such as burying radioactive isotopes in a tray of sand and using a Geiger counter to test
for the presence of -hand data.
(b)(ii)two major factors affecting ore
production and income are the grade of the
ore be it percentage or grams /tonne and the
market value of the ore being mined.
The higher the grade of the ore the more
economically profitable it will be. Similarly of
the ore is in high demand then higher prices
can be asked for it, further increasing the
profit.However if the grade is low and there is
little market value for the ore then it may not
be economically viable to even mine the ore.
(c) (i) The magnet will direct the string(pull the string)
towards the area where the metal is present.
(ii) Fill a tray with sand about half way
Gather two magnets that match in size
Bury one of the magnets under the sand (preferably by
someone who will not control the other magnet)
Tie a piece of string to the other magnet so it is able to
move freely without any force
Gently fly the magnet over the whole tray until a pull is
felt.
Dig up the area to see if the magnet is there and check
that the area where the pull is felt corresponds to the
area of the hidden metal
Repeat the activity several times to ensure the same
results occur.
(iii) Gloves were used
throughout the whole
investigation to ensure
hygiene and to make sure
no sand nor magnetic
particles were left on the
hands.
(d) The best responses used scientific principles to show a thorough understanding of
an environmental impact statement (EIS) by describing the effect of the mine on biotic
and abiotic features, and infrastructure.
These responses stated the need for an environmental impact statement clearly and
related their judgement to the benefits of having an environmental impact statement.
Weaker responses confused an environmental impact statement with a feasibility study.
30 (d)
Need :- An EIS allows both the government and the public to evaluate a
mining company's proposal and to monitor the project during the mining
process.
EIS covers the following .Description of the existing area, particularly its geology, soils, flora and
fauna with particular emphasis on unique and endangered species
.Details of environmental control measures to be used during the life of the
project, including air and water pollution control
.The location and nature of nearby towns, roads and other infrastructure
are described and an outline of how the mine development will affect these
areas is included. This will include both negative and positive impacts.
The protection of sacred sites and other sites of cultural significance are
also considered.
Plans for monitoring mining activities
.Discussion of mining techniques to be used
Judgement -EIS is necessary to ensure mines reduce or limit impacts of
mining on the environment and rehabilitate mine site
OR
As a result of introducing EIS, sites are safer, less toxic and communities
are well informed.
(e) (i) Stronger responses used the same scale for copper and lead concentration on the
vertical axis. Their graph used the full grid and provided a key.
(ii) Stronger responses calculated the answer from their graphs. Weaker responses
tried to calculate the answer from the table.
30 e(i)
30 e(ii) Copper 82-20 = 62m
Lead 72-20= 52m
The width where both metals are present with good economic grades is 52m
(e)
(iii) when the mine is closed all open pits should
be filled in and shafts stabilised.
This can then be revegetated and used pasture for
grazing. This will also help minerals to be placed
back into the soil. All infrastructure, machines and
buildings should be demolished and it should be
turned into its natural environment. Water used for
mining such as tailings should be carefully treated
and disposed of safely with no effect on the
environment.
By planting trees in the area it helps to rehabilitate
the land and brings native animals back to the
area.
Question 31
(a) (i) The best responses identified calcareous and siliceous oozes as the source of
sediment. Weaker responses confused clay, basalt and granite as sediment that are
biological in origin.
(ii) The better responses stated that manganese nodules begin to grow on a previously
existing particle, such as a small fishbone, forming layers through the process of
precipitation from seawater supersaturated in manganese.
Question 31
(a) (ii) The better responses stated that manganese nodules begin to grow on a
previously existing particle, such as a small fishbone, forming layers through the process
of precipitation from seawater supersaturated in manganese.
31 (a)(i)Calcareous ooze, Siliceous ooze.
31 (a)(ii) Manganese nodules form through
manganese precipitating in the ocean into
sediment.
Manganese must precipitate into sediment in
order to form eg on a grain of sand or on a
sharks tooth that has fallen out. Once
manganese has precipitated into the sediment
the nodule forms by the manganese forming in
layers around the piece of sediment. Nodules
can form anywhere in the ocean falling to the
sea floor or alternatively they can form directly
in the depths of the ocean.
(b) (i) The best responses identified that the temperature was constant for the top 200
metres of the ocean due to the sun’s ability to penetrate and warm to this depth.
(ii) The best responses described two factors, such as light, pressure, salinity, current
characteristics, and clearly stated how they changed with depth.
31 (b)(i) The water temperature in the
top 200m stays the same at 17C This
is because the water in the top 200m
is in the photic or euphotic zone
which is heated by the suns energy.
There is no change in temperature
until you go down below 200m
(b) (ii) The best responses described two factors, such as light, pressure, salinity, current
characteristics, and clearly stated how they changed with depth.
31 (b)(ii) Density changes with depth . The average
density of the ocean is 1.020 g/cm3 - 1.030 g/cm3
however density is greatest at the bottom of the
ocean. This is due to the pressure and weight of the
water above it. Water is least dense in the top 100m
of the ocean . density steadily increases as depth
increases.
Salinity also changes with depth. At the poles salnity
moves from a low concentration at the surface to a
concentrated form as depth increases. However this
trend changes at the equator with water being highly
saline in the top 100m becoming less saline with
depth. This is due to the high amounts of
evaporation which occur at the equator.
(c) (i) The best responses gave a hypothesis that stated that common salts would be
more soluble in water as the temperature of the water increased. Weaker responses
confused an aim with a hypothesis.
31 (c) (i) Hypothesis that
salt would dissolve more
quickly in warm water than
cold water.
(c) (ii) The best responses compared the mass of at least two named salts that can be
added to a specific volume of water at three different temperatures to obtain a saturated
solution. Weaker responses did not state the equipment used or name the salts that
were used, or discussed dissolving the salts at one temperature only.
31 (c) (ii) 2 beakers each with 100mL of
water were used.
One beaker had boiled water in it and
the other had been refridgerated.
One teaspoon of salt NaCl was poured
into each beaker of water and was
stirred at a constant rate until both were
dissolved. This was timed.
The process was repeated with
Magnesium Chloride used in step 3
instead of Sodium Chloride
(c) (iii)
(iii) Safety glasses were worn to
avoid the splashing of hot water in
ones eyes. Gloves were worn
when moving the hot beaker filled
with boiling water
(d) The best responses described the scientific principles associated with the laws
of the ocean that they included. They stated the need for each law clearly, and
related their judgement to the consequences of not having those laws.
31 (d)The ocean is a dynamic entity and as such affects everyone on a global
scale. Laws concerning the oceans need to be implemented in order to maintain
its health and sustainable use of its resources which benefits the world society
Laws concerning pollution need to be carefully conducted. Pollution including
sewerage heavy metals and dioxins and other chemicals can be transported over
vast distances by surface currents and deep sea circulation. Organisms can also
transport these substances through biomagnification and bioaccumulation.
These pollutants are harmful to marine life as they can cause death and thus
disrupt the functioning of the ocean ecosystems. International laws therefore
need to be implemented to control the amount and type of pollution entering
ocean waters in order to reduce it becoming widespread.
This pollution problem further affects society has reduced fishing stocks that are
fundamental to the economies of many countries.
Laws also need to be enacted concerning oil spills by enforcing fines on the
responsible companies so that they may obtain an immediate clean up of the
area before it becomes widespread.
Additionally transport needs to be monitored. The ballast water in ships for
example needs to be boiled and filtered in order to exclude some exotic species
that may be present in the ballast water taken up and then transported to these
regions when released. Eg North Pacific Sea star introduced into Australian
Harbours.
Laws are also important in the maintaining the sustainable use of ocean
resources. Limits on the type and amounts of resources such as fish and
crustaceans exploited need to be enforced to enable the species to continue
into the future and thus support future generations.
Thus laws concerning our oceans are vital for our world societyas everyone is
affected and so the laws are required to maintain the health of the oceans fr the
benefit of the world as a whole.
Need:- Oceans are a source of food and minerals. They are also a site of
disposal of waste eg from sewage and transport eg ballast. Excessive
dumping of waste can seriously effect food chains eg biomagnification.
Or All nations have a right to the mineral wealth on the sea floor
International laws (need to be described) .Pollution
.Sustainability of fishing by limiting numbers
.Transport -ballast
.Mining of sea bed
Justification -International laws provide an effective control on waste
dumping, fishing and exploration of ocean resources which if properly
supervised leads to a cleaner and more sustainable environment for world
society .
(e) (i) The best responses had graphs that included appropriate scales and labelling of
axes, filled the full grid and had a key.
31 (e) (i)
(e) (ii) The best responses stated that phosphorus concentration levels tracked
temperature. Weak responses described the graph without linking the relationship
between phosphorus concentration and temperature.
31 (e) (ii) The general trend is that as the temperature
decreases the phosphorous concentration also
decreases.
However there seems to be a lagging effect for the
Phosphorous concentration whereby it increases as a
result of the warmer summer months before
decreasing and remains at 20 ppm beyond the period
in which the temperature remains at its lowest.
However the general trend is decrease in temperature
corresponds with a decreased phosphorous
concentration.
(e) (iii) The best responses related hydrothermal waters to their mobility in the hot crust,
leaching out minerals into super hot water. They also noted that high pressure allowed
the water to remain liquid at high temperatures.
31(e) (iii)
The conditions for hydrothermal waters to scavenge
welements from rocks are
1 there must be a fault or some jointing near a
hydrothermal vent to allow colder ocean waters to seep
into the cracks and therefore give it the opportunity to
leach the metals from the rocks.
2 The heat of the mantle must heat this water and thus
encourage it to leach all metal sulfides and elements
from the rocks and, as it becomes less dense, rise to be
expelled through the hydrothermal vent.
31 (e) (iii) Hydrothermal waters need to circulate amongst
partly solidified rock underneath Hydrothermal vents and
also need to be hot in order to dissolve