Download 2005 HSC Notes from the Marking Centre Earth and

STANSW Meet the Markers
2005 HSC Notes from
the Marking Centre
Earth and Environmental
Science
David Tweed, Penrith Anglican College [email protected]
Fiona Branch, Sydney Grammar, [email protected]
General Comments
• 1131candidates attempted the Earth and
Environmental Science examination.
• The most popular electives were
Introduced Species and the Australian
Environment (76%) and Oceanography
(10%).
Content
• knowledge, understanding and skills
developed through the study of discrete
sections should accumulate to a more
comprehensive understanding than may
be described in each section separately
• It is important to understand that the
Preliminary HSC course is assumed
knowledge for the HSC course.
Skills 9.1
• at least one question in Section 1 Part B
focused on the mandatory skills content in
Module 9.1. Candidates who had actively
planned and performed practical
experiences clearly demonstrated a
deeper knowledge and understanding of
the content described in this module.
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. This may
include the use of dot points, diagrams and/or
tables, and avoids internal contradictions. This
isparticularly so in holistic questions which need
to be logical and well structured.
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.)
Scaling of EES
http://www.uac.edu.au/pubs/pdf/2005-Table-A3.pdf
b) Oceanic crust is denser and thinner than continental crust.
c) The collision of two plates results in Compressive Forces that cause
faulting, folding and metamorphism of rocks
17 a) Pyroclastic flow, Lahar.
b) Sumatra is Located near a subduction zone. The subduction of the indo Australian
plate beneath Sumatra causes the production of magma due to partial melting. This
magma creates the composite volcanoes like Toba.
18 a) Radon gas meters measure the level of radon gas released from faults. An
increase in the level of radon detected could indicate an increase in earthquake
activity, and thus prove useful in predicting earthquakes.
b) Current technology has many problems predicting earthquakes. Improved
methods would lead to more accurate early warning systems and evacuation
plans decreasing the loss of life and the destruction of infrastructure.
19 Heat generated from the base of the mantle circulates in convection
currents. The mantle material becomes less dense and rises when heated.
The horizontal motion of the convecting mantle results in friction with the
plates producing basal drag. This drives the plates in the direction of the
convecting currents.
DIAGRAM of convection Cell
20
(a)
Length of time (Ma)
Time Division
Proterozoic
1950 Ma
Archean
1300 Ma
Cenozoic
50Ma
Triassic
40 Ma
(b)
Precambrian
Postcambrian
Soft body parts
Development of hard body parts
Simple life forms
More complex life forms
Generally less predation
More predation
Vulnerable to predation
More protective body parts less vulnerable
to predation
21
(a) BIF’s are sedimentary rocks formed of alternating layers of
Iron oxide rich (indicating increasing oxygen levels) and iron
oxide poor (indicating low oxygen concentration) high silicate
sediments. They indicate fluctuating levels of O2 in the aquatic
environment, produced by cyanobacteria.
The O2 released, reacted with the Fe2+ dissolved in the oceans
to form FeO which settled on the bottom of the aquatic
environment. As the cyanobacteria populations varied so to
did the oxygen levels and the consequent FeO levels in the
Sediment
(b) The media report is unreliable as the Cretaceous environment was highly
Oxygenated supporting a wide variety of life forms that used respiration. All the free
Fe2+ had precipitated out of the ocean by this stage allowing oxygen to enter the
atmosphere, form ozone and allow terrestrial ecosystems to develop.
Roots/Rhizoids – would only need small root hairs as they would be mainly
used for attachment to some substrate in a swampy environment.
a more extensive root system would be required for the absorption of water and
nutrients and for anchorage of the plant.
Stem – Plant stem in water is buoyed up by the water therefore does not
require much structural material.
In a terrestrial environment the stem would need to be strengthened by
lignin/cellulose for support.
Reproduction
- Sporangia would release spores into a watery environment.
on land, seeds would be needed prevent dessication
23 (a) Oxygen is composed of 2 atoms O2
Ozone is a molecule combining 3 oxygen atoms O3
(b) The general trend is a decline in Ozone over 45 years
There are many fluctuations over this time
The most rapid decline is between 1980 and 1990. The levels seem to be
stabilising between 1995 and 2000
(c) Montreal protocol – early signs show success as ozone depletion stabilised.
Banning of ozone depleting substances (eg CFC Halides, Methyl bromide) used in
aerosols, refrigerants, extinguishers.
Impact on society increased awareness, finding alternatives impacts upon
industry, decrease in skin cancer in the long term.
Impact on the environment- Increasing levels of ozone once again, reduction in
level of UV reaching the earth. Some replacements for CFCs are greenhouse
gases creating/enhancing other problems.
Sewage treatment is a current method. It involves the primary, secondary and
tertiary stages of treatment as detailed below.
This is an effective method as it removes all solid wastes, kills bacteria, removes
organic material and soluble nutrients. It prevents the growth of algal blooms and
eutrophication and is and environmentally friendly process. This along with the
fact that the recycled water can be returned to town catchment water supplies
used to drink, irrigate or maintain environmental flows makes it an effective
method.
Lquid waste
(sewage)
Filtration (PRIMARY)
Grates mesh filters are used to
filter out solid larger material as
liquid waste passes through
Sedimentation (PRIMARY)
Liquid waste is placed in tankes and
settles. Denser materials accumulate at
the bottom known as sludge.
Liquid is decanted from the sludge
Filtered waste sludge to
landfill and fertiliser
Nutrient Removal
Ponds lagoons are used
for algae to absorb the
soluble nutrients
Sterilisation of waste by
UV
Addition of chlorine to
remove bacteria
Aeration Churning of
remaining wastes helps
remove organic material
SECONDARY
Recycled Water
Bacterial Decomposition Trickled over rocks
coated with bacteria. Organic material is
removed.
SECONDARY
Appropriate use of drinking irrigation
agriculture environmental flows
catchments
25
An environmental flow introduces released dam water back into the environment
in cycles.
This is important as the introduction of water stimulates breeding /dispersal of
some species and ensures biodiversity is maintained.
It allows the dispersal of organic material over flood plains which contributes to
the soils fertility and maintains plant diversity and health.
26
Soils in the west are vastly older than soils in the east. Soils in the west
are also nutrient poor ( less fertile ) compared to the soils in the east. The
age of soils affects the amount of weathering and erosion that they have
undergone. WA soils have undergone millions of years of leaching
depleting them of any nutrients they may have had.
Soils in eastern Australia have not gone through as much leaching so
have still retained many of their original nutrients.
Recent volcanic activity in the east has also lead to the formation and
replenishment of basalt derived nutrient rich soil. A lack of volcanic
activity of any recency in the west means there has been no
replenishment of nutrients via weathering and erosion of basalt.
27
i) A table was used to present the data. It had three columns for name, type and
description of the indigenous and non indigenous species in the area
(ii) This investigation was best undertaken by a team as we needed a wider
knowledge of introduced species for identification. More people gave us a wider
knowledge and enabled us to finish the job in a shorter time
(a)(i) Graph Q27b Abundance of species over time
(ii) the number of species 1 increases rapidly from 30July to 5 August2002
indicating that it was well adapted to the environment. Between 5 August 2002 and
17 February 2003 the number of species declined rapidly due to the a drought as
they were not adapted to the change. After that the species that survived started to
increase slowly.
Species 2 declined throughout the whole range but were less affected by the
drought, as they were better adapted to these conditions.
Salvinia molesta is a pond weed that was introduced in the 1950’s and escaped
from fish ponds and entered waterways
Recently there has been an outbreak of this plant in the Hawkesbury Nepean river
system. Salvinia lives in waterways with high nutrient levels resulting from
agricultural runoff It’s high reproductive capacity means that the plant can double
it’s size in two days covering an area of 100km2 in just three months. Salvinia
floats on the surface of the water preventing light from penetrating , and thus
killing aquatic plants, reducing aquatic Oxygen and leading to eutrophication.
A number of strategies have been implemented to control this species. A biological
control has been released to naturally control the plant growth. A brazilian weevil
was released to burrow into the salvinia, allowing bacterial spores to enter the
plant and kill it. This method is effective on large outbreaks as it isn’t labour
intensive and is cost effectiveonce it has been trialled and released.
This trial process is however expensive and timely. The weevil doesn’t survive in
cooler areas. So despite it’s success it has it’s limitations as a means for control.
Herbicides have also been used to effectively control large populations of salvinia
however this process is expensive as it is labour intensive and it also adversely
affects non target species. Salvinia’s high reproductive capacity means that if only
a few plants excape the spraying then it could quickly repopulate the area.
Methods used to control the spread of Salvinia are effective in some ways but
ineffective in others. An integrated approach may be the best option to control
salvinia and rehabilitate the ecosystem
d (i) European farmers introduced plants for agriculture eg fruit trees
because they had a better knowledge of farming methods of crops
cultivated in their homeland and preferred to eat European food types.
(ii) The garden in photo 1 has involved the removal
of native species and their replacement with lots of
introduced species. Abiotic characteristics that
have been altered include:Pine trees drop needles and increase the acidity of
the soil
Use of excess water on the garden or plants with
shallower roots may cause the watertable to rise
and create salinity problems.
Less sunlight reaching the soil due to more dense
vegetation compared to native garden.
(iii) The garden in photo 1 will start to die off since the plants do not have special
adaptations to prevent water loss or conserve water. For example the plants possess
shallow roots that do not allow them to suck up water if the watertable drops severely
during the drought or they have large thick leaves or lots of large stomates that cause
them to loose water quickly through their leaves. The garden in photo2 will survive
since native plants are well adapted to dry Australian conditions. They possess
smaller leaves with waxy coatings or the trees possess deep roots that will enable
them to suck up water from a lowered water table.