Exemplar for internal assessment resource Science for Achievement Standard 90945
Exemplar for Internal Achievement Standard
Science Level 1
This exemplar supports assessment against:
Achievement Standard 90945
Investigate implications of the use of carbon compounds as
fuels
An annotated exemplar is an extract of student evidence, with a commentary, to explain key
aspects of the standard. These will assist teachers to make assessment judgements at the
grade boundaries.
New Zealand Qualification Authority
To support internal assessment from 2014
© NZQA 2014
Exemplar for internal assessment resource Science for Achievement Standard 90945
Grade Boundary: Low Excellence
1.
For Excellence the student needs to investigate, comprehensively, implications of the
use of carbon compounds as fuels. This involves analysing the links between the
selected properties of the different carbon compounds, their uses as fuels and
implications of the use of different carbon compounds as fuels.
The evidence is at Low Excellence because the student has comprehensively
investigated and discussed the science of burning carbon compounds as fuels (1) and
the implications for the environment have been investigated in depth with key reasons
(2).
To reach a secure Excellence the student could more comprehensively link the science
of carbon compounds used as fuels to the implication(s) for society. For example, the
student could discuss more fully the role of carbon dioxide in global warming and how
burning fossil fuels contributes to this and then describe ways in which we can cut our
dependence on fossil fuels.
© NZQA 2014
Student 1: Low Excellence
AS 90945
Student 1
Implications of burning fuels on the environment.
Since the invention of the internal combustion engine by Otto Benz in 1896 millions of cars,
trucks and aircraft have burnt many millions of tonnes of carbon based fuels and realised
their combustion products into the environment. Key compounds released are carbon
dioxide, carbon monoxide and nitrous oxide. When fuels are burnt a lot of energy is released
and is used to run cars etc.
Example of burning fuel:
Methane
+
oxygen
→
carbon dioxide
+
water
CH4
+
O2
→
CO2
+
H2O
From the equation we see that two key substances are released into the atmosphere: water
plus carbon dioxide. Of these two compounds carbon dioxide is the more harmful on the
environment. (1)
Since 1850 carbon dioxide levels have risen from 280 ppm to 400ppm in 2013. Carbon
dioxide is known as a “greenhouse gas” this means it stores heat. Light coming in from the
sun hits the ground and is converted to heat. This heat rises in the atmosphere and is
trapped close to the ground by carbon dioxide. This means less heat is lost to space and
stays close to the ground. Evidence for this has now shown that since 1850 the average
temperature of the Earth has risen 10C. While this seems to be small and unimportant it is
critical. If the rise was only 10C it would not be a problem but the predictions are that the
amount of carbon dioxide will continue to rise and could be 500ppm by the end of this
century. This could equate to a rise of 4-50C. This will lead to a change in the environment
on Earth; the sea level will rise 1.5-2.5m and flood most cities in the world. London would go
under water. Christchurch would be under ~ 2m of water. Not nice. (2)
The burning of fuels has led to this change of the world temperature. What can we do? We
need to reduce our reliance on carbon compounds as fuels. We need to come up with ways
of collecting carbon dioxide and storing it underground. Big problems but can be fixed. We
have no choice. Do nothing and we could become extinct. Governments need to quickly act
and cut our CO2 levels and use less fossil fuels. This could be done by using more
renewable fuels. A possible solution could be using solar panels. (2)
Exemplar for internal assessment resource Science for Achievement Standard 90945
Grade Boundary: High Merit
2.
For Merit the student needs to investigate, in depth, implications of the use of carbon
compounds as fuels. This involves making links between the selected properties of
carbon compounds, their uses as fuels and implications of their uses as fuels.
The evidence is at High Merit because the student has investigated and explained in
depth the science of burning carbon compounds as fuels (1) and the implication for
society has been explained in depth with reasons for the link to global warming (2).
To reach Excellence the student could comprehensively explain how carbon dioxide
causes global warming and how to control the levels of carbon dioxide gas in the
future. For example, the student could describe how an increase in the carbon dioxide
levels traps heat in the atmosphere which causes a temperature rise.
© NZQA 2014
Student 2: High Merit
AS 90945
Student 2
Implications of burning fuels on the environment.
Since the invention of the internal combustion engine by Otto Benz in 1896 millions of cars,
trucks and aircraft have burnt many millions of tonnes of carbon based fuels and realised
their combustion products into the environment. Key compounds released are carbon
dioxide, carbon monoxide and nitrous oxide. When fuels are burnt a lot of energy is released
and is used to run cars etc.
Example of burning fuel:
Methane
+
oxygen
→
carbon dioxide
+
water
From the equation we see that two key substances are released into the atmosphere: water
plus carbon dioxide. Of these two compounds carbon dioxide is the more harmful on the
environment. (1)
Since 1850 carbon dioxide levels have risen from 280 ppm to 400ppm in 2013. Carbon
dioxide is known as a “greenhouse gas” this means it stores heat. Light coming in from the
sun hits the ground and is converted to heat. This heat rises in the atmosphere and is
trapped close to the ground by carbon dioxide. This means less heat is lost to space and
stays close to the ground. Evidence for this has now shown that since 1850 the average
temperature of the Earth has risen 10C. While this seems to be small and unimportant it is
critical. If the rise was only 10C it would not be a problem but the predictions are that the
amount of carbon dioxide will continue to rise and could be 500ppm by the end of this
century. This could equate to a rise of 4-50C. This will lead to a change in the environment
on Earth; the sea level will rise 1.5-2.5m and flood most cities in the world. London would go
under water. Christchurch would be under ~ 2m of water. Not nice. (2)
Exemplar for internal assessment resource Science for Achievement Standard 90945
Grade Boundary: Low Merit
3.
For Merit the student needs to investigate, in depth, implications of the use of carbon
compounds as fuels. This involves making links between the selected properties of
carbon compounds, their uses as fuels and implications of their uses as fuels.
The evidence is at Low Merit because the student has investigated in depth the
science of burning carbon compounds as fuels (1) and shown an awareness of the
implication for society which has been explained (2).
To reach a secure Merit the student could explain in greater depth, for example, how
carbon particles of various size cause cancer and how carbon monoxide causes other
health issues; this is because the lungs cannot get rid of carbon soot particles of 2.5
microns in size by their normal cleaning methods.
© NZQA 2014
Student 3: Low Merit
AS 90945
Student 3
Implications of burning diesel on human health.
These days many cars are now running on diesel as a fuel. Diesel is a long chained carbon
molecule (15 carbon atoms) and carries a lot of energy. When diesel is burnt in an engine it
releases a lot of energy which is converted to kinetic energy and cars can move. Oxygen is a
limiting factor when diesel burns so it cannot convert all the diesel to carbon dioxide and
water. With limited air the diesel goes to carbon monoxide and pure carbon compounds.
Carbon monoxide is poisonous to humans. It combines with haemoglobin and the red blood
cell then must be destroyed by the liver. Too much carbon monoxide destroys too many
blood cells and you die. If humans lose half of their red blood cells you die. To stop this
many vehicles have a catalytic converter that adds extra oxygen to the waste gases and
converts carbon monoxide to safe carbon dioxide. (1)
Pure carbon emitted from exhaust pipes is a more major concern. Some of the carbon
particles are 2.5 microns in size and others are 10 microns in size. Carbon particles of this
size are sucked in when we breathe, get trapped in the mucous of the lungs, but are to small
to be removed. These particles touch our unguarded lung cells and are known to be cancer
causing. There is now some evidence these particles cause more cancer than smoking. This
is a major concern for health authorities (2).
How can we solve these problems: Do we stop the importation of diesel cars? Cars new to
NZ must meet certain requirements. Catalytic converters are at a high standard of
construction and stop carbon monoxide and carbon particles. Imported second hand cars
are not required to be at the same level and constitute a problem. I think we should stop the
inport of these cars.
Exemplar for internal assessment resource Science for Achievement Standard 90945
Grade Boundary: High Achieved
4.
For Achieved the student needs to investigate and describe implications of the use of
carbon compounds as fuels. This involves, for example, describing selected properties
of carbon compounds and implications of their use as fuels.
The evidence is at High Achieved because the student has described how the burning
of carbon compounds as fuels (1) has led to an awareness of two major health hazards
for humans (2).
To reach Merit the student could explain in greater depth how the products of burning
carbon compounds as fuels cause the health problems identified. For example, carbon
soot particles at 2.5 microns in size that are released when carbon fuels are burnt in
limited oxygen have been linked to lung cancer and other lung illnesses.
© NZQA 2014
Student 4: High Achieved
AS 90945
Student 4
Implications of burning diesel on human health.
These days many cars are now running on diesel as a fuel. Diesel is a long chained carbon
molecule (15 carbon atoms) and carries a lot of energy. When diesel is burnt in an engine it
releases a lot of energy which is converted to kinetic energy and cars can move. Oxygen is a
limiting factor when diesel burns so it cannot convert all the diesel to carbon dioxide and
water. With limited air the diesel goes to carbon monoxide and pure carbon compounds. (1)
Carbon monoxide is poisonous to humans. It combines with haemoglobin and the red blood
cell then must be destroyed by the liver. Too much carbon monoxide destroys too many
blood cells and you die.
Pure carbon emitted from exhaust pipes is a more major concern. Some of the carbon
particles are 2.5 microns in size and others are 10 microns in size. Carbon particles of this
size are sucked in when we breathe, get trapped in the mucous of the lungs, but are too
small to be removed and cause cancer. (2)
Exemplar for internal assessment resource Science for Achievement Standard 90945
Grade Boundary: Low Achieved
5.
For Achieved the student needs to investigate and describe implications of the use of
carbon compounds as fuels. This involves, for example, describing selected properties
of carbon compounds and implications of their use as fuels.
The evidence is at Low Achieved because the student has described the burning of
carbon compounds as fuels (1) and shown an awareness of two health problems
associated with burning of carbon compounds as fuels (2).
To reach a secure Achieved the student could describe how the two identified health
problems link to the risks of burning carbon compounds as fuels. For example, carbon
soot particles released from diesel engines have been linked to lung cancer.
© NZQA 2014
Student 5: Low Achieved
AS 90945
Student 5
Implications of burning diesel on human health.
These days many cars are now running on diesel as a fuel. Diesel is a long chained carbon
molecule (15 carbon atoms) and carries a lot of energy. When diesel is burnt in an engine it
releases a lot of energy which is converted to kinetic energy and cars can move. Oxygen is a
limiting factor when diesel burns so it cannot convert all the diesel to carbon dioxide and
water. With limited air the diesel goes to carbon monoxide and pure carbon compounds. (1)
Carbon monoxide is poisonous to humans. (1) It combines with haemoglobin and the red
blood cell then must be destroyed by the liver.
Pure carbon emitted from exhaust pipes is a more major concern. Some of the carbon
particles are 2.5 microns in size and others are 10 microns in size. Carbon particles of this
size are sucked in when we breathe, get trapped in the mucous of the lungs. They cause
cancer. (2)
Exemplar for internal assessment resource Science for Achievement Standard 90945
Grade Boundary: High Not Achieved
6.
For Achieved the student needs to investigate and describe implications of the use of
carbon compounds as fuels. This involves, for example, describing selected properties
of carbon compounds and implications of their use as fuels.
The evidence does not reach Achieved because the student has described the burning
of carbon compounds as fuels (1) but needs to demonstrate more awareness of the
effects of this on global warming (2).
To reach Achieved the student could clearly describe how burning carbon compounds
as fuels have contributed to greenhouse gases and describe their effect on the
environment.
© NZQA 2014
Student 6: High Not Achieved
AS 90945
Student 6
Implications of burning fuels on the environment.
Since the invention of the internal combustion engine by Otto Benz in 1896 millions of cars,
trucks and aircraft have burnt many millions of tonnes of carbon based fuels and realised
their combustion products into the environment. Key compounds released are carbon
dioxide, carbon monoxide and nitrous oxide. When fuels are burnt a lot of energy is released
and is used to run cars etc. (1)
Example of burning fuel:
Methane
+
oxygen
→
carbon dioxide
+
water
From the equation we see that two key substances are released into the atmosphere: water
plus carbon dioxide. Of these two compounds carbon dioxide is the more harmful in the
atmosphere where it makes global warming. This is where seas get hot. (2)