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TRANSCRIPT
CPE 2015 Science Examiners’ Report
Mauritius Examinations Syndicate April 2016
Science CPE 2015 Examiners’ Report
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KEY MESSAGES
Candidates must be encouraged to:
read the instructions and questions carefully;
practice responding to open – ended questions and to write down their
answers;
apply their knowledge to the context set;
give precise answers;
give answers which is directly linked to the question;
refrain from giving vague answers;
understand the concept of scientific methods
understand and use the correct scientific vocabulary and terminologies
where applicable.
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GENERAL COMMENTS
The pass rate for school candidates in the Science CPE 2015 paper was 73.7 %
which is lower by about 2% from 2014. As in previous years, a high number of
candidates were able to achieve the highest grades, A* and A, with fewer
obtaining the grades C – E. At the lower end, there is a difference of about 11%
between boys and girls with more boys scoring a U. At the upper end, the
difference is significantly reduced to only 1% with more girls getting an A*. As it
has been highlighted in previous reports, the underperformance of boys is a
concern which deserves the attention of all stakeholders concerned.
Candidates from all the ability groups were able to score most marks from
Question 2A. The types of questions set were mostly fill-in-the blanks or
matching which were within the reach of most candidates. Throughout the paper,
it was noticed that wherever a one-word answer was expected, candidates were
able to respond with more confidence than for open-ended questions where they
had to express their ideas in a sentence. The difficulty with the language is
recurrent as well as the use of scientific terminologies.
However, some scripts contained precise and concise answers showing that
some candidates mastered both the scientific concepts and the linguistic skills
required. It was interesting to note that some candidates came up with
unexpected answers and were able to apply their knowledge and understanding
to the contexts given in the questions set.
The 2015 Science paper also showed some difficulties that pupils faced with
regard to topics/concepts. For instance, the concept of energy conversion, the
difference between evaporation and condensation or the processes of
germination and photosynthesis were not fully grasped by all.
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Candidates also found it difficult to make the distinction between sources and
uses or between causes and consequences.
As previously reported, it is important that candidates give precise answers which
are directly linked to what is being asked. Sometimes, answers given reflected
either rote learning of particular concepts and styles of questions or a lack of
mastery of the idea or concept being assessed. For instance, for the questions
related to Global Warming or to renewable or non-renewable sources of energy,
answers given were not always pertinent to the questions asked but contained
information which only remotely related to the topics being assessed.
Some candidates continued to read the questions superficially and to answer
without thinking carefully. Questions set are often within a particular context and
answers given are expected to take into consideration the context given.
As in the past years, language was a major hurdle for many candidates. Although
most candidates were able to read the questions with understanding, some could
not express themselves properly in writing. This difficulty often resulted in
answers which were not precise enough to deserve full marks.
Candidates faced difficulties in questions related to scientific methodology.
Though the question set, Question 4 – 1(a), was relatively basic, many
candidates could not differentiate between the idea of testing or carrying out an
investigation from the expected results of this investigation.
To help pupils perform better and to like Science, the teaching of Science should
be more explorative, with hands-on activities, simple experiments, formulation
and the testing of simple hypotheses, deductive and inductive reasoning. Based
on their previous knowledge, pupils must be encouraged to formulate hypotheses
which they can test. They should be aware of the basis of scientific testing where
only one variant must be manipulated and that it is important to have a control in
all experiment. They should be encouraged to explain the results they obtain
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whether these were expected or unexpected. All the above should be dealt with
bearing in mind the level of the pupils and the topics and concepts in their
syllabus.
SPECIFIC COMMENTS
Section A
Section A comprised Question 1 and Questions 2A and 2B. The items focused
on the Essential Learning Competencies. It carried 60% of the total marks of the
question paper. The mean mark in Section A was 36.7
A number of the items required only a one word answer or were of the fixed item
response type. Candidates were able to score more marks on these items. They
faced more difficulties to answer some of the items which required longer
responses.
QUESTION 1
This question comprised 10 multiple choice items covering the different topics in
the syllabus.
Items: 1, 2 and 5 were found to be relatively easy by most candidates with more
than 75 % obtaining the correct answer:
The following items proved to be more challenging:
Item 3 Through which one of the following processes does water vapour
turn into rain?
A significant number of candidates opted for the wrong answer ‘evaporation’.
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Pupils have not mastered the concepts of ‘evaporation’ and ‘condensation’.
These
are basic scientific concepts which pupils experience in their everyday life. It is
important that they understand the process and not merely try to remember the
words and their corresponding definitions by heart.
Item 4 Which one of the following conditions is necessary for coral polyps to
grow?
The three distractors were chosen by candidates but the most popular distractor
was ‘Shallow, warm and freshwater’. Candidates did not read the different
options given with enough attention.
Item 6 Which one of the following is the source of energy in an electric
circuit?
The word ‘source’ was not understood by some candidates who opted for one of
the wrong answers. Besides knowing the components making up an electric
circuit, pupils must also understand the functions of each of these components in
the circuit. For instance, that the source of energy is the dry cell.
Thus, for example, if we have two dry cells rather than one dry cell (of the same
capacity), there will be more energy which will be available in the circuit. This will
cause the light or bulb to shine brighter or a buzzer to ring louder. The bulb or the
buzzer would indicate whether electricity is flowing in a circuit.
The electric wire needs to have a conductor of electricity to allow the flow of
electricity from the source of energy. Since electricity is flowing, to prevent us
from getting electric shocks, the electric wires need to be insulated or covered
with plastic. The switch stops the flow of electricity in or opens the circuit by
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causing a gap in the connection. When this gap is closed, the electric flow will
resume.
Item 7 In which one of the following is chemical energy converted into
electrical energy?
This item was the least well done within the multiple choice questions.
Candidates opted for all the distractors indiscriminately. When we are dealing
with energy conversion, pupils have to know the form of energy from the source
and the conversion of energy that has taken place.
In ‘Movement of the wind in a wind turbine’, the source of energy is the force of
the wind which pupils learn as being movement energy at this level. This energy
is converted into electrical energy. In ‘Falling water in a hydroelectric power
station’, it is again movement energy as it is the force of the falling water which is
converted into electrical energy. When solar panels capture light, the source is
the light energy from the sun which is then converted into electrical energy. While
when bagasse is burnt, chemical energy in the bagasse is converted into
electrical energy which is used in sugar factories mostly.
Item 8 Which one of the following will form a clear solution when mixed with
water?
A number of candidates did not understand the word ‘clear’. It is the concept of a
substrate dissolving in a given solvent that they should understand here as well
as the meaning of a clear solution (which is not necessarily transparent) as
opposed to a solution containing undissolved particles.
Item 9 Animals have different habitats. What is a habitat?
This item was a knowledge question and pupils were expected to know the term
‘habitat’ in the way it is used scientifically. Though the word ‘habitat’ is a word
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which is close to the French or Creole word ‘habiter’ or ‘habitation’, some
candidates did not find the correct answer.
Item 10 Which one of the following food items will cause obesity if eaten in
excess?
A relatively common wrong answer was ‘beans’. Pupils have learnt that pulses
are a source of protein. However, the influence of common experience might
have impacted on this item. For instance, it is a common perception that kidney
beans (gros pois) cause an increase in weight.
QUESTION 2A (20 marks)
As is usually the case, candidates performed relatively well in this question.
Many of the items were of fixed – response type and were within the reach of
most candidates. However, where a simple sentence was required as answer,
some candidates were unable to express themselves.
Part 1: Fill in the blanks
Many candidates, from most ability groups, were able to score full marks in this
part of the question. However, some continue to make mistakes in copying the
given words from the list. Pupils must be encouraged to copy the words exactly
as given in the list.
Candidates found the word ‘gills’ quite easily for the item The………….. of fish
help them to breathe in water.
It was noted, that a few candidates instead of giving ‘fur’ as the answer for the
item The ……………….. of the dog protects it against cold weather, gave ‘hair’ as
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answer. ‘Hair’ was not one of the given words in the list and though it is a correct
answer, candidates must follow the instructions given for the question.
A number of candidates also confused between the words ‘endemic’ and ‘exotic’.
These are scientific terms with which they ought to be familiar. Pupils should be
encouraged to name and be familiar with the classification of different animals
and plants. It is worth having some practical activities on such topics so that
pupils understand the terms better.
Part 2
a) Give one importance of hens to humans.
A number of correct answers were given by candidates which included the ideas
of hens as a source of food or protein and as pets. However, some candidates
did not give a direct importance of hens to humans. Rather, they gave the
characteristics of hens such as ‘Hens lay eggs but humans do not’.
b) Give one way how rare birds are protected in Mauritius.
A number of correct answers were given by candidates. Answers ranged from
the way the rare birds should be conserved to the laws that should be passed
and enforced to ensure that they are not killed and that their habitats are not
destroyed.
However, there were some incomplete answers or answers which were not
exactly related to the Mauritian context, such as, ‘They should be put in caves’.
Other answers did not really respond to the question, for instance, ‘Rare birds
should be saved’. Pupils must also be encouraged to give full answers which
respond exactly to the question and context, for instance it is important not to
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only say ‘Pass laws’ but for example ‘Pass laws to prevent the destruction of
native forests which are their habitats’.
Part 3: Matching
Many pupils were able to do the matching well. They did not have any major
difficulty in this part of the question.
Question 2B
Part 1
Candidates were required to complete a partly filled table by either giving the
sources of different materials, naming the materials obtained from certain
sources or giving the use of the different materials.
(i) Material: Leather
Pupils had to find out from where leather is obtained as well as to give one of its
use. A significant number of students gave plant as the source for leather. It may
be concluded that they confused leather with rubber. This was sometimes
confirmed by the use of the material given, that is, to make car tyres.
For such questions, it is also important that candidates give common sources
and not sources which can considered as exceptions or being rare, such as
leather from lion, cheetah or elephant. These animals are often preserved under
conservation laws and it is not common to use their skin as leather or the use of
leather made from these skins can be confined to only a few countries or regions.
Correct uses given by candidates included the making of clothes such as Jackets
or to make boots for example. Some candidates also gave answers such as ‘To
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make dresses or to make T-shirts’. Though nowadays we can have dresses or
T-shirts made up of different types of material it is important that pupils give
common uses and not the exceptional ones. The examiner must be able to
ascertain beyond any reasonable doubt that the candidates had understood that
concept. The uses made of a particular material will thus depend a lot on the
properties of this material and this knowledge must be conveyed through the
answers given by the candidates.
(ii) Material obtained from sheep
The expected answer for material obtained from sheep was Wool but Leather
was also accepted as a correct answer. Though this item was accessible to most
candidates, a common wrong answer was Cotton. This answer was derived from
the creole use of the word ‘cotton’.
Candidates were able to give the uses made of either wool or leather, depending
on the answers they gave for the first part. Answers such as ‘To make pullovers’
or ‘To make jackets’ were accepted. Here also, it was important that candidates
conveyed their understanding and answers such as ‘To make T-shirts’ did not
exactly show that the pupils understood the specific uses of wool based on the
properties of the material.
(iii) To make aeroplanes
The expected material to make aeroplanes was Aluminium. Answers such as
wood, leather, stainless steel or plastic were not accepted as the aim was to find
the material used for its specific characteristic which is its weight. A number of
candidates found it difficult to write the word Aluminium. Words such as Aiumroll,
Alumion were quite common. As stressed in previous examiners’ reports, it is
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very important that pupils are encouraged to write down their answers and not
only give answers orally.
Candidates were able to give ‘from the earth’ or ‘from the soil’ for the part on
‘material obtained from’. However, many candidates found it difficult to express
themselves in this part of the question. Some candidates for instance wrote only
‘Land’ as answer.
Part 2 – based on a picture showing a boy burning leaf litter from his
garden
a) Which gas is needed for this fire to burn?
A fair number of candidates were able to give the answer ‘Oxygen’. However,
‘Carbon dioxide’ was a relatively common wrong answer. Pupils must also be
able to make the distinction between a particular gas such as oxygen from air.
b) The fire is giving out smoke. Explain how this form of air pollution affects
plants.
Wherever candidates had to express their answers in a relatively longer
sentence or phrase, they experienced some difficulties. A number of incomplete
answers were obtained or answers which did not fully respond to the question.
For instance, answers such as ‘Plants absorb air pollution’ or ‘Plants breathe
dust in the air’ did not explain how the air pollution is affecting plants. When the
question required an explanation to be given, only the observation based on the
phenomenon or the causes would not be enough to score full marks. The effects
of the causes have to be given as well.
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However, some complete and praiseworthy answers were also obtained such as
‘By blocking the pores of the leaves thus it cannot breathe and manufacture
its food’.
c) Give one way how the boy can extinguish this fire.
A number of candidates came up with correct answers which related to their own
experience and were answers which were not necessarily drawn from their
textbook. It is encouraging that pupils were able to understand the concept of a
fire deprived of a supply of oxygen will eventually die out. Answers such as
‘Throwing rocksand on it’ or ‘The boy must cut out the supply of oxygen by
throwing a wet blanket of it’ were therefore fully credited.
This item also required that the answer carried a small description of what
needed to be done to extinguish the fire. An answer such as ‘Water’ only was
not considered enough to be accepted as a fully correct answer.
d) Instead of burning the garbage, what beneficial use could the boy make of
it?
For this item also, it was expected that answers are not limited to one word only
such as Compost. A number of candidates gave fully correct answers such as
‘He can bury it as it will fertilise the land’ or ‘Bury it to make compost’.
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SECTION B
Section B consisted of two questions, questions 3 and 4 each with different sub
parts. Questions from Section B assessed mostly the Desirable Learning
Competencies. Candidates from all the ability groups should be encouraged to
attempt all the questions as a number of items are within the reach of most
pupils. Usually, items within a question are graded so as to build up confidence in
the candidates when they tackle the tasks. Candidates scored a mean mark of
17 over 40 in Section B.
Part 1
a) A green potted plant which is regularly watered is placed in a dark room.
(i) Give one factor which is absent from the room, thus preventing the
plant from making its own food.
A significant number of candidates gave the correct answer Light or Sunlight.
Some candidates did not read the first part of the question carefully and gave
‘carbon dioxide’ as answer.
Pupils’ attention should be drawn to the words which are in bold in the question.
These emboldened words are meant to guide the pupils and to draw their
attention on specific steps that they ought to take when responding to questions
set.
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(ii) Which gas is given out by this plant when it is in the dark?
Though a number of candidates gave the correct answer Carbon dioxide, a
number of them also gave ‘oxygen’ as answer. The word carbon dioxide was also
often wrongly spelt.
Pupils often forget or do not really grasp the concept that all living things breathe,
be it animals or plants. In the absence of light, for instance at night, plants
breathe normally as all living things do, taking in oxygen and giving out carbon
dioxide.
b) Give one condition which is necessary for a seed to transform into a new
plant.
Seeds from different plants need different conditions for germination to take
place. For instance, some seeds need high temperatures while others need
alternate freezing and thawing. Some will germinate in a sandy or rocky
substrate while still others would need a fertile soil or to pass through the
intestinal tract of specific animals.
However, the most common conditions necessary for all seeds to germinate are
the right temperature (be it hot or cold or room temperature) and moisture to
soften the seed coat. As all living things, the seeds also need oxygen though
often in very small quantities. It is important that pupils understand this concept.
They can be given the example of seeds which germinate only after forest fires,
for example certain pine seeds, so they can understand the idea of right
temperature. They can also be given the example of seeds which will germinate
on tissue paper or newspaper even, for example beans.
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Pupils must also be able to distinguish between the processes of germination
and photosynthesis. A seed does not have a shoot and thus does not have
leaves. As seeds do not have green leaves, they cannot carry out photosynthesis
and thus do not require light. Therefore, light is not an essential condition for a
seed to germinate.
When only one condition is required, candidates are encouraged to give only one
condition unless they are absolutely confident that all the conditions they are
giving are correct ones. By giving more than one condition, they will not be given
extra marks but if all the conditions they have given are not correct they might
lose marks.
c) Give one reason why plants are important to animals.
Most candidates were able to provide a correct answer to this item. Examples of
correct answers were ‘Plants help maintain the composition of air so animals
can breathe’, ‘Plants provide a source of food to herbivorous animals’ or
‘Plants provide shelter to animals’.
However, it was found that some candidates found it difficult to express
themselves. For instance answers such as ‘Animals can live there’ or ‘She gives
fruits’ show the difficulty that some candidates have to convey their
understanding.
Some answers, though in some cases were accepted, ought to be better
formulated so that the meaning is clear to the examiners. For instance answers
such as ‘Because animals can eat many fruits’ or ‘Plants help them to grow
well’ do not answer directly to the question though it is rather clear what the
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candidates had in mind. Answers such as ‘Animals need plants’ do not give any
reason why the animals need the plants.
d) Explain how plants help to prevent soil erosion.
When candidates are required to ‘explain how’, they need to give a more in depth
answer, describing the process and, often, a couple of words only as answer will
not fully answer the question and would not suffice to get full marks. For this
item, it was expected that the candidates would explain that the roots of the
plants trap the soil and prevent it from being washed away.
Some candidates were able to give a complete answer. The idea of plants
reducing the force of the rain thus preventing the soil from being washed away
was also given by a number of candidates and accepted as a fully correct
answer. However, answers such as ‘They are grown around the coast to
prevent soil erosion’ did not explain how the plants prevented soil erosion. Here
also some candidates had difficulty in expressing themselves and answers such
as ‘It maintain the soil’ or ‘It attract the soil erosion’ were obtained.
It is also important that candidates give full answers and relate the function of the
roots of the plants in preventing soil erosion. Thus, by giving vague answers such
as ‘They are wind breakers’ or ‘hold the soil’, the candidates did not explain
fully how the plants prevent soil erosion.
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Part 2
(a) Carnivores need to have strong canines. Explain why.
The idea of carnivores eating meat or their prey which they have to tear had to
be conveyed. A number of candidates gave answers which, though expressed
differently, were correct. For instance, some of them gave ‘Carnivores need to
have strong canines as they feed on meat which is very difficult to tear’ or
‘They need strong canines to capture and tear their prey’.
However, it was expected that candidates would be able to make the difference
between the functions of the canines which is to tear and that of the molars which
is to crush or grind. Thus answers such as ‘To crush meat’ were not accepted.
This item also required candidates to ‘explain why’, that is, they had to relate the
teeth of the carnivores to their diet. An answer such as ‘Carnivores eat meat’
does not fully explain why strong canines are required. Some candidates also
gave answers such as ‘To crush bones’ which is not the function of the canines.
(b) Give one reason why human babies who are aged less than 8 months do
not need to have molars.
Some candidates were able to relate the diet of an 8 months baby with their
dentition and the types of teeth they have. Answers such as ‘Because they don’t
eat food which must be crushed’ showed that the understanding of the concept
was acquired.
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An answer such as ‘Because they are child only and will have molars later’ did
not convey the understanding of the concept. It also demonstrated that pupils
had difficulty in expressing themselves when they were required to explain.
Some candidates gave incorrect elements in their answer and thus could not be
given marks. For instance, ‘Molars grow only in permanent teeth set but
babies have milk teeth set’ contained a wrong concept.
(c) Give one precaution you must take to protect your teeth from decay.
This was a fairly common type of question and pupils are familiar with the
different ways of protecting the teeth. Correct answers included ‘Brush our teeth
after each meal’, ‘I must stop eating sugary food and drinks’ or ‘visit the
dentist for a dental checkup at least one per year’.
It was found that some candidates had confused the topic of prevention of dental
decay with that for how to avoid obesity or to stay in good health. An answer
such as ‘We must not eat oily food’ was also obtained.
Part 3
a) Write down three food items which will make a balanced meal.
Candidates were expected to give one food item from each of the three food
groups carbohydrates, protein and vitamins and minerals. This was an item that
was accessible to a majority of candidates. Some of them however gave at least
two food items from the same food group. Some candidates gave the names of
the food groups instead of that of the food items. The importance of reading the
questions carefully is stressed once again here.
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b) Give one reason why we must store food at low temperature in the
refrigerator.
It was expected that candidates’ answers would include the idea of a slowing
down of activities of microorganisms/ bacteria/ microbes or that these organisms
would not be able to reproduce at low temperatures. As a result, the food would
take longer to decay or rot.
Some candidates had the misconception that low temperatures would kill the
bacteria or microorganism. Others only gave answers such as ‘cold
temperature’. Some pupils also had difficulty in conveying their ideas because of
limited linguistic skills and answers such as ‘microbes can slowly multiply’ or ‘to
be able to eat it next time’ were obtained.
Question 4
Part 1 – This question was based on an experiment involving two potted plants
which were being watered using two different types of water, plant A with fresh
water and plant B with water from a river containing detergents.
a) What is this experiment testing?
While a number of candidates were able to give the idea that it was an
investigation being carried out to find out what will happen to the plants under the
given conditions, many others gave the outcome or the expected results of the
experiment. Correct answers included ‘If the water containing detergents is
better than the fresh water’ or ‘if the plants can survive with polluted
water’. Answers such as ‘We can water plants from fresh water and not with
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water coming from rivers’ or ‘that experiment shows that with polluted
water plants cannot grow well’ did not answer the question.
This item was quite revealing in terms of the understanding that pupils have at
this level on scientific methodologies. Inquiry skills are the basis of Science
learning and without these skills, Science is often perceived as the rote learning
of a series of facts, science vocabulary and theories.
It is important that pupils be initiated to the scientific methodology consisting of
systematic observation, formulation of hypotheses, measurement,
experimentation, testing, and modification of hypotheses and drawing
conclusions. They must be encouraged to understand the difference between
testing a hypothesis from the results obtained. They must also be able to
distinguish between the observations made or results obtained from the
interpretation of results. It is expected that at this level, the teaching of these
skills is done for simple experiments linked to the concepts that they have to
understand within their syllabus.
b) What will happen to plant A and plant B after a few weeks under the same
conditions as at the beginning of the experiment?
Candidates found this item within their reach and many gave the correct
answers. From the experiment, the expected results were that plant A would
grow healthily while plant B would be affected by the polluted water and would
wither or die.
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c) Give one way how polluted water can be purified.
In this item, polluted water referred to any type of pollutants, whether solid,
chemical or organic. Thus answers such as ‘We must boil the water for more
than 15 minutes’ or ‘Filter the water and add chlorine to it’ were both
accepted as correct.
Part 2
a) Give one way how plastic bags harmed the environment in Rodrigues.
Though candidates sometimes had difficulty in expressing their ideas, a range of
correct answers were obtained. The answers given were often linked to real life
experiences. Answers such as ‘They clog drains or rivers’ or ‘they polluted the
environment as they are not biodegradable’ or ‘Since they do not degrade,
they are an eyesore’ were all credited with full marks.
It was however noticed that a number of candidates confused the concept of
rusting with that of non-biodegradable. Some candidates’ answers did not refer to
the harm being caused to the environment but instead to other ideas such as ‘It
may cause severe burns when melted’. Though this is true, it did not answer the
question.
b) Explain how the use of fossil fuels contributes to Global warming.
Few candidates were able to score full marks on this item. Answers often
referred to the consequences of Global Warming instead of how it is caused. It
was expected that candidates would write about the release of toxic gases,
namely carbon dioxide when fossil fuels are burnt and that these gases would
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contribute to Global warming. These gases are part of the greenhouse gases
which when trapped in the atmosphere contributes in making the Earth warmer.
Answers such as ‘When mixed with rain it causes acid rain’ or ‘it causes
pollution’ did not explain how the fossil fuels are contributing to Global Warming
but referred to the other harmful effects of the burning of fossil fuels.
c) Give one way how the consequences of Global Warming affect people’s
lives.
For this item, it was expected that the consequences of Global Warming would
be given and a range of answers were possible. Correct answers from
candidates included ‘because of the melting of ice caps’, ‘people living in
coastal regions may die’ or ‘Global Warming causes severe droughts in some
countries’.
Some answers did not give a consequence but only reiterated what was already
said in the question, that is, people’s lives would be affected. Other answers
were too vague, for example ‘It damages the Earth’.
Part 3
a) Explain why it is better to use light from the sun rather than fossil fuels to
produce energy.
The main ideas expected were either that the sun is a renewable source energy
while fossil fuels will run out one day or that production of energy from the sun
does not cause pollution as the burning of fossil fuels to produce energy. The
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idea of solar energy being less expensive in the long term as compared to fossil
fuel was also accepted.
Many candidates were able to give one or more of these ideas. Those whose
answers included the idea of cost were expected to give the correct explanation
and not only ‘It is cheap’ or ‘It is expensive’. Pupils must be encouraged to give
precise answers and not to answer in a vague way. For instance, for this item, it
would have been better had they indicated solar energy or energy from fossil fuel
when referring to the different sources instead of writing ‘it’. They must also be
encouraged to give more details on how this source of energy is cheap or
expensive (for instance in the short term or long term or as compared to other
sources of energy) or how it is free (for instance, in the long term, there is no
investment to be made).
b) Explain what is the difference between a renewable and a non-renewable
source of energy.
The idea of a renewable source energy being always available while a non –
renewable source of energy would run out one day is sometimes difficult for
pupils to grasp. Though some candidates were able to find the correct answer, a
common wrong answer was that renewable sources of energy do not cause
pollution whereas non-renewable sources of energy cause pollution.
It is important for pupils to make the distinction between these two concepts. We
can have, for instance, renewable but polluting sources of energy such as
bagasse or charcoal or non- renewable and less polluting sources of energy such
as natural gas. Nuclear energy on the other hand can be considered as non-
renewable. Although it causes less air pollution than the burning of fossil fuels, it
can cause different types of pollution on a larger scale and with more devastating
consequences.
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c) Although charcoal is a renewable source of energy, it is not commonly
used. Explain why.
This was an item where candidates were required to use their logical thinking
and it was pleasant to see that a range of correct answers were obtained. Some
candidates had even mentioned the idea of charcoal having a lesser energy
content than some other sources of energy. More common correct answers
carried the idea that the burning of charcoal causes pollution or that charcoal is
made from trees. Consequently a large number of trees have to be cut to make
charcoal which is harmful to the environment.