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Example Candidate Responses
(Standards Booklet)
Cambridge IGCSE®
Co-ordinated Sciences
0654
Cambridge Secondary 2
Cambridge International Examinations retains the copyright on all its publications. Registered Centres are
permitted to copy material from this booklet for their own internal use. However, we cannot give permission
to Centres to photocopy any material that is acknowledged to a third party even for internal use within a
Centre.
® IGCSE is the registered trademark of Cambridge International Examinations.
© Cambridge International Examinations 2013
Contents
Introduction ........................................................................................................................... 2
Assessment at a glance ........................................................................................................ 3
Paper 2 – Core ...................................................................................................................... 4
Paper 3 – Extended ............................................................................................................ 69
Paper 5 – Practical ............................................................................................................ 173
Paper 6 – Alternative to practical ...................................................................................... 212
Introduction
Introduction
The main aim of this booklet is to exemplify standards for those teaching Cambridge IGCSE Co-ordinated
Sciences (0654), and to show how different levels of candidates’ performance relate to the subject’s
curriculum and assessment objectives.
In this booklet a range of candidate responses has been chosen to exemplify grades C and E for Paper 1,
and A, C and E for Papers 3, 5 and 6. Each response is accompanied by a brief commentary explaining the
strengths and weaknesses of the answers.
Each question paper (candidate script) is graded on the overall mark awarded, not on each question or part
question. It is therefore possible that, on some questions, lower grade candidate scripts are awarded the
same or higher marks than higher grade candidate scripts.
For ease of reference the following format for each paper has been adopted:
Mark scheme
Example candidate
response
Examiner comment
For each question an extract from the mark scheme, as used by examiners, is followed by examples of
marked candidate responses, each with an examiner comment on performance. Comments are given to
indicate where and why marks were awarded, and how additional marks could have been obtained. In this
way, it is possible to understand what candidates have done to gain their marks and what they still have to
do to improve their grades.
Past papers, Examiner Reports and other teacher support materials are available on Teacher Support at
http://teachers.cie.org.uk
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Assessment at a glance
Assessment at a glance
Candidates are awarded grades A*A* to GG.
Candidates expected to achieve grades DD, EE, FF or GG study the core curriculum only and are eligible for
grades CC to GG.
Candidates expected to achieve grades CC or higher should study the core and extended curriculum areas.
All candidates must enter for three papers.
Candidates take:
Paper 1
(45 minutes)
(30% of total marks)
A multiple-choice paper consisting of 40 items of the four-choice type.
and either:
or:
Paper 2
(50% of total marks)
(2 hours)
Core curriculum – Grades C to G available
Paper 3
(50% of total marks)
(2 hours)
Extended curriculum – Grades A* to G available
Core theory paper consisting of short-answer
and structured questions, based on the core
curriculum.
Extended theory paper consisting of shortanswer and structured questions. A quarter
of the marks available will be based on core
material and the remainder on the supplement.
and:
Practical assessment
either:
Paper 4
Coursework
or:
Paper 5
Practical test (2 hours)
or:
Paper 6
Alternative to practical (1 hour)
(20% of total marks)
Teachers are reminded that a full syllabus is available on www.cie.org.uk
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Paper 2 – Core
Paper 2 – Core
Question 1
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
Examiner comments – grade C
(a) (i) The candidate is able to select both of the binary compounds in the list, showing a good
understanding of the term binary. 1/1
(ii) Here the candidate fails to make the connection between tungsten and its symbol. There is only one
formula containing the symbol W. 0/1
(b) The candidate shows a good understanding of basic atomic structure, identifying the positively charged
particles as protons and then, by elimination, identifying the other particles in the nucleus as neutrons.
2/2
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Paper 2 – Core
(c) (i) The candidate makes one satisfactory observation. The appearance of smoke was not accepted. The
candidate needs to focus on observations such as the evolution of a gas or the sodium melting. 1/2
(ii) Here, the candidate makes the connection between reactivity trends within a group in the Periodic Table
and the positions of sodium and potassium within that group. 1/1
(iii) Hydrogen is a correct product gaining one mark. The candidate is not able to use knowledge of the
resulting solution being alkaline and therefore potassium hydroxide being the other product. Few
candidates were able to identify potassium hydroxide as the other product. Potassium oxide was a very
common wrong answer. 1/2
Total mark awarded = 6 out of 9
Example candidate response – grade E
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Paper 2 – Core
Examiner comments – grade E
(a) (i) There are two binary compounds in the list. The candidate is only able to select one of these. The
mark is for both answers. 0/1
(ii) Here the candidate makes the connection between tungsten and its symbol. There is only one
formula containing the symbol W. 1/1
(b) The candidate shows a good understanding of basic atomic structure, identifying the positively charged
particles as protons and then identifying the other particles in the nucleus as neutrons. 2/2
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Paper 2 – Core
(c) (i) The candidate makes two satisfactory observations. 2/2
(ii) The candidate does not answer the question and gives a difference in a physical property rather than
a difference between the reaction of sodium or potassium and water. 0/1
(iii) The candidate is unable to recall any of the products of the reaction. 0/2
Total mark awarded = 5 out of 9
Question 2
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
Examiner comments – grade C
(a) Here the candidate shows a level of competence in handling data and drawing graphs. The candidate
would have scored all four marks if all the lines drawn had been straight. Consequently, only three marks
are awarded. 3/4
(b) The candidate correctly writes a formula for the calculation using words. This is acceptable. It is also
acceptable in questions such as this to omit the left hand side of the formula as it is assumed to speed.
The candidate gains two marks. 2/2
(c) (i) The candidate gains no marks here. The response given is really a repeat of the question. 0/3
(ii) Here, the candidate correctly suggests temperature although higher temperature would have been
a more accurate answer. However, to gain the mark the candidate needs to identify two factors –
lower humidity or wind speed – but is unable to suggest either of these. 0/1
Total mark awarded = 5 out of 10
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Paper 2 – Core
Example candidate response – grade E
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Paper 2 – Core
Examiner comments – grade E
(a) The candidate gains one mark for placing the correct units on each axis. The axes are not labelled
correctly – time is missing. The horizontal axis scale is not linear. It is impossible to ascertain whether
the candidate has correctly positioned the key points on the graph. The candidate does not appreciate
that the lines drawn on the graph should be straight lines. 1/4
(b) The candidate correctly writes the formula for the calculation using suitable symbols. However the
candidate, carelessly perhaps, completes the calculation incorrectly, having correctly substituted values
into the formula. 1/2
(c) (i) The candidate gains one mark for implying that the fast/faster moving water molecules escape. The
candidate does not appear to really grasp what is happening during the process of evaporation. 1/3
(ii) Here, the candidate correctly suggests more heat, although higher temperature would have been
a more accurate answer. However, to gain the mark the candidate needs to identify two factors –
lower humidity or wind speed – but is unable to suggest either. 0/1
Total mark awarded = 3 out of 10
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Paper 2 – Core
Question 3
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
Examiner comments – grade C
(a) One mark is gained by the candidate. The reference to something happening in the body was accepted as a
reference to an enzyme working in living organisms. There is a good definition in the syllabus. 1/2
(b) Although there is a reference to pH 4 and pH 9, there is not a correct description of what is happening at
or beyond these two values. The candidate is unable to identify the pH where there is maximum activity,
suggesting that the candidate was unable to use the data on the graph. 0/2
(c) (i) The candidate is able to translate the information in the question into a curve drawn on the graph. The
graph needs to have a similar shape to the original and peak at pH4 or below. 1/1
(ii) The candidate knows that the pH rises and although this fact isn’t expressed clearly, one mark is
awarded. 1/2
(iii) The terms substrate and product are not understood. The candidate is therefore unable to correctly
identify either of the substances. 0/2
(iv) The candidate suggests that the food molecules are broken down into smaller ones and, although there
is not a clear suggestion that the food molecules are large molecules, the mark was awarded. The
candidate suggests that the digested molecules can pass through the walls of the digestive system,
however, this was not considered sufficiently accurate. 1/2
Total mark awarded = 4 out of 11
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Paper 2 – Core
Example candidate response – grade E
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Paper 2 – Core
Examiner comments – grade E
(a) The candidate’s answer gains no marks. There is a good definition in the syllabus, which would have gained
full marks. 0/2
(b) One mark is awarded for the suggestion that the greatest activity is between pH6 and pH7. 1/2
(c) (i) The candidate is unable to translate the information in the question into a suitable curve drawn on the
graph. The graph needs to have a similar shape to the original and peak at 4 or below. 0/1
(ii) The candidate is unable to make a suitable suggestion in terms of acidity and neutralisation. 0/2
(iii) This answer suggests that the candidate has some idea about the terms substrate and product. However,
the candidate is unable to correctly identify either of the substances. 0/2
(iv) A very vague response is provided which does not correctly answer the question. 0/2
Total mark awarded = 1 out of 11
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Paper 2 – Core
Question 4
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Examiner comments – grade C
(a) A grade C candidate would normally be expected to gain at least one mark here. Although the candidate
does refer to the air molecules, there needs to be a mention of collisions with the tyre wall. More able
candidates would also be able to explain that this means that a force is exerted, which causes the
pressure. 0/2
(b) The candidate explains that a force can change the motion of an object by stating that a force stops an
object. The other two answers are really just definitions of forces. 1/2
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Paper 2 – Core
(c) The candidate knows that the car is decelerating and should then be able to state that force B is greater
than force F. 0/1
(d) Four marks are scored here, showing that the candidate has a fairly good understanding of the ideas.
However, the candidate confuses boiling with burning and therefore is not awarded that mark. 4/5
(e) Apart from the switch symbol, the candidate uses correct symbols to construct a suitable circuit, but
then adds a resistor in a totally impossible place, resulting in the loss of a mark. 3/4
Total mark awarded = 8 out of 14
Example candidate response – grade E
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Paper 2 – Core
Examiner comments – grade E
(a) This is a question on which a grade E candidate would not be expected to score. The candidate’s
answer shows some understanding of the concepts but isn’t close enough to the mark scheme. 0/2
(b) The candidate doesn’t seem to understand the question. 0/2
(c) Again, the candidate does not seem to understand the question. 0/1
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(d) One mark only is scored here. A grade E candidate would normally be expected to score at least two
marks. This shows that the candidate has a poor understanding of the ideas. 1/5
(e) The candidate finds this difficult. Only having one lamp is the major mistake. The decision to draw a
pedal as part of the switch adds to the confusion. 0/4
Total mark awarded = 1 out of 14
Question 5
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
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Paper 2 – Core
Examiner comments – grade C
(a) (i) The clues given on the diagram are enough for the candidate to work out that the process is
cracking. In this instance there was no requirement to specify either thermal or catalytic cracking.
1/1
(ii) The candidate knows a simple definition of the term catalyst but this only gains one mark. For a
second mark, the candidate needs to explain that the catalyst remains unchanged at the end of the
reaction. 1/2
(iii) Although the candidate seems to be aware that the test involves an addition reaction, they have
not described the test stated in the syllabus. Alternative correct positive tests would have been
accepted. 0/2
(b) (i) Good data handling skills are shown here. The candidate uses the data in the table and correctly
describes the trend required. 1/1
(ii) The candidate displays good recall in quoting a relevant use for refinery gas. 1/1
(iii) The question required two ideas. The candidate correctly describes why carbon monoxide is
considered to be a pollutant but does not mention how carbon monoxide is formed in a car engine.
1/2
Total mark awarded = 5 out of 9
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Paper 2 – Core
Example candidate response – grade E
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Paper 2 – Core
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Paper 2 – Core
Examiner comments – grade E
(a) (i) The candidate mentions one of the reactions associated with hydrocarbon chemistry but it is
incorrect. 0/1
(ii) The candidate knows a simple definition of the term catalyst but this only gains one mark. For a
second mark, the candidate needs to explain that the catalyst remains unchanged at the end of the
reaction. 1/2
(iii) The candidate describes a chemical test but not the correct one for an unsaturated hydrocarbon. 0/2
(b) (i) The candidate is unable to describe the trend. The answer given suggests that they have not
understood the question. 0/1
(ii) The candidate displays good recall in quoting a relevant use for refinery gas. However, the answer
given could have been clearer. 1/1
(iii) The question requires two ideas. The candidate does not explain why carbon monoxide is
considered to be a pollutant but does describe simply how carbon monoxide is formed in a car
engine. 1/2
Total mark awarded = 3 out of 9
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Paper 2 – Core
Question 6
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
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Paper 2 – Core
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Paper 2 – Core
Examiner comments – grade C
(a) The candidate is possibly confused by the slightly different layout of the genetic diagram in the question.
There is evidence that the candidate knows the male and female gametes because the last part of the
answer is correct, but has shown them incorrectly earlier on in the answer. 2/3
(b) (i) This part of the question was difficult. The candidate is asked to process data is the form of a
diagram, graph and table and the question then expects them to use this data. The candidate
suggests that the trees make the sand cooler but is unable to make a quantitative comparison using
data from the graph. 1/2
(ii) The answer requires reference to the temperature of the sand and the candidate does not manage
to do this. 0/2
(iii) The candidate’s answer contains a reference to less males being born and also a reference to this
making breeding difficult and therefore gains both marks. 2/2
(c) The candidate suggests drought as an answer and this is given a mark for a reference to the effects of
global warming. 1/2
Total mark awarded = 6 out of 11
Example candidate response – grade E
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Paper 2 – Core
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Paper 2 – Core
Examiner comments – grade E
(a) The candidate is possibly confused by the slightly different layout of the genetic diagram in the question.
The candidate gives an incorrect male genotype and then works through the rest of the question with
this error, so although the final answer clearly contradicts the statement in the question, two marks are
awarded. 2/3
(b) (i) This part of the question was difficult for a grade E candidate. The candidate is asked to process
data is the form of a diagram, graph and table. The question then expects them use this data.
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Paper 2 – Core
The candidate suggests that the trees make the sand cooler but is unable to make a quantitative
comparison using data from the graph. 1/2
(ii) The answer requires reference to the temperature of the sand and the candidate does not manage
this. 0/2
(iii) The candidate’s answer contains a reference to less males being born and also a reference to this
making breeding difficult and therefore gains both marks. 2/2
(c) The candidate suggests that less oxygen will be produced and gains one mark. The candidate also
suggests that the weather conditions would change. This was considered too vague to be a reference to
climate change. There were many other answers, which could have been given, to get a second mark.
1/2
Total mark awarded = 6 out of 11
Question 7
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
Examiner comments – grade C
(a) The candidate does not answer the question. The answer must explain how the two radiations can be
distinguished from each other by their penetrative powers. The candidate attempts to compare beta
radiation with alpha radiation. 0/2
(b) By labelling the wavelength from a mid-point on one wave to a mid-point on the next wave, the
candidate makes it difficult to ascertain whether they know that the wavelength is the distance between
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Paper 2 – Core
identical points on two successive waves. It would have been clearer if the candidate had chosen two
peaks or troughs as the points between which to label a wavelength. 1/2
(c) Few candidates gained full marks here. The candidate correctly gives one result of exposure to alpha
radiation but does not explain that the radiation is ionising radiation. 1/2
Total mark awarded = 2 out of 6
Example candidate response – grade E
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Paper 2 – Core
Examiner comments – grade E
(a) The candidate does not answer the question. The answer must explain how the two radiations can be
distinguished from each other by their penetrative powers. 0/2
(b) It is impossible to tell whether the candidate knows that the wavelength is the distance between
identical points on two successive waves. It would have been clearer if the candidate had chosen to
draw the line showing the wavelength between two peaks or troughs. 1/2
(c) Few candidates gained full marks here. The candidate correctly explains that the radiation is ionising
radiation but is unable to describe how the radiation will affect the body. 1/2
Total mark awarded = 2 out of 6
Question 8
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
Examiner comments – grade C
(a) The candidate knows a suitable method but is unable to explain how it works. 1/2
(b) The question gives an example which the candidate is unable to use in describing differences between a
mixture and a compound. 0/2
(c) (i) The reference to boiling gains one mark but the candidate is unable to explain how the sodium chloride
sample is obtained. 1/2
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Paper 2 – Core
(ii) The reference to hexane being a liquid is sufficient for one mark. However, although the candidate
suggests that filtration needs a solid and a liquid, there is no explanation as to why this is the case.
1/2
(d) (i) A very easy mark is gained for stating that the type of element was a metal. Although the candidate
suggests that all metals are solid, the important fact is that it is the metal oxides which are solid. 1/2
(ii) Although the candidate states an incorrect colour for the indicator, the second marking point is given
as an error carried forward from the incorrect colour. 1/2
Total mark awarded = 5 out of 12
Example candidate response – grade E
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Paper 2 – Core
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Paper 2 – Core
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Paper 2 – Core
Examiner comments – grade E
(a) The candidate knows a suitable method but is unable to explain how it works. 1/2
(b) The question gives an example which the candidate is unable to use in describing differences between
a mixture and a compound. The candidate muddles up ideas about elements, mixtures and compounds.
This is a difficult question for a grade E candidate. 0/2
(c) (i) The reference to evaporation gains one mark but the candidate is unable to explain how the sodium
chloride sample is obtained. 1/2
(ii) This is again a difficult question for a grade E candidate. The candidate is unable to use the
information given to explain why hexane and water cannot be separated by filtration. 0/2
(d) (i) Although the candidate identifies a possible metal, this is not a type of element and so no marks are
awarded. 0/2
(ii) The candidate states a correct colour for the indicator. The candidate is unable to explain correctly
why the colour should be blue. A reference to the basic nature of metal oxides is required. 1/2
Total mark awarded = 3 out of 12
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Paper 2 – Core
Question 9
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
Examiner comments – grade C
(a) Knowledge of photosynthesis is shown as the candidate correctly identifies two products for the
reaction. The idea that light is the other reactant was a common error. 1/2
(b) The candidate knows that structure A is mesophyll but is unable to correctly identify the epidermis.
The response offered suggests that the candidate realises that the structure is on the outside and then
confuses cell structure with plant structure. 1/2
(c) This answer shows an excellent understanding of the role of stomata. The candidate gains both marks
at the start of the answer and then quotes the third marking point as well. 2/2
(d) There is further evidence here that the candidate knows the basics of plant biology. 1/1
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Paper 2 – Core
(e) The candidate again uses the information in the question and a knowledge of plant biology to correctly
identify the reason for less stomata. 1/1
(f) This question requires not only knowledge but the ability to solve problems by using the information
given. The candidate does not identify the significance of photosynthesis requiring access to the air. 0/2
(g) The candidate’s answer does not include the syllabus statement referring to the function of magnesium
ions – chlorophyll synthesis. 0/1
Total mark awarded = 6 out of 11
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Paper 2 – Core
Example candidate response – grade E
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Paper 2 – Core
Examiner comments – grade E
(a) Knowledge of photosynthesis is shown as the candidate correctly identifies one reactant and one
product for the reaction. The idea that light is the other reactant or product was a common error. One
mark is awarded for the correct reactant. 1/2
(b) The candidate knows that structure A contains the chloroplasts but is unable to identify the palisade
layer. The candidate is unable to correctly identify the epidermis. The response offered suggests that
the candidate realises that the structure is on the outside and then confuses cell structure with plant
structure. 0/2
(c) Although the candidate is unable to identify either of the gases entering or leaving the leaf, there is a
reference to diffusion and one mark is scored. 1/2
(d) Evaporation was a very common wrong answer here. 0/1
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(e) The candidate again uses the information in the question and knowledge of plant biology to correctly
identify the reason for less stomata. 1/1
(f) This is a high level question requiring not only knowledge but the ability to solve problems by using the
information given. The candidate does not identify the significance of photosynthesis requiring access to
the air. Very few candidates were able to explain this correctly. 0/2
(g) The candidate’s answer does not include the syllabus statement referring to the function of magnesium
ions – chlorophyll synthesis. 0/1
Total mark awarded = 3 out of 11
Question 10
Mark scheme
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Paper 2 – Core
Example candidate response – grade C
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Paper 2 – Core
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Examiner comment – grade C
(a) The question was designed to allow the candidates to show what they knew about waves and there were
many possible answers.
The candidate shows in the first answer a very common problem, where the candidate describes
something which one of the waves does or is, but does not describe anything about the other wave.
However, the mark was awarded in this instance.
The other two answers given are either inaccurate or vague. In this instance a mark was awarded for the
reference to sound waves not being able to travel through a vacuum. 2/3
(b) The mark scheme for this question was very generous. The candidate correctly links up two radiations and
their uses and is awarded two marks. 2/3
(c) The candidate correctly writes the formula for the calculation using suitable symbols and is able to
substitute the correct values into the formula and calculate the correct answer. This shows good data
handling and numeracy skills. 2/2
(d) Again, the candidate correctly writes the formula for the calculation using suitable symbols and is able
to substitute the correct values into the formula and calculate the correct answer, showing good data
handling and numeracy skills. 2/2
Total mark awarded = 8 out of 10
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Example candidate response – grade E
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Paper 2 – Core
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Paper 2 – Core
Examiner comment – grade E
(a) The question was designed to allow candidates to show what they knew about waves and there were
many possible answers. It was also a question which a grade E candidate would find difficult.
The candidate has tried to compare the waves, but all the answers given are either inaccurate or vague,
so no marks are awarded. 0/3
(b) The mark scheme for this question was very generous. However, the candidate is unable to link any
radiation to its use. 0/3
(c) The candidate correctly writes the formula for the calculation using suitable symbols, and is able to
substitute the correct values into the formula and calculate the correct answer. This shows good data
handling and numeracy skills. 2/2
(d) Again, the candidate correctly writes the formula for the calculation using suitable symbols. The
candidate is able to substitute the correct values into the formula and calculate the correct answer, again
showing good data handling and numeracy skills. 2/2
Total mark awarded = 4 out of 10
Question 11
Mark scheme
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Example candidate response – grade C
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Paper 2 – Core
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Examiner comment – grade C
(a) (i) The candidate knows that potassium hydroxide solution is an alkali and knows therefore that it must
be potassium hydroxide and hydrochloric acid which react in a neutralisation reaction. 1/1
(ii) Again, the candidate shows a good knowledge of basic chemistry and explains that an endothermic
reaction is one in which the temperature of the reaction mixture decreases. 1/1
(iii) A grade C candidate should be able to identify trends or patterns in given information. The candidate
does this by using the data in the table to infer that there was no reaction. 1/1
(b) Here the candidate shows that the effect of surface area on the rate of a reaction is known, but is
unable to gain a second mark because there is no mention of the fact that the candidate identified the
experiment because the rate of reaction was greater. 1/2
(c) (i) Although the candidate identifies the wrong gas, one mark is awarded for describing the correct
chemical test to identify ammonia. 1/2
(ii) More able candidates should be able to describe the correct procedures for a multi-stage
experiment. The candidate does not do this and is only able to gain one mark for an implication that
the copper is left behind and therefore has not reacted. 1/3
Total mark awarded = 6 out of 10
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Example candidate response – grade E
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Paper 2 – Core
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Examiner comment – grade E
(a) (i) The candidate is unable to identify the correct experiment or explain why. 0/1
(ii) The candidate knows what an endothermic reaction is but identifies the wrong experiment. 0/1
(iii) The candidate correctly explains that there is no temperature change because no reaction takes
place. 1/1
(b) The candidate correctly identifies experiment 5 and goes on to make a vague reference to the rate of
reaction increasing. This gains one mark. An explanation about increased surface area is needed for the
second mark. 1/2
(c) (i) The candidate identifies the correct gas, but is unable to quote the correct chemical test to identify
it. One mark is awarded. 1/2
(ii) Less able candidates may find it difficult to describe the correct procedures for a multi-stage
experiment. The candidate describes a sequence of procedures but it is incorrect and so no marks
are scored. 0/3
Total mark awarded = 3 out of 10
Question 12
Mark scheme
66
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 2 – Core
Example candidate response – grade C
Examiner comment – grade C
(a) The candidate is awarded the mark for appreciating that nutrients are broken down, but is unable to gain
the mark for suggesting that respiration releases energy. 1/2
(b) Very few candidates gained full marks here. Many candidates made the question more complex than it
really was by attempting to make both columns add up to exactly 100%.
Marks were awarded for the values in each row being within a fairly narrow range. The candidate
manages to do this easily. 3/3
(c) The candidate gains one mark for the idea that the oxygen is carried in the red blood cells, but is unable
to expand on this and describe the mechanism involving haemoglobin. 1/2
Total mark awarded = 5 out of 7
Cambridge IGCSE Co-ordinated Sciences 0654
67
Paper 2 – Core
Example candidate response – grade E
Examiner comment – grade E
(a) The candidate confuses respiration with photosynthesis and consequently gains no marks. 0/2
(b) Marks were awarded for the values in each row being within a fairly narrow range. The candidate is
unable to do this. The values given suggest that the candidate has not experienced a question like this
before. 0/3
(c) The candidate gains one mark for the idea that the oxygen is carried in the red blood cells, but is unable
to expand on this and explain the mechanism involving haemoglobin. Candidates should be discouraged
from using abbreviations such as RBC. 1/2
Total mark awarded = 1 out of 7
68
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Paper 3 – Extended
Question 1
Mark scheme
Cambridge IGCSE Co-ordinated Sciences 0654
69
Paper 3 – Extended
Example candidate response – grade A
70
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
71
Paper 3 – Extended
Examiner comment – grade A
(a) (i) The candidate stated the formula for kinetic energy and correctly substituted the square of the
velocity. They realised that the total mass of the train was required and showed how this was
obtained in the working. The sum might have been placed in brackets to avoid ambiguity. The final
calculation was correct and units were included. 2/2
(ii) The formula for work was stated but the candidate failed to realise that distance must be converted
to metres in the unit system. Otherwise the calculation and unit of work were correct. 1/2
(iii) The formula for power was stated and the candidate realised that the power output was related to
the work done exerting the whole driving force, rather than just the work done in accelerating the
train. The work calculated in (ii) was correctly carried forward. The unit of time was inconsistent
with the watt, the candidate failing to convert 5 minutes into 300 seconds. Otherwise the calculation
and units of power were correct. 1/2
(b) (i) The candidate realised that the total energy of 1 kg of water did not change as it fell, so that its
maximum kinetic energy was 300 J. The statement of the law of conservation of energy was
sufficient explanation. 1/1
(ii) The formula for temperature change was stated in words and symbols, with change in temperature
correctly shown as ∆T rather than T. Substitution into the formula was correct and working was
shown with appropriate units. 3/3
Total mark awarded = 8 out of 10
72
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade C
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73
Paper 3 – Extended
74
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade C
(a) (i) The candidate stated the formula for kinetic energy and correctly substituted the square of the velocity.
They realised that the total mass of the train was required but did not show how this was obtained in the
working. The final calculation was correct but units were omitted. 1/2
(ii) The formula for work was stated but the candidate failed to realise that distance must be converted to
metres in the unit system. Otherwise the calculation and unit of work were correct. 1/2
(iii) The formula suggested some confusion between power and work done. The calculation process and
unit of power were correct, with the result for the work done in (ii) carried forward, but the time was not
converted from minutes to seconds. 0/2
(b) (i) The candidate realised that the total energy of 1 kg of water did not change so that its maximum kinetic
energy was 300 J. The statement that energy was neither lost nor gained showed an understanding of
the principle of conservation of energy. 1/1
(ii) The formula for energy transferred in terms of temperature change was stated correctly. The formula was
not rearranged for change in temperature as subject, which led to an incorrect substitution. 1/3
Total mark awarded = 4 out of 10
Cambridge IGCSE Co-ordinated Sciences 0654
75
Paper 3 – Extended
Example candidate response – grade E
76
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Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
77
Paper 3 – Extended
Examiner comment – grade E
(a) (i) The formula for kinetic energy was incorrect, with the power of 2 omitted. The mass substituted
was that of the engine and trucks without their load, rather than that of the whole train. The value of
the mass of the load was used as the velocity instead of 0.5 m/s stated in the stem of the question.
The calculation based on these figures was correct but the joule was not given as the unit of energy.
0/2
(ii) The formula for work was stated but the candidate failed to realise that distance must be converted
to metres in the unit system. The joule was not given as the unit of work. 1/2
(iii) The formula suggested the concept of power was not understood. Minutes were not converted to
seconds. The unit of power was incorrect but was consistent with the formula used. 0/2
(b) (i) The candidate realised that the total energy of 1 kg of water did not change so that its maximum
kinetic energy was 300 J. The statement that the energy at the top was the same as the energy at
the bottom did not add information to the statement of the maximum amount of kinetic energy. The
fact that energy was not lost or gained would have completed the explanation. 0/1
(ii) Omission of the subject of a formula is only acceptable where it is the quantity required. In this case
‘energy’ was omitted and ‘temperature’ used instead of ‘change in temperature’. The relationship
with mass was incorrect. 0/3
Total mark awarded = 1 out of 10
Question 2
Mark scheme
78
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade A
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79
Paper 3 – Extended
80
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade A
(a) (i) The bonding diagram of a nitrogen molecule clearly showed three shared pairs of electrons and one
lone pair on both atoms. 2/2
(ii) The diagram showed all the electrons in a nitride ion in two shells with the 2, 8 configuration. In
this case it was not necessary to distinguish between electrons originating from the nitrogen atom
and those from the magnesium, and the charge on the ion is given in the question, although this
information was included correctly by the candidate. 1/1
(iii) The candidate did state that a nitride ion contains three more electrons than protons, but without
including a statement of the charge on a proton and an electron the explanation was incomplete. 1/2
(iv) The formula for magnesium nitride was correct. The working used in the deduction of the formula
was shown with a statement of the principle of charge balance in the compound. This was sufficient
for full marks. The additional explanation in terms of numbers of magnesium and nitride ions would
have been better expressed as a ratio. 2/2
(b) (i) The gaseous element forming at the anode was correctly suggested to be chlorine. 1/1
(ii) The gas forming at the cathode in this cell was correctly suggested to be hydrogen. The description
of the test for the gas required the use of a burning splint rather than a glowing splint. 1/2
Total mark awarded = 8 out of 10
Cambridge IGCSE Co-ordinated Sciences 0654
81
Paper 3 – Extended
Example candidate response – grade C
82
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Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
83
Paper 3 – Extended
Examiner comment – grade C
(a) (i) The bonding diagram of a nitrogen molecule clearly showed three shared pairs of electrons and one lone
pair on both atoms. The origin of the outer electrons was indicated by dots and crosses although this
information was not required for full marks in this question. 2/2
(ii) The question required a diagram which showed all the electrons in a nitride ion, but this candidate
showed only the outer electrons. 0/1
(iii) The candidate knew that gaining electrons caused the ion to have a charge of 3 – , but neither compared
the number of electrons with the number of protons, nor made a statement of the charges on protons
and electrons. Hence the explanation was incomplete. 0/2
(iv) The formula for magnesium nitride was correct. Although the technique of ‘crossing valences’ could
have been used as a tool, it should not have been regarded as an explanation of how the chemical
formula was deduced, as it did not involve the need for charge balance. 1/2
(b) (i) It was necessary to specify chlorine as the halogen formed at the anode. 0/1
(ii) The candidate did not realise that hydrogen, rather than chlorine, was formed at the anode when
aqueous magnesium chloride was substituted for the molten salt. Nevertheless, credit was given for
knowing the test for chlorine. 1/2
Total mark awarded = 4 out of 10
84
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Paper 3 – Extended
Example candidate response – grade E
Cambridge IGCSE Co-ordinated Sciences 0654
85
Paper 3 – Extended
86
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Paper 3 – Extended
Examiner comment – grade E
(a) (i) Although this candidate appreciated the need for a shared, bonding pair of electrons in a covalent
molecule, extra electrons were introduced into the system. 0/2
(ii) The diagram showed all the electrons in a nitride ion in two shells with the 2, 8 configuration. 1/1
(iii) The candidate attempted to explain why the nitride ion was formed rather than why it carried a
charge. 0/2
(iv) The candidate seems to have confused the term ‘chemical formula’ with ‘chemical equation’. 0/2
(b) (i) By suggesting the formation of carbon dioxide, the candidate has perhaps assumed that the gas is
produced by oxidation of the carbon electrode rather than electrolysis of the magnesium chloride.
0/1
(ii) While incorrectly stating that oxygen was formed at the cathode during the electrolysis of aqueous
magnesium chloride, the candidate suggested an inconsistent test for this gas. 0/2
Total mark awarded = 1 out of 10
Question 3
Mark scheme
Cambridge IGCSE Co-ordinated Sciences 0654
87
Paper 3 – Extended
Example candidate response – grade A
88
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade A
(a) The root hair cell was correctly labelled. 1/1
(b) (i) This candidate correctly explained the absorption of water by root hair cells in terms of osmosis
across a partially permeable membrane. The cause of this process was given as the greater
concentration of water in the soil than in the cell, which would be sufficient to imply movement
down a water potential gradient. 2/2
(ii) Another function of root hair cells was stated correctly as the absorption of mineral salts. 1/1
(iii) The adaptation of root hair cells was explained correctly in terms of a large surface area having
maximum absorption. 2/2
(c) (i) The tissue responsible for transport of the coloured water was correctly named as the xylem. 1/1
(ii) The xylem was clearly labelled. 1/1
(iii) This answer implied that only water evaporated from the plant, but it could have been expanded to
explain the process on a molecular level, and differentiating between the behaviour of a mixture and
a compound. 1/2
Total mark awarded = 9 out of 10
Cambridge IGCSE Co-ordinated Sciences 0654
89
Paper 3 – Extended
Example candidate response – grade C
90
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade C
(a) The root hair cell was correctly labelled. 1/1
(b) (i) This candidate attempted to describe the adaptation that enabled absorption to occur, rather than to
explain the process. 0/2
(ii) Another function of root hair cells was stated correctly as the absorption of minerals. 1/1
(iii) Describing the dimensions of the root did not explain the adaptation of the root hair cell. Helping to
ease the absorption of water was too vague to imply absorption of water in greater amounts or at a
greater rate. 0/2
(c) (i) The tissue responsible for transport of the coloured water was correctly named as the xylem. 1/1
(ii) The xylem was correctly labelled, although difficult to read. It is recommended that diagrams and
figures are labelled on the outside with a line to the target. 1/1
(iii) Reference to ‘transpiration’ and ‘water vapour’ was sufficient to imply that water evaporated and the
dye did not. Further explanation at the molecular level was missing. 1/2
Total mark awarded = 5 out of 10
Cambridge IGCSE Co-ordinated Sciences 0654
91
Paper 3 – Extended
Example candidate response – grade E
92
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Paper 3 – Extended
Examiner comment – grade E
(a) The root hair cell was correctly labelled. 1/1
(b) (i) The description of the distribution of root hair cells was not sufficient to explain the absorption process.
0/2
(ii) “To hold the plant into the soil” is a function of the whole root rather than another function of root hair
cells. 0/1
(iii) The comment on the number of root hair cells did not provide information about how the cells
themselves were adapted. 0/2
(c) (i) The tissue responsible for transport of the coloured water was correctly named as the xylem. 1/1
(ii) The xylem was incorrectly labelled. 0/1
(iii) This explanation in terms of the escape of water vapour was sufficient to imply that only water
evaporated from the plant. There was no comparison of water and dye in terms of the behaviour of
their molecules. 1/2
Total mark awarded = 3 out of 10
Cambridge IGCSE Co-ordinated Sciences 0654
93
Paper 3 – Extended
Question 4
Mark scheme
94
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade A
Cambridge IGCSE Co-ordinated Sciences 0654
95
Paper 3 – Extended
96
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade A
(a) (i) The meanings of frequency and wavelength were stated accurately. The wavelength definition was
supported by a clear diagram. 2/2
(ii) The formula for wave speed was given using standard symbols. The working showed the correct
substitution leading to the correct answer with appropriate units. Where there was a discrepancy
between the result of a calculation and the answer line, the latter was usually taken as the intended
answer. Hence, in this case the candidate was given the benefit of the doubt. 2/2
(iii) This question required an explanation of the terms ‘compression’ and ‘rarefaction’. The response
added nothing to the information supplied. 0/2
(b) (i) The normal was drawn. The angles of incidence and rarefaction made between the ray and the
normal were correctly identified. 2/2
(ii) Although of the same magnitude, the angle of incidence was incorrectly labelled as the angle of
reflection. 0/1
(iii) Fibre optic cable was rightly given as a use of total internal reflection, and “carry information” was a
description of that use. 2/2
Total mark awarded = 8 out of 11
Cambridge IGCSE Co-ordinated Sciences 0654
97
Paper 3 – Extended
Example candidate response – grade C
98
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Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
99
Paper 3 – Extended
Examiner comment – grade C
(a) (i) The effect of frequency on the perception of sound did not constitute a meaning of the term. The
definition of wavelength given did not add to the understanding of the meaning of the word. 0/2
(ii) The formula for wave speed was given using standard symbols. The value of frequency was
incorrectly substituted which resulted in an incorrect answer. The units would have been
appropriate. 1/2
(iii) The reference to air ‘particles’ themselves being compressed was inaccurate, but their separation
did provide a meaning of the word rarefaction. 1/2
(b) (i) The normal was not drawn so it was not possible to identify the angles of incidence and refraction.
0/2
(ii) Again this candidate did not recognise that the angle of reflection should have been measured with
reference to the normal to the surface. 0/1
(iii) A reflective road sign was an appropriate example of the use of total internal reflection, but there
was no attempt to describe how the sign was used to reflect light from headlamps back to the
driver. 1/2
Total mark awarded = 3 out of 11
100
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Paper 3 – Extended
Example candidate response – grade E
Cambridge IGCSE Co-ordinated Sciences 0654
101
Paper 3 – Extended
102
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade E
(a) (i) The relationship between frequency and pitch did not constitute a meaning of the term frequency.
The candidate appeared to confuse the terms ‘wavelength’ and ‘reverberation time’. 1/2
(ii) It was acceptable to provide the formula for speed of sound in words. The frequency was
substituted in kilohertz, which could have yielded the correct answer had it been given in units of
kilometres per second. 0/2
(iii) The candidate realised that compression was related to pressure but no further information was
supplied. 0/2
(b) (i) It was not evident that the angles of incidence and refraction should be measured with reference to
the normal to the surface. 0/2
(ii) The label did not show that the angle of reflection was that made between the reflected ray and the
normal. 0/1
(iii) By suggesting a mirror as a possible use, the candidate did not appreciate the special features of
total internal reflection. 0/2
Total mark awarded = 1 out of 11
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103
Paper 3 – Extended
Question 5
Mark scheme
104
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade A
Cambridge IGCSE Co-ordinated Sciences 0654
105
Paper 3 – Extended
106
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
107
Paper 3 – Extended
Examiner comment – grade A
(a) This candidate explained how marmots used food to help keep their body temperature constant by
referring to the use of oxygen in respiration, releasing energy. The answer would have been complete if
the involvement of glucose had been included. 3/3
(b) (i) This candidate acknowledged the requirement to eat a lot of food, but did not explain that the
excess carbohydrate not used immediately was converted to fat. 1/2
(ii) The relationship between body mass and chance of surviving was described, but the reducing effect
at higher masses was not mentioned. Numerical data might have been taken from the graph to
support the statement, which could have taken the form of simply comparing the chances at low
and high body masses. 1/2
(iii) Recognising that fat was an insulator was sufficient to explain how heat transfer was reduced by
poor conduction. 1/1
(c) The candidate explained that deforestation meant that there were fewer trees to absorb carbon dioxide.
Reference to excess amounts of the gas suggested that human activities caused the addition of carbon
dioxide to the atmosphere, but the importance of methane was not mentioned. The opportunity to
describe the mechanism of global warming in terms of the effect of greenhouse gases on radiation was
not taken. 2/3
(d) (i) The concept of a general trend was understood, and the increase in body mass was identified. 1/1
(ii) The candidate realised that less mass was lost by using less body fat during shorter winters. 1/1
Total mark awarded = 10 out of 13
108
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Paper 3 – Extended
Example candidate response – grade C
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109
Paper 3 – Extended
110
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
111
Paper 3 – Extended
Examiner comment – grade C
(a) This candidate stated that chemical energy stored in food was converted to heat energy, but did not
explain how respiration was involved in this process. 1/3
(b) (i) The candidate acknowledged the requirement to eat a lot of food, but did not attempt to explain
how fat stores were created by conversion of excess carbohydrate. That marmots could consciously
avoid exercise was a common misconception. 1/2
(ii) A simple statement of the relationship between body mass and chance of surviving was described,
but the trend at higher masses was not mentioned. 1/2
(iii) Describing the layer of fat as a barrier did not make use of appropriate scientific terms such as
conduction or insulation. 0/1
(c) Deforestation was identified as contributing to global warming, as there were fewer trees to absorb
carbon dioxide, but the response did not explain that human activities caused the addition of carbon
dioxide to the atmosphere. 1/3
(d) (i) The candidate differentiated between a general trend and annual variations, and the increase in body
mass with time was identified. 1/1
(ii) It was stated that marmots ate more in the spring following a shorter winter, but the cause in terms
of more time for feeding or more food being available was not identified. 0/1
Total mark awarded = 5 out of 13
112
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade E
Cambridge IGCSE Co-ordinated Sciences 0654
113
Paper 3 – Extended
114
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Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
115
Paper 3 – Extended
Examiner comment – grade E
(a) The candidate described how the fat store helped to keep the body temperature constant, rather than
chemical energy in food being transferred as heat through the process of respiration. 0/3
(b) (i) The answer suggested a result of not eating rather than how a fat store was built. 0/2
(ii) The relationship between body mass and chance of surviving was described, but the decreasing
effect at higher masses was not included. 1/2
(iii) The insulating property of fat was recognised. 1/1
(c) The role of the addition of carbon dioxide and methane was not stated. The inclusion of CFCs suggested
the common misconception that ozone depletion was responsible for global warming. Although the
cutting down of trees was given as a contributory activity, the reduction in the rate of carbon dioxide
removal was not mentioned. 0/3
(d) (i) The general trend was given as an increasing body mass. 1/1
(ii) It was recognised that marmots ate more in the spring following a shorter winter, but the cause was
not identified. 0/1
Total mark awarded = 3 out of 13
Question 6
Mark scheme
116
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade A
Cambridge IGCSE Co-ordinated Sciences 0654
117
Paper 3 – Extended
118
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade A
(a) The two variables that needed to be kept the same were temperature and surface area of the
magnesium. Keeping the size of the magnesium constant was sufficient to imply constant surface area.
1/1
(b) (i) That “the volume of gas collected increased faster” and the “reaction finished before” were both
equivalent to stating that it was experiment B that had the greater rate of reaction and so must have
used acid with the higher concentration. 1/1
Cambridge IGCSE Co-ordinated Sciences 0654
119
Paper 3 – Extended
(ii) The values of maximum volume of gas collected and minimum time taken were read accurately from
the graph and recorded using the correct units. The values were substituted into the formula and the
rate was quoted in units consistent with those values. 3/3
(c) (i) The symbol (aq) was correctly recognised as standing for dissolved in water. 1/1
(ii) The working showed the value of one mole of magnesium atoms, with the correct method of
calculating the number of moles in 6.0 g. 2/2
Total mark awarded = 8 out of 8
Example candidate response – grade C
120
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Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
121
Paper 3 – Extended
Examiner comment – grade C
(a) The only variables that needed to be kept constant were temperature and surface area of magnesium.
“The mass (amount) of magnesium” was taken to imply constant surface area. 1/1
(b) (i) Experiment B was correctly identified as having the greater rate of reaction and therefore using acid
with the higher concentration. 1/1
(ii) Only the substituted formula and the calculation were shown. The values of volume of gas and
time taken, as read from the graph, with their units, as well as the units of rate of reaction, were all
missing from the response. 1/3
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Paper 3 – Extended
(c) (i) It was recognised that ‘(aq)’ implied that the material was in solution, but omitted to specify the
nature of the aqueous solvent. 0/1
(ii) Credit was given for showing the value of one mole of magnesium atoms, but this information was
used incorrectly in the calculation. 1/2
Total mark awarded = 4 out of 8
Example candidate response – grade E
Cambridge IGCSE Co-ordinated Sciences 0654
123
Paper 3 – Extended
124
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade E
(a) The only variables that needed to be kept constant were temperature and surface area of magnesium.
While ‘mass of magnesium’ would have been taken to imply an increased surface area, “amount” was
considered to be too vague. Any effect of changing the equipment would be minimal. 0/1
(b) (i) Although the explanation of which experiment used acid with the higher concentration was
satisfactory, it was inconsistent with the identification of the correct experiment. 0/1
Cambridge IGCSE Co-ordinated Sciences 0654
125
Paper 3 – Extended
(ii) This question required a statement of the values of volume of gas and time taken obtained from the
graph, with their units, and the consistent units of rate of reaction. Only the substituted formula and
the calculation were shown. 1/3
(c) (i) The symbol ‘(aq)’ was taken to mean liquid, which is not the same as aqueous solution. 0/1
(ii) There was no useful information in this response. 0/2
Total mark awarded = 1 out of 8
Question 7
Mark scheme
126
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade A
Cambridge IGCSE Co-ordinated Sciences 0654
127
Paper 3 – Extended
Examiner comment – grade A
(a) Benefit of the doubt was given, assuming ‘split up’ referred to the fission of nuclei. 1/1
(b) (i) A beta particle was correctly described as an electron. 1/1
128
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Paper 3 – Extended
(ii) The candidate did know that loss of one negatively charged particle from a nucleus resulted in an
increase of one in the number of protons, but incorrectly suggested the neutron number decreased
by two. 1/2
(iii) The change in the neutral atom was described as ionisation but there was no explanation referring to
the loss of an electron from outside the nucleus. 1/2
(c) (i) The count rate for source X after 10 hours was accurately read from the graph. Credit was allowed
for a value without units on this occasion. 1/1
(ii) The source with the shortest half-life was correctly identified. 1/1
Total mark awarded = 6 out of 8
Cambridge IGCSE Co-ordinated Sciences 0654
129
Paper 3 – Extended
Example candidate response – grade C
130
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Paper 3 – Extended
Examiner comment – grade C
(a) Nuclear fission was correctly described as the splitting of nuclei. 1/1
(b) (i) The candidate knew that a beta particle had a negative charge, but did not identify it as an electron.
0/1
(ii) By halving the numbers of neutrons and protons, this candidate may have confused beta decay with
a simple view of nuclear fission. 0/2
(iii) The response suggested an incorrect assumption that a beta particle was captured by the neutral
atom. 0/2
(c) (i) The count rate for source X after 10 hours was accurately read from the graph. Credit was allowed
for a value without units on this occasion. 1/1
Cambridge IGCSE Co-ordinated Sciences 0654
131
Paper 3 – Extended
(ii) The source with the shortest half-life was correctly identified. 1/1
Total mark awarded = 3 out of 8
Example candidate response – grade E
132
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Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
133
Paper 3 – Extended
Examiner comment – grade E
(a) Use of the word “separate” implied movement of nuclei away from each other rather than individual
nuclei splitting into smaller entities. 0/1
(b) (i) “Radiation” was too vague a term to be used as a description of beta particles. 0/1
(ii) By halving the numbers of neutrons and protons, this candidate may have confused beta decay with
a simple view of nuclear fission. 0/2
(iii) This response inferred incorrectly that the beta particle had a positive charge and was captured by
the neutral atom. It suggested a misconception that the collision brought about a nuclear event,
rather than affecting external electrons. 0/2
(c) (i) The count rate for source X after 10 hours was accurately read from the graph. Credit was allowed
for a value without units on this occasion. 1/1
(ii) The choice of source Y as that having the shortest half-life indicated a lack of understanding of the
term. 0/1
Total mark awarded = 1 out of 8
Question 8
Mark scheme
134
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Example candidate response – grade A
Cambridge IGCSE Co-ordinated Sciences 0654
135
Paper 3 – Extended
136
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 3 – Extended
Examiner comment – grade A
(a) (i) The candidate successfully used the electronic structures to state the group numbers of the
elements, explaining the role of the number of outer electrons in their determination. 2/2
(ii) The least reactive element was identified and correct reference made to its full outer shells. 1/1
(iii) The good conductor was identified using knowledge that electrical conduction was a property of
metals. 1/1
(b) (i) The candidate knew that it was the calcium carbonate in limestone that was added to a modern
blast furnace to remove impurities. Benefit of the doubt was allowed by assuming that “silicon
impurities” referred to a silicon compound and knowledge of the nature of the impurity was not
required. 2/2
(ii) Carbon monoxide was correctly named as the reacting gaseous oxide of carbon. It was not realised
that a chemical equation should contain only chemical elements and compounds, as the other
reactant was given as iron ore instead of iron oxide. The products of the reaction were correct. 1/2
(c) (ii) The effect of sacrificial protection was given as zinc being oxidised instead of steel. This was
allowed, taking ‘oxidised’ to be a colloquial alternative to ‘corroded’. The higher position of zinc in
the reactivity (series) was stated, and the comparison with iron supported by reference to electron
transfer. 2/2
Total mark awarded = 9 out of 10
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137
Paper 3 – Extended
Example candidate response – grade C
138
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Paper 3 – Extended
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139
Paper 3 – Extended
Examiner comment – grade C
(a) (i) The role of electrons in outer shells in determining Periodic Table group numbers was described.
In this examination it was a requirement that candidates adhered to the practice of using zero as
the group number for noble gases, consistent with the version of the Periodic Table printed in the
question paper. 1/2
(ii) The least reactive element was identified and correct reference made to its full outer shells. 1/1
(iii) The good conductor was not identified correctly, the candidate being under the misapprehension
that elements which were good conductors of electricity had atoms with outer shells a few
electrons short of completion. 0/1
(b) (i) Carbon was identified as the additional raw material used in a modern blast furnace, even though it
had been listed in the description of charcoal in the shaft furnace. 0/2
(ii) The compound in iron ore was correctly written in the equation as iron oxide, but the gaseous oxide
of carbon was not specified as its monoxide. The product was given as iron but the carbon dioxide
bi-product was missing from the right hand side of the equation. 0/2
(c) (ii) It was felt that ‘absorption’ of water by zinc did not imply reaction, and there was no comparison
with the reactivity of the iron in steel. Although prevention of rusting of steel was mentioned, the
sacrificial corrosion of zinc was not described. 0/2
Total mark awarded = 2 out of 10
140
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Paper 3 – Extended
Example candidate response – grade E
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141
Paper 3 – Extended
142
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Paper 3 – Extended
Examiner comment – grade E
(a) (i) The role of the outer shell in the electronic structure in determining Periodic Table group numbers
of elements was stated. In this examination it was a requirement that candidates adhered to the
practice of using zero as the group number for noble gases, consistent with the version of the
Periodic Table printed in the question paper. 1/2
(ii) The least reactive element was not correctly identified, and an explanation in terms of speed of
reaction simply repeated the question. 0/1
(iii) The good conductor of electricity was not correctly identified, caused by the misconception shown
by an attempted explanation describing neon as a metal. 0/1
(b) (i) Coal was identified as another raw material used in a modern blast furnace. Credit was not given
as it was felt that coal (in the form of coke) is an alternative, rather than another raw material.
Limestone was the expected response as there was no material in the shaft furnace that would
remove impurities. 0/2
(ii) The reacting gaseous oxide of carbon was not identified. With iron and iron oxide on the wrong side
of the equation, this candidate seemed unaware of the convention of writing chemical equations in
the form: reactants → products. 0/2
(c) (ii) The purpose of the zinc application in the prevention of the rusting of steel was stated, but the
sacrificial corrosion of zinc was not mentioned. No explanation in terms of the differing reactivity of
zinc and iron was attempted. 0/2
Total mark awarded = 1 out of 10
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143
Paper 3 – Extended
Question 9
Mark scheme
144
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Paper 3 – Extended
Example candidate response – grade A
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145
Paper 3 – Extended
Examiner comment – grade A
(a) This candidate could recall an excellent definition of a hormone, aware of its chemical nature, travelling
in the bloodstream, released by glands and reaching target organs. 3/3
(b) (i) There was confusion between the target organ and the site of production when the liver was named
as the gland that produced insulin and glucagon. 0/1
(ii) It was known that glucose was converted to glycogen, but the liver was not named as the site of
this process. 1/2
(c) The candidate matched the effects of adrenaline with explanations of how it helped. Increased heart
rate was linked with the supply to the body of more oxygen, and increased conversion of glycogen to
glucose was linked to respiration and the release of energy. 4/4
Total mark awarded = 8 out of 10
146
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Paper 3 – Extended
Example candidate response – grade C
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147
Paper 3 – Extended
Examiner comment – grade C
(a) This candidate gave an example of the function of a named hormone which was not required, and
attempted a rather vague general definition. 0/3
(b) (i) The gland that produced insulin and glucagon was correctly identified as the pancreas. 1/1
(ii) The candidate was aware of the role of glycogen as a means of glucose storage, but the ‘breaking
down’ of glucose was a contradiction. 0/2
(c) ‘The heart beating faster’ was a correct effect of adrenaline, but ‘more blood being pumped around the
body’ did not explain how it helped. Faster breathing was regarded as a secondary effect. 1/4
Total mark awarded = 2 out of 10
148
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Paper 3 – Extended
Example candidate response – grade E
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149
Paper 3 – Extended
Examiner comment – grade E
(a) The definition did not make it clear that a hormone was a chemical substance, and its effect on a target
organ was too vague. 0/3
(b) (i) The gland that produced insulin and glucagon was correctly identified as the pancreas. 1/1
(ii) The answer to how insulin helped lower glucose concentration simply restated the question. 0/2
(c) The source of the “boost of energy” was not made clear. The emotional changes suggested were
secondary effects. 0/4
Total mark awarded = 1 out of 10
Question 10
Mark scheme
150
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Paper 3 – Extended
Example candidate response – grade A
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151
Paper 3 – Extended
152
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Paper 3 – Extended
Examiner comment – grade A
(a) (i) The circuit diagram was carefully drawn with the conventional symbols for ammeter and voltmeter
in a workable circuit. A means of varying the potential difference across the lamp, such as a variable
resistance or variable power supply, was omitted. 2/3
(ii) The Ohm’s Law formula for resistance was quoted and the correct working shown to calculate the
resistance of the lamp with appropriate units. 2/2
(b) (i) Wire D was correctly identified as having a greater resistance than wire B due to its being longer.
1/1
(ii) Wire A was correctly identified as having a greater resistance than wire E due to its being thinner.
1/1
(iii) The resistance of wire C was quoted correctly as twice that of wire A because it was double the
length. The resistance of wire E was quoted incorrectly as four times that of wire A. The assumption
was that resistance was directly proportional to the square of cross-sectional area rather than being
inversely proportional. 1/2
Total mark awarded = 7 out of 9
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153
Paper 3 – Extended
Example candidate response – grade C
154
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Paper 3 – Extended
Cambridge IGCSE Co-ordinated Sciences 0654
155
Paper 3 – Extended
Examiner comment – grade C
(a) (i) A workable circuit was drawn, so allowance would have been made in this case for unconventional
symbols for the lamp and cell. However, the correct symbol for an ammeter was placed in parallel
with the lamp instead of in series. 0/3
(ii) The correct value of resistance was calculated with the appropriate unit. The formula was not
acceptable as it was stated as a relationship between units. Conventional symbols for quantities
should have been used, as quoted in the syllabus. 1/2
(b) (i) Wire D was correctly identified as having a greater resistance than wire B due to it being longer. 1/1
(ii) Wire A was correctly identified as having a greater resistance than wire E, but describing wire A as
smaller did not make the relationship between resistance and cross-sectional area clear. 0/1
(iii) The resistance of wire C was quoted correctly as twice that of wire A due to it having twice the
length. The resistance of wire E was quoted correctly as half that of wire A, but the reason, that wire
E had twice the cross-sectional area, was not given. 1/2
Total mark awarded = 3 out of 9
156
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Paper 3 – Extended
Example candidate response – grade E
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157
Paper 3 – Extended
158
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Paper 3 – Extended
Examiner comment – grade E
(a) (i) A workable circuit was drawn, and allowance made in this case for untidy symbols. The symbol for
an ammeter was placed correctly in series with the lamp but the voltmeter was in series instead of
in parallel. There was no representation of the means of varying the potential difference across the
lamp. 1/3
(ii) A formula was not shown and an incorrect value for resistance derived without units. 0/2
(b) (i) Wire B was incorrectly quoted as having a greater resistance than wire D as the wrong relationship,
that the shorter wire had the greater resistance, had been used. 0/1
(ii) Similarly, wire E was incorrectly quoted as having a greater resistance than wire A as the wrong
relationship, that the thicker wire had the greater resistance, had been used. 0/1
(iii) The resistance of wire C was stated correctly, but without units, and no explanation was offered. 0/2
Total mark awarded = 1 out of 9
Question 11
Mark scheme
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159
Paper 3 – Extended
Example candidate response – grade A
160
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Paper 3 – Extended
Examiner comment – grade A
(a) This response stated that haploid cells were created by meiosis, although comparison between the
numbers of cells formed during division was incorrect. There was reference made to the production of
genetic variation. 2/2
(b) (i) The probability that the first child would have cystic fibrosis was correctly quoted as
1
4
. 1/1
(ii) The genetic diagram explained the probability by pairing the alleles from both parents. The parents’
genotypes were missing. 3/4
(c) Diffusion of gases between blood vessels and alveoli was mentioned, but the effect of increased
distance between the alveoli surface and blood vessels on the time taken for diffusion was omitted. 1/2
Total mark awarded = 7 out of 9
Cambridge IGCSE Co-ordinated Sciences 0654
161
Paper 3 – Extended
Example candidate response – grade C
162
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Paper 3 – Extended
Examiner comment – grade C
(a) The term diploid was not used correctly in this answer. The point made about cells produced by mitosis
carrying the exact gene code as the parent was good. 1/2
(b) (i) The probability that the first child would have cystic fibrosis was incorrectly quoted as
was at least consistent with the diagram in part (ii). 0/1
1
3
but this
(ii) The parents’ genotypes were shown in the genetic diagram but the nature of the gametes and one
of the possible combinations of alleles in the offspring were missing. The genotype for having cystic
fibrosis was not identified. 1/4
(c) The problem caused by mucus in the alveoli was confused with that caused by mucus in the trachea.
0/2
Total mark awarded = 2 out of 9
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163
Paper 3 – Extended
Example candidate response – grade E
164
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Paper 3 – Extended
Examiner comment – grade E
(a) Mention of the different amount of chromosomes was imprecise. 0/2
(b) (i) The probability that the first child would have cystic fibrosis was incorrectly quoted as ‘1:4’,
suggesting uncertainty about the use of ratios. 0/1
(ii) The genetic diagram was of the correct form but did not show the parents’ genotypes, although
gametes were shown. An error was made in pairing the alleles from the gametes. 2/4
(c) Reference to blockage of the lungs suggested confusion with mucus in the trachea. 0/2
Total mark awarded = 2 out of 9
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165
Paper 3 – Extended
Question 12
Mark scheme
166
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Paper 3 – Extended
Example candidate response – grade A
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167
Paper 3 – Extended
Examiner comment – grade A
(a) (i) The three molecules were all assigned to their correct families of carbon compounds. 2/2
(ii) The molecular structure of butane was drawn correctly. 2/2
(b) This candidate recognised that electrical energy was supplied by burning fossil fuels which released
carbon dioxide, negating the predicted reduction in carbon dioxide emissions. 2/2
(c) (i) The candidate correctly described the conversion of ethene to ethanol by reaction with water, under
the action of heat, and with the aid of a catalyst. 3/3
(ii) Sterilisation was correctly given as a use of ethanol. 1/1
Total mark awarded = 10 out of 10
168
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Paper 3 – Extended
Example candidate response – grade C
Cambridge IGCSE Co-ordinated Sciences 0654
169
Paper 3 – Extended
Examiner comment – grade C
(a) (i) The candidate identified ethanol as an alcohol but confused alkanes with alkenes. 1/2
(ii) The formula of butene contained the correct numbers of carbon and hydrogen atoms but lacked the
double bond. 0/2
(b) The response focused on the social implications of the use of electric cars rather than a scientific
explanation in terms of electricity generation adding carbon dioxide to the air. 0/2
(c) (i) The candidate realised that water was required in the conversion of ethene to ethanol but did not
describe the conditions necessary. 1/3
(ii) “To kill…bacteria” was a good suggestion for the use of ethanol. 1/1
Total mark awarded = 3 out of 10
170
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Paper 3 – Extended
Example candidate response – grade E
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171
Paper 3 – Extended
Examiner comment – grade E
(a) (i) The candidate identified ethane as an alkane but confused alcohols with alkenes. 1/2
(ii) The formula of butene lacked a double bond and contained the wrong numbers of carbon and
hydrogen atoms even though they were given in the question. 0/2
(b) The candidate was under the misapprehension that carbon dioxide was used as a fuel. 0/2
(c) (i) The candidate noted the difference in the structures of ethene and ethanol but did not suggest an
addition reaction between ethene and water to bring about the conversion. 0/3
(ii) The suggested use of ethanol was as a fuel even though the question directed the candidate away
from this option. 0/1
Total mark awarded = 1 out of 10
172
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Paper 5 – Practical
Paper 5 – Practical
Question 1
Mark scheme
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173
Paper 5 – Practical
Example candidate response – grade A
174
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Paper 5 – Practical
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175
Paper 5 – Practical
176
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Paper 5 – Practical
Examiner comment – grade A
(a) This was a basic test of observations and conclusions. The candidate provided ideal responses for all
parts. 5/5
(b) (i) This is the type of question which attracts a wide range of possible responses, a selection of these
appear in the mark scheme. In this case the candidate demonstrated a clear understanding of why
the leaf was placed in boiling water. 1/1
(ii) The candidate’s answer is the reverse argument of the mark scheme which concentrated on the
linking of light, photosynthesis and starch. 3/3
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Paper 5 – Practical
(c) (i) The statement about no CO2 being able to enter the test-tube was just enough for the mark for
gases not being able to enter or leave the test-tube, however this was cancelled by the wrong
statement “so the leaves do not have air”. 0/1
(ii) This was answered with one of the possible answers in the mark scheme. 1/1
(iii) For test-tube C there was no mention of photosynthesis but the candidate’s answer was just
equivalent to carbon dioxide being used up and a mark was given. For test-tube D the candidate
made it clear that there is no photosynthesis, which scores a mark, but there was no mention of
carbon dioxide being released or carbon dioxide levels rising; the candidate simply stated that carbon
dioxide was not taken in, which was not enough for the mark. 2/4
Total mark awarded = 12 out of 15
178
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Paper 5 – Practical
Example candidate response – grade C
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179
Paper 5 – Practical
180
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Paper 5 – Practical
Cambridge IGCSE Co-ordinated Sciences 0654
181
Paper 5 – Practical
Examiner comment – grade C
(a) This was a basic test of observations and conclusions. The candidate provided ideal responses for all
parts. 5/5
(b) (i) The answer muddled the ideas of ‘killing the leaf’ and ‘softening the cuticle’ so the candidate was
not awarded a mark. 0/1
(ii) Although the candidate’s answer did not mention A or B, the link between photosynthesis and light
was made clearly therefore two marks were awarded. The third mark for ‘making starch’ was not
given because the statement, “starch … present”, was simply repeating the answer for (a)(ii) and
this was not credited. 2/3
(c) (i) The answer did not specifically state that gases could not enter or leave the test-tubes and it was
only factually correct for test-tube E. 0/1
(ii) The candidate provided the answer ‘to show that the leaf causes the colour change’ in a different
yet acceptable way. 1/1
(iii) The candidate confused the indicator colour with the biuret test for proteins. 0/4
Total mark awarded = 8 out of 15
182
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Paper 5 – Practical
Example candidate response – grade E
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183
Paper 5 – Practical
184
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Paper 5 – Practical
Cambridge IGCSE Co-ordinated Sciences 0654
185
Paper 5 – Practical
Examiner comment – grade E
(a) (i) This was answered correctly. 2/2
(ii) ‘Blue-black’ was an acceptable colour for A in but not for B. There was no attempt to make
conclusions. 1/3
(b) (i) The candidate’s answer “to destarch” did not represent an acceptable response. 0/1
(ii) There was no attempt to answer this question. 0/3
(c) (i) The candidate specifically referred to carbon dioxide rather than any gas but included the idea of
preventing gas escaping so scored the mark. 1/1
(ii) ‘Control’ was in the answer to so the mark was awarded. 1/1
(iii) The answer for test-tube C was not correct as there was no mention of carbon dioxide being used
up or of photosynthesis, so no marks were awarded. There was no attempt to explain the colours in
test-tube D. 0/4
Total mark awarded = 5 out of 15
186
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Paper 5 – Practical
Question 2
Mark scheme
Cambridge IGCSE Co-ordinated Sciences 0654
187
Paper 5 – Practical
Example candidate response – grade A
188
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Paper 5 – Practical
Cambridge IGCSE Co-ordinated Sciences 0654
189
Paper 5 – Practical
190
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Paper 5 – Practical
Examiner comment – grade A
(a) Table 2.1 was completed with realistic potential difference and current values which show the correct
trends down the table. At least four resistance values were calculated correctly and recorded to the
same number of decimal places, correctly rounded. One decimal place would have been accepted. 5/5
(b) (i) The graph was correctly labelled with units and linear scales using more than half of the grid
provided. At least four points were plotted correctly and the best straight line, which had points
evenly distributed either side of it or on it, correctly passed through the origin. 4/4
(ii) The working for the gradient was shown both on the graph and as a fraction. The length for 10 ohms
should be 79 cm rather than 80 cm but, as this was within half a square of the grid and the fraction
was correctly evaluated, this scored two marks. Note that a correct value for the gradient often
attracted both marks, but it is always considered good practice to show the working, either on the
graph, in the space provided for the answer, or both. 2/2
(iii) The value of C was correctly calculated. 1/1
(iv) The conversion to m2 was actually a conversion from cm to m because C was divided by 100 rather
than 10000. This was a common error. 0/1
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Paper 5 – Practical
(c) “The current will increase” was correct, although candidates often suggested that the current
decreased when a greater cross-sectional area was used. This candidate then made the common error
of stating that the resistance increased. 1/2
Total mark awarded = 13 out of 15
192
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Paper 5 – Practical
Example candidate response – grade C
Cambridge IGCSE Co-ordinated Sciences 0654
193
Paper 5 – Practical
194
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 5 – Practical
Cambridge IGCSE Co-ordinated Sciences 0654
195
Paper 5 – Practical
Examiner comment – grade C
(a) Table 2.1 was completed with realistic potential difference and current values which showed the correct
trends down the table. The one reading of potential difference recorded to a different number of decimal
places was ignored. At least four resistance values were calculated correctly, recorded to the same
number of decimal places and correctly rounded. One decimal place would have been accepted. 5/5
(b) (i) The graph was incorrectly labelled as there were no units on the axes but the candidate used
linear scales using more than half of the grid provided. The 20 cm and 40 cm points were plotted
incorrectly so, with only three points plotted correctly, the plotting mark was not awarded. Although
the line did go through the origin, it was not the line of best fit, as shown by only the 100 cm point
being to the right of the line; so the ‘line’ mark was not awarded. 1/4
(ii) The working for the gradient was shown on the graph and in the answer space, which was good
practice. The value given for the x-axis as (50-44) was wrong; it should have been (72–44). Because
‘error carried forward’ was applied to this wrong working, the answer 0.67 scored one mark. 1/2
(iii) Again ‘error carried forward’ was applied to give a value of C equal to 0.000073. The candidate’s
value of C was not evaluated so this mark was not accessed. 0/1
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Paper 5 – Practical
(iv) ‘Error carried forward’ gave an answer of 7.3 x 10 -9. The candidate’s answer was therefore wrong.
0/1
(c) Both changes were correct. 2/2
Total mark awarded = 9 out of 15
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197
Paper 5 – Practical
Example candidate response – grade E
198
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Paper 5 – Practical
Cambridge IGCSE Co-ordinated Sciences 0654
199
Paper 5 – Practical
200
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 5 – Practical
Examiner comment – grade E
(a) Table 2.1 was completed with realistic potential difference and current values which showed the correct
trends down the table. At least four resistance values were calculated correctly, recorded to the same
number of decimal places and correctly rounded. If there had been one incorrectly calculated resistance
value, this mark would still have been scored because the 100 cm resistance value of 11.8 (1 decimal
place) would have been accepted since 1.77/0.15 = 11.8 exactly. 5/5
(b) (i) The candidate did not label the axes. The chosen scales made good use of the grid. The x-axis
should have been numbered in a linear fashion as the y-axis was, however the scale mark was given
because the values and marks on the x-axis showed that it was a linear scale. The points were
plotted correctly but the line was not straight. Overall, the candidate scored the scale and plotting
marks. 2/4
(ii) No marks were awarded for the gradient because the line was not straight and there was no
working shown. 0/2
(iii) ‘Error carried forward’ was applied so the candidate’s answer for C should have been 2.2897 x 10 -5
not 2.2897. 0/1
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Paper 5 – Practical
(iv) ‘Error carried forward’ was also applied to this question and so the answer should have been
2.2897 x 10 -9 not 0.0228. 0/1
(c) The candidate recorded the effects on current and resistance the wrong way round so no marks were
scored. 0/2
Total mark awarded = 7 out of 15
Question 3
Mark scheme
202
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Paper 5 – Practical
Example candidate response – grade A
Cambridge IGCSE Co-ordinated Sciences 0654
203
Paper 5 – Practical
Examiner comment – grade A
(a) (i) The candidate answered this question correctly. It is worth noting that other candidates who gave
‘clear’ as a description of the colour of the filtrate did not gain the mark. 2/2
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Paper 5 – Practical
(ii) ‘Fizzing’ was accepted as an alternative to ‘bubbles’ or ‘effervescence’, and ‘blue/green’ was accepted for
‘green’. ‘Blue solution’ was only allowed if the supervisor reported that this was the case, emphasising the
importance of the supervisor’s results. 3/3
(iii) This candidate gave a very full answer and scored both marks. 2/2
(b) (i) The candidate observed a white precipitate and correctly concluded the presence of the chloride ion. The
solubility of the precipitate was not relevant in the test and so was ignored. 2/2
(ii) The answer “No change” because there is no sulfate present was correctly recorded. Many candidates
recorded the presence of a white precipitate because they felt that all tests should have been positive
ones which was definitely not the case. 2/2
(iii) Red litmus only turned blue if the paper was dipped in the mixture or if the mixture was heated too
strongly causing a fine spray to hit the paper. If the test was carried out correctly the red litmus remained
red because there was no ammonium ion present and hence no ammonia produced. No ‘error carried
forward’ was allowed here for the conclusion or for the cation identification. 0/4
Total mark awarded = 11 out of 15
Cambridge IGCSE Co-ordinated Sciences 0654
205
Paper 5 – Practical
Example candidate response – grade C
206
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Paper 5 – Practical
Cambridge IGCSE Co-ordinated Sciences 0654
207
Paper 5 – Practical
Examiner comment – grade C
(a) (i) The candidate described the residue correctly as ‘green’ but ‘clear/transparent’ was not accepted as
the colour of the filtrate which would have been colourless. 1/2
(ii) ‘Effervescence’ but not ‘green’ was recorded. The candidate correctly concluded the presence of
the carbonate ion scoring two marks overall for this part. 2/3
(iii) The correct observation and conclusion were recorded, copper(II) being an acceptable alternative for
Cu2+. 2/2
(b) (i) The candidate observed a white precipitate and correctly concluded the presence of the chloride ion.
The statement that the chloride was ‘formed’ was ignored. 2/2
(ii) Many candidates recorded the presence of a white precipitate because they felt that all tests should
have been positive ones which was definitely not the case. This candidate did this and scored
nothing for this part. Interestingly the correct observation was crossed out. 0/2
(iii) Red litmus only turned blue if the paper was dipped in the mixture or if the mixture was heated
too strongly causing a fine spray to hit the paper. If the test was carried out correctly the red litmus
remained red because there was no ammonium ion present and hence no ammonia produced. No
‘error carried forward’ was allowed here for the conclusion or for the cation identification. 0/4
Total mark awarded = 7 out of 15
208
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Paper 5 – Practical
Example candidate response – grade E
Cambridge IGCSE Co-ordinated Sciences 0654
209
Paper 5 – Practical
210
Cambridge IGCSE Co-ordinated Sciences 0654
Paper 5 – Practical
Examiner comment – grade E
(a) (i) The candidate described the residue as green which was correct but the filtrate would have been
colourless and not light green if the filtration was carried out correctly. 1/2
(ii) “Effervescence” but not ‘green’ was recorded. The candidate correctly concluded the presence of
the carbonate ion scoring two marks overall for this part. 2/3
(iii) The candidate recorded the colour of the precipitate as white, which is incorrect. ‘Error carried
forward’ was not applied here for the conclusion, otherwise candidates could have scored a mark for
simply making up an observation with its conclusion. 0/2
(b) (i) The candidate correctly observed a white precipitate. The solubility of the precipitate was not
relevant in this test and so was ignored. The conclusion given was not credited because chlorine
is not accepted as an alternative for chloride. Firstly, the name of the ion was clearly stated in the
Chemistry Practical Notes at the end of the paper and, secondly, ‘chlorine ion’ could have meant
charged Cl 2. 1/2
(ii) Many candidates recorded the presence of a white precipitate because they felt that all tests should
have been positive ones which was definitely not the case in this question. This candidate did this
and scored nothing for this part. 0/2
(iii) Red litmus only turned blue if the paper was dipped in the mixture or if the mixture was heated
too strongly causing a fine spray to hit the paper. If the test was carried out correctly the red litmus
remained red because there was no ammonium ion present and hence no ammonia produced. The
candidate made a wrong conclusion (Fe2+); if the conclusion had been given as NH4+ this would still
have been marked as wrong because no ‘error carried forward’ was given in this case for the same
reason as stated in (a). 0/4
Total mark awarded = 4 out of 15
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Paper 6 – Alternative to practical
Question 1
Mark scheme
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Example candidate response – grade A
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Examiner comments – grade A
(a) (i) The thermometer has been correctly read. The comment about “the human body temperature”
achieves the mark. The rest of the answer is irrelevant. 2/2
(ii) The candidate has correctly converted the time on the stop watches from minutes and seconds to
seconds, two marks for three correct calculations. 2/2
(iii) A correct calculation of the average time. 1/1
(b) A good answer, the candidate has used the information given and with their knowledge of neutralisation
has gained two marks. 2/2
(c) The candidate has realised the importance of allowing the tubes to heat up for ten minutes. 1/1
(d) The candidate suggests setting up two test tubes then testing for the presence of fat using ethanol,
without saying how and what the result should be. However, the candidate suggests that the lipase
test tube should produce negative results when, in fact, it would give a positive test. In questions of
this type candidates should base their answer on the original question, without the need for additional
reagents like ethanol. To test if lipase is an enzyme, the experiment should be repeated using boiled or
denatured lipase. There will then be no change of indicator colour. 0/2
Total mark awarded = 8 out of 10
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Example candidate response – grade C
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Examiner comments – grade C
(a) (i) The temperature has been read correctly and the reason is correct. The last four words “rate of
reaction increases” is irrelevant and is ignored. 2/2
(ii) The candidate has correctly converted minutes and seconds to seconds and recorded them in the
table. Three correct entries for two marks. 2/2
(iii) The candidate has correctly calculated the average time and quoted the answer to three significant
figures. Candidates that gave the answer to a greater number of significant figures were not
penalised, but those that rounded their answer to 200 seconds were not awarded credit. 1/1
(b) The candidate has not used any of the information given in the question. There is no way chlorine could
be present and no mention of litmus paper in the question. The indicator is pink because of the alkaline
sodium carbonate in the mixture. The fatty acids produced when lipase breaks down fats will neutralise
the alkali turning the indicator colourless. 0/2
(c) To heat the tubes is incorrect, otherwise a Bunsen burner could be used. The use of a water bath for 10
minutes ensures the entire contents of all tubes are at the required temperature. 0/1
(d) There is no credit-worthy content to this answer. It was expected that candidates would review the
experiment and realise that by boiling or denaturing the lipase and repeating the experiment no colour
change would occur showing that the lipase was indeed an enzyme. 0/2
Total mark awarded = 5 out of 10
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Example candidate response – grade E
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Examiner comments – grade E
(a) (i) The value of 37 oC is correct. The reason is also correct. 2/2
(ii) The candidate has to read the times on the stop watches and convert to seconds. Values of 205,
217 and 185 were expected. 0/2
(iii) The calculation, using incorrect figures carried forward from (ii), is correct, so the candidate achieves
full credit for this part. 1/1
(b) This answer shows a lack of understanding of the processes involved and does not use all the
information given in the question. However the candidate has noted a neutralisation has taken place, so
gains one mark. 1/2
(c) The candidate has failed to appreciate the need to keep the tubes in the water for 10 minutes in order
for the contents to fully heat through. 0/1
(d) Questions like this require the candidate to use the same experiment used in the rest of the question
but altered slightly in order to answer the particular point. In this case, to prove that lipase is an enzyme
the experiment could be repeated with boiled or denatured lipase. This would not show the colour
change seen before. 0/2
Total mark awarded = 4 out of 10
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Question 2
Mark scheme
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Example candidate response – grade A
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Examiner comments – grade A
(a) This question requires only measuring and mathematical skills and most grade A candidates scored
maximum marks. This candidate has correctly read the balance window. 1/1
(b) (i) A ruler was required to measure the actual lengths on the printed exam paper. All three correct. 3/3
(ii) A fully correct calculation for two marks. 2/2
(iii) Correct substitution and calculation, another two marks. 2/2
(c) The candidate has recalled the correct formula for calculating density and used it to find the density of
the piece of pipe. 2/2
Total mark awarded = 10 out of 10
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Example candidate response – grade C
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Examiner comments – grade C
(a) The candidate has correctly read the balance window. 1/1
(b) (i) The candidate has used a ruler to correctly measure the length, but the values for the external and
internal diameters are very different from the expected values of 2.5 and 1.8 cm respectively. 1/3
(ii) If the candidate had measured correctly in (i) they would have obtained the expected answer of
3.1 cm3. However, this answer is consistent with the incorrect figures carried forward, so full marks
for this part. 2/2
(iii) Again, this answer is consistent with the incorrect measurements carried forward from (i), so full
marks for this part as well. 2/2
(c) The candidate has used the wrong formula to calculate the density so no marks were awarded. 0/2
Total mark awarded = 6 out of 10
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Example candidate response – grade E
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Examiner comments – grade E
(a) The candidate has read the mass and it is within tolerance for this question. 1/1
(b) (i) The candidate has either misread the question or does not have a ruler. It is important that candidates
come to the examination properly prepared with items that are often required in this paper such as
erasers, pencils, rulers, protractors and calculators. 0/3
(ii) The candidate has not shown any working, but simply subtracted the diameters rather than using the
squares. No marks. 0/2
(iii) Again the candidate has not shown any working. However, this answer is the correct result of using the
incorrect answers carried forward from previous parts, so full credit is gained. 2/2
(c) The candidate has not shown the formula to calculate density but this is not the way to calculate it. 0/2
Total mark awarded = 3 out of 10
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Question 3
Mark scheme
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Example candidate response – grade A
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Examiner comments – grade A
(a) The candidate has correctly read the temperatures shown on the thermometers and recorded them to one
decimal place. 3/3
(b) (i) The candidate has used the entire grid to plot the graph, the scales are correct and labelled. The points
are plotted correctly and a smooth curve used to join them. The graph reaches a maximum between
the second and third points. A very good graph. 4/4
(ii) The candidate has found the maximum temperature rise by subtracting the starting temperature of
20 ºC from the high point of their graph. 1/1
(iii) A correct calculation. The volume of solution B is found by reading the information in the question. 2/2
Total mark awarded = 10 out of 10
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Example candidate response – grade C
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Examiner comments – grade C
(a) Three correct readings, with all three answers to 1 decimal place, for three marks. 3/3
(b) (i) The axes are correct and labelled and the points are plotted correctly. However, the candidate has
not joined the first point to the second, so cannot score the mark for the curve. There should be a
maximum between the second and third points to about 54 ºC. 2/4
(ii) 52 ºC is the maximum value on this graph, but the question asked for the maximum temperature
rise. The candidate should subtract the starting temperature (20 ºC) from this value. 0/1
(iii) The candidate has substituted the correct figures into the formula. The candidate’s value of 52 ºC
is not penalised further. The volume of solution B is found in the information in the question. The
calculation is incorrect as the candidate seems to have cubed the 25. 1/2
Total mark awarded = 6 out of 10
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Example candidate response – grade E
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Examiner comments – grade E
(a) The candidate has correctly read and recorded the values of the thermometer readings. 3/3
(b) (i) The candidate has drawn and labelled the scales correctly for one mark. The points are plotted
correctly for a second mark. The candidate was instructed to draw a smooth curve between the
points, but has used a ruler so did not gain this mark. A maximum in the graph should be seen
between the second and third point. 2/4
(ii) The candidate has misread the question. The maximum temperature rise of the candidate’s graph is
32 ºC. 0/1
(iii) The candidate has multiplied his temperature rise by 4.2, but has failed to multiply by the volume of
solution B. This value is 25 cm3 and can be found in the information given in the question. 0/2
Total mark awarded = 5 out of 10
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Question 4
Mark scheme
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Example candidate response – grade A
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Examiner comments – grade A
(a) (i) The candidate has correctly changed the number of beats in 30 seconds to the number of beats in a
minute. 1/1
(ii) The scales are correct and labelled, the points are plotted correctly and the curve is drawn correctly. 3/3
(iii) The line appears quite thick because of the horizontal line below, which has been crossed out, so the
maximum value of the graph is not totally clear. However, the recorded value of 17.5 minutes is correct.
1/1
(b) (i) The candidate has correctly noted that exercise would affect the heart rate. It was not necessary to say
the heart rate would be increased. 1/1
(ii) The two quantities that need to be kept the same are the volume and the concentration of the coffee.
“Amount” is an inexact term that could mean either volume or concentration, so one mark awarded.
1/2
(iii) The candidate has correctly suggested that readings should be taken more frequently, i.e. “every
minute”. The second half of the answer suggests that the peak would be seen more clearly so credit
given. 2/2
Total mark awarded = 9 out of 10
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Example candidate response – grade C
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Examiner comments – grade C
(a) (i) The candidate has correctly converted the number of beats in 30 seconds to the number of beats in
one minute. 1/1
(ii) The scales on the graph are correct but without labels (beats per minute and time in minutes) and
the points are very difficult to see. However, as the line is in the correct place credit is awarded, but
candidates should be encouraged to make their points obvious. One mark awarded for the curve.
2/3
(iii) A correct time has been read off the graph. 1/1
(b) (i) The candidate has realised that exercise will increase heart beat and ruin the test. 1/1
(ii) The candidate has been asked for two quantities that should be kept the same, therefore drinking
the same coffee is not creditworthy; similarly the candidate has no control over how much caffeine
is used. The quantities that can be controlled are the volume and concentration of the coffee. The
term ‘amount’ is an inexact term that could mean either volume or concentration, so one mark
awarded. 1/2
(iii) This answer does not address the question. The maximum heart rate occurs between the 15th
and 20th minute after drinking the coffee, therefore more frequent measurements should be taken
between these times to reach a more accurate value. 0/2
Total mark awarded = 6 out of 10
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Example candidate response – grade E
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Examiner comments – grade E
(a) (i) The candidate has correctly converted beats per 30 seconds to beats per minute. 1/1
(ii) The scales and labelling is correct, and there is no problem with the broken scale on the vertical axis.
The points are plotted correctly, but they are not joined by a curve. 2/3
(iii) The time to maximum effect is somewhere between 15 and 20 minutes. It is possible that the
candidate has read the wrong axis to get 90 minutes. 0/1
(b) (i) The candidate has correctly noted that exercise would increase the heart rate. 1/1
(ii) The candidate has failed to identify the two quantities that need to remain the same; the volume and
concentration of coffee. The candidate has not given quantities. 0/2
(iii) The candidate is asked to identify a method to obtain a more accurate value of the maximum rate of
heart beat. More frequent readings need to be taken between the 15th and 20th minutes. This would
produce a clearer peak on the graph. The candidate’s suggestion does not address the question. 0/2
Total mark awarded = 4 out of 10
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Question 5
Mark scheme
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Example candidate response – grade A
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Examiner comments – grade A
(a) (i) The candidate has correctly measured the indicated length. 1/1
(ii) A correct calculation. The value from (i) multiplied by 30 to calculate the actual distance, and then
multiplied by 2 as the sound travels to the wall and back again. 2/2
(iii) This is not a valid reason. The timer may have been distracted or forgot to press the button on the
clock. The wind would have little effect on the speed of sound. 0/1
(iv) A correct calculation. 1/1
(v) Another correct calculation. 2/2
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(vi) A comment on the accuracy was required. The response “somewhat correct” is vague, but the
additional calculation allows the mark to be awarded. 1/1
(b) A correct explanation of why the speed of sound in water is faster than in air. One mark for knowing that
particles are required and a second for appreciating that they are closer together. 2/2
Total mark awarded = 9 out of 10
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Example candidate response – grade C
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Examiner comments – grade C
(a) (i) The candidate has correctly measured the distance indicated. 1/1
(ii) The candidate has correctly calculated the actual distance the sound travelled from the girl to the wall,
but not the total distance as it returns to the timer. The candidate gains one of the two available marks.
1/2
(iii) Candidates were asked to suggest a reason for the time in experiment 5 being much longer, for
example the timer being distracted or not concentrating. No marks awarded. 0/1
(iv) The candidate has correctly calculated the average time. 1/1
(v) The calculation is correct, using their value for distance calculated in (ii). 2/2
(vi) Candidates were given the actual speed of sound and had to make a comment on their value.
Here,
the candidate’s answer is unclear but could suggest that the speed of sound is incorrect rather
than their value. It was expected that candidates would justify their answer, for example, ‘my value
is not very accurate as it is less than half of the expected value’. 0/1
(b) This answer shows that the candidate has failed to grasp the idea of sound being a longitudinal wave
requiring a medium. The speed is faster in water as the particles are closer together. 0/2
Total mark awarded = 5 out of 10
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Example candidate response – grade E
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Examiner comments – grade E
(a) (i) The measurement is just inside the acceptable range. 1/1
(ii) The value from (i) should be multiplied by 30 to calculate the scaled-up distance from the girl to the
wall, then multiplied by 2 to give the total distance travelled by the sound. The candidate has not
multiplied by 2. 1/2
(iii) Because the time for experiment 5 is so much longer than the others shows that it’s a mistake. The
question asks for a reason, for example perhaps the timer was not concentrating or was distracted.
0/1
(iv) The candidate has correctly calculated the average time of the first four experiments. 1/1
(v) The candidate has shown the working so it can be seen that the correct figures have been used.
The answer has been rounded incorrectly, and so the candidate was not awarded credit. When
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the number of decimal places are not specified any reasonable answer is acceptable, but must be rounded
correctly. In this case 151, 151.27 or 151.3 are acceptable. 1/2
(vi) The value calculated is not accurate and there is no valid comment. 0/1
(b) The candidate’s answer does not make sense. 0/2
Total mark awarded = 4 out of 10
Question 6
Mark scheme
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Example candidate response – grade A
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Examiner comments – grade A
(a) The correct test and result for hydrogen. 2/2
(b) (i) A perfect answer. 1/1
(ii) Several answers have been given here: “so it will not react with acid”, “or produce the least
hydrogen bubbles”, “copper is denser than the acid”. Candidates should be discouraged from
giving multiple answers as any wrong one negates a correct answer. The correct answer is the first
response, and the other two in this case do not negate the answer (if it does not react with acid it
will produce the least bubbles i.e. none) so a mark is awarded. 1/1
(c) The candidate has correctly stated that graph A is steeper than graph B, however the reason given is
incorrect. The volume of hydrogen produced is the same in both experiments, and copper does not
react with hydrogen. The correct answer, that hydrogen is produced at a faster rate, is missing. 1/2
(d) A correct observation is given; there would be some unreacted magnesium ribbon left. 1/1
(e) Two marks awarded, one for the drawn line being below the printed graphs and a second for levelling off
at the same final volume of hydrogen. 2/2
(f) A very good diagram of a syringe, showing gradations. 1/1
Total mark awarded = 9 out of 10
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Example candidate response – grade C
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Examiner comments – grade C
(a) The candidate knows the correct test for hydrogen, a lighted splint. The result of the test is incorrect, so only
one mark scored. 1/2
(b) (i) The candidate has correctly identified that it is the formation of bubbles making the magnesium rise. 1/1
(ii) The candidate has identified the important point that copper does not react with the acid. 1/1
(c) The candidate’s answer that there is “more volume of hydrogen in the reaction” is wrong in three respects.
Firstly, the question asks for a difference in the shape of the graphs i.e. graph A is steeper. Secondly, the
volume of hydrogen given off is the same in both experiments, as the graphs finish at the same level. Finally,
if the statement was true, credit could not be given as the candidate does not state which experiment
produces the “more volume of hydrogen”. The reason for the difference is that hydrogen is produced faster in
experiment A. 0/2
(d) A correct observation, there would be some ribbon left after the reaction has finished. 1/1
(e) The sketch line is correct; it is below the printed graphs and finishes at the same volume of hydrogen. 2/2
(f) It is not clear what apparatus the diagram shows, but it is clear that this will not collect and measure the gas
evolved. 0/1
Total mark awarded = 6 out of 10
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Example candidate response – grade E
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Examiner comments – grade E
(a) The candidate has correctly given the test and result for hydrogen. Both marks were awarded despite
the spelling of “lightning” splint. 2/2
(b) (i) Candidates had to suggest why the piece of magnesium rose to the surface, and (a) had the
information that hydrogen was given off. An indication that it was this hydrogen being produced in
bubbles that floated the magnesium to the surface was required. 0/1
(ii) The fact that copper does not react with the acid is the important idea here. The candidate has
stated that it is less reactive than hydrogen so the mark is awarded. 1/1
(c) The important point to note here is that the volume of hydrogen does not increase. Both graphs finish
at the same volume of hydrogen. The production of hydrogen is faster in graph A, thus the graph is
steeper. 0/2
(d) The candidate’s description has shown that the reaction has finished. It does not indicate that the
magnesium was in excess. 0/1
(e) The curve the candidate has drawn should be below both graphs A and B, but does finish at the same
volume so scores one mark. 1/2
(f) This diagram looks very much like the diagram shown in Fig. 6.1. A syringe should be used. 0/1
Total mark awarded = 4 out of 10
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