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General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
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SCIENCE
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Paper 5126/01
Multiple Choice
Question
Number
Key
Question
Number
Key
1
2
3
4
5
D
C
C
A
A
21
22
23
24
25
C
A
A
B
D
6
7
8
9
10
A
B
A
C
D
26
27
28
29
30
A
C
D
B
B
11
12
13
14
15
D
D
B
B
A
31
32
33
34
35
A
A
B
B
D
16
17
18
19
20
B
C
B
B
B
36
37
38
39
40
A
B
D
B
A
General Comments
Candidates found Questions 2, 4, 9, 15, 21, 22, 31 and 27 to be straightforward, showing good subject
knowledge, and many questions, for example, Questions 6, 24, 29, 34 and 35 discriminated well between
the more and less able candidates.
Comments on Specific Questions
Question 1
A large proportion of the candidates correctly identified the burette as the piece of apparatus; however, there
were a significant number of candidates who chose option B, the pipette.
Question 3
Atomic structure is well understood by many of the candidates though many of the weaker candidates simply
added the mass number and the proton number together and chose option D.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
Question 5
The majority of the candidates recognised that X is an inert gas and does not bond with other atoms, thus
discounting options B and C. A large proportion of the candidates chose option D, the formation of an ionic
compound, rather than the correct option, A, where a covalent bond is formed between atoms of the same
element.
Question 7
There was evidence of guesswork amongst the weaker candidates. Candidates should know that reactions
involving bond breaking are endothermic.
Question 8
This question was well answered by the more able candidates. A majority of the candidates chose option B,
which is half the total time for the reaction to be complete but not the time when half the volume of carbon
dioxide has been evolved because the reaction slows down as the calcium carbonate is used up.
Question 10
There was evidence of guesswork particularly amongst the weaker candidates but the more able candidates
knew that bromine is a liquid and displaces iodine from potassium iodide.
Question 11
A large number of the candidates chose option C, an ionic compound, which shows a regular pattern of the
two different atoms. Candidates should be able to recognise that an alloy is a regular arrangement of atoms
with a random pattern of a second atom.
Question 12
The determination of a reactivity series from experimental data proved difficult for some of the candidates. A
significant number of candidates chose option B, which is the reversed order of reactivity.
Question 14
The production of ammonia by the reaction between an ammonium salt and an alkali, sodium hydroxide, is
not known by the majority of the candidates. Option C, dilute hydrochloric acid was incorrectly chosen by
many of the weaker candidates.
Question 17
The more able candidates knew that cracking produces an unsaturated molecule, ethene but a large
proportion of the weaker candidates incorrectly chose option A, ethane, a saturated molecule.
Question 23
While most candidates got this question (on water absorption by plants) correct, significant numbers had the
water concentrations reversed.
Question 25
Some candidates do not realise that osmosis always refers to the movement of water and here incorrectly
chose an answer that specified osmosis.
Question 26
Most candidates understand that carbon dioxide can limit the rate of photosynthesis.
Question 27
This question required careful reading. The majority of candidates who got it incorrect had the answers
exactly reversed.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
Question 28
Here again, there was confusion over the process of osmosis.
Question 33
This question (on accommodation) caused problems. Even the stronger candidates were evidently guessing
– they did not realise that most of the refraction occurs at the eye surface (and not at the lens).
Question 36
Some candidates did not believe that carbon compounds are excreted by living organisms. Presumably,
they forgot that carbon dioxide is a waste product of respiration.
Question 40
Most candidates could distinguish between continuous and discontinuous variation.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
SCIENCE
Paper 5126/03
Theory (Chemistry)
Key message
Candidates’ performance is enhanced by the ability to interpret information and solve problems.
General comments
The general quality of candidates' work appeared much improved on previous years. The ability to
handle information and solve problems was highly in evidence. Skill at writing balanced, chemical
equations, an important chemical ability, was often shown as was the ability to solve problem of a
chemical and mathematical nature.
Comments on Specific Questions
Section A
Question 1
Any of the many uses of these materials, in addition to those specified in the syllabus, were
accepted. The main responses were: aluminium – aircraft construction, having a low density;
calcium carbonate – soil treatment, reducing acidity, but not as a fertiliser; diamond –
drilling/cutting, having great hardness, though not strength, as commonly given; helium - filling
balloons, being lighter than air is the most important reason for using helium to fill (weather)
balloons but it is not used, of course, in filling hot-air balloons.
Question 2
This was variably answered, with some answers being excellent. As the question required
‘names’, correct chemical formulae were accepted but if this was the case, full credit could not be
achieved.
(a)
Either ‘carbon dioxide’ or ‘ethanol’ were accepted as the product of fermenting sugar.
(b)
Either ‘brass’ or an ‘alloy’ were the correct answers here. This was not well known.
(c)
‘Ammonia’ was accepted but neither ‘ammonium’ nor ‘NH4’ were awarded credit.
(d)
The name of the substance formed, i.e. silver chloride, was needed but ‘white precipitate’
was rejected.
(e)
‘A sodium ion’ results from removing an electron from a sodium atom. This was not well
known.
Question 3
(a)
Either ‘filter funnel’ or ‘filter paper’ were accepted as pieces of apparatus used to separate
a precipitate from a solution.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
(b)
‘Measuring cylinder’ was the correctly given answer. ‘Volumetric flask’, though only
occasionally given, was not accepted. ‘Pipette’ was not considered as an appropriate and
practicable choice.
(c)
‘Condenser’ was accepted with ‘Liebig condenser’, equally valid, being commonplace.
(d)
Few candidates chose a ‘burette’ to add 17.3 cm3 of solution to a flask. Evidently some
Centres use ‘graduated pipettes’ and this was accepted as a correct response.
Question 4
(a)
Partial credit was awarded where A was the most reactive metal and D the least reactive.
Further credit was available if candidates had positioned C and B correctly.
(b)
The deductions required here could best be based on a knowledge and recall of the
reactivity series listed in the examination syllabus. Many candidates sketched in rough on
the examination paper this reactivity series and were evidently using it as a basis for their
answer. However, when a candidate correctly chose a metal outside the series given in
the syllabus, the response was awarded full credit.
Question 5
In the first row, the name and formula was usually correctly given. In the second row, ‘methanoic
acid’ was often given, incorrectly, for ‘ethanoic acid’. ‘COOH’ written as such was sufficient to earn
the credit available for ‘characteristic group of atoms’.
Question 6
(a)
The correct name and formula for an acid was often written correctly but not so those of
an alkali.
(b)
While the name of a particular salt and water were expected to be answered as the
product of the reaction of a named acid and a named alkali, ‘salt and water’ were also,
perhaps generously, accepted. This was well answered.
(c)
While some candidates knew that hydrogen ions in excess are the cause of acidity, very
few knew that alkalinity is caused by an excess of hydroxyl ions.
Question 7
(a)
That this atom has seventeen protons and eighteen neutrons in its nucleus was well
determined.
(b)
Candidates did not find the general nature of this question easy. Explanations needed
candidates to apply their knowledge of electrovalent and covalent bonding to a chlorine
atom when donating or sharing an electron.
Question 8
Candidates were not expected to have any experience of this mineral, its chemical formula being
given in the question thus testing their problem solving rather than factual recall skills.
(a)
(i)
Most candidates could correctly calculate the relative molecular mass of vanadanite.
(ii)
Few candidates realised that as three vanadium atoms are present in vanadanite’s
molecule, all should be included in the determination of its percentage by mass.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
(b)
(i)
This was not an easy chemical equation to balance but many candidates were
successful in doing so.
(ii)
Most candidates realised that to calculate the mass of magnesium needed to
produce 5 kg of vanadium the chemical equation, previously balanced, needed to be
used. If the candidate had not been successful in balancing the equation in (i) yet
had used it correctly here, credit was awarded. In other words, candidates were not
penalised twice for making a single error.
Section B
Question 9
(a)
(b)
(i)
The substances E, F, G and H were, respectively, copper(II) nitrate, ammonia,
ammonium hydroxide, and copper(II) hydroxide. Identification and not naming was
required and so chemical formulae were accepted, but only when the completely
correct chemical formula was used. This was very well answered.
(ii)
Most candidates decided to give the chemical equation for the reaction between
sodium hydroxide and copper(II) sulfate, though other, perhaps simpler, equations
were equally acceptable. Many correctly balanced equations were given.
To gain full marks in describing a means of forming crystals from a dilute solution
candidates needed to include any four of the following in logical order: boil to concentrate,
leave to crystallise/cool, separate/filter, wash with distilled water, dry with filter/blotting
paper. Many candidates gained full marks.
Question 10
(a)
A simple description of ‘cracking’ was expected but many candidates described ‘fractional
distillation’ and hence received no credit for this section. The description should have
included any four of ‘cracking’, ‘heat (or a specific temperature e.g. 600 oC ± 50 oC)’,
‘catalyst’, ‘name of catalyst (any one of aluminium oxide, silicon(IV) oxide, porous pot,
zeolite – at 500 oC) and ‘finely divided’.
(b)
Using bromine to distinguish between ethene and ethane was well known and correctly
described. ‘Going clear’ was not accepted as a correct description of ‘turning colourless’.
(c)
This problem was often attempted via ‘mass of oxygen formed’, and while this will
ultimately supply a correct answer there are so many stages that an arithmetical slip can,
and often did, take place. The application of Avogadro’s Principle is much simpler and an
answer then comes quickly by direct application of the chemical equation.
Question 11
There were many excellent answers here.
(a)
Lithium and sodium were usually identified correctly by using the proton numbers and the
Periodic Table of Elements supplied in the question paper.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
(b)
Candidates had little difficulty in writing the electronic structures of these two elements
and realised that the group of the Periodic Table in which they are placed depends upon
the number of electrons in their outer shells.
(c)
These three elements show many of the physical and chemical properties of metals and
all were acceptable including electrical and thermal conductivity. High reactivity earned
no marks. Trends in properties were not as well known. The most common error was to
believe that the trend moving from lithium to potassium in melting/boiling points is to
become higher rather than lower. Many gave the correct trend in chemical reactivity.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
SCIENCE
Paper 5126/04
Theory (Biology)
Key Message
To perform well in Section A candidates need to follow the wording of the questions carefully.
Answers need to be clear and concise. Some elaboration is required to achieve full credit, but
excessively long answers should be avoided.
In Section B candidates have more freedom to express ideas. Answers should demonstrate their
knowledge and understanding of the subject in more detailed and involved aspects.
In both sections, candidates are expected to be able to interpret data presented in a variety of
formats. In Section B this is likely to involve candidates using their knowledge in less familiar
situations.
General comments
The number of candidates taking this component was very small. Some very good scripts were
seen, showing that these candidates had a good knowledge base and a sound grasp of the ideas
in the syllabus. Many others were able to give factual recall, but could not give interpretations or
explanations that were worthy of credit. Some wrote answers that were not of direct relevance to
the question asked or suggested they had misinterpreted the information given. For a number of
candidates, performance was weaker in Section B, where candidates were given less guidance in
how to frame their answers.
Comments on specific questions
Section A
Question 1
Most candidates showed good knowledge of blood components.
(a)
Many candidates correctly suggested carbon dioxide but fewer could find a second correct
answer.
(b)
Most candidates knew this to be a white blood cell, though some suggested a red blood
cell. Fewer could give a correct function.
(c)
Structures and functions of red blood cells were generally well known. A significant
number of candidates suggested that the biconcave shape was to allow travel through
narrow capillaries rather than to increase surface area for rapid diffusion of oxygen.
Question 2
Most candidates interpreted the data quite well.
(a)
More able candidates gave a clear description of a drug, but others had little idea of the
correct definition.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
(b)
(c)
(i)
Most candidates correctly worked out the risk to be five times greater.
(ii)
More able candidates realised that increase in risk is proportional to the percentage
of alcohol in blood, and that a decrease in the latter would give a decrease in the
former.
(i)
The majority of answers correctly referred to the slowing down of reactions or the
reduction of inhibitions and how these would affect driving.
(ii)
Most candidates gave two correct harmful effects. Some weaker candidates gave
harmful effects of smoking tobacco.
Question 3
The calculation proved to be a problem for many candidates.
(a)
(b)
(i)
Most candidates correctly suggested sun or sunlight. A common incorrect answer
was glucose.
(ii)
Only the more able performed this calculation correctly.
(i)
More able candidates gave the correct equation. Some weaker candidates gave the
equation for anaerobic respiration.
(ii)
Only the most able realised that heat is produced and lost to the atmosphere.
(iii)
Most candidates could give one correct way that energy is lost, but only the more
able could give two.
Question 4
Most candidates showed good graph plotting skills.
(a)
Most candidates plotted the results correctly but fewer could draw a curve of best fit.
(b)
Only the more able made sensible suggestions.
(c)
The majority of answers correctly included ideas of optimum temperature and denaturing
of the enzyme. Few also indicated that reaction rate, and therefore enzyme activity,
increases with increase in temperature (up to the optimum).
(d)
More able candidates gave the correct equation. A common error was to include lactic
acid.
Question 5
Most found interpretation of the diagram difficult.
(a)
Few candidates showed an understanding of the terms genotype and phenotype.
(b)
Most candidates could not translate the information in the diagram to give a sensible
answer to this question.
(c)
Most candidates had similar problems to question (b). Few sensible answers were seen.
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© 2011
General Certificate of Education Ordinary Level
5126 Science November 2011
Principal Examiner Report for Teachers
(d)
All but the weakest candidates filled in the diagram correctly to obtain a chance of 1 in 4.
A few used incorrect letters for the alleles, but still gained marks.
Section B
Question 6
Ideas about pollination had clearly been learned.
(a)
Many candidates had clearly learned this process and gained most of the marks. Others
gave vague rambling answers that gained little credit.
(b)
Weaker candidates confused seed dispersal with pollination. Others gave brief answers
that did not fully address the question. Few candidates gained more than one or two
marks.
Question 7
Few candidates had sensible ideas of how to conduct the investigation.
(a)
Most candidates knew that water is lost through stomata, but few could give any further
description of the process or explain its importance to plants.
(b)
Very few candidates gave a sensible answer. The idea that measurements were involved
occurred to only a few of the most able. Common incorrect answers involved leaving
plants in hot, dry conditions and observing that they wilt.
Question 8
This question allowed most candidates to gain marks.
(a)
Most candidates could relate energy intake to one or two of age, sex and activity, but only
the most able gave sensible answers for all three. Most realised that excessive intake
could lead to obesity, but few went further to suggest the long term effects this would
have.
(b)
More able candidates suggested two other nutrients. Some weaker candidates included
nutrients already given in the question. Adverse effects of nutrient deficiency were less
well known.
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