GCE - Xtreme Level...Unit 5B Unit 5H 6105 6115 Genetics, evolution and biodiversity Genetics, human...

GCE Edexcel GCE

Biology (8040/ 9040)

Biology (Human) (8042/ 9042)

This Examiners’ Report relat es t o Mark

Scheme Publ icat ion code: UA016324

Summer 2005

Examiners’ Report

Ed

exce

l G

CE

Bio

logy (

80

40

/9

04

0)

Bio

logy (

Hu

ma

n)

(80

42

/9

04

2)

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Summer 2005

Publ icat ions Code UA016324

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© Edexcel Lt d 2005

Summer 2005 i 8040/ 8042/ 9040/ 9042 Examiners’ Report s

Contents

pg

Unit 1 6101 Molecules and cel ls 1

Unit 2B

Unit 2H

6102

6112

Exchange, t ransport and reproduct ion

Exchange, t ransport and reproduct ion in humans

3

6

Unit 3 6103/ 01 T1

6103/ 02 W1*

6103/ 03

Individual invest igat ion

Writ t en al t ernat ive t o coursework*

Energy and t he environment

7

10

12

Unit 4 Core mat erial

Opt ion A

Opt ion B

Opt ion C

Respirat ion and coordinat ion

Microbiology and biot echnology

Food Science

Human heal t h and f it ness

14

16

17

18

Unit 5B

Unit 5H

6105

6115

Genet ics, evolut ion and biodiversit y

Genet ics, human evolut ion and biodiversit y

20

22

Unit 6 6106/ 01 T2

6106/ 02 W2

6106/ 03

Individual St udy

Writ t en al t ernat ive t o coursework

Synopt ic paper

24

27

29

Appendix A: Unit Grade Boundaries and Uniform Marks 32

Appendix B: The Uniform Mark System 34

* 6103/ 02 W1 Writ t en al t ernat ive t o coursework is only available t o Int ernat ional cent res.

Summer 2005 6101 Biology Unit 1

6101 Unit 1 Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 60

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 32.5

St andard deviat ion . . . . . . . . . . . . . . 10.8

General comments

Quest ions 1, 2, 3(a) and (b), 5(c) and 6(c)(i i) were high scoring. Quest ions 4(b), 5(a), 7(a)(i i)

and 8(b)(i) and (b)(i i) were low scoring. Of t hese low scoring quest ions, 4(b) and 8(b) required

candidat es t o read and int erpret t he informat ion provided while 5(a) and 7(a)(i i) were bot h

relat ed t o pract ical t echniques.

Question 1

A signif icant number of candidat es were able t o gain ful l marks in part (a). Some answers,

however, did not include bot h monosaccharides present in lact ose. In part (b) it was pleasing

t hat t he maj orit y of candidat es were able t o name t he bond t hat was present bet ween t wo

monosaccharides.

Question 2

Many candidat es performed wel l on t his quest ion, demonst rat ing a good knowledge of t he

prot ein st ruct ure. Some referred only t o hel ix rat her t han alpha hel ix when describing

secondary st ruct ure and some used t he t erm double hel ix. There was l i t t le reference t o R

groups in relat ion t o t ert iary st ruct ure.

Question 3

In part (a) about half of t he candidat es correct ly label led al l t hree part s but some referred t o

chlorophyl l rat her t han chloroplast . A signif icant number of candidat es disappoint ingly

ident if ied part C in t he bact erial cel l as a nucleus. Many candidat es were able t o give a

dif ference bet ween t he cel l wal ls in part (b) and while most candidat es achieved t he f irst point

in part (c) for enabl ing movement , very few at t empt ed t o give a reason for t he movement .

Question 4

Many candidat es seemed famil iar wit h t he names of t he molecules in part (a) (i) and (i i) but

only a few candidat es could give a correct funct ion of t he glycoprot ein. There were some very

good answers in part (i i i) and t he maj orit y of candidat es were able t o make suit able references

t o hydrophobic and hydrophil ic propert ies.

A lot of candidat es could not int erpret t he informat ion in part (b). Many candidat es made no

at t empt t o answer t he quest ion while ot hers gave irrelevant descript ions about t ransport

across t he membrane.

Question 5

The t echnique referred t o in part (a) remains one t hat a signif icant number of candidat es are

not famil iar wit h. Marks were most ly gained for referring t o t he name of a suit able st ain or for

squashing under a coversl ip. Some candidat es referred t o t he point s t hat examiners were

looking for, but not in t he correct sequence.

In part (b) t he maj orit y of candidat es were able t o use t he dat a t o ident ify t he longest and

short est st age. A good number of candidat es also successful ly compared t wo phases by

manipulat ing f igures and t his was most encouraging. However, many candidat es simply quot ed

percent ages and made no reference t o t ime at al l . Most candidat es gained bot h marks in part

(c).

8040/ 8042/ 9040/ 9042 Examiners’ Report s Page 1 Summer 2005


Question 6

Alt hough many candidat es gained a mark in part (a) for explaining magnif icat ion only a few

candidat es could give an appropriat e st at ement about resolut ion wit h many candidat es

referring t o clarit y.

It was pleasing t o not e t hat many candidat es were able t o correct ly complet e t he calculat ions

in part s (b) and (c)(i). This was an area of t he specif icat ion t hat had not been t est ed before in

t his way.

When required t o make a drawing of somet hing t hat can be seen in a phot ograph, some

candidat es include st ruct ures t hat are not visible in t he original phot ograph.

Question 7

In part (a)(i), al t hough most candidat es knew a buf fer could be used t o cont rol pH only a few

candidat es could ident ify t hat t he area of t he clot h was import ant for cont rol l ing t he volume of

subst rat e.

A vast maj orit y of candidat es were unable t o accurat ely describe a cont rol in part (a)(i i). The

most common approach was t o leave out t he buf fer rat her t han t he enzyme.

In part (b) many candidat es correct ly referred t o a change in shape of act ive sit e and t hat t his

af fect ed t he enzyme-subst rat e binding. However, st at ement s about denat urat ion were of t en

not in a suit able cont ext .

Part (c) was very wel l answered, wit h many candidat es scoring bet ween 3 t o 5 marks or ful l

marks. Candidat es seemed t o have a good underst anding of t he st ruct ure of bot h amylase an

amylopect in wit h clear references t o bonding and shape.

Question 8

In part (a), drawings ranged f rom very poor t o excel lent . Candidat es who did draw it wel l

showed a clear st ack of cist ernae. Many candidat es also drew vesicles close by and labels were

correct . However, some candidat es drew what looked l ike vesicles but label led t hem

ribosomes. Cist ernae were somet imes incorrect ly label led crist ae. Ot hers put ribosomes on

t he cist ernae.

In part (b)(i) most candidat es described t he radioact ivit y decreasing and t herefore obt ained

t he f irst mark. However, not many candidat es were able t o go on and give a reason why t here

was a decrease. A signif icant number of candidat es made no at t empt t o answer quest ion (b)

(i i). Those who did give an answer of t en j ust described t he result s rat her t han explain t hem.

Explanat ions t hat were seen usual ly only made references t o radioact ivit y moving and did not

refer t o prot eins. Some candidat es could make a reference t o format ion of vesicles wit h

prot ein in t hem (point f ive on t he mark scheme).


Summer 2005 6102 Biology Unit 2B

6102 Unit 2B Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 60

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 32.7


General comments

The usual wide range of responses was seen t o t his Paper, f rom t hose candidat es wit h a sound

knowledge and underst anding of t he specif icat ion, t o t hose for whom most , or al l , of t he

quest ions proved t o be dif f icul t t o answer successful ly.

In general, candidat es coped wel l wit h quest ions 1, 2(b), 7 and 8(a)(i i i ). There were also many

good answers t o quest ion 8(b). Answers t o t he ot her quest ions were more variable; in

part icular, many candidat es found quest ions 2(a), 4(b), 5(a)(i), 6(c) and 8(a)(i) dif f icult . In a

number of cases, marks were lost by candidat es fail ing t o read and assimilat e informat ion

given in t he quest ions, and including irrelevant det ails in t heir answers. In many cases

candidat es’ answers were poorly expressed.

Question 1

The maj orit y of candidat es coped wel l wit h t his quest ion and gained good marks. One common

error was naming ‘ phagocyt es’ as a specif ic t ype of leucocyt e. Some candidat es also found it

dif f icul t t o select an appropriat e word t o describe t he shape of a lymphocyt e nucleus.

Question 2

Part (a) of t his quest ion was of t en answered more successful ly t han part (b), where candidat es

were able t o give a more accurat e account of myoglobin t han of haemoglobin. In part (a),

many candidat es gave descript ions of t he st ruct ure and propert ies of red blood cel ls but were,

nevert heless, somet imes able t o score marks for incident al references t o t he propert ies of

haemoglobin. There were, however, a number of good answers including references t o t he

reversible nat ure of t he af f init y of haemoglobin for oxygen, it s abil i t y t o t ransport carbon

dioxide, and descript ions of t he Bohr ef fect .

Many candidat es were able t o describe t he role of myoglobin as a st ore of oxygen and referred

t o t he release of oxygen at very low part ial pressures of oxygen. There were also a number of

good descript ions of t he t ransfer of oxygen f rom oxyhaemoglobin t o myoglobin.

Question 3

In part (a), t he maj orit y of candidat es correct ly named St age B as vent ricular syst ole, but t he

answers t o part (b) were more variable. Many of t he answers gave complet e account s of t he

cardiac cycle and it s coordinat ion, rat her t han focusing specif ical ly on t he event s during

complet e cardiac diast ole. In part (c), t here were some good descript ions of t he coronary

circulat ion, but also a number of inaccurat e descript ions of t he circulat ory syst em in general .

Many candidat es scored at least one mark for an appropriat e reference t o t he coronary

art eries. However, some candidat es made references t o t he heart being ‘ surrounded wit h

capil laries’ , where it was expect ed t hat candidat es would indicat e t hat t he capil laries are

wit hin t he cardiac muscle.



Question 4

In part (a), many candidat es incorrect ly ident if ied cel l st ruct ure A as a vi l lus but , in a number

of cases, were able t o gain good marks for t he rest of t his part . Candidat es were asked t o

explain how t hese part s assist in glucose absorpt ion, but t his was ignored by a number of

candidat es who gave general descript ions of t he funct ions of microvil l i and capil laries.

Answers t o part (b) f requent ly showed t hat candidat es had not assimilat ed t he informat ion

provided in t he int roduct ion; not ably t hat t he concent rat ion of glucose in t he solut ion was

lower t han t he concent rat ion of glucose inside t he epit hel ial cel ls. Consequent ly, t here were a

number of descript ions of upt ake by dif fusion. There were, however, a number of good

account s in which candidat es recognised t hat t he upt ake of glucose was against t he

concent rat ion gradient and correct ly described act ive upt ake. Many candidat es gained a mark

for a simple reference t o t he increase in glucose concent rat ion in t he cel ls; i t was also pleasing

t o not e t hat some candidat es int erpret ed t he graph as showing a const ant rat e of upt ake.

Question 5

Part (a)(i) proved chal lenging for many candidat es, who found it dif f icult t o describe t he

relat ionship bet ween dept h and t he concent rat ion of dissolved oxygen. This may be because

t he informat ion in t he graph was present ed in an unfamil iar way, but nevert heless candidat es

are expect ed t o be able t o int erpret and t ranslat e dat a f rom one form int o anot her. Many of

t he answers were poorly art iculat ed and it was not always clear, for example, whet her

candidat es were describing an increase, or a decrease in dept h. Part (a)(i i) was general ly

answered more successful ly t han part (a)(i) and candidat es f requent ly gained marks for

references t o t he presence of a respirat ory pigment , or a breat hing t ube.

Part (b) of t his quest ion was int ended t o t est candidat es’ underst anding of t he relat ionship

bet ween t he ext ernal feat ures of an organism and t he physical charact erist ics of a specif ic

habit at . Candidat es almost invariably gained marks here; usual ly for references t o t he

presence of a eit her a t ai l , or gil ls, in relat ion t o t he aquat ic habit at .

Question 6

In part (a), al t hough many candidat es referred t o t he ant her, t here were also a number of

incorrect references t o pol len grains. Part (b) was usual ly answered correct ly, al t hough various

ot her st ages of meiosis were also seen. Answers t o part (c) were very variable. This is anot her

quest ion in which candidat es appeared not t o use t he informat ion provided, as many of t he

chromosome numbers candidat es gave were based on a diploid number of 46, or anot her

number, rat her t han 14. Several candidat es, who gave t he correct number of chromosomes in

t he female gamet e, t he zygot e nucleus and t he endosperm cel l , incorrect ly indicat ed t hat t he

pol len t ube nucleus is diploid.

Question 7

Many candidat es ident if ied t he t issue correct ly in part (a)(i) and gave good descript ions of gas

exchange in part (a)(i i), including references t o t he air spaces and dif fusion of gases.

Relat ively few candidat es comment ed on t he irregular shape of t hese cel ls as a reason for t heir

increased surface area, and some answers included irrelevant det ails about t he lower

epidermis and st omat a.

In part (b)(i), t here were many correct suggest ions t hat t he volumes of carbon dioxide and

oxygen are t he same, but some candidat es incorrect ly assumed t hat t he respiromet er was

being used t o invest igat e phot osynt hesis. In part (b)(i i), marks were somet imes lost by careless

subt ract ion, or by fail ing t o include t he unit s, but many candidat es gained ful l marks for t his

part .



Question 8

Part (a)(i) was rarely answered correct ly and a number of candidat es did not at t empt t his part .

Answers t o part (a)(i i) were also very variable. Alt hough many candidat es ident if ied t his

correct ly as a Graaf ian (or mat ure) fol l icle, t here were many ot her suggest ions, including

t ert iary fol l icle. The hormones secret ed by t he corpus lut eum were, however, more famil iar t o

t he maj orit y of candidat es and many gained bot h marks here.

Answers t o part (b) f requent ly cont ained det ailed account s of t he event s leading t o

fert i l isat ion, wit h t he process it self described, in some cases, almost as an af t ert hought .

Candidat es f requent ly gained marks for indicat ing t hat fert i l isat ion occurs in t he fal lopian

t ube, and for describing t he release of enzymes f rom t he acrosome. References t o t he fusion

of sperm and egg membranes, and fusion of sperm and egg nuclei were seen on a minorit y of

script s. Some of t he answers t o part (c) were rat her vague, referring t o, for example, t he

t ransfer of nut rient s, oxygen and wast e product s but wit hout any clear indicat ion of which way

t he t ransfer occurs. Nevert heless, t here were also some very good answers t o t his part ,

including most of t he point s on t he mark scheme, and gaining ful l marks.


Summer 2005 6112 Biology (Human) Unit 2H

6112 Unit 2H Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 60

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 27.3


General comments

Quest ions 1, 2, 3, 4 and 8 on t his Paper were common bet ween 6102 and 6112 and t he st andard

of answers was considered t o be comparable. As wit h 6102, a wide range of responses was

seen. One t opic which seems t o cause part icular dif f icult ies for candidat es is t he regulat ion of

body t emperat ure and t he answers t o quest ion 5 were general ly poor. Candidat es also found it

dif f icul t t o express t heir ideas accurat ely in quest ion 6 part (b) and, in quest ion 7 part (a),

t here was some confusion bet ween breat hing rat e and pulse rat e.

Questions 1 to 4

Common wit h 6102

Question 5

There were some good answers t o part (a), in which candidat es accurat ely compared t he

changes in t emperat ure, al t hough a number of candidat es st at ed incorrect ly t hat t he

t emperat ure of t he hand in air remained at 26 °C. Many candidat es st ruggled t o give accurat e

physiological explanat ions for t he dif ferences in t emperat ures and it appeared t hat a number

of candidat es did not appreciat e t he fact t hat t he volunt eer was immersed in wat er at 10 °C.

Some of t he answers t o part (c) included references t o vasoconst rict ion, but somet imes t he

cont ext was poor, suggest ing t hat t he meaning of t his t erm was unclear. However, t here were

also a number of correct references t o shivering and t he consequent generat ion of met abol ic

heat .

Question 6

The maj orit y of candidat es correct ly ident if ied t he t ype of cel l division in part (a), al t hough

t his was not always support ed wit h an appropriat e reason. Answers t o part (b) were of t en

poorly expressed, using inaccurat e words, such as ‘ exchange of informat ion’ bet ween

chromat ids. Alt hough many candidat es recognised t hat pairing of chromosomes occurs during

prophase I, t his was not always qual if ied wit h reference t o homologous chromosomes. Part (c)

was of t en answered correct ly.

Question 7

In part (a) many candidat es gave descript ions of a met hod for f inding t he pulse rat e, rat her

t han for f inding t he breat hing rat e. The maj orit y of candidat es gained one mark in part (b)(i)

for describing t he relat ionship bet ween walking speed and t he pulmonary vent i lat ion rat e. It

was pleasing t o not e t hat many candidat es also qual if ied t heir descript ion wit h an appropriat e

quant it at ive comment and gained bot h marks. In part (b)(i i), many candidat es at t empt ed t o

explain t he mechanism in t erms of an increased demand for oxygen, rat her t han as a

consequence of t he increased product ion of carbon dioxide. However, one mark was usual ly

gained for a reference t o t he respirat ory cent re, or t o t he medul la.

The st andard of answers t o part (c) was very similar t o t he st andard of t he equivalent

calculat ion in 6102. A number of candidat es incorrect ly divided t he dif ference by 72, but

were, nevert heless, given credit for t heir consequent ial error.

Question 8

Common wit h 6102


Summer 2005 6103 Biology Unit 3 paper 01 T1

6103/ 01 Unit 3 T1 Individual Investigation Moderators’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 32

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 20.1


General comments

Most cent res’ candidat es undert ook invest igat ions t hat could ful f i l t he coursework crit eria, but

t he qual it y wit h which t hey were carried out was very varied. Nevert heless t he general

st andard was similar t o t hat of last year. When broken down by skil l area, however, Planning

and Implement ing were somewhat improved, whereas Analysing and Evaluat ing were not .

It was found t hat many able candidat es played safe in t heir invest igat ions by choosing

hypot heses t hat were mainly about proof of wel l-known fact s. Occasional ly, coursework of t his

t ype led t o t he reinforcement of misconcept ions about enzyme-cont rol led react ions,

part icularly about t he ef fect s of t emperat ure and subst rat e concent rat ion, and subsequent ly,

t o poor Analysing and Evaluat ing sect ions. On f inding result s t hat did not f i t t he expect ed

pat t ern, t his t ype of candidat e t ook furt her measurement s unt i l t hey did f i t rat her t han

comment ing on t his in t heir work.

Annot at ions improved t his year, but more cent res f i l led in pro f ormas which t hey had devised,

rat her t han providing ful l comment s in t he body of t he report . In a minorit y of cases, t he only

marks on a script were t he four t ot als for t he various skil ls. In such cases, in t he fut ure, work

may be ret urned for marking, especial ly where t he U9 Report f rom a previous session

comment s about t his. It is import ant t o not e t hat cent res in which annot at ions are sket chy at

best are t hose whose marks are most unrel iable. Final ly, t here are cent res t hat st i l l do not

recognise t he hierarchical nat ure of t he assessment crit eria, so t hat marks are not awarded at

a part icular level, when a candidat e’ s work cont ains omission(s) at t hat level.

The vast maj orit y of cent res recorded marks wit h which moderat ors agreed, but t here were

quit e a number who awarded highly inf lat ed scores for some invest igat ions, but not for ot hers.

Cent res are reminded t hat whilst moderat ors record marks for a sample of script s, i t is al l t he

candidat es f rom t he cent re t hat may be af fect ed by t he over-inf lat ed scores of a few.

Most cent res used t he up-t o-dat e Record Sheet s, but many did not . There is a requirement for

t wo signat ures on each sheet , one for t he t eacher and t he ot her for t he candidat e. The

relevant Record Sheet may be found in t he most recent copy of t he Specif icat ion or by logging

on t o www.edexcel.org.uk and fol lowing t he rout e t hrough Qual i f icat ion ~ GCE, Subj ect area ~

Biology/ Biology (Human), AS GCE ~ Biology, t hen look under Guides and cl ick on t he l ink

Record Sheet .



Planning

There was evidence t hat many candidat es’ plans are not being checked before t he candidat es

are al lowed t o proceed. It is import ant t hat checks are made at t his st age, so t hat candidat es

are given t he opport unit y t o make changes, in order t hat t he planned measurement s are l ikely

t o yield dat a suit able for Analysing and Evaluat ing at t he highest level. Candidat es need

guidance on t he accept abil i t y of t heir plans.

Suf f icient , relevant biological knowledge and adequat e cont rol of variables remain l imit ing

fact ors in Planning. For example, candidat es describe everyt hing t hey know about enzymes,

wit hout suf f icient det ail about t he variable being invest igat ed. Of t en variables are ment ioned

in t he procedure, but t here are no specif ic st at ement s about variable cont rol i t sel f .

Candidat es are st rongly advised t o provide a separat e sect ion on t his aspect .

Risk assessment s are much improved, but for 8 marks t hese must be l inked t o t he specif ic

procedures and chemicals used.

Implementing

There were st i l l problems moderat ing t his sect ion as many cent res failed t o provide

informat ion about a candidat e’ s performance. Moderat ors expect t o see not es on sub-sect ions

(a) and (b). Absence of t hese may l imit a candidat e’ s marks overal l , especial ly i f t he only

evidence in t he work is a t able of raw dat a. For t he award of higher levels t he invest igat ion

must normally al low for t he demonst rat ion of manipulat ive skil ls and yield suf f icient dat a. In

many invest igat ions at AS, t hree or possibly more repeat s wil l be required.

Analysing

Graphical present at ion was bet t er t han in previous sessions, but lack of select ivit y remains a

problem. Cent res are reminded of t he Inst it ut e of Biology’ s recommendat ion t hat ‘ a smoot h

curve should only be drawn i f t here is good reason t o bel ieve t hat int ermediat e values f al l on

t he curve […] ot herwise, st raight l ines j oining point s should be drawn’ . Drawing a curve or

l ine of best f i t may hide import ant t rends and pat t erns exhibit ed by t he dat a. Large numbers

of candidat es drew error (range) bars t o show variat ion in t he dat a, however 8 marks cannot be

awarded unless more basic skil ls, such as plot t ing and l ine drawing, are also ful f i l led

sat isfact ori ly. Many cent res’ candidat es calculat ed st andard deviat ions f rom t hree repeat s.

There is l i t t le point in doing t his; range bars are cert ainly much more informat ive at t his level.

Many, bet t er candidat es fai led t o score t he higher marks for t heir descript ions of t rends,

pat t erns and anomalies. This was mainly because t rends and pat t erns were incomplet ely

and/ or superf icial ly described, so t hat a mark of 6(b) could not be awarded.

Final ly, t he biological support for t he result s of t en l imit ed t he marks for Analysing. Somet imes

t his was because of a failure t o describe in biological t erms t he t rends candidat es described,

but most f requent ly because t he explanat ions of fered were based on incorrect science.

Candidat es who obt ained unexpect ed dat a f requent ly fai led t o explain t hem in any meaningful

way. This was unfort unat e, because it is at st ages such as t his t hat candidat es can real ly begin

t o engage in scient if ic analysis and t hus score t he highest marks in t his sect ion.



Evaluating

Many candidat es st i l l appear uncert ain about what is required in t his skil l . Sensible comment s

on t he rel iabil i t y of t he dat a or t he accuracy of t he t echniques used were rare. Many

candidat es l ist ed experiment al errors or problems t hat should have been el iminat ed in t he

Planning st age. Many candidat es’ dif f icul t ies were of t he general kind and failed t o address

t hose dif f icul t ies act ual ly experienced during t heir own invest igat ions. Limit at ions were rarely

described or explained. These might be relat ed t o t he inst rument s used (provided t hat t hey

were appropriat e t o AS-level).

Whilst error bars appear more f requent ly in graphs, most candidat es did not underst and t he

need for t hem. These need t o be used t o comment on t he rel iabil i t y of t he dat a and t he

conclusions reached.

It is in Evaluat ing, t hat moderat ors’ and cent res’ marks dif fered most widely. Cent res

f requent ly gave high marks when one of t he sub-sect ions was dist inct ly weak. Usual ly, t his was

because E (a) was credit ed wit h 6 or 8 marks when t he words rel iabil i t y and variabil i t y had

been used in a very short paragraph, which described t hese t erms in a very general sense.

These ranges of marks are t oo generous.

Furt her work must be l inked t o t he original hypot hesis, which demands close at t ent ion t o t he

variable invest igat ed. Candidat es do not gain credit by launching int o complet ely new st udies.

Final ly, some candidat es wrot e a general ‘ conclusion’ covering Analysing and Evaluat ing, wit h E

(a) omit t ed. These t wo areas are best addressed separat ely.

Administration

Reminders:

Do hold sheet s for each report t oget her wit h a t reasury t ag. Please do not enclose report s in

t ransparent pocket f i les or organise t hem in bulky folders.

Do annot at e coursework.

Do use Report Sheet s wit h spaces for t eacher and st udent signat ure.


Summer 2005 6103 Biology Unit 3 paper 02W1 Avai lable t o Int ernat ional cent res only

6103/ 01 Unit 3 W1 Written Alternative Examiners’ Report International Only

Maximum mark . . . . . . . . . . . . . . . . . . . 32

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 16.4


General comments

Once again, quest ion 1 produced some very good answers, which were general ly bet t er t han

t hose in quest ion 2. Nevert heless, in t his second quest ion, candidat es were much more

focused t han in t he past on providing relevant , experiment al det ail . Overal l , t he st andard was

much bet t er t han last summer.

Question 1

(a) Most candidat es successful ly complet ed t he t able. For t hose who did not , t he most

common errors were:

• Unit s included wit h t he dat a

• Rounding errors when calculat ing percent ages

• Missed f igures for dist i l led wat er

(b) Most graphs were correct ly format t ed, wit h precise plot s and accurat ely drawn l ines.

However, a surprisingly large number cont ained axes errors more usual ly on t he x-axis

wit h a non-uniform scale.

(c) Few candidat es clearly ident if ied t wo of t he t hree marking point s. A large number

merely described every event and did not score at al l . The most common response

focused on t he maximum ef fect at 0.05 mol dm-3

.

(d) Similar t o last year, references t o t he hypot hesis were rare. Many answers j ust

repeat ed part (c). It was rare t o see t wo correct point s. Candidat es appeared t o be

very uncert ain about t heir responses, which should have relat ed not only t o t he init ial

hypot hesis and t o t he dat a, but also t o t he biology of st omat al opening.

(e) Many candidat es answered t his part in t erms of ‘ l imit at ions’ and ‘ improvement s’ rat her

t han on ‘ addit ional evidence’ . Unfort unat ely, relevant answers lacked clarit y. For

example, many candidat es referred t o ‘ dif ferent leaves’ whereas examiners were

looking for somet hing more specif ic, relat ing t o t ype or even species.


Summer 2005 6103 Biology Unit 3 paper 02W1 Avai lable t o Int ernat ional cent res only

Question 2

(a) Maximum marks for t his sect ion were not uncommon t his year. The mark scheme

al lowed for a variet y of ways for t he det erminat ion of t he disappearance of prot ein,

t hough most chose t he Biuret rout e. Many candidat es used a specif ied prot ein t o st udy

t he enzyme ef fect s, t hough a sizeable minorit y used cont act lenses t hemselves.

Variable cont rol was general ly sound, and specif ic names and quant it ies of mat erials

used were clearly st at ed. It was pleasing t o see t he at t empt s by candidat es t o secure

equivalent prot ein quant it ies on cont act lenses. However, relat ively few candidat es

dissolved t he enzymes, which were suppl ied as a powder.

(b) Two, or even maximum, marks were not uncommon in t his sect ion. Tables general ly

ref lect ed t he procedures used in planning and most graphs were correct . Nevert heless

t hey somet imes lacked precision or clarit y eit her in t heir labels, or t ype. Descript ions

of t he graphical format rarely score t wo marks.

(c) This was t he most discriminat ing part of quest ion 2. Many candidat es scored zero or

only one mark, wit h scores of four marks or more being very rare. The most common

answer focused on end point dif f icul t ies, but t his could only be awarded if t he planned

met hod would produce such problems. Marks for l imit at ions are never awarded for

references t o omissions in planning.

Answers on furt her work lacked precision. There was also evidence of t he use of past

mark schemes here, which gained l i t t le credit . Answers must be specif ic t o an

invest igat ion, ot herwise t hey are not credit wort hy.


Summer 2005 6103 Biology Unit 3 paper 03

6103/ 03 Unit 3 Paper 03 Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 38

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 18.9


General comments

The examiners were pleased t o see t hat t he maj orit y of t he candidat es were able t o at t empt

al l sect ions of t his paper. It was evident t hat many candidat es had a sound knowledge of t he

specif icat ion requirement s and were able t o apply t his knowledge t o t he informat ion in t he

quest ions. Candidat es who did not read al l of t he informat ion in t he quest ions or who did not

t ake int o account t he mark al locat ions t ended t o produce answers t hat fel l short of t he

required marking crit eria.

Question 1

In part (a), most candidat es gave accept able responses. Common errors included put t ing

decomposit ion in boxes B and C and reversing phot osynt hesis and respirat ion in boxes C and D.

In part (b), relat ively few candidat es were able t o give a sat isfact ory explanat ion of t he t erm.

Most candidat es could name an example. The most common misunderst anding was t hat t he

carbon compounds formed by phot osynt hesis e.g. glucose, st arch, make up t he carbon sink.

Some candidat es confused t he t erm wit h “ source and sink” in t ranslocat ion.

In part (c), many candidat es confused t he forms of radiat ion. Common errors included

reference t o l ight being t rapped, UV t urning t o inf ra red, carbon dioxide becoming part of t he

ozone layer and t he sun being absorbed by t he gases. Bet t er candidat es did give accurat e and

det ailed explanat ions t hat of t en would have qual if ied for al l of t he mark point s.

In part (d), most candidat es could name t wo accept able gases. A signif icant number named

sulphur dioxide or referred vaguely t o nit rogen oxides.

Question 2

In part (a), most candidat es gave accept able responses. However, some candidat es gave

cont radict ory answers e.g. herbivores as secondary consumers.

In part (b), most candidat es were able t o calculat e t he percent age correct ly al t hough t here

were many candidat es who st ruggled wit h basic arit hmet ic. Some candidat es who gave t he

correct answer did not show a calculat ion t hat would have given t his answer. Some performed

t he calculat ion correct ly and t hen gave incorrect unit s for t he answer.

In part (c), only t he bet t er candidat es gave answers t hat involved t he relat ive posit ion of cat t le

and maize in t he food chain t hat has humans as t he f inal consumer. Many answers included

references t o maize using less energy t han a cow because it does not move around or urinat e.

A large number of candidat es at t empt ed t o explain t hat t he cat t le would eat t he maize and

t hat t his is why t here would be less available t o humans.


Summer 2005 6103 Biology Unit 3 paper 03

In part (d), many candidat es were able t o make suf f icient comment about each of t he label led

st ruct ures t o gain ful l credit . A signif icant number of candidat es included irrelevant

descript ions involving t he diast ema and t he t ongue. Overal l t his sect ion was wel l-answered.

In part (e), only a few candidat es could give answers t hat explained ways in which more energy

can be obt ained f rom plant mat erial by a ruminant such as a cow. Alt hough many candidat es

referred t o regurgit at ion only t he bet t er candidat es explained t hat t his enables more digest ion

or chewing t o t ake place. References t o t he presence of microoorganisms were common but

only a few candidat es could give det ails of t heir act ion upon cel lulose. Some candidat es gave

answers t hat were ext ensions of t heir answers t o part (d).

Question 3

In part (a), t he maj orit y of candidat es made reference t o t he fact t hat t here was no change in

Papua New Guinea. Alt hough most candidat es recognised t hat bot h Thailand and Brunei

showed decreases, a large number of candidat es wrot e t wo separat e descript ions and did not

make any comparisons. Many candidat es quot ed f igures wit hout making any comparat ive

manipulat ion. Some candidat es included Malaysia and Indonesia in t heir answers.

In part (b), most candidat es could give t wo accept able responses. The most common error was

t o give reasons t hat included t he use of t imber as building mat erial .

In part (c), most candidat es were able t o make an accept able comment about t he loss of

prot ect ive cover for t he soil or t he fact t hat t he t ree root s are involved in holding t he soil

t oget her. Many candidat es were unable t o gain furt her credit by explaining t hat soil would be

washed away by rain or t hat t he wind would blow soil away, inst ead candidat es st at ed t hat t he

rain or wind would erode t he soil . Some candidat es concent rat ed upon t he loss of nut rient s

inst ead of t he soil .

In part (d), t here were some very confused account s. Alt hough many candidat es referred t o

less t ranspirat ion relat ively few explained t hat t his would cause lower humidit y and less

rainfal l . References t o an increased risk of f looding were common alt hough t his was not always

l inked t o t he increased run-of f int o lakes and rivers. There were relat ively few references t o

t he possible ef fect s upon global cl imat e. Some candidat es cont inued t o describe t he soil

erosion ef fect s.

In part (e), a signif icant number of candidat es did not concent rat e upon t he changes in t he

habit at but described t he changes in t he apes and monkeys in t he habit at , al t hough some

candidat es real ised t his and renumbered t heir answers. Candidat es who concent rat ed upon

t he habit at t ended t o score high marks. It is emphasised t hat at t his level loss of homes is not

considered equivalent t o loss of habit at . Most candidat es concent rat ed upon t he loss of

habit at and t he ef fect s upon t he food chain. However, many of t hese answers did not refer t o

t he loss of habit at for t hose species t hat rel ied upon t he t imber t rees. Only bet t er candidat es

made point s concerning t he advant ages t hat ot her species may gain as a result of t he removal

of t he t imber t rees.

In part (f )(i), most candidat es were able t o st at e t hat t here was a decrease in al l t hree of t he

species as a result of t he logging and described some of t he changes af t er t his. However, t he

wording in t he quest ion indicat es t hat it was expect ed t hat t he changes would be relat ed t o

t he t ime scale t o be given credit . Vague descript ions of fal ls and rises wit hout any reference

t o t he dat a penal ised large numbers of candidat es.

In part (f )(i i ), very few candidat es were able t o give accept able explanat ions. Many candidat es

made no reference t o t he dist urbance t hat t he logging might cause. A few candidat es used t he

informat ion given by t he phot ograph t hat t he gibbon might require closed forest t o move

t hrough t he canopy. A large number of candidat es confused t he dif ferent species of langur.


Summer 2005 6104 Biology Unit 4 Core

6104 Unit 4 Core Examiners’ Report

Core informat ion for:

Opt ion A Opt ion B Opt ion C

Maximum mark. . . . . . . . . . . . . . . . . . . . . . . . . 40 40 40

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.8 19.4 21.1

St andard deviat ion . . . . . . . . . . . . . . . . . . . . 6.9 6.8 6.9

Question 1

Part (a) was reasonably wel l done wit h t he maj orit y of candidat es scoring 2 or 3 marks. One of

t he common errors t hat candidat es made was t o simply st at e t hat t he met hod of t ransmission

was ‘ neurone’ or ‘ blood’ inst ead of act ual ly answering t he quest ion by explaining t hat it was

‘ along a neurone’ and ‘ in t he blood’ . There were a number of candidat es who did not

appreciat e t hat durat ion referred t o a period of t ime and gave t he dif ferences as ‘ fast ’ and

‘ slow’ or ‘ immediat e’ and ‘ delayed’ .

In part (b) t here were quit e a number of candidat es who did not ident ify t hat chemicals were

act ual ly involved in bot h forms of communicat ion.

Question 2

‘ Glucagon’ was f requent ly named as t he hormone secret ed in ant icipat ion of exercise in part

(a), presumably because t he quest ion had not been read properly or been t hought about long

enough.

Candidat es were not penal ised for referring t o t he wrong hormone in part (b) and many went

on t o score highly, even t hough t here were some very long-winded ways of simply st at ing t hat

t he glucose was being produced where it was going t o be used. There were a surprisingly high

number of candidat es who t hought t hat readily available glucose would enable t he muscle cel ls

t o cont inue respiring aerobical ly. The t erms glucogenolysis and gluconeogenesis were of t en

used wrongly; i t would have been bet t er for candidat es t o simply describe what was

happening.

Question 3

Part (a) of t his quest ion was very wel l done wit h many candidat es scoring t he maximum 4

marks. The rest of t his quest ion was less wel l answered. A whole range of values were given

in part s (b) and (c) (i) for t he number of ATP molecules produced, which seemed t o bear no

resemblance t o t he informat ion given in t he diagram. In part (c)(i i) a number of candidat es

got int o t he quest ion and t hen real ised what t hey were being asked. A number of candidat es

t alked about t he need for a lot of energy being required t o break t he high energy bonds

present in t he l ipid.


Summer 2005 6104 Biology Unit 4 Core

Question 4

In past examinat ions candidat es have not answered quest ions about t he kidney very wel l , so it

was pleasing t o see candidat es doing wel l on t his quest ion.

In part (c) a lot of informat ion irrelevant t o t he quest ion was writ t en by many candidat es who

did not know t hat t he ADH was already in t he blood st ream; long account s of t he det ect ion by

osmorecept ors of blood solut e pot ent ial and subsequent product ion and secret ion of ADH were

t herefore given. These candidat es event ual ly got around t o explaining what happened in t he

kidney and were awarded t he marks accordingly.

Part (d) was answered wel l by t hose candidat es who real ized t hat t hey were being asked about

t he det ect ion by osmorecept ors of blood solut e pot ent ial and subsequent product ion and

secret ion of ADH. Candidat es who t hought t hat an increase in solut e concent rat ion caused

eit her t he solut e pot ent ial or t he wat er pot ent ial t o increase as wel l lost marks. Again,

candidat es who cannot use t he t erms “ solut e pot ent ial” and “ wat er pot ent ial” correct ly may

be wel l-advised t o describe solut e concent rat ion in t his t ype of quest ion. A number of

candidat es t ried t o say t hat t he salt inj ect ion would eit her ef fect ul t raf i l t rat ion or increase t he

concent rat ion of salt in t he medul la.

Question 5

Most answers t o t his quest ion were very good, wit h many candidat es scoring highly. However,

t here were answers t hat included diagrams t hat were poorly label led and so did not yield any

marks.


Summer 2005 6104 Biology Unit 4 Opt ion A

6104/ 01 Unit 4 Option A Examiners’ Report

Opt ion only Core + Opt ion

Maximum mark . . . . . . . . . . . . . . . . . . . 30 70

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 13.0 34.3

St andard deviat ion . . . . . . . . . . . . . . 5.6 12.0

Question 6

Many candidat es are now famil iar wit h t he gram st aining t echnique and have a good

underst anding of t he principals behind it . The most common error was made by t hose

candidat es who t hought t hat you could wash out or ret ain ‘ colour’ as opposed t o “ st ain” or

“ dye” .

Question 7

The role of yeast in dough product ion has not been t est ed t oo f requent ly in t he past but it is

clear t hat candidat es do underst and t his part of t he biot echnology syl labus. There were st i l l a

number of candidat es t hat t hink st arch is broken down int o glucose by amylase and t hat yeast

can only respire anaerobical ly.

Part (c) was probably t he least mark yielding sect ion of t his quest ion as many candidat es failed

t o comment on bot h t he t emperat ure and t ime component of proving t he dough.

Question 8

This quest ion was novel in it s approach t o t est ing candidat es on t he growt h of microorganisms

in cult ure, but t he candidat es responded wel l wit h t he maj orit y at t empt ing t o answer t he

quest ion and scoring wel l . A number of candidat es clearly appreciat ed t he mode of nut rit ion

of fungi, so in part (a) could go furt her t han simply st at ing t hat t he mould had t o accl imat ize

t o it s new environment by explaining t hat it t ook t ime t o secret e t he enzymes, absorb t he

nut rient s and t hen assimilat e t hem. Few appreciat ed t hat using a mycel ial plug t o sub cult ure

a mould would damage t he hyphae.

The calculat ion caused a few problems for t hose candidat es who did not real ize t hat rat e needs

t o be expressed as per unit t ime, but t hey could st i l l score 2 out of t he 3 marks. On t he whole

candidat es were st at ing t he correct unit s t oo.

Question 9

The part s of t his quest ion which t est ed t he st ruct ure and classif icat ion of t he viruses scored

wel l .

Part (b) was not wel l answered wit h lot s of confusion bet ween t he cel l infect ion cycle and

lat ency. A number of account s suggest ed t hat t he phage DNA was incorporat ed int o t he

bact erial DNA and, in some, t hat t his t ook place in t he nucleus. A high number of candidat es

in part (i) described t he event s t hat t ake place in t he lag phase and t hen went on t o give t he

correct answer t o part (i) in part (i i ). Very few candidat es appreciat ed t he ext remely high

numbers of part icles which get formed in any one cel l at any one t ime and t hat t heir release is

synchronized.

In part (d) many candidat es’ answers were writ t en eit her in t erms of t he lag, exponent ial and

st at ionary phase or t he growt h of viruses, bot h of which are inappropriat e in t his cont ext .


Summer 2005 6104 Biology Unit 4 Opt ion B

6104/ 02 Unit 4 Option B Examiners’ Report


Maximum mark . . . . . . . . . . . . . . . . . . . 30 70

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 14.2 35.4


General comments

Quest ions 6, 8(a)(i) and (i i) were high scoring. Quest ion 8(b) was answered bet t er t han

previous quest ions relat ing t o pract ical work. Quest ions 7(a) and (c), 9(a)(i i) and 9(b) proved

cal lenging for candidat es.

Question 6

The maj orit y of candidat es gained t hree or four marks. More would have gained ful l marks if

t hey had described t he ef fect of a def iciency rat her t han j ust named a def iciency disease.

Question 7

In part (a) candidat es of t en referred t o inhibit ion of respirat ion, reduct ion of et hene

product ion and slowing of t he ripening process but only a few could gain al l four marks

available. Most candidat es underst ood t he reason for addit ion of ant ioxidant s in part (b) but in

part (c) answers usual ly lacked det ail , wit h candidat es referring t o a high t emperat ure rat her

t han quot ing a suit able value. Alt hough many answers st at ed t hat al l microorganisms are kil led

j ust as many answers gave t he impression t hat t hey were describing past eurisat ion.

Question 8

Most candidat es gained al l of t he marks available in part (a)(i) and (i i) for deal ing wit h t he dat a

but dropped a mark in sect ion (i i i). Answers here t ended t o be rest r ict ed t o references t o

excess carbohydrat e in t he diet and a lack of exercise. Few candidat es made t he import ant

l ink bet ween t he int ake of energy being great er t han t he usage of energy.

There were some good descript ions of t he use of a calorimet er in part (b) wit h many

candidat es scoring at least t hree of t he four marks available. Weaker candidat es of t en did not

refer t o t he mass of t he fat sample or t he volume of wat er. Temperat ure change of t he wat er

was t he point awarded most commonly. A few answers were complet ely irrelevant describing

t he use of skinfold cal ipers.

Question 9

Many candidat es gave very l imit ed answers in part (a)(i) and only described t hat t here was a

decrease in mort al it y as diet ary f ibre int ake increases. Answers in which t here was a failure t o

manipulat e dat a accurat ely or at al l were common.

In part (a)(i i) t here was much confusion bet ween increased and decreased t ransit t ime. Also

many referred t o digest ed food rat her t han faeces. Most answers t hat gained credit did not go

beyond a reference t o a decrease in t ransit t ime of faeces in t he gut .

In part (b) many candidat es seemed unaware t hat t his quest ion was no longer asking about

cancer of t he colon and almost repeat ed t heir answer t o part (a)(i i). Very few candidat es

could give any det ails about divert icular disease at al l . Most candidat es gaining a mark here

did so for referring t o a low level of diet ary f ibre. A signif icant number of candidat es

described coronary heart disease.


Summer 2005 6104 Biology Unit 4 Opt ion C

6104/ 03 Unit 4 Option C Examiners’ Report


Maximum mark . . . . . . . . . . . . . . . . . . . 30 70

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 15.5 37.9


General comments

Candidat es performed wel l on t his Opt ion. Al l sect ions produced some very clear responses

indicat ing a f irm grasp of t he physiological principles involved. However many candidat es

wrot e lengt hy answers t o direct quest ions which meant t hat t hey of t en cont radict ed

t hemselves and t herefore gained no marks. It was also clear t hat some candidat es did not read

t he informat ion provided careful ly or t horoughly and as a result wrot e a lot of irrelevant

informat ion t hat was not pert inent t o t he quest ion.

Question 6

This was a st raight forward recal l quest ion based upon t he pract icals l ist ed in t he specif icat ion.

Many candidat es failed t o recognise t he feat ures of myof ibri ls f rom an elect ronmicrograph.

The commonest answer t o part (a) was 4 inst ead of 10. The calculat ion posed few problems.

The demonst rat ion of t he act ion of ATP was wel l known by many candidat es but a signif icant

number of candidat es seemed t o have no idea how t his might be carried out . References t o

measuring muscles af t er exercise and inj ect ing ATP int o f rog’ s legs were seen several t imes.

Some candidat es had missed t he informat ion in t he f irst l ine asking for a descript ion of a

pract ical procedure and described t he mechanism for muscle cont ract ion.

Question 7

This was answered wel l by t he maj orit y of candidat es. Part (b) aimed t o t est a candidat e’ s

knowledge of how t he immune syst em is able t o prevent t he development of a disease by using

ant ibodies and/ or macrophages keeping bact erial numbers t oo low t o cause cl inical sympt oms.

In part (c) it was clear t hat candidat es appreciat ed t he need for prolonged t reat ment . It was

pleasing t o see how many candidat es were able t o name t he specif ic drugs used.

Question 8

There were some excel lent answers t o t his quest ion. Some candidat es gave very clear and

concise answers whereas ot hers provided large amount s of irrelevant mat erial . A number of

candidat es referred t o vent i lat ion in t heir opening st at ement s and t hen proceeded t o explain

t he increase in cardiac out put . A large number of candidat es incorrect ly cit ed t he need for

oxygen as t he driving force for increased vent i lat ion rat her t han t he build up carbon dioxide in

t he blood. Many candidat es cont radict ed t hemselves by st at ing t hat increased acidit y

increased t he pH of plasma. At A2 it is expect ed t hat candidat es would refer t o specif ic

ef fect ors such as t he diaphragm and int ercost als muscles.

Part (b) asked for a descript ion of a very simple graph and many candidat es gained al l t hree

marks by using adj ect ives t o describe t he changes and qual i f ying t heir answers using t he t ime

t o pin point t hem. Part (c) was answered wel l .


Summer 2005 6104 Biology Unit 4 Opt ion C

Question 9

There were a high percent age of correct answers t o part s (a) and (b)(i) al t hough t he spel l ings

of Bainbridge were varied; ‘ Brainbridge’ being t he most f requent ly seen.

In part (b)(i) candidat es made good use of t he diagram provided and most gained t hree marks.

The f irst mark point was for recognising t hat an increase in blood volume would lead t o an

increase in blood pressure. This mark point was not awarded as of t en as expect ed.

Part (c) was asking about a specif ic t ype of pacemaker used t o t reat heart block but many

candidat es gave ful l and det ailed account s of t he dif ferent t ypes. They did gain t he mark

point s available but possibly wast ed t ime including irrelevant det ails. The most common error

was t o suggest t hat t he art if icial pacemaker was wired direct ly t o t he SAN rat her t han t o t he

cardiac muscle.



6105 Unit 5B Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 70

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 38.6


General comments

This paper proved t o be accessible t o candidat es of al l abil i t ies. As in previous years, t here

were a number of sect ions wort h 4, 5 and 6 marks t o al low candidat es t o writ e more det ailed

answers t o quest ions. However it is import ant for t he candidat e t o st ick t o t he quest ion and

writ e concisely. No credit is gained if candidat es repeat t he quest ion. There was a poor qual i t y

of writ ing t his year and a number of script s were almost i l legible. Since t he script s are scanned

and marked onl ine it is part icularly import ant t hat candidat es writ e neat ly in blue or black ink.

Question 1

Part (a) was wel l answered and candidat es showed a good underst anding of why DNA was

heat ed. Some candidat es referred t o H bonds breaking but fai led t o ment ion bases or

nucleot ides. In part (b), t here seemed t o be a great deal of misconcept ion about t he st ruct ure

of primer which was f requent ly referred t o as DNA. The bet t er candidat es were able t o

ment ion t he short lengt h of nucleot ides, but few ment ioned t hat primers were single st randed.

Most candidat es were able t o refer t o complement ary bases or nucleot ides, but few ment ioned

t hat t he primer st art ed t he polymerase react ion. In part (c) most candidat es were able t o

suggest lengt h of t ime.

Question 2

Part (a) was answered wel l , al t hough a number of candidat es wrot e at lengt h about isolat ion

and speciat ion rat her t han focussing on t he meaning of t he t erm ‘ species’ . A surprising number

of candidat es were unable t o ident ify a procedure and simply repeat ed t he phrase ‘ DNA

analysis’ f rom t he quest ion. Part (c) proved t o be a good discriminat or. The f irst t hree marking

point s were easy t o obt ain. However, marking point s 6 8 and 9 were only ment ioned by t he

higher abil i t y candidat es.

Question 3

This was a high scoring quest ion wit h many candidat es gaining ful l marks. Weaker candidat es

muddled NADP wit h NAD and were unable t o explain t he role of RuBP. In part (d)(i i), a number

of candidat es failed t o gain credit because t hey fai led t o l ink t heir explanat ions t o t heir answer

t o part (i).

Question 4

In part (b) most candidat es referred t o t he immediat e food chain and did not t hink lat eral ly int o

ot her part s of t he food web. In part (c) marks were sparse. Many candidat es referred t o

fert i l isers and pest icides as if t hey had t he same ef fect s. However, t here were some good

account s of bioaccumulat ion. Answers t ended t o be repet it ive and candidat es wrot e a lot but

made very few pert inent point s. As a consequence, candidat es t ended t o gain credit for

comment s on food availabil i t y and habit at loss and l i t t le else.



Question 5

In part (a) t here were some excel lent , concise answers. However, a number of candidat es went

furt her t han t he cel lulose molecule and described cel lulose (t he subst ance) and cel l wal ls.

Some weaker candidat es referred t o polypept ides and bet a pleat ed sheet s. In part (b), many

candidat es gave separat e descript ions rat her t han a comparison. Part (c) was very wel l

answered wit h some excel lent account s covering al l 8 marking point s. However part (d) was not

wel l answered wit h only a few candidat es ment ioning t he rumen or t he source of t he cel lulose.

Ot hers incorrect ly described cel lulose as being broken down t o fat t y acids.

Question 6

Part (a) was very easy t o answer for some candidat es and dif f icult ot hers. Part (b) proved t o be

a discriminat ing quest ion. There was a lot of confusion bet ween “ bases” and “ amino acids”

wit h t he t wo t erms of t en being used int erchangeably. Most candidat es were able t o pick up one

point for referring t o delet ion, addit ion or subst it ut ion. However many candidat es described

amino acids as coding for a prot ein or a change in a codon causing a dif ferent amino acid t o be

produced. Answers t o part (c) varied in st andard. Many candidat es did not answer t he

quest ion, which was concerned wit h t he role of a t ransmit t er and inst ead provided a st andard

answer on t he workings of a synapse. As in previous years, t here was some confusion bet ween

pre- and post -synapt ic membranes. Some candidat es cont inue t o use t erms such as a

“ message” or “ signal” which are not appropriat e for A2.

Question 7

In part (a), a number of candidat es described t ranspirat ion as t he movement of wat er f rom

root s t o leaf rat her t han t he loss of wat er vapour f rom t he aerial part s of a plant . Part (b) was

poorly answered wit h candidat es not making good use of t he informat ion provided. In part

(b)(i i), t he most common point s seen were t he decrease in t ranspirat ion over t he t hree days,

reduced upt ake by t he root s and st omat a closing. However, t he general underst anding of t his

process was poor. Most candidat es gained ful l marks for part (d).


Summer 2005 6115 Biology (Human) Unit 5

6115 Unit 5H Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 70

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 33.7


General comments

This paper shared common quest ions 1, 2, 4, 5 and 6 wit h 6105/ 01. The performance on t his

paper was ext remely variable on al l quest ions. There was no evidence t hat candidat es were

not able t o complet e t he quest ions in t he t ime al locat ed.

Question 1 and 2

Common wit h 6105

Question 3

In part (a), most candidat es were able t o gain some credit for t heir descript ion of an al lele.

Only t he bet t er candidat es explained t hat t he dif ferent al leles for a gene could occupy t he

same locus. Many candidat es included irrelevant det ail concerning t he phenomenon of

dominant and recessive al leles. Some candidat es described al leles as being let t ers of t he

alphabet .

In part (b), most candidat es could name a t echnique. The descript ions of t he met hod were less

accurat e. Most candidat es described t he sampling of amniot ic f luid. Some of t he errors

included needles or ot her inst rument s being insert ed int o t he fet us it self , insert ing needles

int o t he st omach or removing samples f rom t he vagina. Some det ailed and accurat e

descript ions were seen.

In part (c)(i), most candidat es were able t o give t he correct probabil i t y. It is t o be not ed t hat ,

at t his level, a rat io is not considered t o be t he same as a probabil i t y. It was also evident t hat

many candidat es were able t o use t he informat ion in t he quest ion t o back up t heir suggest ion.

A large number of candidat es suggest ed t hat as t he couple had already had a child wit h MSUD

t heir chance of having anot her was reduced.

In part (c)(i i), many candidat es were able t o deduce t hat at least one of t he t wo parent s must

be a carrier. Only t he bet t er candidat es were able t o fol low t his by using some evidence

correct ly.

Question 4 to 6

Common wit h 6105

Question 7

In part (a), only a few candidat es could give answers t hat showed very much progress beyond

GCSE. It was expect ed t hat det ailed explanat ion would be given as t o how t he st ruct ures

facil i t at e gas exchange. It was common t o see t he descript ion of a st ruct ure being fol lowed by

answers similar t o “ t o make dif fusion easier” . The t hin wal l was t he most common st ruct ural

feat ure given wit h relat ively few ext ra det ails such as t he single layer of cel ls or t he squamous

epit hel ium being included. Many candidat es use t he t erm “ membrane” as synonymous wit h

“ wal l” . Some candidat es referred vaguely t o blood vessels rat her t han capil laries. There were

some very good descript ions of t he role of t he surfact ant in lowering surface t ension or

prevent ion of alveolar col lapse. Many candidat es st i l l mist akenly bel ieve t hat t he rat e of

dif fusion of respirat ory gases is fast er in solut ion t han it is in t he gaseous phase.


Summer 2005 6115 Biology (Human) Unit 5

In part (b)(i), only a few candidat es could explain t hat oxygen is being removed f rom t he

alveolar air. Some candidat es made reference t o t he expired air being a mixt ure of air f rom

t he alveolus and t he inspired air. In part (b)(i i), many candidat es repeat ed t he informat ion

t hat t he dif fusion gradient s would be maint ained but only t he bet t er candidat es could explain

how t his was brought about .

In part (c), t here were some very good answers wit h good descript ions of t he ef fect of carbon

monoxide and nicot ine. Many candidat es st at ed t hat harmful subst ances could pass across t he

placent a but det ails concerning t heir ef fect s were usual ly not given. Most candidat es scored

some credit by reference t o low birt h weight or increased risk of miscarriage. A number of

candidat es suggest ed t hat t he fet us would inhale t he smoke. Some candidat es st at ed t hat t he

mot her’ s blood would carry subst ances int o t he fet us.

In part (d), most candidat es gained credit by referring t o one or more of t he diseases t hat are

associat ed wit h smoking. Many candidat es were t hen able t o gain furt her credit wit h a

reference t o one of t he appropriat e ef fect s upon a part icular age group.



6106/ 01 Unit 6 T2 Individual Study Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 32

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 18.7


General comments

Once again t here were many individual invest igat ions which demonst rat ed excel lent planning

skil ls and int erest ing, original scient if ic st udies. However, a small number of cent res appeared

t o int erpret ‘ individual ’ as merely t he idea t hat candidat es have writ t en t heir plans under

supervision regardless of t he fact t hat a highly direct ed approach has result ed in almost

ident ical out comes which do not provide accept able evidence of each candidat es’ abil i t y t o

meet t he crit eria.

Cent res are also st rongly recommended t o advise candidat es not t o submit invest igat ions such

as enzyme experiment s which are very similar t o common approaches at AS or even GCSE level.

Where t hey choose t o do so, it is expect ed t hat t hey wil l display clear evidence of progression

in dept h of t hought and underst anding in al l crit eria if t hey are t o be awarded more t han

minimal marks. A t horough underst anding of rat es, precisely what rat e is being measured by

t he t echniques adopt ed and how t his may be accurat ely t est ed st at ist ical ly would be a basic

minimum at A2 level.

Planning

Where ecological st udies are planned it would be have been helpful t o many candidat es t o

ensure t hat t heir hypot hesis was more specif ic, ei t her by considering individual species, or by

resist ing t he t empt at ion t o include more t han one variable. There were many more candidat es

who used a careful choice of sit e t o mit igat e t he ef fect s of several variables in such

invest igat ions, but t his was not always clear. The main causes of signif icant dif ferences

bet ween examiners and cent re assessment s in t his sect ion were a lack of evidence of individual

planning and a failure t o consider al l import ant variables. A clear, wel l-def ined hypot hesis

wit h a careful ly j ust if ied st at ist ical t est is of t en t he def ining feat ure of a successful, high-

scoring invest igat ion.

Implementing

It is essent ial t hat t here is some annot at ion on t he script s t hemselves t o indicat e why cent res

have awarded marks for I(a) and I(b).

Only minimal marks can be support ed for highly inaccurat e met hodology such as bubble count s,

height of f rot h or dough, even t hough, regret t ably, t hey appear t o be accept ed in some cases.

To support cent re marks for t his sect ion examiners check evidence for I(c) in t abulat ion of raw

dat a. Where marks cannot be support ed it is of t en because of element ary errors in format t ing

and label l ing of t ables.

Introduction

Many candidat es st i l l lack t he select ivit y expect ed at A2 level in t he copious amount s of

t heoret ical background t hey quot e. This is also an ideal sect ion t o provide accurat e

referencing in cont ext t o meet t he crit eria for St yle 3(b).



Method

A surprising number of candidat es gave met hod account s which simply could not be repl icat ed.

A part icular problem arises in ecological st udies where exact locat ions are not ident if ied. It is

not expect ed t hat candidat es wil l simply dupl icat e t heir planned met hod in t his sect ion.

Where one clear account has been given t his is suf f icient , but examiners are looking for

det ailed amendment s and furt her development s in t he l ight of conclusions f rom pilot

experiment s or prel iminary work.

Analysing

For high marks in A(a) summary t ables are expect ed t o be accurat e and clearly format t ed

including consist ent and sensible signif icant f igures.

Careful select ion of t he relevant graphical format st i l l provides problems for many candidat es.

Quant it y of graphs of t en t akes precedence over relevance t o t he hypot hesis and many

candidat es do not at t empt t o include error bars. There appeared t o be an increased t rend t o

producing l ines of ‘ best f i t ’ which were of t en not j ust if ied by t he dat a. This was somet imes

compounded by select ing such l ines and t hen claiming variabil i t y was low because most point s

were close t o t hese l ines despit e t he fact t hat t hey had been del iberat ely chosen t o be so.

Many candidat es f ind t he l ine bet ween describing import ant t rends and pat t erns and simply

repeat ing t he dat a t hey have t abulat ed dif f icul t t o j udge. Where t here are clearly no

anomal ies it is accept able t o simply st at e t his rat her t han at t empt t o label t he smallest

variat ion as anomalous or remove dat a because it does not convenient ly f i t t he predict ed

pat t ern.

Whilst examiners accept a wide range of relevant st at ist ical t est s, t his should normally be a

single calculat ion and int erpret at ion using a 5% conf idence level. Where comput er

programmes are used for processing it is essent ial t hat t hese are ident if ied and t hat t he

int erpret at ion of t he f inal t est st at ist ic is clearly described in t he candidat e’ s own words.

Where mult iple t est s are submit t ed, t hey are almost always a ref lect ion of poor planning and

candidat es can rarely make meaningful conclusions f rom t hem.

Discussion and Evaluation

This remains t he weakest sect ion for many candidat es. Too of t en biological knowledge and

underst anding are simply regurgit at ed f rom t he int roduct ion wit hout clear reference t o t he

act ual dat a col lect ed.

There st i l l appears t o be a widespread misunderst anding of t he requirement s for D(b). Only a

few candidat es appeared t o fol low t he pat t ern of t hought encouraged by several l inked

crit eria. Whilst i t is appreciat ed t hat clear obj ect ive ref lect ion of t he invest igat ion is a

dif f icult skil l , many candidat es would have scored more highly had t hey made l inks bet ween

t he dif ferent crit eria. Those who drew error bars on t heir graphs in A(a) and ident if ied real

anomal ies of t en cont inued t o discuss t he variabil i t y in t heir dat a in some way. Only a small

minorit y of candidat es were able t o cont inue along t his l ine t o act ual ly use t heir comment s t o

assess rel iabil i t y for D(b)6+.

The f inal st age in t his logical progression is t o consider t he quest ion ‘ No mat t er how careful ly

t his invest igat ion was carried out , what could st i l l be causing variat ions in my repeat readings?’

Those who fol lowed t his reasoning were able t o suggest sensible ideas for furt her work but

many ignored t he key phrase in t he crit eria ‘ which would provide considerable addit ional

evidence f or t he conclusions’ and suggest ed launching complet ely new invest igat ions which

were not relat ed t o t he original hypot hesis and t herefore could not gain signif icant credit .



Style

Many more candidat es now include an abst ract which is concise but do not always include al l

t he element s suggest ed in t he crit eria. Many invest igat ions were wel l present ed and

demonst rat ed good scient if ic l i t eracy. Referencing was very varied. Int ernet sources are

accept able but candidat es need t o ensure t hat ful l det ails are given and t hat t hey consider t he

rel iabil i t y of t he sources t hey quot e.


Summer 2005 6106 Biology Unit 6 paper 02 W2

6106/ 02 Unit 6 W2 Written Alternative Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 38

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 18.3


General comments

There was a marked dist inct ion bet ween candidat es who sought t o apply t heir underst anding of

scient if ic invest igat ions t o t he act ual quest ions and t hose who were simply seeking t o apply

previous mark schemes. Those who rel ied heavily on t his lat t er approach of t en gained few

marks in several sect ions. It is import ant t o st ress t hat point s on t he mark scheme are only

awarded in t he correct cont ext . This was especial ly t rue for st at ist ical analysis in quest ion 1

and suggest ions for t abulat ion and graphical analysis in quest ion 2 part (b). First -hand

experience of planning and carrying out a range of pract ical work is clearly t he best

preparat ion for t his paper in addit ion t o being an int egral part of t he Advanced Level course.

Question1

Knowledge of medians is a clearly st at ed requirement of t he specif icat ion and many candidat es

answered t his quest ion wel l . Whilst t he Mann-Whit ney U t est is not a specif ic requirement , ful l

det ails were given in t he rubric and candidat es were only expect ed t o apply t heir knowledge of

int erpret ing st at ist ical t est s.

(a) Most candidat es were able t o rank t he dat a in a suit able t able and hence could gain

most marks wit hout knowledge of medians.

(b) A variet y of appropriat e graphical format s was accept ed but it was disappoint ing t o see

a subst ant ial minorit y of candidat es using sample number as an x axis and at t empt ing t o

pair what were random samples.

(c) The examiners were looking for precision in st at ing t he nul l hypot hesis, especial ly a

‘ signif icant ’ dif ference bet ween t he medians.

(d) Many candidat es gained t wo marks for int erpret ing t he t est result correct ly but it was

expect ed t hat candidat es would demonst rat e t heir underst anding of a 5% signif icance

level rat her t han simply quot e p=0.05 f rom t he t able wit hout explanat ion.


Summer 2005 6106 Biology Unit 6 paper 02 W2

Question 2

(a) There was a wide range of approaches t o t his quest ion, many of which covered a large

number of marking point s. At t empt s t o st andardise plot s of land and t he beet les were

common but precise det ails of pract ical met hods of assessing t he result s were more

l imit ed.

It is recommended t hat plans are writ t en in cont inuous prose t o meet t he crit eria for 2

marks. Numbered or bul let ed point s can be accept ed but many are l ist -l ike and

ungrammat ical. Only very l imit ed credit can be given where sequencing is poor or

af t ert hought s are ‘ added on’ t o t he main account .

(b) Tabulat ion of dat a was very variable. Many candidat es omit t ed columns for t he t ype of

raw dat a t hey had suggest ed in t heir plans and some were det ermined t o calculat e

means f rom inappropriat e dat a. Similarly many candidat es named st at ist ical t est s

regardless of what had been measured. Suggest ions of t -t est s on measurement s t aken

over t ime were common wit hout furt her explanat ion of precisely what was t o be t est ed.

(c) Overal l t his was t he weakest area for many candidat es. Suggest ions for correct ing

obvious errors in planning are not considered as l imit at ions. It was evident t hat some

candidat es were simply at t empt ing t o recal l l ist s f rom previous mark schemes wit hout

applying t hem careful ly t o t heir planned met hod.

Al l sect ions of t his paper are closely l inked t o t he coursework crit eria and hence

suggest ions for furt her work are expect ed t o provide addit ional evidence t o support t he

conclusions concerning t he hypot hesis under t est . Suggest ions which involve launching

complet ely new hypot heses t herefore do not gain credit .


Summer 2005 6106 Biology Unit 6 paper 03 Synopt ic

6106/ 03 Unit 6 Synoptic Examiners’ Report

Maximum mark . . . . . . . . . . . . . . . . . . . 38

Mean mark . . . . . . . . . . . . . . . . . . . . . . . . 18.5


General comments

Synopt ic quest ions are int ended t o assess t he abil i t y of candidat es t o bring t oget her principles

and concept s f rom at least t wo unit s of t he specif icat ion and apply t hem in a part icular

cont ext , expressing ideas clearly and logical ly and using appropriat e special ist vocabulary.

Candidat es are also expect ed t o apply biological skil ls in cont ext s which bring t oget her

dif ferent areas of biology.

Success in synopt ic quest ions, t herefore, requires a sound knowledge and underst anding of t he

specif icat ion cont ent , and an abil i t y t o apply t his in new cont ext s. One part icular area of

weakness not ed on t his, and previous synopt ic papers, has been a general ly rat her poor recal l

of fact ual informat ion f rom t he AS unit s. This was evident in quest ion 3, for example, where

t here were numerous errors in bot h t he st ruct ure and digest ion of carbohydrat es. It is also

import ant t hat candidat es read t he quest ions careful ly before at t empt ing t o answer t hem.

There were a number of inst ances where t he answers were irrelevant , or cont radict ed

informat ion included in t he quest ion.

In general , quest ions 1 (a)(i) and 2 (c) were answered correct ly by t he maj orit y of candidat es

and t here were also some good answers t o quest ion 3. Quest ions 1 (b)(i i) and 2 (d) were less

wel l answered, answers t o ot her part s of bot h quest ions were very variable. The st andard of

writ t en Engl ish in t he essays, in part icular, cont inues t o be a source of concern t o t he

examiners. Some of t he essays were, however, careful ly planned and coherent ly writ t en and

were, consequent ly, a pleasure t o read.

Question 1

The great maj orit y of candidat es answered part (a)(i) correct ly. In part (a)(i i), whilst many

candidat es were able t o suggest advant ages of budding, t here were a number of answers giving

advant ages of meiosis, in t erms of increased genet ic diversit y. The most f requent advant age

given was t hat it enables rapid populat ion growt h; many references were also seen t o t he fact

t hat t he daught er cel ls are genet ical ly ident ical t o t he parent cel ls and are t herefore adapt ed

t o t he prevail ing condit ions. In part (a)(i i i), many candidat es used t heir knowledge of t he cel l

surface membrane and correct ly referred t o membrane glycoprot eins act ing as recept ors and

comment ed on t he complement ary nat ure of t he small prot eins and t heir recept ors. However,

t here were also many irrelevant answers, giving general descript ions of membrane st ruct ure,

including references t o permeabil it y, wit hout addressing t he quest ion.

Many candidat es answered part (b)(i) correct ly, but t here were also various incorrect

suggest ions, including st ruct ures t hat are not part of a mit ochondrion. In part (b)(i i), t here

were many det ailed account s of t he funct ion of t he elect ron t ransport chain (in some cases

f i l l ing t he ent ire page) and including a rest at ement of t he informat ion given in t he quest ion.

However, t hese answers did not always explain why t he pet it e cel ls grow slowly compared wit h

normal yeast cel ls. The maj orit y of candidat es correct ly suggest ed t hat t hese mut ant cel ls

may produce less ATP t han normal cel ls, but t his was rarely qual if ied ot her t han wit h a vague

st at ement about ATP being ‘ needed for growt h’ . A number of candidat es, however, st at ed

t hat ATP is required for processes such as prot ein synt hesis and were, accordingly, given

credit .



Answers t o part (c) were very variable. Alt hough many candidat es sensibly int erpret ed t he

dat a and concluded t hat t he cause of t he pet it e phenot ype is a mut at ion in t he mit ochondrial

DNA, t here were also a number of vague and incorrect suggest ions. Some candidat es ignored

t he informat ion included in bot h part s (b) and (c) and concluded t hat t he pet it e phenot ype is

due t o, for example, environment al condit ions.

Question 2

Part (a) of t his quest ion required candidat es t o apply t heir knowledge of immobil ised enzymes

and fact ors af fect ing enzyme act ivit y t o t his invest igat ion. There were some good, concise

answers including references t o t he bact eria remaining on t he discs so t hat t he emission of

l ight is easier t o see, and references t o t he ef fect s of changes in t emperat ure on enzyme

act ivit y and on met abol ism. There were, however, some very vague answers including only

references t o cont rol l ing variables and ‘ making it a fair t est ’ .

In part (b), many candidat es gave an overal l descript ion of t he relat ionship bet ween t he

concent rat ion of mercury chloride and t he durat ion of l ight emission and support ed t his wit h an

appropriat e reference t o t he dat a. There were also a number of answers giving eit her t he

t rend, or a reference t o t he dat a, but not bot h. Part (c) was answered successful ly by most

candidat es, who correct ly ident if ied mercury and support ed t heir answer by comparing t he

ef fect of mercury wit h t he ot her met als.

Answers t o part (d) were very variable. Whilst a number of candidat es suggest ed an

appropriat e met hod, wit h experiment al det ails, many did not . A number of candidat es

suggest ed t ot al ly dif ferent approaches, including t oxicit y t est ing wit h ot her organisms. Marks

were of t en gained for references t o t he use of a cont rol and for indicat ing t hat pol lut ion wit h

heavy meals would be expect ed t o decrease t he durat ion of l ight emission.

Question 3

This was by far t he most popular choice of essay, but t he st andard was very variable. Some

essays cont ained pract ical ly no relevant , or correct , informat ion, whilst ot hers gave good,

det ailed account s of al l t hree aspect s of t his quest ion. Many candidat es did not at t empt t o

explain what carbohydrat es are; t hose who did of t en st at ed only t hat t hey consist of carbon,

hydrogen and oxygen. Indeed it was clear f rom many account s t hat a number of candidat es

were under t he impression t hat t he word carbohydrat e is synonymous wit h st arch. Digest ion

was f requent ly described inaccurat ely and, al t hough sal ivary amylase was usual ly included, t he

sources and ef fect s of ot her carbohydrases were general ly inaccurat e. Some account s included

irrelevant informat ion on t he digest ion of prot eins and t riglycerides. Explanat ions of t he

upt ake of monosaccharides were of t en brief , somet imes wit h only a passing reference t o t he

dif fusion of glucose int o capil laries. A number of candidat es used t he t erm ‘ reabsorpt ion’ of

glucose in t he i leum, and t hen digressed int o descript ions of kidney funct ion.

Descript ions of digest ion and absorpt ion were usual ly fol lowed by an abrupt change t o account s

of t he regulat ion of blood glucose. Candidat es rarely made coherent l inks bet ween t he

absorpt ion of glucose, consequent changes in blood glucose, det ect ion and regulat ion. Perhaps

inevit ably, t here was much confusion bet ween glycogen and glucagon, and t he sources of bot h

insul in and glucagon were of t en cit ed incorrect ly. It was also not able how many candidat es

incorrect ly described det ect ion of changes in blood glucose concent rat ion by t he hypot halamus

and t he apparent involvement of t he pit uit ary gland. Numerous essays gave t he impression

t hat insul in is secret ed only when t he concent rat ion of glucose in t he blood is high, rat her t han

a more accurat e indicat ion t hat t he rat e of secret ion of insul in increases as t he blood glucose

concent rat ion increases.



However, t here were also some good, accurat e account s including det ails of carbohydrat e

digest ion (somet imes wit h references t o bot h ruminant s and saprobiont s), absorpt ion and

regulat ion, wit h good descript ions of t he roles of insul in, glucagon and adrenal ine.

Question 4B

The general st andard of t his essay was rat her poor, wit h few det ails of t he upt ake, t ransport

and roles of mineral ions. Many candidat es who at t empt ed t his essay gave general descript ions

of t he movement of wat er across t he cort ex of a root and t here were also some quit e good

account s of t he upt ake of ions by dif fusion and act ive upt ake. However, many candidat es t hen

incorrect ly described t he movement of wat er and mineral ions upwards in t he phloem, and

included irrelevant det ails of phloem st ruct ure and funct ion. Some essays included l i t t le or no

informat ion f rom Unit 5B on mineral nut rit ion in f lowering plant s; indeed some cont ained no

named examples of mineral ions at al l .

Question 5H

This essay required int egrat ion of knowledge and underst anding of t opics f rom Unit s 2H and

5H. A small minorit y of candidat es at t empt ed t his essay and, as wit h Quest ion 4B, t he general

st andard was poor. Some essays included lengt hy, and irrelevant , account s of human

evolut ion, wit hout including any det ails of primat e feat ures and diversit y. There were few

accurat e account s of adapt at ions t o high al t i t ude; some of t he answers were rat her superf icial ,

referring only t o t he consequences of low part ial pressure of oxygen and not including ot her

environment al condit ions at high alt i t ude. There is a t endency for candidat es t o refer vaguely

t o ‘ t hin air’ or ‘ less oxygen’ at high alt i t udes, when a more precise reference t o t he part ial

pressure of oxygen is expect ed.

Very occasional ly, an essay included det ails of primat e feat ures and diversit y, and t he

physiological and st ruct ural adapt at ions of humans t o l i fe at high alt i t udes.


Summer 2005 Appendix A - Unit Grade Boundaries and Uniform Marks

APPENDIX A

UNIT GRADE BOUNDARIES AND UNIFORM MARKS

The raw mark obt ained in each module is convert ed int o a st andardised mark on a uniform

mark scale, and t he uniform marks are t hen aggregat ed int o a t ot al for t he subj ect . Det ails of

t he met hod of aggregat ion are given in Appendix A.

For AS examinat ions, t he t hree unit t est s each have a weight ing of 33.3% wit h a maximum of

100 uniform marks.

For t he A level, t he six unit t est s each have a weight ing of 16.7% wit h a maximum of 100

uniform marks.

The t able below shows t he boundaries at which raw marks were convert ed int o uniform marks

in t his examinat ion. The A and E grade boundaries are det ermined by inspect ion of t he qual it y

of t he candidat es’ work. The ot her grade boundaries are det ermined by dividing t he range of

marks bet ween A and E. Marks wit hin each grade are scaled appropriat ely wit hin t he

equivalent range of uniform marks.

In Unit 3, t he A and E boundaries are det ermined separat ely on t he t wo component s Paper 01

(T1) and Paper 03 (or Paper 02 (W1) and Paper 03 for Int ernat ional candidat es only). These

marks are t hen added t oget her t o f ind t he A and E boundaries for Unit 3 as a whole, and t he

ot her grade boundaries for t he Unit are t hen found as described above. Boundaries for t he B, C

and D grades for each component can be calculat ed in t he same way, but please not e t hat

t hese are not simply added t oget her t o obt ain t he B, C and D boundaries for t he unit as a

whole.

In Unit 6, t he A and E boundaries are det ermined separat ely on t he component s Paper 01 (T2),

Paper 02 (W2) and Paper 03. These marks are t hen added t oget her t o f ind t he A and E

boundaries for Unit 6 as a whole, and t he ot her grade boundaries for t he Unit are t hen found as

described above. Boundaries for t he B, C and D grades for each component can be calculat ed

in t he same way, but please not e t hat t hese are not simply added t oget her t o obt ain t he B, C

and D boundaries for t he unit as a whole.

Unit grade boundaries for Summer 2005 can be found on t he next page.


Summer 2005 Appendix A - Unit Grade Boundaries and Uniform Marks

Unit grade boundaries

Grade Maximum mark

A B C D E

Unit Unif orm marks

100 80 70 60 50 40

Raw marks

6101 Unit 1 60 42 37 32 28 24

6102 Unit 2B 60 42 38 34 30 27

6112 Unit 2H 60 42 37 32 28 24

6103 Unit 3 70 50 44 38 32 27

Paper 01 T1 32 26 22 18 15 12

Paper 03 38 24 21 19 17 15

6103 Unit 3 (Int ernat ional opt ion)

70 46 41 36 31 26

Paper 02 W1 Int ernat ional only

32 22 19 16 13 11

Paper 03 32 24 21 19 17 15

6104 Unit 4 Opt ion A 70 48 43 38 33 28

6104 Unit 4 Opt ion B 70 47 42 38 34 30

6104 Unit 4 Opt ion C 70 50 45 41 37 33

6105 Unit 5B 70 50 45 41 37 33

6115 Unit 5H 70 50 45 41 37 33

6106 Unit 6 (Opt ion 1)

70 49 44 39 34 29

Paper 01 T2 32 24 21 18 15 12

Paper 03 38 25 23 21 19 17

6106 Unit 6 (Opt ion 2)

70 48 43 38 33 28

Paper 02 W2 32 23 20 17 14 11

Paper 03 38 25 23 21 19 17


Summer 2005 Appendix B: The Uniform Mark Syst em

APPENDIX B

The Uniform Mark System for AS and A level Unit Schemes

The result for each unit wil l be issued as a st andardised mark on a uniform mark scale. AS

subj ect s have a t ot al of 300 uniform marks and A level subj ect s have a t ot al of 600 uniform

marks.

Tables 1 and 2 show t he numbers of uniform marks required t o gain each subj ect grade in AS

and A level examinat ions. They also indicat e t he number of uniform marks in unit s wit h

various weight ings t hat wil l aggregat e int o t he appropriat e subj ect grade. These provide a

guide t o t he level of performance in each unit .

The uniform marks shown for each unit do not necessari ly represent t he act ual mark range

used for marking. Grade boundaries are set at Awarding meet ings on t he basis of candidat e

performance on t he act ual mark range used. These boundaries are t hen convert ed t o t he

uniform marks shown in t he t ables, wit h int ermediat e values calculat ed accordingly.

Table 1 – Advanced Subsidiary Subjects

Subject Unit Weighting

Grade UMS 20% 30% 331

3% 40% 50% 60%

Max mark 300 60 90 100 120 150 180

A 240 48 72 80 96 120 144

B 210 42 63 70 84 105 126

C 180 36 54 60 72 90 108

D 150 30 45 50 60 75 90

E 120 24 36 40 48 60 72

For example, a candidat e for AS Biology or Biology (Human) must t ake t hree modules, al l

weight ed at 33.3% of t he subj ect .

Uniform mark obtained

Approximate level of

performance

Unit 1 65 C

Unit 2 73 B

Unit 3 80 A

Subject Total 218 Subject Grade = B


Summer 2005 Appendix B: The Uniform Mark Syst em

Table 2 – Advanced Level Subjects

Subject Unit Weighting

Grade UMS 15% 162

3% 20% 25% 30%

Max mark 600 90 100 120 150 180

A 480 72 80 96 120 144

B 420 63 70 84 105 126

C 360 54 60 72 90 108

D 300 45 50 60 75 90

E 240 36 40 48 60 72

For example, a candidat e for A level Biology or Biology (Human) must t ake six unit s, al l

weight ed at 16.7%. The candidat e in t his example has four unit s in t he bank.

Uniform Mark Obtained

Approximate level of

performance

Unit 1 78 B

Unit 2 65 C

Unit 3 75 B

Unit 4 82 A

Unit 5 50 C

Unit 6 *

Partial Total in Bank = 350

The candidat e already has 350 uniform marks in t he bank. If a Grade C is required in t he

subj ect , t he candidat e must obt ain at least 10 UMS marks f rom Unit 6 or if a Grade B is

required t he candidat e must obt ain 70 UMS marks or more f rom Unit 6.

There is no rule requiring candidat es t o t ake unit s amount ing t o 30% of t he examinat ion at t he

t ime of cashing in, nor do candidat es have t o t ake al l papers wit h synopt ic assessment at t he

same t ime at t heir f irst cash in.


Furt her copies of t his publ icat ion are available f rom Edexcel Publ icat ions, Adamsway, Mansf ield, Not t s, NG18 4FN Telephone 01623 467467 Fax 01623 450481

Email publ icat ions@linneydirect .com

Order Code UA016324 Summer 2005 For more informat ion on Edexcel qual if icat ions, please visit www.edexcel.org.uk/ qual if icat ionsAlt ernat ively, you can cont act Customer Services at www.edexcel.org.uk/ ask or on 0870 240 9800 Edexcel Limit ed. Regist ered in England and Wales no.4496750 Regist ered Of f ice: One90 High Holborn, London, WC1V 7BH

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