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Mark Scheme Summer 2008

GCE

GCE O Level Human Biology (7042)

Edexcel Limited Registered in England and Wales No 4496750 Registered Office: One90 High Holborn, London W

Contents

Page

1. 7042/ 01 (Paper 1) Mark Scheme 1

2. 7042/ 02 (Paper 2) Mark Scheme 13

7042 GCE O Level Human Biology

7042/ 01 O LEVEL HUMAN BIOLOGY MARK SCHEME - JUNE 2008

Quest ion

Number

Answer Mark

1(a)

� X – pelvis / hip;

� Y – t ibia / pat el la;

(2)

Quest ion

Number

Answer Mark

1(b)(i)

� blood cel ls;

(1)

Quest ion

Number

Answer Mark

1(b)(ii)

� l ight er (but st i l l st rong) / st ronger per unit

mass;

� less energy t o move around;

� less minerals needed t o form it ;

max (2)

Quest ion

Number

Answer Mark

1(c)(i)

� t o prevent / reduce f r ict ion / shock absorber;

(1)

Quest ion

Number

Answer Mark

1(c)(ii) 1 mark for each dif ference – maximum 3 marks

Difference Bone Cartilage

1 rigid/ not f lexible f lexible

2 heavy l ight

3 cont ains marrow no marrow

4 cont ains calcium

salt s

no calcium salt s

5 int ernal blood

vessels

no int ernal / has

ext ernal blood

vessels

6 muscle at t ached muscle not

at t ached

max (3)


Quest ion

Number

Answer Mark

1(c)(iii)

� al lows bone / bone shaf t t o increase in lengt h

/ grow;

Rej ect st ret ch

(1)

Quest ion

Number

Answer Mark

1(c)(iv)

� r ib at t achment t o st ernum;

� base of st ernum;

� in t rachea;

� ear / pinna;

� (int ervert ebral) discs;

� nose;

max (2)

(Total 12 marks)


Quest ion

Number

Answer Mark

2(a)(i)

� inverse relat ionship / less f ibre – more cases of

bowel cancer / ORA;

(1)

Quest ion

Number

Answer Mark

2(a)(ii)

� 87/ 88 per 100 000 / range 87-88 per 100 000;

(1)

Quest ion

Number

Answer Mark

2(a)(iii)

� 2.50 g;

(1)

Quest ion

Number

Answer Mark

2(a)(iv)

2.22g gives 93 deat hs, 2.50g gives 8- deat hs per

100 000;

� (change is) decrease of 13 deat hs per 100 000;

2 marks for correct answer wit hout working shown

(2)

Quest ion

Number

Answer Mark

2(b)(i)

� any leafy veget able;

� root veget able;

� f ruit s;

� al l bran / any whole grain cereal ;

� (wholemeal) bread;

� (brown) r ice

max (2)

Quest ion

Number

Answer Mark

2(b)(ii)

� increases / aids perist alsis;

� prevent s const ipat ion / removes faeces easily;

� reduces risk of bowel cancer / eq;

� less t ime for t oxins t o accumulat e;

max (2)

(Total 9 marks)


Quest ion

Number

Answer Mark

3 1 mark for each correct answer (x).

Process mit osis meiosis

Result s in t he format ion of haploid

cel ls

x

Nuclear membrane disappears

during division x x

Homologous chromosomes l ine up in

pairs

x

Only t wo daught er cel ls produced

x

Genet ic mat erial exchanged

bet ween chromosomes of a

homologous pair

x

Daught er cel ls al l ident ical t o

parent

x

Nuclear spindle forms during

division

x x

DNA cont ent doubled before next

division

x x

Occurs only during gamet e

format ion

x

(9)

(Total 9 Marks)


Quest ion

Number

Answer Mark

4(a)(i)

� t rachea – P;

� bronchi - R;

� diaphragm – S;

(3)

Quest ion

Number

Answer Mark

4(a)(ii)

� heart / pericardium;

(1)

Quest ion

Number

Answer Mark

4(a)(iii)

� breat hing is movement of air in and out /

vent i lat ion of lungs;

� respirat ion is t he release of energy (in cel ls);

(2)

Quest ion

Number

Answer Mark

4(b)

� int ercost al muscles cont ract ;

� r ibs swing up and out wards;

� diaphragm (muscles) cont ract s;

� diaphragm less dome shaped / f lat t ened;

Rej ect moves down

� leads t o increase in volume of t horax / chest

cavit y;

max (4)

Quest ion

Number

Answer Mark

4(c)

� part icles / pol len / dust / eq;

� t rapped by mucus;

� air warmed;

� by radiat ion / surrounded by t issues at higher

t emperat ure;

� air moist ened;

� by evaporat ion f rom l ining of t rachea / mucus;

max (4)

(Total 14 Marks)


Quest ion

Number

Answer Mark

5(a)(i)

� uret er;

(1)

Quest ion

Number

Answer Mark

5(a)(ii)

� urine;

Rej ect urea

(1)

Quest ion

Number

Answer Mark

5(a)(iii)

� cort ex – f i l t rat ion / ul t ra f i l t rat ion / eq;

� medul la – (select ive) reabsorpt ion / eq;

(2)

Quest ion

Number

Answer Mark

5(b)

� glucose used by kidney cel ls for respirat ion;

(1)

Quest ion

Number

Answer Mark

5(c)(i)

� bulk of wat er in f i l t rat e reabsorbed;

� some solut es reabsorbed;

� urea lef t behind / not reabsorbed;

max (2)

Quest ion

Number

Answer Mark

5(c)(ii)

� al l glucose reabsorbed;

� f rom f i l t rat e / kidney t ubule int o blood;

(2)

Quest ion

Number

Answer Mark

5(d)(i)

� sweat ing;

� less wat er in t he blood;

� ref . t o ADH;

� produced by pit uit ary;

� st imulat es nephrons t o reabsorb more wat er;

max (3)


Quest ion

Number

Answer Mark

5(d)(ii)

� i t wil l increase / eq;

(1)

(Total 13 Marks)


Quest ion

Number

Answer Mark

6(a)(i) 1 mark for correct answer.

� male;

(1 Mark)

1 mark for each correct answer f rom any of t he

fol lowing – maximum 3 marks

� ref . t o unpaired X chromosome in males /

male XY;

� recessive (al lele / gene) present in male

always shows feat ure;

� females can have recessive al lele hidden by

dominant al lele;

� females must receive a recessive al lele f rom

bot h parent s / be homozygous recessive t o

show feat ure;

(3 Marks)

(4)

Quest ion

Number

Answer Mark

6(a)(ii)

� Xh

Y;

(1)

Quest ion

Number

Answer Mark

6(b)(i) 1 mark for each correct answer f rom any of t he

fol lowing (Accept ot her logical explanat ions for t hese

point s) – maximum 3 marks.

� haemophil ia al lele is recessive;

� Sarah het erozygous / carries recessive Xh;

� Ian’ s mot her / Cat herine inherit s Xh

f rom her

mot her / Sarah / carrier;

� Ian inherit s Xh f rom his mot her / carrier;

max (3)

Quest ion

Number

Answer Mark

6(b)(ii)

� Colin is not af fect ed / does not carry Xh / does

carry XH

;

� t hus gir l cannot have XhX

h / have t wo recessive

al leles / must have an XH;

(2)

(Total 10 Marks)


Quest ion

Number

Answer Mark

7(a)

� mot her’ s blood has higher carbon monoxide

cont ent t han normal;

� mot her’ s blood carries reduced amount of

oxygen / A/ W;

� fet us receives reduced / t oo l i t t le oxygen

supply;

� baby born wit h reduced birt h weight / mass /

smal l ;

� may show brain damage sympt oms;

max (3)

Quest ion

Number

Answer Mark

7(b)

� may cause sunburn / bl ist ering;

� can damage skin t issues / cel ls;

� ult ra-violet can cause cel l / nucleus /

chromosome damage;

� could lead t o (more) mut at ions;

� could lead t o skin cancer / melanoma;

max (4)

Quest ion

Number

Answer Mark

7(c)

� loud noise causes large vibrat ions of eardrum;

� t his causes large vibrat ions of middle earbone

/ mal leus;

� l igament s t o middle ear bone / mal leus

slackens;

� person cannot hear / suf fers t emporary

deafness;

� (ext ensive exposure) can lead t o cochlea

damage / deafness;

max (3)

(Total10 Marks)


Quest ion

Number

Answer Mark

8(a)

Cerebral hemispheres

� cont rols int el l igence / reasoning / learning /

cont rols volunt ary muscle / memory / vision /

hearing / personal it y;

(1 Mark))

Cerebel lum

� balance / involunt ary cont rol of skelet al

muscles / learned ref lexes / named example;

(1 Mark)

(2)

Quest ion

Number

Answer Mark

8(b)

� deat h;

� part C cont rols al l involunt ary muscles / gut /

heart beat / breat hing;

(2)

Quest ion

Number

Answer Mark

8(c)

� spinal cord;

� no impulses below break / lower body;

� no sensat ions (below break);

� paralysis (below break);

Rej ect

max (3)

(Total 7 Marks)


Quest io

n

Number

Answer Mark

9(a) 1 mark for each correct answer – maximum 4 marks

(4)

Quest ion

Number

Answer Mark

9(b)(i)

� prevent s furt her blood loss;

� prevent s ent ry of bact eria / pat hogens;

Rej ect germs

(2)

Quest ion

Number

Answer Mark

9(b)(ii)

� clot s / t hromboses could occur in blood vessels

and block t hem / cause st rokes / heart at t ack

/ eq;

(1)

(Total 7 Marks)

Blood vessel cut or damaged

plat elet s;

Soluble prot hrombin is

changed int o t hrombin

plasma;

f ibrin;

Eryt hrocyt es/ red

blood cel ls Clot formed


Quest ion

Number

Answer Mark

10(a)(i)

� grinding / crushing / chewing (food);

(1)

Quest ion

Number

Answer Mark

10(a)(ii)

� molars / (t ype) A;

(1)

Quest ion

Number

Answer Mark

10(a)(iii)

� remove al l bact eria / f ood remains / plaque

col lect ing here;

(1)

Quest ion

Number

Answer Mark

10(b)

� enamel;

� dent ine;

� calcium;

� bact eria;

� acid;

� erodes / corrodes / dissolves;

(6)

(Total 9 Marks)


7042/ 02 PAPER 2 MARK SCHEME – JUNE 2008

Quest ion

Number

Answer Mark

1(a)(i)

1. r ight at rium;

2. at rium (wal l ) cont ract s;

3. pushes blood int o vent ricle;

4. (via) cuspid valve;

Rej ect bicuspid

5. vent ricle (wal l) cont ract s;

6. forces blood int o pulmonary art ery;

7. (via) semilunar valves;

8. t hrough lung capil laries;

9. via pulmonary vein t o lef t at rium;

10. valves prevent backf low of blood;

max (7)

Quest ion

Number

Answer Mark

1(a)(ii)

1. blood in vena cava has raised carbon dioxide

level;

2. blood in vena cava has lower oxygen level; R

– none

3. carbon dioxide produced by body cel ls;

4. oxygen removed f rom blood as it passes

t hrough t issues;

5. blood in vena cava has low pressure;

6. pressure increased by pumping of heart ;

7. alveolar air has high concent rat ion of oxygen;

8. oxygen dif fuses int o capil laries;

9. combines wit h haemoglobin / forms

oxyhaemoglobin;

10. low carbon dioxide concent rat ion in alveolar

air;

11. carbon dioxide dif fuses out of blood;

12. suit able ref . t o concent rat ion gradient ;

13. glucose level drops;

14. reference t o respirat ion in alveol i;

max (9)


Quest ion

Number

Answer Mark

1(b) 2 marks for each correct answer f rom any of t he

fol lowing pairs – maximum 4 marks.

� cardiac muscle involunt ary;

� skelet al muscle volunt ary;

� cardiac muscle single cel ls;

� skelet al muscle f ibres wit h scat t ered nuclei /

coenocyt e described;

� cardiac muscle no fat igue;

� skelet al muscle fat igues;

� cardiac muscle not j oined t o skelet on;

� skelet al muscle j oined t o bones;

� cardiac muscle myogenic;

� skelet al muscle neurogenic;

max (4)

(Total 20 marks)


Quest ion

Number

Answer Mark

2(a)

� t hey det ect a st imulus / eq ;

Accept changes in environment

� t hey respond by generat ing elect rical impulse;

� pass t his t o CNS / brain / sensory neurone;

� one example f rom fol lowing l ist : skin / t ongue

/ cochlea / semi-circular canals / nose / eye ;

Rej ect senses

max (3)

Quest ion

Number

Answer Mark

2(b) Accept point s on label led / annot at ed diagram

1. l ight rays (almost ) paral lel ;

2. ent er via cornea;

3. rays ref ract ed / bent ;

4. pass (unalt ered) t hrough aqueous humour;

5. ent ers lens via pupil ;

6. lens made less convex / f lat t er;

7. by relaxat ion of ci l iary muscles;

8. suspensory l igament s pul l on lens;

9. f ine adj ust ment / f inal ref ract ion by lens;

10. pass (unalt ered) t hrough vit reous humour;

11. f inal focus on fovea / yel low spot ;

max (7)

Quest ion

Number

Answer Mark

2(c)

hard lens

� more dif f icul t t o change shape of lens /

accommodat ion dif f icul t ;

� dif f icul t t o form sharp focus;

� especial ly on dist ant / very close obj ect s;

cloudy lens

� l ight rays cannot penet rat e / scat t ered;

� image is blurred / fuzzy;

max (4)


Quest ion

Number

Answer Mark

2(d)(i)

� (mechanism t hat ) keeps int ernal condit ions /

cel l environment ;

� const ant / wit hin narrow l imit s;

(2)

Quest ion

Number

Answer Mark

2(d)(ii) 1 mark for each correct answer f rom any of t he


� regulat es t he amount of l ight reaching t he

ret ina;

� t oo much / bright l ight / ORA;

� circular muscles of ir is cont ract / ORA;

� radial muscles of ir is relax / ORA;

� pupil becomes smaller / less l ight ent ers

/ ORA;

(4)

(Total 20 marks)


Quest ion

Number

Answer Mark

3(a)(i)

� respirat ion;

� glucose;

� energy released in mit ochondria;

� suit able ref . t o enzymes;

� present on crist ae / inner membranes;

� (glucose) react s wit h oxygen;

� wast e product s are carbon dioxide and wat er;

� in aerobic respirat ion;

� energy released used t o form ATP;

max (6)

Quest ion

Number

Answer Mark

3(a)(ii)

� energy is used t o form ATP;

� combines ADP and phosphat e group;

� st ored in cel l ;

� when energy required ATP breaks down;

max (3)


Quest ion

Number

Answer Mark

3(b)(i) Any t hree pairs – up t o 2 marks each

� anaerobic – end product is lact ic acid;

� aerobic - end product s are carbon dioxide and

wat er;

� aerobic - requires oxygen;

� anaerobic - no oxygen needed;

� aerobic – glucose molecule complet ely broken

down;

� anaerobic – glucose molecule only part ial ly

broken down;

� aerobic – large number of ATP molecules

formed / a lot of energy released;

� anaerobic - few ATP molecules formed / l i t t le

energy;

(6)

1 mark for correct answer

� only minimal amount of lact ic acid t olerat ed as

it is t oxic / causes cramp;

� anaerobic respirat ion wast eful of energy

reserves / eq;

(1)

max (7)

Quest ion

Number

Answer Mark

3(b)(ii)

� carbon dioxide removed via alveol i / lungs;

� carbon dioxide used t o form urea;

� wat er removed via alveol i / lungs;

� wat er removed by kidney;

� lact ic acid oxidised (when oxygen is available);

� lact ic acid convert ed t o glycogen;

� in t he l iver;

max (4)

(Total 20 marks)


Quest ion

Number

Answer Mark

4(a)(i)

� long st ruct ure/ folded int ernal ly;

� large surface area;

� ref . t o ent ry of bi le / pancreat ic duct s;

� secret ion of enzymes;

� presence of vi l l i ;

� muscles move food along / mixing;

max (4)

Quest ion

Number

Answer Mark

4(a)(ii)

� for absorpt ion mat erials must be soluble;

� enzymes act ivat ed by alkal ine condit ions /

higher pH;

� bile produces alkal ine condit ions;

� bile emulsif ies fat s / eq;

� l ipase;

� fat s t o fat t y acids and glycerol;

� amylase;

� st arch t o malt ose;

� malt ase;

� malt ose t o glucose;

� pept idase / relevant named example e.g.

t rypsin;

� prot ein / pept ides t o amino acids;

(Accept any ot her relevant enzyme and ef fect )

max (8)

Quest ion

Number

Answer Mark

4(a)(iii)

� glucose absorbed int o blood capil laries;

� amino acids absorbed int o blood capil laries;

� fat t y acids / glycerol absorbed int o lact eals;

� ref . t o dif fusion gradient / relat ive

concent rat ions;

� ref . act ive upt ake;

max (3)


Quest ion

Number

Answer Mark

4(b)

� met abol ism of product s of digest ion / eq;

� glucose convert ed t o glycogen;

� st ored in l iver;

� excess amino acids deaminat ed;

� urea formed;

� alcohol broken down / oxidised;

� harmful subst ances det oxif ied;

max (5)

(Total 20 marks)


Quest ion

Number

Answer Mark

5(a)

� progest erone produced / level high;

� fert i l ised egg cel l / zygot e passes t o ut erus;

� moved along oviduct (by ci l ia);

� ut erine l ining rich in blood vessels;

� zygot e set t les on / sinks int o / at t aches t o

ut erine l ining / implant s;

� zygot e divides t o form bal l of cel ls;

� cel ls dif ferent iat e / eq;

� some cel ls form placent a / at t ach t o ut erine

l ining;

� ot her cel ls become embryo / fet us;

max (5)

Quest ion

Number

Answer Mark

5(b)(i)

� int erlocking of mat ernal and fet al t issues;

� ref . t o vi l l i ;

� large surface area in cont act ;

� a rich blood supply in bot h mat ernal and fet al

t issues;

� very t hin barrier bet ween blood suppl ies;

� al lows dif fusion t o occur readily (f rom one

syst em t o t he ot her);

� ref . t o concent rat ion gradient s;

� blood syst ems are not connect ed t o each ot her

/ no mixing of blood;

max (5)

Quest ion

Number

Answer Mark

5(b)(ii)

smal l int est ine

� higher concent rat ion in mat ernal blood;

� glucose / amino acids / vit amins / mineral

sal t s / fat t y acids / glycerol ;

� dif fusion int o fet al blood;

lungs

� oxygen higher concent rat ion in mat ernal blood;

� carbon dioxide higher concent rat ion in fet al

blood;

� dif fusion down concent rat ion gradient ;

kidneys

� urea in fet al blood dif fuses t o mat ernal blood;

max (6)


Quest ion

Number

Answer Mark

5(c)

� progest erone;

� prevent s breakdown of ut erine l ining;

� t hus prevent s miscarriage abort ion;

� ut erine l ining furt her vascularised / blood

vessels grow int o l ining;

� st imulat es placent al growt h;

� prevent s furt her ovulat ion / implant at ion / FSH

product ion;

max (4)

(Total 20 marks)


Quest ion

Number

Answer Mark

6(a)

� an organism t hat t ransfers pat hogens f rom

host t o host ;

� not it sel f harmed by t he pat hogen;

(2)

Quest ion

Number

Answer Mark

6(b)(i) 1 mark for correct answer.

� louse;

(1 Mark)



� pat hogen / bact erium / microbe on body / in

faeces of louse; R - germ

� lef t on human skin;

� louse bit es cause irr i t at ion;

� scrat ching breaks skin surface / al lows

pat hogen ent ry;

(max 3 Marks)

(4)

Quest ion

Number

Answer Mark

6(b)(ii) 1 mark for correct answer.

� anophel ine mosquit o;

(1 Mark)



� bit es/ st ab and sucks human blood;

� i f vict im has malaria parasit e ent ers mosquit o

wit h blood;

� when bit ing inj ect s sal iva t o prevent blood

clot t ing;

� sal iva cont ains cont ains parasit e;

(max 3 Marks)

(4)


Quest ion

Number

Answer Mark

6(c)

� (Schist osoma) eggs present in faeces / urine;

� hat ch in wat er t o release larva;

� larva ent ers body of snail ;

� develops int o second t ype of larva;

� released int o wat er;

� t his larva can penet rat e human skin

max (5)

Quest ion

Number

Answer Mark

6(d)

� obj ect s t hat pierce skin / named example;

� may be cont aminat ed by virus f rom user;

� i f not st eri l ised can pass virus t o second user;

� direct t ransfusion of cont aminat ed blood /

blood product s;

� sexual t ransmission;

� l ining of penis / vagina has no epidermis;

� t ransmission f rom mot her t o fet us / child;

� across placent a / during birt h;

max (5)

(Total 20 marks)


Quest ion

Number

Answer Mark

7(a)(i) 1 mark for each correct answer f rom any of t he


If nucleus included – maximum 3 marks

Accept marks on a label led diagram

� ref . t o smal l size / possible shape;

� cel l wal l ;

� cel l membrane;

� cyt oplasm;

� t hread / coi l of nucleic acid / DNA;

� f lagel lum / f lagel la;

� presence of plasmids;

max (4)

Quest ion

Number

Answer Mark

7(a)(ii) Accept point s on a label led diagram

� most cannot manufact ure own food;

� parasit es or saprophyt es;

� saprophyt es secret e enzymes / eq;

� ext ernal digest ion;

� (bot h groups) absorb / t ake in digest ed foods;

� by dif fusion;

� food sources - l iving organism / dead organic

mat t er;

� ref . t o chemot rophs;

� ref . t o phot osynt het ic bact eria;

max (5)

Quest ion

Number

Answer Mark

7(b)(i) 1 mark for correct answer.

� name / descript ion of disease; (must be a

bact erial example);

(1 mark)


fol lowing – maximum 4 marks (t reat ment s and

cont rols must be specif ic t o named disease)

For non-bact erial diseases al low t reat ment and

cont rol

� use of ant ibiot ics;

� named example;

� second met hod of t reat ment ;

� vaccinat ion / medical met hod of cont rol ;

� environment al met hod of cont rol ;

(maximum 4 marks)

(5)


Quest ion

Number

Answer Mark

7(b)(ii) Accept any t hree recognised processes wit h

examples – 2 marks each

� food product ion;

e.g. yoghurt / cheese / soy sauce;

� decomposit ion;

format ion of humus / manure / compost / et c;

� recycl ing;

e.g. nit rogen cycle / carbon cycle / sewage

t reat ment ;

� biot echnological processes;

genet ic engineering / named example;

accept any relevant examples

need explanat ion / descript ion for second mark

max (6)

(Total 20 marks)


Quest ion

Number

Answer Mark

8(a)

� an inj ect ion / oral l iquid;

� cont aining weakened / dead pat hogens /

ant igens;

max (2)

Quest ion

Number

Answer Mark

8(b)(i)

� ant igens;

� prot eins on surface of pat hogen

� st imulat e whit e blood cel ls / lymphocyt es;

� t o form ant ibodies;

� act ion of ant ibody / dest roy / agglut inat e

pat hogens;

� remain in blood for some t ime;

� memory cel ls ret ain abil i t y t o make

specif ic ant ibody;

� t hus can respond t o fut ure infect ions;

� before sympt oms appear;

max (6)

Quest ion

Number

Answer Mark

8(b)(ii)

� t akes some t ime for ant ibodies t o be formed;

� i f infect ed ant igens already present ;

� t hus whit e blood cel ls al ready st imulat ed;

max (2)


Quest ion

Number

Answer Mark

8(b)(iii)

� ant ibodies present in mot her’ s blood;

� f rom infect ions / immunisat ions she has had;

� ant ibodies can cross placent a;

� ant ibodies act ive in child at birt h;

� memory cel ls do not cross placent a;

� child’ s organs dest roy / excret e ant ibodies

wit hin mont hs;

� presence of fut ure ant igens needed t o t r igger

child’ s own immune syst em;

max (5)

Quest ion

Number

Answer Mark

8(c)

� whit e blood cel ls / lymphocyt es needed t o form

immune syst em;

� baby not able t o form ant ibodies;

� t herefore unable t o dest roy pat hogens;

� even normal ly mild infect ions can become fat al ;

� whit e blood cel ls formed in bone marrow;

� t issue mat ching necessary for donor t issue t o

avoid rej ect ion;

� successful t ransplant wil l form new act ive whit e

blood cel ls;

max (5)

(Total 20 marks)


Quest ion

Number

Answer Mark

9(a)(i)

� process of phot osynt hesis;

� l ight energy;

� absorbed by chloroplast s / chlorophyl l ;

� convert ed t o chemical energy;

� used t o combine carbon dioxide and wat er;

� t o form glucose / simple sugar;

� glucose convert ed t o ot her subst ances;

� e.g. st arch / fat s / prot eins;

� passed t o consumers;

� some ATP formed;

max (6)

Quest ion

Number

Answer Mark

9(a)(ii)

� suit able food chain;

(must st art wit h producer have a suit able

herbivore and end wit h human)

� eat en / digest ion by consumers;

� mat erials assimilat ed in body of consumer;

� energy lost at each st age of chain;

Maximum of 2 marks f rom

� by respirat ion;

� by defaecat ion;

� excret ion;

� heat / movement undigest ed mat erial ;

max (4)

Quest ion

Number

Answer Mark

9(b)(i)

� for manufact ure of prot eins;

� nit rat es needed for conversion glucose t o

amino acids;

� amino acids formed int o prot eins;

� nit rat es supply increased by use of manure /

compost / humus;

� increased by use of chemical fert i l isers;

� use of leguminous crop (explained);

max (4)


Quest ion

Number

Answer Mark

9(b)(ii)

� nit rat es very soluble;

� easily leached int o lakes / r ivers;

� eut rophicat ion can occur;

� rapid growt h of algae (on surface) / algal bloom;

� l ight excluded f rom deeper layers;

� deat h of algae and ot her aquat ic plant s;

� provide food for bact eria;

� rapid reproduct ion of bact eria;

� use up oxygen / creat e anaerobic condit ions;

� aquat ic animals die f rom lack of oxygen;

max (6)

(Total 20 marks)

Furt her copies of t his publ icat ion are available f rom Edexcel UK Regional Of f ices at www.edexcel.org.uk/ sfc/ feschools/ regional/ or Int ernat ional Regional Of f ices at www.edexcel-int ernat ional.org/ sfc/ academic/ regional/ For more informat ion on Edexcel qual if icat ions, please visit www.edexcel-int ernat ional.org/ quals Alt ernat ively, you can cont act Customer Services at www.edexcel.org.uk/ ask or on + 44 1204 770 696 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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