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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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
Quest ion
Number
Answer Mark
5(d)(ii)
� i t wil l increase / eq;
(1)
(Total 13 Marks)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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
7042 GCE O Level Human Biology
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 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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
fol lowing – maximum 4 marks
� 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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
1 mark for each correct answer f rom any of t he
fol lowing – maximum 3 marks
� 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)
1 mark for each correct answer f rom any of t he
fol lowing – maximum 3 marks
� 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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
Quest ion
Number
Answer Mark
7(a)(i) 1 mark for each correct answer f rom any of t he
fol lowing – maximum 4 marks
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)
1 mark for each correct answer f rom any of t he
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
7042 GCE O Level Human Biology
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)
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