(a)
4.
2. 3.
1. (In la latency) th there is is a delay lay be between in infection an and {symptoms / lysis} / eq ; (In latenc latency) y) viral viral gene genetic tic materi material al is is inco incorpo rporate rated d into into hos host’s t’s DNA / eq ; Reference to a trigger / eq ;
2
(b)
Reverse transcriptase ;
1
(c )
Makes DNA ; Using viral RNA as template / eq ;
2 [5]
(a) (a) 2. 3.
5.
(b)
1. Sub Substan stancce pro produ duce ced d by by an an {or {orga gan nism ism / mi micro croorga organ nism ism / fun fung gus} us} ; That That {ki {kills lls / inhi inhibi bits ts} } the the grow growth th of of {bac {bacte teria ria / othe otherr orga organis nisms ms} }; (often (often)) a second secondary ary metabo metabolite lite / prod produce uced d {at {at end of expone exponenti ntial al phase phase / during stationary phase} ;
(i)
1. The lag phase is longer with E.coli / L.bulgaricus begins to increase before E.coli ; The growth is more ra rapid (in growth phase) with E.coli ; Credit manipulated use of figures to compare growth rate ; The stati tatio onary period iod is reache ched earlier with ith E.co .coli / E.coli has a shorter exponential phase ; More cells per cm3 (maximu imum) in E.coli tha than in L.bu .bulga lgaricus ;
2. 3. 4. 5.
(ii)
2
1.
3
Penicillin (affects growth of L.bulgaricus) because it is Gram positive ; Bacteriostatic / eq ; No effect during lag phase ; Starts having effect once bacteria in growth phase ; Only affects dividing cells ; Because it interferes with structure of {cell wall / mucopeptide} 4
2. 3. 4. 5. 6. ;
[9]
6.
st
(a)
(i)
1.
Lag period / no immediate rise {rise / production} of in antibodies AND
nd
1 injection
2
injection immediate
antibodies;
2.
4 weeks to reach peak peak;
3.
Peak Peak afte afterr first first inject injection ion is 2 au and and peak peak afte afterr seco second nd is 5.5 – 5.7 5.7 au au / {175% increase / increases by 3.5 – 3.7 au / greater increase} after 2
4.
nd
2 weeks to reach
injection; st
More More rapi rapid d dec decli line ne in anti antibo body dy leve levell aft after er 1 injection less rapid decline in antibody level after 2
nd
injection
3
(ii)
(b)
1.
Antigens {activate / detected by} lymphocytes;
2.
Referenc ence to specificity; ty;
3.
B ce cells{ ls{divi ivide/re /replica icate} te};
4.
Deve evelop lop into plas lasma cells ells;;
5.
(Pla (Plasm smaa cell cells) s) {se {secr cret ete/ e/pr prod oduc uce} e} ant antib ibod ody; y;
6.
Reference to memory cells;
3
Passiv Passivee immunit immunity y comes comes from from antib antibodi odies es provi provided ded by by {mother {mother// injecti injection} on};; Body never exposed to the antigens; So no ability to make the antibodies; Short lived / only lasts for as long as antibodies present in body / no memory cells produced
(c)
3
Protei Protein n conte content nt of lymph lymph is is higher higher than than that that of tiss tissue ue flui fluid d but but lower lower than that of (blood) plasma; Reference to {low permeability of capillary wall to protein / high permeability of lymphatic capillary to protein / overall movement of protein into lymphatic capillary / antibodies produced in lymph node};
2 [11]
(a)
7.
(b)
9.4 and 11.4
1
Women Women of 15–49 15–49 are {ferti {fertile le / of reprod reproduct uctive ive age}; age}; {Approximately / eq} half of all women aged 15-49 are infected with HIV; They could give birth to infected children;
(c) (c)
Die before giving birth / not have children;
2
Over Overal all, l, popu popula latio tion n will will get get sma small ller er;; Fewer women surviving to give birth, so fewer children; {1 in 5 adults / eq) will die of AIDS in future; Children dying of AIDS; So population consists of older people;
2 [5]
3
8.
(b)
(a)
1.
2.
Stimu Stimula late te immu immune ne resp respon onse se / antib antibod ody y prod produc uctio tion n by B cells;
3.
Clon lonal selec electi tion on by the the ant antig igen en / eq eq;
4.
B cel cells ls {pro {proli life fera rate te / clo clone ne / div divid idee / clo clona nall lly y expand / undergo mitosis};
5.
To plasma cells;
6.
(Pla (Plasm smaa cell cells) s) {pro {produ duce ce / eq} eq} (spe (speci cifi fic) c) antib antibod odies ies;;
7.
Reference to antigenic presentation;
1.
(HIV pr proteins act as) an antigens;
4
Not much effect in first few years;
2.
Numb Number er of T help helper erss fall fallss (wit (with h time time); );
3.
Refer eferen ence ce to role role of cyto cytoki kine ness;
4.
Less Less able able to to {re {resp spon ond d to to ant antig igen en / mou mount nt immu immune ne response / eq} / not enough cytokines produced;
5.
More More dif diffficul icultt to preve revent nt infe infect ctio ion; n;
6.
Heal Health th dete deterio riora rate tess / more more inf infec ectio tious us ill illne ness ss / opp oppor ortun tunis istic tic infection / example;
7.
Refer eferen ence ce to T ce cells lls goi going ng belo below w 200 200;;
8.
Reference to AIDS;
9.
Death likely;
4 [8]
9.
(b)
(a) (a) Prod Produc uced ed by a {fu {fung ngus us / mic micro roor orga gani nism sm / orga organi nism sm); ); Bactericidal / kills another {microorganism / bacteria} OR bacteriostatic / inhibits growth of microorganisms;
2
Acquire Acquired d {abilit {ability y / eq} of of microo microorga rganis nism m to resis resistt effect effect of of an antibi antibioti otic; c; To which is normally susceptible; Reference to {gene / plasmid};
2
(c )
1.
Overuse / {unnecessary / inappropriate} use;
2.
{Pro {Proph phyl ylac actic tic / eq} eq} treatm treatmen entt (of (of pati patien ents ts / ani anima mals ls); );
3.
Used Used in {cat {cattl tlee / poul poultr try} y} food food;;
4.
Not finish ishing the the course;
5.
Conc Concen entr trat atio ion n presc rescri ribe bed d is too too low; low;
6.
Use of broad spectrum antibiotics;
2 [6]
(a) (a) Orga Organi nism sm that that caus causes es dise diseas ase; e; E.g. {virus / bacterium / fungus};
10.
(b)
(ii)
(iii) (iii)
2
(i) (Release) histamine; Dilation of arterioles / increased blood flow / vasodilation; Oedema / swelling / leakage of plasma; More white blood cells / eq (attack pathogens); Mast cells;
3
Enzyme; Tears / saliva / nasal secretions; Breaks down (cell walls of) bacteria / kills bacteria / lysis;
2
{Destr {Destroys oys / preven prevents ts repli replicat cation ion of} of} virus viruses es OR Secreted by infected cells;
1 [8]
(a) {Foreig {Foreign n / nonnon-sel selff / eq} eq} sub substan stance ce / eq; Which Which stim stimula ulates tes an immune response / eq; Antibodies produced / reference to specificity / binds to antibodies;
11.
(b)
(i)
(ii)
(c)
1.
Increase is more rapid;
2.
More More ant antib ibod ody y prod produc uced ed ove overa rall ll by seco second nd inj injec ectio tion n / conv conver erse se;;
3.
Seco Second nd inj injec ectio tion n peak peakss befo before re fir first st inj injec ecti tion on / con conve vers rse; e;
4.
Antib Antibod ody y pres presen entt at at 0 week weekss for for seco second nd inje inject ctio ion; n;
5.
Plat Platea eaus us at peak peak only only in seco second nd inje inject ctio ion; n;
6.
Credit quantitative comparison;
1.
2
3
Memory cells already present;
2.
More More cell cellss to resp respo ond to ant antigen igen;;
3.
So mor moree like likely ly tha thatt the the ant antig igen en woul would d be dete detect cted ed;;
4.
Refe Refere renc ncee to to {cl {clon onal al selec selectio tion n / clo clone ne / clon cloning ing}; };
5.
Refer eferen ence ce to pla plasm smaa cel cells ls pro produc duced {faster / in greater numbers};
6.
Plas Plasma ma cell cellss prod produc ucee the the anti antibo bodi dies es;;
7.
Reference to {primary / secondary} immune response;
High High circu circulat lating ing antibo antibody dy;; Remov Removes es strep streptok tokina inase se / preven prevents ts streptokinase activity; Not an effective treatment; Could cause damaging response;
4
2
5
(d)
{Response / antibodies} specific to this antigen / different antigen;
1 [12]
12.
(ii)
(a)
(i)
2.
The The bigg bigger er the the mes mesh, h, the the gre great ater er the the bre break akdo down wn / leav leaves es in in the the 5 mm mesh {broken down / eq} more quickly than the other bags;
3.
Leav Leaves es in the the air air brok brokee dow down n the the lea leasst;
4.
In {1 mm / 5 mm mesh mesh} } no no cha chang ngee afte afterr {No {Nov v 198 1989 9 / May May 199 1990} 0} but 0.05 mm continued to break down over entire period / eq;
5.
In fir first st six six mon month ths, s, lea leave vess rema remain ining ing in 5 mm mes mesh h was was {half {half / eq} eq} that remaining in {0.5 mm / 1 mm} mesh / any other valid comparison;
6.
Comp Compar aris ison on of 0.05 0.05 in air air and and 0.05 0.05 in soil soil;;
7.
Cred Credit it for for suit suitab able le com compa para rativ tivee mani manipu pulat lation ion of of data data e.g e.g.. 19% 19% more leaves were broken down in 5 mm mesh compared with 61 % in 1 mm mesh; 4
1.
1.
Reference to all decrease;
{Soil animals / organisms / microorganisms / decomposers} {responsible for the breakdown of the leaves / feed on the
leaves};
(b)
2.
The The bigg bigger er the the mes mesh, h, {the {the more more ani anima mals ls / lar large gerr anima animals} ls} are are able able to enter the bags to feed on the leaves / eq;
3.
Cred Credit it a spe speci cifi ficc examp example le,, e.g. e.g. wor worms ms can canno nott ente enterr the the bags bags with with smaller mesh;
4.
Bag Bag in the the air air had had leas leastt brea breakd kdow own n beca becaus usee {few {fewer er / no} no} {soi {soill animals / organisms / microorganisms / decomposers} could get at the leaves / reference to {lack of moisture / dry air} / eq;
The high higher er the the nitro nitrogen gen conten contentt {the {the great greater er the the break breakdow down n / eq}; eq}; {Soil animals / microorganisms / decomposers} {more numerous / breed more / grow more} in leaves with higher nitrogen content OR leaves with more nitrogen were more {palatable / nutritious} reference to lignin / eq;
(c )
1.
2
2
Decomposition affected by {climate / weather};
2.
{Hot {Hot / wet wet} } clim climat atee incr increa ease sess rate rate of of deco decomp mpos osit itio ion n so lea leave vess are are broken down quickly;
3.
Pine Pine need needles les {do {do not not brea break k down down qui quick ckly ly / har harde derr to brea break k dow down} n} (so build up on forest floor);
4.
Rain Rainfo fore rest st lea leave vess may may have have high high nitro nitroge gen n cont conten entt so are are bro broke ken n down more;
5.
Refe Refere renc ncee to to {te {temp mper eratu ature re / pH} pH} and and enz enzym ymee act activ ivity ity;;
6.
Pine Pine need needles les {may {may con contai tain n inhib inhibito itory ry che chemi mica cals ls / are are thick thick / are are waxy / are fibrous / eq};
3
(d)
1. {Bacteria / microorganisms / fungi} in soil {breakdown / putrefy / decompose} leaves / reference to bacterial decomposition; 2.
Relea eleassing ing {amm {ammon onia ia / ammo mmoniu nium}; m};
3.
{Nit {Nitro roso somo mona nass / refer referen ence ce to nit nitri rify fying ing bact bacter eria ia [allo [allow w ONCE ONCE]} ]} {converts / oxidise} {ammonia / ammonium) to nitrite;
4.
{Nit {Nitro roba bact cter er / ref refer eren ence ce to to nitr nitrify ifying ing bact bacter eria ia [al [allo low w ONCE ONCE]} ]} {converts / oxidise} nitrite to nitrate; [Max Maximum 2 marks if any reference to nitrogen fixatio ation n or Rhizobium]
3 [14]
(a) (a)
13.
1.
{Mic {Micro roor orga gani nism sm / nam named ed orga organi nism sm} } ent enter erss {tis {tissu sues es / org organ anss / cel cells ls}; };
2.
Beca Becaus usee micro microor orga gani nism sm pen penet etra rate tess host host’s ’s nat natur ural al barr barrier ierss / eq;
3.
Multiplies;
4.
Damages {tissues / cells} / releases toxins;
(b)
(i)
2
Invade cells in the lung;
{Lung tissue / alveoli} destroyed; Blood vessels ruptured;
(ii) (ii)
Coughing to remove debris from lungs;
2
Reas Reason on for for exi exist sten ence ce of of resis resistan tantt bacter bacteria ia;; Any resistant bacteria will multiply; And pass on resistance gene / plasmid / eq;
2 [6]
14.
(a)
3 Active immunity
Passive immunity
1.
Refe Referrence ence to use use of of bo body’s dy’s own own lymphocytes
Own lymphocytes not involved;
2.
Anti Antibo bodi dies es prod produc uced ed with within in the the body
Antibodies {not produced within the body / acquired};
3.
Res Results ults from rom expo expossure ure to {pathogen / antigen / eq}
4.
Long lasting
5.
Make Make more more anti antibo bodi dies es / ref refer eren ence ce to memory cells
Results from {injection / mother during pregnancy / breast milk / breast feeding}; Less long lasting / eq; No ability to make more / no memory cells;
7
(b)
1. {Coal dust / asbestos fibres / other named material} (enters lungs / breathed in); 2.
Refe Refere renc ncee to to inh inhal alat atio ion n ove overr time time peri period od / eq; eq;
3.
Cause ausess infl inflaamma mmatory tory res respon ponse;
4.
Macrophages accumulate;
5.
Causes {lesions / nodules / plaques / fibrosis};
3 [6]
(a)
15.
Skin is a physi physical cal barrie barrierr to bacter bacteria ia /pre /preven vents ts entr entry y / eq;
Normal flora compete {better than / with} pathogens; Surface {too salty / too acidic} for pathogens; Antibacterial agents in {sweat / eq}; Reference to hygiene; Reference to lysozyme / tears / saliva;
(b)
2
Clot formation;
[accept a description] Histamine release; Vasodilation / increased blood flow; Phagocytosis / (increased) phagocytes; Mitosis / cell division;
2 [4]
16.
(a)
1.
Agar {plates /dish};
[Reject agar with no qualification] 2.
{Law {Lawni ning ng / spre spread adin ing g / coa coati ting ng} } with with bac bacte teri ria; a;
3.
Sterility of of eq equipment;
4.
Aseptic technique;
5.
{Wel {W ells ls / disc discss / pape paperr / cont contai aine nerr / eq} eq} wit with h anti antibi biot otic; ic;
6.
Refe Refere renc ncee to to dif differ feren entt con conce cent ntra rati tion onss of of antib antibio ioti tic; c;
7.
Contro Controll of {solve {solvent nt only only / ster sterile ile water water / disc disc alone alone / known known antibi antibioti otic}; c};
8.
Incubation;
9.
Detail Detailss of of safe safe incu incubat bation ion e.g. e.g. tempera temperatur ture, e, taping taping plates plates closed closed;;
10.
{Measure / compare} a dimension of (area without bacteria);
5
(b)
Resist Resistanc ancee deve develop lopss / bacter bacteria ia not not killed killed by existi existing ng antibiotics / disease cannot be cured with existing antibiotics; Alternative pathways / enzymes destroy antibiotic / eq; Explanation of how resistance develops; Rapid {division / mutation / generations} of bacteria / high mutation rate of bacteria;
2
[Reject immune]
(c) (c)
Ensu Ensure re saf safee to use use on on {peo {people ple / mamm mammal als} s} / not not tox toxic ic;; Mammalian cells similar to human cells / eq;
(d)
(i)
10% = 20 (line on graph worth credit); –3
4.3(mg dm ); (ii) (ii)
1
2
Some Some bact bacter eria ia alre alread ady y resi resist stan ant; t; Some (bacteria) {survive / are not all killed} at high concentrations / use of figures; Reference to inheritance of resistance alleles;
2 [12]
(a)
17.
(b)
Lung(s) 1. BCG};
1 They {are immune / are resistant / have been vaccinated / have had
2.
Have Have anti antibo bod dies ies / hav havee mem memo ory cell cells; s;
3.
Bacteria destroyed before they cause damage / eq.
(c )
1.
2
Prolonged drug treatment (3-9 months) / eq;
2.
Antibi ibiotics / iso isoniazi azid / eq;
3.
At leas leastt 3 (an (anti tib biot iotics) ics) are are use used d / eq; eq;
4.
Rest / healthy diet / direct observation therapy;
3 [6]
18.
(a)
A
Chromosome / DNA
B
Ribosomes
C
Plasmid / DNA if not A
D
Cell wall
2
One mark for two correct answers;;
9
(b)
Smaller size; No cytoplasm; No cell membrane; Protein coat; Cannot reproduce independently; Cannot respire;
(c )
1.
3
Easily seen / converse;
2.
Don’t ch change / converse;
3.
Pres Presen entt in in all all memb member erss of of gro group up / con conve vers rse; e;
4.
Appearance is consistent / converse;
2 [7]
(a)
19.
Respon Response se of of the the body’ body’ss immun immunee syste system m / maki making ng anti antibod bodies ies / eq;
To (foreign) antigen / organism / bacterium / pathogen / virus;
(b)
(c)
1.
Detect antigen;
2.
Via surface receptors;
3.
Prolif liferatio tion eg eg mit mito osis / eq eq;
4.
Refe eference to plasma cells;
5.
Antibody (secretion);
6.
Refer eferen ence ce to prim primar ary y resp respo onse; nse;
7.
Refe eference to memory cells;
8.
Refe Refere renc ncee to seco second ndar ary y resp respon onse se /eq; /eq;
9.
Reference to mode of action of antibody;
5
M. bovis antigens similar to tuberculosis / M. fortuitum not similar; No (secondary response / memory cells t o) tuberculosis in A / no immunity / converse;
(d)
2
2
Immunity to M. fortuitum prevents M. bovis growing and dividing;
M. fortuitum immunises against M. bovis / eq.; No stimulation of immune response to TB antigens;
M. fortuitum causes antibody production against M. bovis;
2
(e )
BCG won’t protect against TB / more likely to get TB;
1 [12]
20.
(b) (b)
(a) (a)
1.
(Ran (Rand dom / chan chance ce)) muta utation tion (re (result sultin ing g in resis esista tan nce); ce);
2.
Expo Exposu sure re to antib antibio ioti ticc sel selec ects ts resi resist stan antt mut mutan ants ts;;
3.
More More like ikely to surv surviv ivee / rep reprodu roduce ce;;
4.
Desc Descen end dents ents also also have have res resista istanc nce; e;
5.
Refer eferen ence ce to natu natura rall sele select ctio ion; n;
6.
Reference to transmission of plasmids;
2
Used Used less less freq frequ uentl ently y / eq eq.; Fewer bacteria exposed; Less likely to select resistant mutant;
2
(c )
Untreated paper disc / disc soaked in appropriate solvent;
1
(d) (d)
Anti Antibi biot otic ic alon alonee ine ineff ffec ecti tive ve,, Bodyguard molecule ineffective / eq. ;; Augmentin prevents growth of bacteria;
(e )
1.
3
Bodyguard molecule prevents ba bacterial en enzyme from wo working / bodyguard molecule prevents gene being expressed;
2.
Refer eferen ence ce to enzy enzyme me inhi inhibi bito torr;
3.
Bloc Blocki king ng of activ activee site sitess / othe otherr det detai aill of of inh inhib ibit ition ion;;
4.
Antibi ibiotic no not br broken do down;
5.
Antibiotic can act on bacterium;
2 [10]
11
21. Bacterial cell
Patient’s cell
{70S / smaller} ribosome
{80S / larger} ribosome ;
2.
No membrane bound organelles / mesosomes
Membrane bound organelles / named example / no mesosomes;
3.
No nucleus / nuclear envelope
1.
4. 5. 6.
Nucleus / nuclear envelope ;
Circular DNA
Linear DNA ;
(Peptidoglycan) cell wall
No cell wall ;
Prokayotic
Eukayotic ;
2
(b)
(i)
(ii)
1. Bacteria type B is sensitive to antibiotics p and q whereas type A is {resistant / not sensitive} ;
2.
Bacte Bacteria ria type type B are are more more sen sensi sitiv tivee than than typ typee A to antib antibiot iotic ic R ;
3.
Neither types of bacteria are sensitive to antibiotic S ;
1.
2
Antibiotic S ;
2.
Beca Becaus usee it it is is ine ineff ffec ecti tive ve on both both type type A & B / eq eq ;
3.
(bec (becau ause se peni penici cill llin in)) onl only y wor works ks on gram gram posi positiv tivee bacteria / converse;
4.
Interferes with synthesis of cell wall ;
3 [7]
22.
(b)
(a)
1.
Similar route for infection;
2/3. 2/3.
Exampl Examples es of means means of transm transmiss ission ion;; ;;
4.
Immu mmunosu nosupp ppre resssion ion in HIV/ HIV/eq eq;;
5.
Reference to opportunistic infection / eq;
T(-cell) / T-lymphocyte / T-killer;
(c )
1.
2
1
Signal from surface protein;
2.
Activation of PKR;
3.
Refe Refere renc ncee to to pro prote tein in synt synthe hesis sis / tra trans nsla latio tion n / eq; eq;
4.
No production of virus;
5.
Cell death / cell function disrupted;
3
(d)
1.
PKR binds to virus protein;
2.
Does Does not prev preven entt pro prote tein in syn synthes thesis is;;
3.
Viruses re reproduce; 2
(e )
1.
Rapid reproduction;
2.
Many Many (ge (gene ne)) mutati mutation onss / relev relevan antt muta mutatio tion n more more like likely ly in giv given en time time;;
3.
Refer eferen ence ce to var variety iety of prot protei eins ns;;
4.
Large variation;
5.
Selection;
6.
Of res resis ista tan nt ph pheno enotype / ge gene;
7.
Short time;
8.
Long drug development time;
4 [12]
23.
(a) (a)
An exp expla lana nati tion on to inc inclu lude de six six fro from: m:
1.
Increased use;
2.
More bacteria exposed;
3.
Reference to mutation;
4.
Reference to plasmids;
5.
Refe Refere renc ncee to conj conjug ugat atio ion n / sexu sexual al repr reprod oduc uctio tion; n;
6.
Refe Refere renc ncee to gen genet etic ic var variat iatio ion n / exis existen tence ce of of diff differ eren entt gene genes; s;
7.
Refe Refere renc ncee to to sel selec ecti tion on by the the ant antib ibio ioti tic; c;
8.
Descript iption of selec lectio tion;
9.
Refe Refere renc ncee to resi resist stan ance ce gene gene pass passed ed to offs offspr prin ing; g;
10. 10.
Sele Select cted ed org organ anis isms ms bec becom omee more more commo common; n;
11/12. Reference to graphs;;
(b)
(i)
(ii) (ii)
Greater clear area;
6
1
An expl explan anat atio ion n to inclu include de two two from from:: 1.
Larg Larger er mol molecu ecule less / anti antibi biot otic ic C {dif {diffu fuse se / eq} eq} more more slow slowly ly
2.
Through agar;
3.
Does Does not not rea reach ch as as many many bacte bacteria ria as the the sma smalle llerr antib antibio iotic tic B;
4.
Clear ear area of C is reduced;
5.
Under estimates the effectiveness of C / converse;
2
13
(iii (iii))
An expl explan anat atio ion n to inclu include de:: 1.
Viruses no cell wall;
2.
or ribosomes/ viruses use host cell for protein synthesis;
2 [11]
24.
(a) (a)
An expl explan anat atio ion n to to inc inclu lude de two two fro from: m:
1.
Engulfed / endocytosis;
2.
Digested / eq;
3.
Reference to enzymes / lysosomes;
(b)
(i)
(ii) (ii)
(c) (c)
2
An explanation to include three from:
1.
Reference to APC;
2.
Reference to to cy cytokines;
3.
(T ce cells) st stimulate response;
4.
CD4 dep deple lete ted d ca cannot re respond;
5.
Inje Inject cted ed cell cellss res resto tore re immu immune ne resp respon onse se;;
6.
Refer eferen ence ce to sp specif ecific ic resp respon onsse;
7.
Prevents TB;
3
An expl explan anat atio ion n to inclu include de two two from from:: 1.
HIV destr estro oys / kil kills ls T hel helpe perr cel cells ls;;
2.
Reduced re response;
3.
More likely to show symptoms / develop TB;
2
An expl explan anat atio ion n to to inc inclu lude de two two fro from: m: 1.
Chem Chemic ical alss (fr (from om inf infec ecte ted d lung lung)) sti stimu mula late te NV NV prod produc ucti tion on;;
2.
In T helper cells;
3.
Reference to control;
2
(d) (d)
A sugg sugges esti tion on to inc inclu lude de thr three ee fro from: m: 1.
Chem Chemic ical alss / lymp lympho hoki kine ness from from rna rnacr crop opha hage gess from from inf infec ected ted lung lung
2.
F-HV F-HV inf infec ects ts mor moree / help helper er cel cells ls / numb number er of of T help helper er cel cells ls fal falls ls;;
3.
Less able to destroy M tuberculosis / eq;
4.
More phagocytosis;
5.
More More lymph ympho okines ines / chem hemical icalss;
6.
Refer eferen ence ce to posi positi tiv ve fe feedba edback ck / eq eq;
7.
Both diseases progress more rapidly;
3 [12]
(a) (a) A - (B (B-cel -cell/ l/BB-ly lymp mpho hocy cyte te)) B - clone of B cell / activated B c ells / B effector cells / eq; C - memory B cells; D - plasma cell / antibody secreting cell; E - T-cell / helper T-cell / eq;
25.
(b) (b)
(c )
A sugge uggesstio tion to inc includ lude
two
4
from:
1.
HIV HIV kill killss lym lymph phoc ocyt ytes es / red reduc uces es lymp lympho hocy cyte te numb number ers; s;
2.
reference to T helper / CD4 cells;
2
(Aabb × aaBb) Gametes Ab, ab; aB, ab; aabb, aaBb, Aabb, AaBb; correct genotype identified; ¼ / 1:3 / 25%;
4
15
(d)
Any two from: 1.
karposi’s sarcoma;
2.
excessive sweating;
3.
chronic lu lung in infection ions/TB /TB;
4.
pneumonia;
5.
opportun tunistic tic inf infect ection ion;
6.
weight loss;
7.
extr extreeme leth ethargy argy / tired iredne nesss;
8.
any valid point;
2 [12]
(a) Penicillin: no cell wall in virus;
26.
Tetracycline: no protein synthesis in virus;
(b) (b)
(c) (c)
2
A desc descri ript ptio ion n and and an an exp explan lanati ation on to inc inclu lude de four from: 1.
penicillin llin bacter teriocida idal;
2.
because cell de destroyed / eq eq;
3.
decr decrea easses numb number er (of (of liv livin ing g cel cells ls));
4.
tetr tetrac acyc yclline ine bact bacteerio riostat tatic; ic;
5.
no reproduction / eq;
6.
same number (of living cells);
A sugge uggesstio tion to inc includ lude
three
4
from:
1.
slows growth / fewer cells; ls;
2.
more more time time for for imm immun unee sys syste tem m to to res respo pond nd;;
3.
refe refere renc ncee to deta detail il of spec specif ific ic immu immune ne resp respon onse se;;
4.
phagocytosis / description;
3 [9]
1.
27.
by inh inhal alat atio ion n of bac bacte teri riaa in (dr (drop ople lets ts/d /dus ust) t);;
2.
called Mycobacterium tuberculosis;
3.
form format atio ion n of of {tub {tuber ercl cles es / pla plaqu ques es / lesi lesion ons} s};;
4.
in the lungs;
5.
ref to invasion of other tissues / organs;
3 [3]
(a)
28.
(b)
present inside {cells/ macrophages};
1
B-cells : antibody production; ref memory cells; ref plasma cells; T-cells : antigenic presentation; stimulation of B-cell proliferation / eq;
(c )
3
(i) HIV destroys T (helper) cells; Bacterial cells not destroyed by the immune system / eq; Bacteria proliferate/eq;
(ii)
2
tubercles; fever; excessive coughing / coughing blood; weight loss; 2 [8]
(a) 1. Gram positive bacteria / S. aureus {more sensitive to /shows greater effect / more susceptible to / shows less resistance} to ampicillin /eq;
29.
2.
S. aureus / Gram positive have thick {cell wall / peptioglycan layer / eq};
3.
ampi ampici cill llin in affe affect ctss cell cell wall wall synt synthe hesi sis; s;
4.
inhi inhibi bits ts for forma mati tion on of of {pep {peptid tidog oglyc lycan an bon bonds ds (in (in cel celll wall wall)) / eq}; eq};
5.
weakening of of ce cell wa walls;
6.
reference to osmotic shock / cell lysis / eq;
(b)
1.
max 4
correct reason for existence of resistant bacteria;
2.
any any resi resist stan antt bact bacter eria ia will will mult multip iply ly;;
3.
(and) pass on {resistance gene/ plasmid};
max 2
17
(c )
(d)
(48-36); /36 × 100 = 33.33%;
2
ampicillin doesn’t fit active site / allosteric effect / eq;
1 [9]
(a)
30.
1.
response of of im immune sy system tem / bo body’s im immun mune ce cells lls /e /eq;
2.
to antigen /eq;
3.
producing antibodies;
4.
T killer cells;
(b)
1.
max 2
memory cells produced;
2.
resp respon onse se more more rap rapid id (on (on rein reinfe fect ctio ion) n) / fast faster er anti antibo body dy production;
3.
prevents symptoms /eq;
4.
high higher er con conce cent ntra rati tion onss of anti antibo bodi dies es pro produ duce ced; d;
5.
anti antibo bod dies ies pro prod duced uced for for lon longer; ger;
6.
reference to secondary response;
(c )
1.
population can be protected more quickly /eq;
2.
poss possib ible le to to kee keep p hig high h lev level elss of of immu immuni nity ty / herd herd immu immuni nity ty;;
3.
dist distri ribu buti tion on mor moree rel reliab iable le / poss possib ible le to to remo remote te are areas as /eq /eq;;
4.
ref. ref. to exam exampl plee of of dis distr trib ibut utio ion n ben benef efit it;;
5.
allows rapid response to change in pathogens /eq;
(d)
1.
max 2
max 3
also T memory cells;
2.
more more lymp lympho hocy cyte tess to to com comb bat infe infect ctio ion n / eq; eq;
3.
virus in infects bo body ce cells;
4.
anti antibo bod dies ies onl only y des destr troy oy viru viruss in in blo blood od / eq; eq;
5.
T kil kille lerr cel cells ls des destr troy oy vir viral ally ly inf infec ecte ted d cel cells ls;;
6.
virus cannot spread / hide inside cells;
max 4 [11]
1.
31.
moul mould d / fung fungu us / yeast east / euk eukar aryo yoti ticc;
2.
virus;
3.
bacteri erium / prokaryotic; ic;
4.
bacteri erium / prokaryotic; ic; [4]
(a) 1. T helper ce cells lls {destro troyed / damaged / redu educed in number / cell lysis / eq};
32.
2.
no T kil kille lerr cel celll {pr {prod oduc ucti tion on / act activ ivat atio ion} n} / eq; eq;
3.
B cel cells ls activ activat ation ion / pla plasm smaa cells cells prod produc ucti tion on / eq; eq;
4.
(less less / no) no) anti antibo bod dy pro produ duct ctio ion n / eq eq;
5.
phagocytosis / phagocytes;
(b)
max 4
1. (inflammation) – preventing infection at site of tissue damage / detail of response e.g. macrophages attracted / oedema / increased blood flow; 2.
phagocytosis;
3.
(lys (lysoz ozym ymee act actio ion n – enzy enzyme me to) to) des destr troy oy bact bacter eria ia / cel celll lysis / breakdown of cell walls;
4.
interferon;
4 [8]
(a)
33.
1.
C is bacteriocidal;
2.
bact bacter erio ioci cid dal kill killss bacte acteri riaa;
3.
B is bacteriostatic;
4.
bacteriostatic prevents reproduction / growth;
(b)
1.
max 3
bacterium is no longer affected by antibiotic A;
2.
refe refere renc ncee to to mut mutat atio ion n / cha chang nged ed {gen {genee /DN /DNA} A};;
3.
reference to resistan tance;
4.
reference to selection ion /eq /eq;
5.
reference to plasmid transmission / horizontal inheritance;
max 4
19
(c )
1.
lawn bacteria / eq;
2.
reference ag agar pl plate / eq;
3.
anti antib bioti ioticc in in wel welll / mult multid idis iscc / eq; eq;
4.
incubation qualified;
5.
measuremen ment of of cl clear ear ar area / eq;
6.
bigge iggerr are areaa im implie pliess mo more effe effect ctiv ive; e;
7.
reference to safety / aseptic technique / eq;
max 4 [11]
(a)
34.
1.
huge numbers / population size / eq;
2.
illu illust stra rate ted d with with exam exampl plee fro from m the the text text;;
3.
varie variety ty in in meta metabo bolis lism/d m/die iet/ t/mo mole lecu cula larr diff differ eren ence cess / eq; eq;
4.
illu illust stra rate ted d with with exam exampl plee fro from m the the text text;;
5.
wide wide habit abitat at dist distrribu ibution tion / eq; eq;
6.
illu illust stra rate ted d with with exam exampl plee fro from m the the text text;;
7.
more more life life unde underr the the eart earth h tha than n on on it / eq; eq;
8.
refe refere renc ncee to “all “all bac bacte teri riaa swim swim in in a sing single le gen genee poo pool” l”// eq; eq;
9.
expl explan anat atio ion n of of sin singl glee gen genee poo pooll con conce cept pt;;
10.
specif specific ic exam example ple of how they they have have a major major influe influence nce on many other living organisms e.g. oxygen production for respiration of other organisms;
11.
bacteria are unlikely to become extinct;
(b)
(i)
1.
max 4
{genetic / DNA}differences;
2.
mole molecu cula larr diff differ eren ence cess / lipid lipidss / pept peptid idog ogly lyca can n / eq; eq;
3.
arch archae aeaa are are more more diff differ eren entt fro from m bac bacte teri riaa tha than n you you and and I are more different from a crab or spider / eq;
(ii)
1.
2.
suita suitabl blee for for micr microb obio iolo logi gist stss / les lesss suita suitabl blee for for botan botanis ists ts and zoologists / too heavily weighted towards the microbial / eq;
3.
nume numeri rica call lly y dis disto tort rted ed i.e. i.e. mos mostt iden identi tifi fied ed spe speci cies es put put into a small section of the classification system / eq;
4.
reference to alternative / updated classification systems;
max 2
did not fit in with old way of classifying in terms of {gross morphological / visible} similarities and differences / Woese’s system focuses on molecular characteristics / eq;
max 2
(c )
1.
eukaryotes have a nucleus, prokaryotes do not;
2.
euka eukary ryot otes es have have {mem {membr bran anee bou bound nd orga organe nelle lless / name named d organelle}, prokaryotes do not;
3.
euka eukary ryot otes es have have larg larger er ribo riboso some mess tha than n pro proka kary ryot otes es;;
4.
euka eukary ryot otic ic cel cells ls are are muc much h lar large gerr than than pro proka kary ryot otic ic cel cells ls;;
5.
euka eukary ryot otic ic cel cells ls wal walls ls (if (if pre prese sent nt)) are are made made of cel cellu lulos losee (or chitin), prokaryotic cell walls are made of other materials (e.g. murein);
6.
plas plasmi mids ds trad tradit itio iona nall lly y thou though ghtt to to be conf confin ined ed to prokaryotic cells;
7.
line linear ar chro chromo moso some mess in euka eukary ryot otes es,, cir circu cula larr DNA DNA in prokaryotes / reference to histone proteins in eukaryotes, not prokaryotes / eq;
(d)
max 2
1. genes can spread between different {species / types / eq} of bacteria; 2.
(e )
thro throug ugh h sex sexua uall rep repro rodu duct ctio ion n / exch exchan ange ge of plasmids / conjugation;
1.
2
prostaglandins released;
2.
reset eset set set po point int of of hyp hypo othal thalam amus us / eq eq;
3.
prod produc ucee fev fever er / cor coree temp temper erat atur uree ris rises es;;
4.
histamine released;
5.
Infl Inflam amma mati tion on / infl inflam amma mato tory ry resp respon onse se;;
6.
{kil {killer ler / cyt cytot otox oxic ic} } T cells cells {des {destro troy y inf infec ected ted cells cells / damage tissues};
7.
clon clonal al selec selecti tion on of whit whitee bloo blood d cel cells ls caus causes es swol swollen len {lymph nodes / glands} / eq;
max 3
21
(f)
1.
rapid reproduction rate / quick generation time;
2.
large populations;
3.
larg largee poo pooll of of mut mutat atio ions ns / lot lotss of of var varia iati tion on;;
4.
stro strong ng sel selec ecti tion on pre press ssur uree of anti antibi biot otic icss /eq; /eq;
5.
wide widesp spre read ad use use of of ant antib ibio ioti tics cs in farm farmin ing; g;
6.
misu misuse se of antib antibio iotic ticss / pres prescr crib ibed ed inap inappr prop opri riat ately ely / course not finished / eq;
7.
conj conjug ugat atio ion/ n/ba bacte cteri rium um can can sha share re plas plasmi mids ds / can can pass pass antibiotic resistance genes from one bacterium to another (species) / eq;
8.
refe refere renc ncee to antib antibio ioti ticc mark marker erss in gene geneti ticc engi engine neer erin ing; g;
9.
corr correc ectt ref refer eren ence ce to hosp hospit ital al hygi hygien enee / comp compro romi mise sed d immune system of patients / intravenous procedures / eq;
(g)
max 4
1. may kill the host before they have a chance to infect other people / eq; 2.
newl newly y evo evolv lved ed stra strain in so it has has not not yet yet beco become me redu reduce ced d in virulence;
3.
reference to isolation of victims /eq;
max 1 [20]
(a) Award Award one one mark mark for each each of the follow following ing points points in cont context ext to a maximum of six marks.
35.
(b)
1.
No anti antibo body dy in bloo blood d pla plasm smaa in in fir first st 5 day days; s;
2.
Beca Becaus usee lymp lympho hocy cytes tes need need to to come come in in con conta tact ct with with antig antigen ens; s;
3.
Time Time need needed ed for for {ly {lymp mpho hocy cyte te activ activat atio ion/ n/ lymp lympho hocy cyte te cloning/ B cell differentiation};
4.
Rise Rise in antib antibod ody y con conce cent ntra ratio tion n bet betwe ween en 5 and and 15 days days;;
5.
As plas lasma cells ells rele releas asee an antib tibody ody;
6.
Decr Decreas easee in in anti antibo body dy conc concen entra tratio tion n after after 15 days days;;
7.
Infec nfecti tio on has has been een clear leared ed up; up;
8.
Anti Antibo bodi dies es remo remove ved d fro from m blo blood od stre stream am by kidn kidney eys; s;
9.
Residual level of antibodies in blood (at 30 days)
(i) 2.
1.
6
Change in sequence of DNA;
Change in {mass of DNA / number of chromosomes};
2
(ii) (ii)
Award Award one one mark mark for for each each of the the foll followi owing ng points points in conte context xt to to a maximum of two marks. 1.
muta mutati tion on caus causes es chan change ge in gene gene prod produc uct/ t/eq eq;;
2.
idea idea that that str struc uctu ture re of anti antige gen n may may chan change ge (as (as res resul ultt of of mutation);
3.
idea idea that that ind indiv ividu idual al wil willl not not be prot protec ected ted if flu flu vir virus us does does not have same antigens present in vaccine;
4.
idea idea that that a cock cocktai taill of of antig antigen enss wil willl incr increa ease se the the cha chanc ncee of matching antigens; 2 [10]
(a)
36.
Award Award 1 mark mark for for each each correc correctt row row in the follow following ing table. table. Structural feature
Bacteria
Viruses
Mesosomes Capsid Nucleic acid Cytoplasm Ribosomes 5
(b)
(i) Award one mark for each of the following points in context to a maximum of two marks.
(ii)
1.
Incr Increa ease se in numb number er of new new cas cases es in Afric Africaa and and Euro Europe pe
2.
Decr Decrea ease se in numb number er of of new new case casess in in Asia Asia and and Sou South th Amer Americ icaa
3.
Any relevant manipulation of data
2
Explanation: •
More More inci incide denc ncee of TB in the the popu popula lati tio on/eq /eq
Award one mark for each of the following points in context to a maximum of two marks. 1.
Ref to oppo opport rtu unis nistic tic infe infecction tion
2.
HIV HIV pos positi itive ve peop people le have have weak weaken ened ed immu immune ne syst system em
3.
A hig highe herr pro propo port rtio ion n of of HIV HIV posi positi tive ve peop people le are are infected by TB 3
23
(c)
Award Award one one mark mark for each each of the follow following ing points points in cont context ext to a maximum of two marks. 1.
TB bact bacter eria ia {mut {mutate ate / bec becom omee res resis istan tantt to to ant antib ibio iotic tics} s}
2.
immi immigr grat atio ion n fro from m cou count ntri ries es with with high high inci incide denc ncee of of TB TB
3.
increased travel
4.
increase in in HI HIV in infection
5.
lower rates of immunisation against TB
2 [12]
(a) (a) (i) (i) Bact Bacter erio iost stat atic ic prev preven entt bac bacte teri riaa mult multip iply lyin ing g and and bac bacte teri rioc ocid idal al kill kill bac bacter teria ia 1
37.
(ii) (ii)
Award Award one one mark mark for for each each of the the follow following ing points points up to to a maximum of two marks. Mammalian cells:
(b)
1.
are eukaryotic
2.
have different enzymes
3.
do not have cell walls
4.
have {80s / larger/eq} ribosomes / different protein synthesis
2
Award Award one one mark for each each of of the the follo followin wing g poin points ts up up to a maximum of three marks. 1.
do not prescr prescribe ibe antibio antibiotics tics for minor minor infect infection ionss /vir /viral al infect infection ionss
2.
do not not pre presc scri ribe be anti antibi biot otics ics to prev preven entt inf infec ectio tions ns
3.
refe refere renc ncee to to nar narro row w spe spect ctru rum m ant antib ibio ioti tics cs
4.
ref ref to to rot rotat atio ion n in in the the use use of of diff differ eren entt ant antibi ibiot otic icss
5.
{adv {advis isee / tak take} e} the the ful fulll cou cours rsee of of ant antib ibio ioti tics cs
6.
ref ref to hand hand-w -was ashin hing g (bet (betwe ween en patie patient ntss / by visi visito tors rs of of hospi hospita tals ls))
7.
use of isolation wards
3
(c) (c)
Awar Award d one one mark mark for for eac each h of the the fol follo lowin wing g poin points ts up up to a maximum of four marks. 1.
Ref. ef. to to a spe speccific ific asept septic ic tech techni niqu quee
2.
Bact acteri erial law lawn/pour plate
3.
Use Use of anti antibi biot otic ic dis discs cs / ant antib ibio iotic ticss inco incorp rpor orat ated ed int into o agar agar /eq /eq
4.
Incubate fo for 24 24-36 ho hours
5.
At 25-30 °C
6.
Record bacterial growth/eq
4 [10]
25
