5 1 1 Cellular Control Ms

8/12/2019 5 1 1 Cellular Control Ms

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1. 1 ref to operon;2 normally repressor substance bound to operator;3 prevents RNA polymerase binding (at promoter) / prevents

transcription;4 lactose binds to repressor;

c!anges s!ape of protein molecule;

" unable to bind (to operator);# RNA polymerase binds (at promoter) / transcription occurs / geness$itc!ed on;

% A&'; e g production of lactose permease / production of betagalactosidase; ma*

[5]

2. a c!ange in t!e genetic material;unpredictable / A+;e*tra detail; e g addition / substitution / deletion / frame s!ift / small

part of c!romosome / may code for different protein /may code for no protein

[2]

3. 1 mark max for general effect of mutations:mutation may give different, amino acid / primary structure;

A ref stop codonsome mutations alter, molecular s!ape / tertiary structure / binding;

max 3 for explaining data in Table:so unable to, accept / transport, -. 3 ;unable to bind A0';

so increase in acidity / decrease in p-;effect on mucus;effect on en yme(s) /ref p- optimum of en yme(s);

poor digestion of, protein / lipid / starc!;

A&'; e g some mutations, give some transport / !ave less effect 33 (of norm) allo$s normal digestive function / "

5A very low 6 does not ma* 3[3]

4. allow max 5 for following:transcription;7NA un ips / - bonds brea8;e*posing re9uired, gene / se9uence of bases;RNA nucleotides align $it! 7NA;: $it! A, A $it! 0, . $it! , and $it! .;RNA polymerase;mRNA formed (using 7NA strand as template);

leaves nucleus t!roug! pore;

allow max 5 for following:

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translation;mRNA attac!es to ribosome;tRNA brings amino acid (to, ribosome / mRNA);eac! tRNA attac!ed to specific amino acid;tRNA binds to mRNA using complementary, base triplet / anticodon;

peptide bond formed bet$een amino acids;7NA / mRNA, (nucleotide / base) se9uence determines se9uence of amino acids;

A&'; e g 2, base triplets / codons, in ribosomeA&'; e g ref to < start / stop, codons

polysomeslarge and small subunit in ribosome=g 2>

[10]

5.1 mark per correct row

Look for both ticks and crosses.

f a table consists of ticks !"L# or crosses !"L#$ then assume that the blank spaces are theother symbol.

f a table consists of ticks$ crosses and blanks then the blanks represent no attempt at theanswer.

Nucleotides line up along an e*posed 7NA strand ;

0!e $!ole of t!e double !eli* ?un ips@ ;

:racil pairs $it! adenine ;

A tRNA triplet pairs $it! an e*posed codon ;

ot! 7NA polynucleotide c!ains act as templates ;

AdBacent nucleotides bond, forming a sugar p!osp!ate bac8bone ;

0!e original 7NA molecule is unc!anged after t!e process ;

Adenine pairs $it! t!ymine ;[8]

6.(a) (i) : A . . A : : . A .;;

1 error % 1$ & errors % '

allow 1 mark for giving T throughout instead of (

)i.e. T * + + , , * T T + * + % 1 mark- 2

(ii) transcription / transcribed; R transcriptase 1

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(b) (i) J anticodon; R anticodonsK transfer RNA / tRNA;L ribosome / rRNA;M codon; R codons 4

(ii) 1 7NA triplet / codon / M / mRNA triplet, codes for

specific amino acid;

2 order of, triplets / bases, determines t!e order of amino acids;

3 tRNA / C, !as, corresponding / complementary,triplet / anticodon;

4 (tRNA / C) attac!ed to specific amino acid;

5 activation of amino acid;

6 2 (tRNA) binding sites on t!e ribosome;

7 codon and anticodon bind; A matc!8 A to : and . to ;

9 adBacent amino acids Boin;

10 peptide bond; 4 ma*

(c) 1 attac!es to ribosome;

2 removes, base / portion, of ribosome;A stops ribosome assembling / c!anges s!ape of ribosome

3 prevents ribosome, attac!ing to / reading, mRNA;4 prevents codons being e*posed;

5 prevents, tRNA / anticodon, attac!ing to, mRNA / codon;

6 prevents / in!ibits en yme responsible for, formation of peptide lin8ages;

7 A&'; e g furt!er detail of any of t!e above points 2 ma*[13]

7. (a) (i) mRNA leaves nucleus; oramRNA, translated / used to ma8e, protein;7NA, transcribed / used to ma8e, mRNA;mRNA s!ort term / 7NA (long term) store; 2 ma*

(ii) siRNA smaller / fe$er nucleotides / only matc!es part of gene; orasiRNA double stranded; ora 2

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(b) (complementary) base pairing;!ydrogen bonding;

bet$een purines and pyrimidines;A $it! :; R A $it! 0. $it! ;ref to 2 or 3 bonds (correct conte*t); 3 ma*

[7]

8. (i) )++ 5 / macrophages-(siRNAs continue to $or8) in long lived cells;only one treatment needed for macrop!ages / ..R ;(siRNAs diluted) as lymp!ocytes divide; orarepeat treatments needed for, lymp!ocytes / .74; 2

(ii) )++ 5- because no essential function in body / absence not a problem; 1

[3]

9. (a) (i) steep increase, for t!e first 1 2 !ours / till 2 2 3 % (a u) ; A linear,steady became constant at, 3 !ours / 4 3 (a u) ;if no figs in description$ e.g. 0rose then constant award 1 mark max 2

(ii) (increased as) en yme $or8ing / rate of reaction !ig! / reaction proceeding ;(increased as) substrate converted into, drug / product ;(levelled off / became constant, after t!e) en yme, became inactive /

$as denatured;(levelled off / became constant) because product in!ibits, reaction /en yme ;

R references to en yme or substrate being used up R 0 D. limiting 2

(b) p- ;degree of mi*ing ;en yme concentration ;A&' ; e g ref to concentration of in!ibitors 1 ma*

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(c) max of & marks for predicting or explaining

P1 concentration of drug !ig!er / A+ ;P2 rate of reaction slo$er / A+ ;P3 may not level off (in time scale s!o$n on grap!) ;P4

time ta8en to reac! t!e ma*imum yield (appro*imately)doubles ; (c f 1 D.)

E1 not denatured ;E2 adapted to D. / optimum / body / usual, temperature ;E3 ref to E 1F of about 2 ;E4 ref to lo$er 8inetic energy / A+ ;E5 ref to G H, collisions / comple*es ;

A&' ; e g ref to active site 3 ma*

(d) (i) (s!aded amino acids) form t!e active site ;

substrate may not attac! to t!e active site ;en yme substrate comple* may not be formed / A+ ; 1 ma*

(ii) 44 and "" not part of active site ;!old, active site / 3D structure / 37 structure, in s!ape ; A stop denaturing!ydrogen bonds $ea8 ;easily bro8en by, vibration / !eat ; A p-disulp!ide bridge strong ;not bro8en by !eat ; 2 ma*

(e) nucleotide / base/ 7NA, se9uence codes for, protein / amino acid, se9uence ;

c!anges 7NA ;A

c!ange tripletma8es different mRNA ; A c!ange codontranscription ;different tRNAs line up ; A c!ange anticodontranslation ;different (amino acid se9uence in), en yme / protein / polypeptide ; 2 ma*

[13]

10. (a) estimate of role of genotype in p!enotypic variation / A+ ;!eritability I & / & ' ;$!en !eritability !ig! muc! of variation is, genetic / not environmental/ ora ;!ig! !eritability $ill result in successful selective breeding / ora ; 2 ma*

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(b) single / maBor / =endelian, gene ;large effect ;little environmental effect ;dominant allele 0 e*pressed in !omo and !etero ygote ;not polygenic ;not additive ;discontinuous variation / not continuous variation ;9ualitative / not 9uantitative ; 2 ma*

(c) (i) triplet of bases t!at does not code for an amino acid ;A00 / A0. / A.0 ;code to mar8 end of gene ;code to stop transcription / ref to disengagement RNA polymerase ; 2 ma*

(ii) transcription !alted early / A+ ; protein $ill, be smaller / !ave fe$er amino acids ;

tertiary structure / 37 s!ape different ; binding / affinity, different ; protein inactive ; 3 ma*

ref to lac operon ;

(iii) ref to, promoter / operator / ?on@ s$itc! ;allele 0 is regulator ;(protein) binds to 7NA ;(protein) binds to repressor and prevents it binding to 7NA ;allo$s RNA polymerase to bind ;A&' ; e g en yme affecting transcription 2 ma*

(d) (i) tt > 0 / A+, increases number of tillers per plant ;

and number of branc!es per tiller ;ref to comparative figures ; 2 ma*

(ii) inserted into genome randomly / cannot c!oose $!ere it is inserted ;may be $it!in a fre9uently e*pressed gene ;may be after an ?on@ s$itc! ;lac8s normal controls ;A&' ; e g no ot!er alleles affecting it 2 ma*

different promoter [15]

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11. plant signal used by ear$orms ;J s$itc!es on gene coding for E ;can t!en brea8 do$n insecticide ;effect on transcription ; (J )reduces mortality ;even in absence of insecticide ;in absence of J , mortality, !ig! / c %# ;ref to comparative figures ;

e g %# to 4% / almost !alved, in presence of insecticide1" to # / more t!an !alved, in absence of insecticide

slig!t e*pression of E in absence of J caused by insecticide ; 4 ma*[4]

12. (a) plasmid 2"* protein

nucleotides / sugar > p!osp!ate > base ; amino acids ;4 different subunits ; 2F different subunits ;

p!osp!odiester bonds ; A p!osp!oester peptide bonds / polypeptide ;contains ' ; contains H / disulp!ide bonds ;double stranded / double !eli* ; may !ave 4D structure ;circular ; ref to, 2D / 3D, structure / A+ ;

A&' ; e g role of - bonds 3 ma*

(b) (i) stimulates, immune response / production of antibodies / 0 or cells ; 1

(ii) stimulate, cell mediated immunity / 0 cells ;antigen, remains in body longer / continuously produced ;antigens in blood only stimulate, !umoral immune system / cells ;antigens (in blood) lost in urine / bro8en do$n in liver ;ref to =-. ; 1 ma*

(c) (i) binds RNA polymerase ;allo$s, transcription / production of mRNA ;s$itc!es gene on / allo$s gene e*pression ; 2 ma*

(ii) (protect against) more t!an one, strain / disease / pat!ogen / A+ ;stronger immune response ;less li8ely mutant form $ill escape immune response / A+ ;A&' ; c!eaper / reduces number of vaccinations 2 ma*

(iii) olgi modifies protein / polypeptide / A+ ;forms glycoproteins / add sugars or carbo!ydrate ;

olgi forms vesicles ;incorporated into cell membrane ; R e*ocytosisA&' ; 2 ma*

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(d) cells that take up 2"* vaccine might

1 function less $ell ;2 be 8illed by immune system / trigger auto immune response ;3 !ave genes disrupted / mutation ;

4 ne$ gene mig!t be in!erited / A+ ;5 plasmid could enter bacteria ;6 superbug / create ne$ disease / A+ ;7 effects un8no$n / ne$ tec!nology / no !uman trials ;8 A&' ; ref et!ics, ref irreversible 3 ma*

[14]

13. (a) (i) AaBB $!ite;aaBB blac8;

Aabb $!ite;aabb bro$n; 4

(ii) (dominant) epistasis; 1

(iii) codes for in!ibitor; protein; bloc8s transcription (of allele coding for pigment);ref to, regulator / promoter;

bloc8s en yme (producing pigment);A&'; e g detail ma* 3

(b) (i) Aa b J Aa b / Aa b J Aabb;

bot! must !ave A because t!ey are $!ite; K bot! must, !ave a / not be !omo ygous AA, because some8ittens coloured; K bot! must !ave b to give bro$n 8ittens;

L 0must be hetero ygous at both loci % 1 only

at least one / one or bot!, must !ave to give blac8 8ittens;credit ref to 'unnett s9uare s!o$ing genotypes;

credit ref to 'unnett s9uare s!o$ing p!enotypes; ma* (ii) Aa b J Aa b 12 $!ite < 3 blac8 < 1 bro$n;;

Aa b J Aabb " $!ite < 1 blac8 < 1 bro$n;; ma* 2[15]

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14. (i) RNA(i) combines $it! mRNA;e g of base pairing (but not 0) A : / .;stops translation;ref to stops mRNA combining $it! ribosomes;stops protein synt!esis; ma* 3

(ii) c!emicals / en ymes in, mout! / toot!paste / bacteria;denature / degrade, RNA;RNA not normally ta8en up by bacterial cells;s!ort life of RNA;RNA not replicated in bacteria $!en bacteria reproduce;toot!paste in mout! only for s!ort time;A&';A&'; e g $as!ed a$ay by saliva ma* 2

[5]

15. 1 ref to operon;

2 normally repressor substance bound to operator;3 prevents RNA polymerase binding (at promoter) / prevents transcription;4 lactose binds to repressor;5 c!anges s!ape of protein molecule;6 unable to bind (to operator);7 RNA polymerase binds (at promoter) / transcription occurs

/ genes s$itc!ed on;8 production of lactose permease;9 production of beta M galactosidase;

[5]

16. 1 proteins needed for repair / A+;2 more transcription of, 7NA / genes;3 more translation;4 protein synt!esis;5 named protein; e g actin / myosin / troponin / tropomyosin

ignore all refs to muscle contraction

6 more aerobic respiration;7 so more, energy released / A0' produced;8 (energy re9uired for) condensation / anabolic, reactions;9 (energy re9uired for) formation of peptide bonds;10 (energy re9uired for) formation of e*tra mRNA; ma*

[5]

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17. (a) provides sites for binding;ref to, spindle fibres / microtubules;ref to genes being spaced out along c!romosome;

places to brea8 and reBoin (during meiotic division); A c!iasmata formation?Bun8@ implies no, function / purpose; orafunction may not yet !ave been discovered;A&'; e g ra$ material for, evolution / natural selection,

re9uired for, cell division / mitosis / meiosis ma* 2

(b) straig!t line sloping up from left to rig!t; (does not need to start at origin) 1

(c) A0' / NA7 / NA7' / RNA / p!osp!olipid / ' / 0' / Ru ' / A7' /R:' / A=' / cA='/ p!osp!ocreatine / A&'; R 7NA 1

[4]

18. 7NA codes for, protein / polypeptide;transcription and translation (or described);en yme is globular (protein);3 bases 1 amino acid;se9uence of bases / triplets, determines, se9uence of amino acids /

primary structure;coiling / !eli* / pleated s!eet / particular secondary structure;determines proBecting side groups;folding / bonding, for tertiary structure;3 7 structure is tertiary structure;A&'; e g ref active site related to s!ape

2 or more genes produce 9uaternary structure 4 ma*[4]

Macmillan Academy 10

5 1 1 Cellular Control Ms

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