8/12/2019 Cellular Control Answers F215
1/33
1. (a) (i) genelength of DNA;codes for a (specific), polypeptide / protein / RNA; max 1
allele
alternative form of a gene;found at a, locus / particular position on, a chromosome; max 1
(ii) assume allele refers to coat colour allele
(coat colour) gene / alleles, only on chromosome;Ano (coat colour), gene / allele, on Y chromosome
male cats, ! / only have one chromosome;males have only one (coat colour) allele / cannot have t"o (coat colour)
alleles;need #lac$ and orange alleles for tortoiseshell colour; %
(#) parental genotypes &r&r' &"&";gametes &
r, &
";
F1genotypes and phenotypes 1 mark:
1genotypes (all) &
r&
"
1phenotypes (all) pin$;
F2genotypes and phenotypes 1 mark
gametes &r, &
"&
r, &
";
%genotypes &
r&
r&
r&
"&
r&
"&
"&
"
%phenotypes red pin$ (pin$) "hite;
%ratio 1%1;
accept other symbols if key given*accept r and as symbols ithout key! +
(c) (i) +; 1-.; +; -
(ii) .*1- 0 .*.. 0 .*.+1; (or other suitable orking).*%.+ 2 .*%.;
2 marks for correct value if no orking shonecf for both marks but calculated value must be to three decimal
places %
(iii) support, figure lo"er than *331 / figure lo"er than critical value;
R"support# on its on!
ecf applies if value in (ii) is incorrect 1[16]
The Henrietta Barnett School 1
8/12/2019 Cellular Control Answers F215
2/33
2. parental genotypes Rr4# ' Rr## ;
gametes R4 R# r4 r# R# r# ;
offspring genotypes RR4# Rr4# (Rr4#) Rr## RR## (Rr##) rr4# rr## ;
offspring phenotypes rough #lac$ rough "hite smooth #lac$ smooth "hite ;
e$pected ratio - - 1 1 ;accept correct gametes, offspring genotypes and offspring phenotypes in
%unnett s&uare
use ecf e$cept for ratioRejectthe ratio ' : ' : 2 : 2
ratio not a stand alone mark there must be some correct orking to support it[5]
3. DNA codes for ,protein / polypeptide;
transcription and translation (or descri#ed);en5yme is glo#ular (protein);
- #ases 1 amino acid;
se6uence of ,#ases / triplets ,determines , se6uence of amino acids /primary structure;
coiling / helix / 7pleated sheet / particular secondary structure;
determines pro8ecting side groups;folding / #onding ,for tertiary structure;-7D structure is tertiary structure;A9:; e*g* ref* active site related to shape
% or more genes produce 6uaternary structure max[4]
4. (a) provides sites for #inding ;
ref to, spindle fi#res / microtu#ules ;
ref to genes #eing spaced out along chromosome ;
places to #rea$ and re8oin (during meiotic division) ; Achiasmata formation
8/12/2019 Cellular Control Answers F215
3/33
5. 1 proteins needed for repair / AB ;
2 more transcription of, DNA / genes ;
3 more translation ;
4 protein synthesis ;
5 named protein ; e*g* actin / myosin / troponin / tropomyosinignore all refs to muscle contraction
6 more aero#ic respiration ;
7 so more, energy released / A>: produced ;
8 (energy re6uired for) condensation / ana#olic, reactions ;
9 (energy re6uired for) formation of peptide #onds ;
10 (energy re6uired for) formation of extra mRNA ; max [5]
6. 1 #oth result from changes in allele fre6uencies ;
2 selective #reeding often faster than evolution / ora ;
3 #oth re6uire selection of parents ;
4 to pass alleles to offspring ;
5 selective #reeding involves artificial selection ;
6 v* evolution involves natural selection ;
7 man selective agent in selective #reeding ;
8 v* "hole environment selective agent in, natural selection / evolution ;
9 selective #reeding for #enefit of man ;
10 may #e detrimental to organism / e*g* detriment ;
11 v* fitness for environment ;
12 single / fe", trait(s) in selective #reeding ;
13 v* "hole, phenotype / genotype ;
14 A9: ;
15 A9: ; max
QWC legible text with acc!ate "#elli$g, #$ctati%$ a$& g!a''a!; 1[9]
7. (i) mutation ;
chance / random / preexisting ;
insecticide acts as selective, agent / pressure ;
suscepti#les die / resistants survive ;
resistants pass, mutation / allele, to offspring ; Agene max -
(ii) mos6uito is vector ; Acarrier
The Henrietta Barnett School 3
8/12/2019 Cellular Control Answers F215
4/33
o#ligatory / AB ;
part of life cycle is in mos6uito ;
not $illed #y insecticide ; max %[5]
The Henrietta Barnett School 4
8/12/2019 Cellular Control Answers F215
5/33
8. (a) (i) Aa## 7 pin$ ;
aa44 7 green ; %
(ii) (dominant) epistasis ;
ref to, epistatic / hypostatic, gene ;
ref to, promoter / gene s"itching ;increased, transcription / expression ; max -
A9: ; en5yme to alter pigment / change structure of pigment /ma$e more pigment / complementary action
(#) (i) parents (Aa4#) red spines ' (aa##) green spines ;
gametes A4 A# a4 a# ' a# ;Afrom %unnett s&uare
offspring genotypes ; ; minus 1 for each of first to mistakes
phenotypes related to genotypes ; Akey
ratio 1 red spines 1 pin$ spines % green spines ; max
gametes * b a* ab
ab a*b abb aa*b aabb
red spines pink spines green spines green spines
(ii) many Aa4# and aa## ;
ref 1 1 ratio of these ;
ref lin$age ;
ref parental types ;
fe" Aa## and aa4# ;
ref 1 1 ratio of these ;
ref recom#inants ;
ref crossing over ;
many red and green spined ;
fe" / no, pin$ spined ;
1 1 green red / more green than red ;
ref proportions depend on ho" close, loci / genes, are ; max
[15]
9. (a) R RR
R7 lo", do not have enough vitamin C in diet / ref to figures ;
RRR
7 high, ("arfarin resistant) and have enough vitamin C
/ ref to figures ;
RR
7 lo" , "ill #e $illed #y "arfarin / ref to effects of "arfarin ;
+f &uote probabilities for survival less than -. is lo and over -. is high -
The Henrietta Barnett School 5
8/12/2019 Cellular Control Answers F215
6/33
(#) (i) mutation / named mutation ;
change in DNA #ase se6uence ; max 1
(ii) variation "ithin population ;
some individuals produce en5yme not suscepti#le to "arfarin ;
these individuals survive / selective advantage ;reproduce / #reed ;
pass, resistance / advantageous allele , to offspring ; Rgene
those "ithout resistance die ;
ref to selective pressure of "arfarin ; max
(c) does not directly involve humans ;
environment selects individuals that "ill reproduce ; max 1
(d) resistant allele / RR, "ill decrease a$&, suscepti#le allele / R
, "ill
increase ;
RRR
Rat a disadvantage due to vitamin C re6uirements / R
R
at
an advantage due to "arfarin #eing removed ;
Afre6uencies of #oth alleles "ill stay the same ;
must be linked to second statement
no longer any selective pressure / no directional selection ; max %[12]
10. 1 ref to operon ;
2 normally repressor su#stance #ound to operator ;
3 prevents RNA polymerase #inding (at promoter) / prevents transcription ;
4 lactose #inds to repressor ;
5 changes shape of protein molecule ;
6 una#le to #ind (to operator) ;
7 RNA polymerase #inds (at promoter) / transcription occurs/ genes s"itched on ;
8 production of lactose permease ;
9 production of #eta 2 galactosidase ;[5]
The Henrietta Barnett School 6
8/12/2019 Cellular Control Answers F215
7/33
11. (i) length of DNA ;
codes for a (specific), polypeptide / protein / RNA ;
found at a, locus / particular position on, a chromosome ; %
variety / form of a gene ; Rtype of gene Atype of a gene 1
(ii) assume the allele coat colour allele(coat colour) gene / alleles, only on chromosome ;
Ano (coat colour), gene / allele, on ! chromosome
male cats, ! / only have one chromosome ;
(males have) only one (coat colour) allele / cannot have t"o(coat colour) alleles ;
need #lac$ and orange alleles for tortoiseshell colour ; max %[5]
12. (a) 1 % 1 ; 1
(#) 1 ref to, codominant / e6ually dominant (alleles) ;
Aincomplete dominance #ut Rgenes as alternative to alleles
2 appropriate sym#ols for t"o codominant alleles ; eg ?1and ?
%
Ra capital and a lo"er case sym#ol or t"o different letterssuch as ? and !
3 parent plant sho"n or stated to #e hetero5ygous ; Aif it is explainedthat any sunny plant is hetero5ygous
4 gamete genotypes sho"n appropriately ;
5 correct offspring genotypes ;
6 the
8/12/2019 Cellular Control Answers F215
8/33
9 chi s6uared test could #e used ;
10 A9: ; max -
The Henrietta Barnett School 8
8/12/2019 Cellular Control Answers F215
9/33
(d) credit ora here
Achloroplast as alternative to chlorophyll
yello" seedlings have, no / very little, chlorophyll ;
cannot photosynthesise ;
die "hen, energy reserve / car#ohydrate (accept food), in seed isexhausted ;
dar$ green gro" more #ecause they have more chlorophyll(than the yello"7green) ;
so dar$ green have more, photosynthetic products / named product ;
ref to competition #et"een the seedlings ;
ref to, selection / selective advantage ; max -[12]
13. (i) economy of, materials / resources ;
economy of energy ;
saves unnecessary, transcription / translation ; % max
(ii) random / chance / preexisting, mutation (for resistance) ;
resistants survive / suscepti#les die ;
natural selection ;
insecticide selective agent ;Aselective pressure
resistants pass, mutation / allele for resistance, to offspring ; Rgenefre6uency of, mutation / allele for resistance, increases in population ; max
[7]
14. (i) RNA(i) com#ines "ith mRNA ;
e*g* of #ase pairing (#ut not >) A7@ / ?7& ;
stops translation ;
ref to stops mRNA com#ining "ith ri#osomes ;
stops protein synthesis ; max -
(ii) chemicals / en5ymes in, mouth / toothpaste / #acteria ;
denature / degrade, RNA ;
RNA not normally ta$en up #y #acterial cells ;
short life of RNA ;
RNA not replicated in #acteria "hen #acteria reproduce ;
toothpaste in mouth only for short time ;
A9: ;
A9: ; e*g* "ashed a"ay #y saliva max %[5]
The Henrietta Barnett School 9
8/12/2019 Cellular Control Answers F215
10/33
The Henrietta Barnett School 10
8/12/2019 Cellular Control Answers F215
11/33
15. plant signal used #y ear"orms ;
)s"itches on gene coding for *;
can then #rea$ do"n insecticide ;
effect on transcription ; (' *)
reduces mortality ;even in a#sence of insecticide ;
in a#sence of ), mortality, high / c* F ;
ref to comparative figures ;
e*g* to F / almost halved, in presence of insecticide
1+ to F / more than halved, in a#sence of insecticide
slight expression of *in a#sence of )caused #y insecticide ; max[4]
16. increase in use of, ? crop / ?G crop / 4t cotton ;
no / less, insecticide needed ;
reduced num#er of cases of pesticide poisoning ;
ref to figures (e*g* #y x *) ;
reduced cost (insecticide) ;
ref to figures (e*g* #y .*+% @H $g71
/ ' 1*-) ;
ref to limitations of survey ;
A9: ;
Areverse arguments max [4]
17. (a) (i) Aa(("hite ;
aa((#lac$ ;
Aabb"hite ;
aabb#ro"n ;
(ii) (dominant) epistasis ; 1
(iii) codes for inhi#itor ;
protein ;
#loc$s transcription (of allele coding for pigment) ;
ref to, regulator / promoter ;
#loc$s en5yme (producing pigment) ;
A9: ; e*g* detail max -
The Henrietta Barnett School 11
8/12/2019 Cellular Control Answers F215
12/33
(#) (i) Aa4# ' Aa4# / Aa4# ' Aa## ;
#oth must have A #ecause they are "hite ;
I #oth must, have a / not #e homo5ygous AA, #ecause some$ittens coloured ;
I #oth must have # to give #ro"n $ittens ;J "must be hetero0ygous at both loci# 1 only
at least one / one or #oth, must have 4 to give #lac$ $ittens ;
credit ref to :unnett s6uare sho"ing genotypes ;
credit ref to :unnett s6uare sho"ing phenotypes ; max
(ii) Aa4# ' Aa4# 1% "hite - #lac$ 1 #ro"n ;;
Aa4# ' Aa## + "hite 1 #lac$ 1 #ro"n ;; max %[15]
18. A/
8/12/2019 Cellular Control Answers F215
13/33
The Henrietta Barnett School 13
8/12/2019 Cellular Control Answers F215
14/33
(c) (i) #inds RNA polymerase ;
allo"s, transcription / production of mRNA ;
s"itches gene on / allo"s gene expression ; % max
(ii) (protect against) more than one, strain / disease / pathogen / AB ;
stronger immune response ;less li$ely mutant form "ill escape immune response / AB ;
A9: ; cheaper / reduces num#er of vaccinations % max
(iii) ?olgi modifies protein / polypeptide / AB ;
forms glycoproteins / add sugars orcar#ohydrate ;
?olgi forms vesicles ;
incorporated into cell mem#rane ; Rexocytosis
A9: ; % max
(d) cells that take up vaccine might
1 function less "ell ;
2 #e $illed #y immune system / trigger auto7immune response ;
3 have genes disrupted / mutation ;
4 ne" gene might #e inherited / AB ;
5 plasmid could enter #acteria ;
6 super#ug / create ne" disease / AB ;
7 effects un$no"n / ne" technology / no human trials ;8 A9: ; ref ethics, ref irreversi#le - max
[14]
20. (i) (334 / macrophages)(siRNAs continue to "or$) in long7lived cells ;only one treatment needed for macrophages / &&R ;(siRNAs diluted) as lymphocytes divide ; orarepeat treatments needed for, lymphocytes / &D ; %
(ii) (334)#ecause no essential function in #ody / a#sence not a pro#lem ; 1
[3]
The Henrietta Barnett School 14
8/12/2019 Cellular Control Answers F215
15/33
21. (i) P, , :, N, , R ; 1
(ii) accept correct names of stages
P ; Aprophase 1
; Aanaphase %
P / ; Aprophase 1 / metaphase 1 ; Ametaphase 1
R ; Atelophase %
(iii) DNA replication ;
synthesis of proteins / named protein ; Atranscription / translation
synthesis of mem#rane ;
synthesis of, organelle(s) / named organelle ;
respiration ;
A9: ; e*g* centrioles replicate ; % max [8]
22. (a) estimate of role of genotype in phenotypic variation / AB ;
herita#ility L 9?
/ 9:;
"hen herita#ility high much of variation is, genetic / not environmental/ ora ;
high herita#ility "ill result in successful selective #reeding / ora ; % max
(#) single / ma8or / endelian, gene ;
large effect ;
little environmental effect ;
dominant allele > expressed in homo7 and hetero5ygote ;
not polygenic ;
not additive ;
discontinuous variation / not continuous variation ;
6ualitative / not 6uantitative ; % max
(c) (i) triplet of #ases that does not code for an amino acid ;
A>> / A>& / A&> ;
code to mar$ end of gene ;
code to stop transcription / ref to disengagement RNA polymerase ; % max
(ii) transcription halted early / AB ;
protein "ill, #e smaller / have fe"er amino acids ;
tertiary structure / -D shape different ;
#inding / affinity, different ;
The Henrietta Barnett School 15
8/12/2019 Cellular Control Answers F215
16/33
protein inactive ; - max
ref to lacoperon ;
(iii) ref to, promoter / operator / / AB , increases num#er of tillers per plant ;
and num#er of #ranches per tiller ;
ref to comparative figures ; % max
(ii) inserted into genome randomly / cannot choose "here it is inserted ;
may #e "ithin a fre6uently expressed gene ;
may #e after an
8/12/2019 Cellular Control Answers F215
17/33
10 reproduce ;
11 pass alleles on (to, offspring / next generation) ;
12 ref to sta#ilising selection (in #oth ha#itats) ;
13 ref to other $a'e&selection pressure(s) ;
14 not a very mo#ile population orlittle, immigration / emigration ;
15 separate gene pools descri#ed ;
16 little mutation ta$ing place ; Ano ne" camouflage method over time
17 ha#itat sta#le ;
18 ref to "hy unfavoura#le alleles have not disappeared ;
19 A9: ; e*g* calculated average figures for #oth ha#itats max
QWC clea! well %!ga$i"e& "i$g "#eciali"t te!'" ;
clear and "ell organised and must include mar$ing points and 1[11]
The Henrietta Barnett School 17
8/12/2019 Cellular Control Answers F215
18/33
24. pigmented #irds more li$ely to #e damaged;at all percentages;more damage as percentage of pigmented #irds increases to %-F;more damage as percentage of "hite #irds increases to %F;fall in damage of "hite #irds at, %F/highest percentage; max -
[3]
25. (i) Qndividual % 7 O
! ;
Qndividual 7 h! ;
Qndividual + 7 O
! ;
Qndividual 3 7 O
h;
ma$ 2 if se$ chromosomes not shon
(ii) half / .* / .F / 1 in % ; A11, .. R1% 1
(iii) carriers have, #oth / O and h / dominant and recessive, alleles ; Aarehetero5ygous Rt"o alleles
females have t"o chromosomes / ora ; %[7]
26. (a) (i) @ A & & ? ? A @ @ & A &;;
1 error 1, 2 errors -
allo 1 mark for giving 7 throughout instead of 8
(i!e! 7 3 3 6 6 7 7 3 3 1 mark) %
(ii) transcription / transcri#ed;R transcriptase 1
(#) (i) ) anticodon;R anticodons+ transfer RNA / tRNA; ri#osome / rRNA;- codon;R codons
The Henrietta Barnett School 18
8/12/2019 Cellular Control Answers F215
19/33
(ii) 1 DNA triplet / codon / -/ mRNA triplet,codes forspecific amino acid;
2 order of, triplets / #ases, determines the order of amino acids;
3 tRNA / C, has, corresponding / complementary,triplet / anticodon;
4 (tRNA / C) attached to specific amino acid;
5 activation of amino acid;
6 % (tRNA) #inding sites on the ri#osome;
7 codon and anticodon #ind;Amatch
8 A to @ and & to ?;
9 ad8acent amino acids 8oin;
10 peptide #ond; max
(c) 1 attaches to ri#osome;
2 removes,#ase / portion, of ri#osome;Astops ri#osome assem#ling / changes shape of ri#osome
3 prevents ri#osome,attaching to / reading, mRNA;
4 prevents codons #eing exposed;
5 prevents,tRNA / anticodon,attaching to,mRNA / codon;
6 prevents / inhi#its en5yme responsi#le for,formation ofpeptide lin$ages;
7 A9:;e*g* further detail of any of the a#ove points % max[13]
27. (i) A, (and *; 1
(ii) apply ora throughout
produced #y, sexual reproduction / fusion of gametes / fertilisation ;
ref to random mating ; random fertilisation 2 marks
contain chromosomes from t"o individuals / diploid organisms ;
more alleles ; % max
(iii) Cand are haploid organisms ;
haploid cells have, one set of chromosomes / half the num#er ofchromosomes ;
meiosis re6uires pairing of homologous chromosomes ;
ref to maintaining chromosome num#er "hen gametes fuse / gametesmust #e haploid ; % max
[5]
The Henrietta Barnett School 19
8/12/2019 Cellular Control Answers F215
20/33
28. (a) any to of the folloing
(monomer) not glucose ;
contains nitrogen ;
contains, sulphur ;
A9: ; Rref to #ranching % max
(#) amount of glycoprotein varies (in different cells) ;
(cells carry out) endocytosis to different extents ;
cells have different life spans / example ;
no time for polysaccharide to accumulate in short lived cells ;
num#er / role, of lysosomes not same in all cell types ;
A9: ; 1 max
(c) ith 9unter#s syndrome, lysosomes / vesicles, might be
larger ;
more numerous ;
have different shape ;
stain differently ;
A9: ; e*g* granular cytoplasm 1 max
(d) (i) unaffected parents can have an affected child ; orae*g* -, , / 11, 1%, 1+, 1 ; 1 max
(ii) only males affected ; ora
mothers pass it on ; ora
on the chromosome ;
carrier "omen asymptomatic / dominant normal allele mas$s trait ;
/ 11 / 1 , could #e carriers ; % max
(e) there are only - cases / too small a sample ;mostly female line sho"n ;
A9: ; e*g* pedigree of, - / 1%, not $no"n
progeny of, 1- / 1 / 1, not $no"n 1 max
The Henrietta Barnett School 20
8/12/2019 Cellular Control Answers F215
21/33
(f) drug must act in all cells ;
lysosomes are "ithin cells ;
hard for drug to reach ;
if drug acts as en5yme, polysaccharide on cell mem#ranes may #e #ro$endo"n ;
tissue mechanical support "ould #rea$ do"n ;
A9: ;
A9: ; e*g* no animal model
protein drug digested in gut
rare condition (6ualified), economic argument % max[10]
29. (a) (i) steep increase, for the first 1 7 % hours / till %*% 7 -* (a*u) ; Alinear,steady #ecame constant at, - hours / *- (a*u) ;
if no figs in description, e!g! "rose then constant# aard 1 mark ma$ %
(ii) (increased as) en5yme "or$ing / rate of reaction high / reactionproceeding ;
(increased as) su#strate converted into, drug / product ;
(levelled off / #ecame constant, after the) en5yme, #ecame inactive /"as denatured;
(levelled off / #ecame constant) #ecause product inhi#its, reaction /
en5yme ;Rreferences to en5yme or su#strate #eing used up R> & limiting %
(#) pO ;
degree of mixing ;
en5yme concentration ;
A9: ; e*g* ref to concentration of inhi#itors 1 max
(c) ma$ of 2 marks for predicting ore$plaining/1 concentration of drug higher / AB ;
/2 rate of reaction slo"er / AB ;
/3 may not level off (in time scale sho"n on graph) ;
/4 time ta$en to reach the maximum yield (approximately)dou#les ; (c*f* 1 &)
*1 not denatured ;
*2 adapted to & / optimum / #ody / usual, temperature ;
*3 ref to P1.
of a#out % ;
*4 ref to lo"er $inetic energy / AB ;
*5 ref to G7, collisions / complexes ;
The Henrietta Barnett School 21
8/12/2019 Cellular Control Answers F215
22/33
A9: ; e*g* ref to active site - max
(d) (i) (shaded amino acids) form the active site ;
su#strate may not attach to the active site ;
en5yme7su#strate complex may not #e formed / AB ; 1 max
(ii) and ++ not part of active site ;
hold, active site / - structure / -D structure, in shape ; Astop denaturinghydrogen #onds "ea$ ;
easily #ro$en #y, vi#ration / heat ; ApO
disulphide #ridge strong ;
not #ro$en #y heat ; % max
(e) nucleotide / #ase/ DNA, se6uence codes for, protein / amino acid, se6uence ;
changes DNA ; Achange triplet
ma$es different mRNA ; Achange codon
transcription ;
different tRNAs line up ; Achange anticodon
translation ;
different (amino acid se6uence in), en5yme / protein / polypeptide ; % max[13]
30. (a) penetration of #iofilm difficult ;
ref to diffusion of anti#iotic ;
detail of diffusion ;
larger A of separate #acteria / ora;
does not reach all #acteria in film / ora;
anti#iotic trapped #y film ;
detail of entrapment ;
dead #acteria in film form #arrier ;A9: ; e*g* hori5ontal transmission / con8ugation, easier in #iofilm
A9: ; max
(#) #oth strains have identical sensitivity "hen in suspension ;
to all three anti#iotics ;
#oth, less sensitive / more resistant, "hen in #iofilms (ora) ;
strain 1 much, less sensitive / more resistant ;
comparative figures ;& most effective / AB ;
4 least effective / AB ; max
The Henrietta Barnett School 22
8/12/2019 Cellular Control Answers F215
23/33
(c) mutation ;
random / chance / pre7existing ;
detail of mutation ; e*g* #ase su#stitution, addition, deletion
ref to, selection / selective advantage ;
codes for different, glucan / #iofilm ;
affects all three anti#iotics ;
#loc$s anti#iotic from reaching cells ;
#inds anti#iotics ; max
The Henrietta Barnett School 23
8/12/2019 Cellular Control Answers F215
24/33
(d) hori5ontal transmission ;
(copy of) plasmid ;
via con8ugation ;
detail ; con8ugation tu#e /
8/12/2019 Cellular Control Answers F215
25/33
34. (a) linkage(t"o or more) genes / loci, on same chromosome ; Rallelesdo not assort independently (in meiosis) / inherited together ;
crossing over
reciprocal exchange of portions of, chromatids / DNA ; As"apping alleles#et"een (paternal and maternal) homologous chromosomes ; A#ivalent
in prophase Q (of meiosis) ; ma$ 2 max -
(#) anthers removed (#efore maturity) (to produce male sterility) ;male sterilisation ;genetic or, %6 / hormone
pollen transferred #y hand ;plants isolated ;flo"ers #agged (#efore and after pollination) ; max -
(c) (i) R
8/12/2019 Cellular Control Answers F215
26/33
35. genetically isolated populations ;allopatric speciation / AB ;ref to genetic drift ;ref to, founder effect / founder population ;loss of alleles / genetic erosion / reduced gene pool / loss of geneticdiversity / AB ;
ref to, disease / population crash ;A9: ; e*g* ref to exposure to different selection pressures max [4]
36. (i) semi7conservative replication ;DNA, polymerase / helicase ;
#rea$s hydrogen #onds #et"een t"o DNA strands / un5ips DNA ;each DNA strand acts as a template / #oth strands copied ;complementary #ase7pairing ("ith free DNA nucleotides) ;sugar7phosphate #ac$#one forms ; % max
(ii) crossing7over ;in prophase ;recom#ination of, non7sister / maternal and paternal, DNA ;A9: ; e*g* matching cuts in DNA
DNA ligase % max
(iii) synapsis / to hold, (homologous) chromosomes / #ivalent, together ;(so close enough) for crossing7over ;so can #e evenly segregated ;A9: ; e*g* to pac$age or support chromosomes,
avoid DNA #rea$ing,easier to move DNA % max
[6]
37. description
D1 chosen male and female mated ;D% ref to desired characteristic / named desired characteristic ;D- ref to AQ ;
D advantage of using AQ ;D offspring inspected and #est mated ;D+ several / many, generations ;D ref to pro#lem in#reeding ;D ref to "ay of minimising in#reeding ;D3 ref to herita#ility ;D1. easier to select for traits "ith high herita#ility / ora ;D11 easier to select for discontinuous variation / ora continuous variation ;D1% ref to polygenes / additive effect ; ma$ ' "describe# marks
The Henrietta Barnett School 26
8/12/2019 Cellular Control Answers F215
27/33
e$planation
G1- selective #reeding involves "hole genomes ;G1 hence other traits follo" selected trait(s) ;G1 ref to lin$age ;G1+ artificial selection ;G1 selection, different from natural selection / for #enefit of humans ;
G1 starter population, small / not representative ;Afounder principle ma$ ; "e$plain# < marks
A9: either D or G mar$ ;e*g* ref to use of, Q9 / surrogate, "ith reason
ref to loss of alleles / genetic erosion max
QWC legible text with acc!ate "#elli$g, #$ctati%$ a$& g!a''a!; 1[9]
38. (i) production of desired changes in phenotype of an organism ;
selection of appropriate alleles / AB ;#y artificial selection ;use as parents / mate, those sho"ing desired phenotype(to larger degree) ; max %
(ii) measure of value of individual=s genotype (for #reeding) ;mate "ith num#er of proven individuals ;assess phenotypes of offspring ; Rgenotypesaverage value ;especially useful for sex7limited traits ; Rsex7lin$ede*g* sex7limited trait ; max
[6]
39. ma$ = from points 1 to
1 limited, food supply / space ;% competition ;- predation ; disease ; reached carrying capacity / death rate L #irth rate ;
marking points 1 linked to keeping population stable
+ individuals sho" variation ; variation due to, com#ination of alleles / mutations ; #est adapted survive / ora ; Asurvival of fittest idea3 reproduce ;1. pass alleles to offspring ;11 fre6uency of favoura#le alleles "ill, increase / #e maintained ; Aora max
[5]
The Henrietta Barnett School 27
8/12/2019 Cellular Control Answers F215
28/33
40. chinchilla &&h
&&h
&&h
&O
&&h
&a;
agouti &A
&A
&A
&&h
&A
&O
&A
&a; %
[2]
41. (i) for #enefit of humans;to improve, trait(s)/named trait;to produce desira#le, phenotype/genotype;to increase num#er of desira#le alleles;to increase homo5ygosity;A9:; max %
(ii) ref* self7pollination;ref* in#reeding;limited gene pool; max %
(iii) ref* different num#ers of chromosomes;hy#rid is -n;sterile;gametes have %% and 11 chromosomes/hy#rid has -- chromosomes;some chromosomes unpaired;failure of meiosis;ref* uneven distri#ution of chromosomes;ref* other #arrier to interspecific cross; max %
[6]
42. (i) ;
;(tic$);;
(ii) discontinuous; Sdo notallo if no reason givenT 1
reason
one, gene/locus; Ama>or/?endelian,genediscrete phenotypes/ora;6ualitative/large effect/little environmental effect; max 1
[6]
43. named characteristic;named environmental factor; (mark first anser only) %
[2]
44. t"o different genes represented in each gamete ie P or 6 and R or r;four correct com#inations ie P and R, P and r, 6 and R, 6 and r; %
The Henrietta Barnett School 28
8/12/2019 Cellular Control Answers F215
29/33
[2]
45. stated advantage;detail; e*g* particular character (not hole phenotype)/can alter one trait
only (ithout affecting background genes)/can add allele fromdifferent ta$on ith hich breeding may not be possible/&uicker
(than the many generations of, selective breeding/backcrossing) %
stated disadvantage;detail; e*g* cannot precisely position insert (so) unknon/unanticipated
effect/may pass to other species (ith unknon/undesirable,
effect)/regarded as ethically undesirable (no market/crop
destroyed by protesters)/cannot breed from 6? (re&uires cloning) %[4]
46. 1 ref to operon;% normally repressor su#stance #ound to operator;- prevents RNA polymerase #inding (at promoter) / prevents
transcription; lactose #inds to repressor; changes shape of protein molecule;+ una#le to #ind (to operator); RNA polymerase #inds (at promoter) / transcription occurs / genes
s"itched on; A9:; e*g* production of lactose permease / production of #eta7
galactosidase; max
[5]
47. deficiency gives resistance to malaria;deficient/resistant, individuals more li$ely to survive;alleles, passed to next generation;natural selection;
presence of%lasmodiumis selection pressure;fre6uency of this allele increases;
phenotype more common in population;A9:; e*g* others more li$ely to die of malaria - max
[3]
The Henrietta Barnett School 29
8/12/2019 Cellular Control Answers F215
30/33
48. gene #an$;source of alleles;for future (selective) #reeding;to counteract, genetic erosion/loss of genetic variation;to counteract, in#reeding/homo5ygosity;to counteract extinction;
for changed conditions;example of changed conditions; e*g* climate/environment/disease/fashionto preserve as yet unidentified, alleles/traits; max
[4]
49. (a) (dominant) epistasis; 1
(#) ref* frame shift;ref* three extra, triplets/amino acids;may introduce stop code so shorter, polypeptide/protein;
may increase length of, polypeptide/protein;may alter, shape/-= structure, of, polypeptide/protein;affects active site;
protein/polypeptide, may lose function;protein/polypeptide, may have different function; max
(c) (i) %arental phenotypes: 5hite @eghorn $ 4ed Aunglefol%arental genotypes: QQ&& x ii&& or QQcc x ii&&;
1genotype Qi&& or Qi&c; %
(ii) - "hite 1 pigmented or 1- "hite - pigmented; 1[8]
50. (i) crossing over; treat chiasma(ta) as neutral 1
(ii) prophase; 1
(iii) have different, alleles/#ase se6uence of DNA;Asister chromatids have same alleles/non sister have different alleles 1
[3]
The Henrietta Barnett School 30
8/12/2019 Cellular Control Answers F215
31/33
51. (i) (parental genotypes) Aa4# ' aa##;
(gametes) A4, A#, a4, a# (all) a#;
(offspring genotypes) Aa4#, Aa##, aa4#, aa##;
(offspring phenotypes) grey #ody/normal "ing, grey #ody/#ent "ing,#lac$ #ody/normal "ing, #lac$ #ody/#ent "ing;
Bse&uence of phenotypes must match genotypes for markT
(phenotypic ratio) 1 1 1 1;
apply ecf!
accept alternative symbols if a key is given, but if no key given ma$ ;
(ii) .,.,.,.; 1
(iii) ("or$ing) .*11% 0 .*-1% 0 .*. 0 .*;L .*3%; A-!C/-!C2/-!C=
2 marks for correct anser ith no orking!
ecf if correctly use rong figures from (ii) %
(iv) yes (but no mark for yes on on)
as calculated figure is smaller than *%;
ecf applies to value calculated in part (iii) 1[9]
52. (a) (i) sympatric; 1
(ii) ranges of t"o species, overlap/close together/AB;no geographical #arrier;ref to #ehavioural/genetic/physiological/pre5ygotic #arrier;correct ref to named area of map; max %
(#) ref to mate selection #y si5e; ie large "ith large or small "ith smallref to monogamy;ref to intermediate si5es, at disadvantage/selected against/ora;
intermediate do not pass on alleles/ora;suggested reason "hy intermediate at disadvantage/ora max -
The Henrietta Barnett School 31
8/12/2019 Cellular Control Answers F215
32/33
(c) female produces a lot of eggs;selects male, that can store lots of eggs/has a large pouch/ora;large males fertilise many eggs/ora;chance of more offspring surviving;
or
large female and small male produce intermediates/ora;
intermediates at disadvantage/ora; max %[8]
53. a change in the genetic material;unpredicta#le / AB;extra detail; e*g* addition / su#stitution / deletion / frame shift / small
part of chromosome / may code for different protein /may code for no protein %
[2]
54. 1 mark ma$ for general effect of mutations:
mutation may give different, amino acid / primary structure;Aref stop codon
some mutations alter, molecular shape / tertiary structure / #inding;
ma$ = for e$plaining data in 7able:
so una#le to, accept / transport, O&-
7;
una#le to #ind A>:;
so increase in acidity / decrease in pO;effect on mucus;effect on en5yme(s) /ref pO optimum of en5yme(s);
poor digestion of, protein / lipid / starch;
A9:; e*g* some mutations, give some transport / have less effect*M --F (of norm) allo"s normal digestive function / K +FSAvery loT does not* max -
[3]
55. allo ma$ for folloing:transcription;DNA un5ips / O #onds #rea$;exposing re6uired, gene / se6uence of #ases;RNA nucleotides align "ith DNA;@ "ith A, A "ith >, & "ith ?, a$&? "ith &;RNA polymerase;mRNA formed (using DNA strand as template);leaves nucleus through pore;
The Henrietta Barnett School 32
8/12/2019 Cellular Control Answers F215
33/33
allo ma$ for folloing:
translation;mRNA attaches to ri#osome;tRNA #rings amino acid (to, ri#osome / mRNA);each tRNA attached to specific amino acid;tRNA #inds to mRNA using complementary, #ase triplet / anticodon;
peptide #ond formed #et"een amino acids;DNA / mRNA, (nucleotide / #ase) se6uence determines se6uence ofamino acids;
A9:; e*g* %, #ase triplets / codons, in ri#osomeA9:; e*g* ref* to start / stop, codons
polysomeslarge and small su#unit in ri#osome
g%0
1.[10]
56. 1 mark per correct ro
@ook for both ticks and crosses!
+f a table consists of ticks D@Y or crosses D@Y, then assume that the blank spaces are the
other symbol!
+f a table consists of ticks, crosses and blanks then the blanks represent no attempt at the
anser!
Nucleotides line up along an exposed DNA strand* ;
>he "hole of the dou#le helix he original DNA molecule is unchanged after the process* ;
Adenine pairs "ith thymine* ;[8]
Top Related