bio ms jan 2011
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Oxford Cambridge and RSA Examinations
GCE
Biology Advanced Subsidiary GCE
Unit F212: Molecules, Biodiversity, Food and Health
Mark Scheme for January 2011
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OCR (Oxford Cambridg e and RSA) is a leading UK awarding body, providing a wide range ofqualifications to meet the needs of pupils of all ages and abilities. OCR qualifications include
AS/A Levels, Diplomas, GCSEs, OCR Nationals, Functional Skills, Key Skills, EntryLevel qualifications, NVQs and vocational qualifications in areas such as IT, business,languages, teaching/training, administration and secretarial skills.
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This mark scheme is published as an aid to teachers and students, to indicate the requirementsof the examination. It shows the basis on which marks were awarded by Examiners. It does notindicate the details of the discussions which took place at an Examiners meeting before markingcommenced.
All Examiners are instructed that alternative correct answers and unexpected approaches in
candidates scripts must be given marks that fairly reflect the relevant knowledge and skillsdemonstrated.
Mark schemes should be read in conjunction with the published question papers and the Reporton the Examination.
OCR will not enter into any discussion or correspondence in connection with this mark scheme.
OCR 2011
Any enquiries about publications should be addressed to:
OCR PublicationsPO Box 5050 AnnesleyNOTTINGHAMNG15 0DL
Telephone: 0870 770 6622Facsimile: 01223 552610E-mail: publications@ocr.org.uk
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F212 Mark Scheme
Question Expected Answer Mark Addit ion1 (a) (i) human immunodeficiency virus / HIV ;
1DO NOT CREDIT if
1 (a) (ii)1
2
3
(infective agent), in blood / body fluids ;
idea of: used needles are contaminated ; ora
reduces chance of sharing needles ; ora2 max
1 ACCEPT any infec
question asks for mo2 ACCEPT e.g. used2 ACCEPT e.g. new2 DO NOT CREDIT
3 IGNORE prevents
1 (b) (i)
amino acid(s) ;
nucleotide(s) ;
2
Answers must be on co ACCEPT phonetic sp
DO NOT CREDIT if
ACCEPT ribonucleo
1 (b) (ii)1
2
3
4
reverse transcriptase in (host) nucleus ;
viral DNA, (inserted) in (host), chromosome / DNA ;
idea of: (viral) RNA / mRNA produced / transcribed ;
(to) code for / make / translate, viral proteins ;2 max
4 IGNORE different
1
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F212 Mark Scheme
Question Expected Answer Mark Addit ion1 (c) (i)
1
2
3
4
5
6
7
8
9
not vaccinated against TB ;
weakened immune system ;
(lifestyle) e.g. poor diet / lack of protein / malnourished /smoking / alcoholism ;
homelessness ;
poor ventilation (of housing) / AW ;
overcrowding ;
close contact with people from / visiting, area where TB iscommon ;
close / prolonged, contact with individual(s) with TB ;
consumption of milk or beef, from infected cattle / indeveloping countries ;
3 max
Mark the first three awhich l ine they are on1 IGNORE general re
3 DO NOT CREDITIGNORE poor health
7 ACCEPT area wherquarantined
2
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F212 Mark Scheme
Question Expected Answer Mark Addit ion(c) (ii)
1
2
3
4
5
cytokine / interleukin / receptor has, specific / unique,
shape ;
(cytokine / interleukin), binds / attaches / bonds to / fits into,receptor ;
receptor on (cell surface) membrane (of B lymphocyte) ;
(receptor and cytokine have) complementary shapes ;
activates / stimulates, clonal expansion / mitosis ; 3 max
1 DO NOT CREDITthis is implied in questi
3 DO NOT CREDIT
5 ACCEPT activates
Total 13
3
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F212 Mark Scheme
Question Expected Answer Mark Addit ion2 (a) (i) blue-black / black / dark blue ;
1
ACCEPT dark purpleDO NOT CREDIT bdarkness
ACCEPT acceptable c
2 (a) (ii)
1
2
between oxygen and hydrogen (atoms) ;
(between) electronegative / -, and electropositive / + ;
2
CREDIT marking poinmax 1 if incorrect cha
1 DO NOT CREDIT
2 DO NOT CREDIT2 ACCEPT slight / pa
2 (a) (iii )1
2
3
hydrogen / H, bonds break ;
helix, lost / unravels / AW ;
iodine, released / no longer in complex / AW ;2 max
IGNORE refs to dena
2 ACCEPT spiral / co
3 ACCEPT no longer
4
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F212 Mark Scheme
Question Expected Answer Mark Addit iontake samples at a range of times / AW ;
same volumes (of solutions) added / removed (each time) ;
heat with, Benedicts (solution) / CuSO 4 and NaOH ;
(use of ) excess Benedicts ; changes to, green / yellow / orange / brown / (brick) red ;
remove precipitate / obtain filtrate ;
colorimeter ;
calibrate / zero, using, a blank / water / (unreacted)Benedicts ;
use (red / orange) filter ;
reading of, transmission / absorbanceORmass of precipitate ;
more transmission / less absorbance, of filtrate,OR greater mass ppt, = more maltose present ; ora
using, standard / known, concentrations (of maltose) ;(obtain) calibration curve ; plot, transmission / absorbance / mass of ppt, against
(reducing sugar) concentration ;use graph to read off concentration of maltose / AW ; 6 max
B2 must be in context reaction mixtureB3 DO NOT CREDITB3 DO NOT CREDIT
mixture at the begin
C6 CREDIT descriptie.g. filtering / ce
8 IGNORE control
9 DO NOT CREDIT
T10 ACCEPT measunot, pass through
11 if unfiltered Benedindicated as being prtransmission / more abpresent11 DO NOT CREDITcolorimeter12 CREDIT serial di
2 (b) 1
B2
B3
B4B5
C6
C7
8
9
T10
11
121314
15 QWC correct sequence ; 1 1 of mps B2 to B5 ,
5
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F212 Mark Scheme
Question Expected Answer Mark Addit ion2 (c) (i)
12
3
increases / greater / faster ;reaction completed in / plateaus after / concentration is
100% after, 3.5 minutes ;figures with units to support mp 1 ;
2 max
1 ACCEPT any time
3 two maltose concentrgiven time or two timesmaltose concentration.3 ACCEPT calculated3 DO NOT CREDIT3 ACCEPT any concewithin 0.05 min.
The percentage concentration of maltose (%) presPresence or absence of chloride ions
0.0
min
0.5
min
1.0
min
1.5
min
2.0
min
Chloride ions present 0 24 54 70 80 8
Chloride ions absent 0 12 20 29 36 4
Difference in maltose concentrationWhen chloride ions are either present
or absent0 12 34 41 44 4
Allow a + /- 1% for any concentration of maltose and a +/- 2% for the difference in
2 (c) (ii) 1
2
3
(acts as a) cofactor ;
(Cl -) binds to, enzyme / amylase / amylose / substrate ;
enzyme substrate complex / ESC, forms more, easily /quickly ;
2 max
1 IGNORE coenzym
2 ACCEPT binds to,
3 ACCEPT descriptio
6
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F212 Mark Scheme
Question Expected Answer Mark Addit ion2 (c) (iii)
1
2
3
4
5
6
temperature ;
pH ;
enzyme / amylase / chloride, concentration ;
substrate / starch / amylose, concentration ;
constant / regular, stirring ;
(fixed) volume of solution
(removed each time for sampling) ; 3 max
Mark the first three awhich l ine they are onDO NOT CREDIT re
3 IGNORE amount 3 DO NOT CREDIT
4 IGNORE amount 4 DO NOT CREDIT
Total 19
7
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F212 Mark Scheme
Question Expected Answer Mark Addit ion3 (a) (i)
1
2
3
4
(all), sub-arctic / all 4 named sub-arctic, species / birds,show decrease ;
(all / most), other / non sub-arctic / all 4 named non sub-arctic, species / birds, show, increase / no change ;
greater change / AW (in breeding success), in sub-arctic
than in non sub-arctic species ; comparative figs (in 1970 AND 2000) ;
3
ACCEPT reference tosuccess throughout1 sub-arctic species = s+ ptarmigan + dotterel
2 non sub-arctic speciemeadow pipit + ring ou
4 number of young for sub-arctic species in 19subtraction between the4 DO NOT CREDIT
2000
number of young raised per yearspecies
1970 2000 difference in number of youngraised between 1970 and 2000Snow bunting* 78 2 Down 76
Lapland bunting* 7 0 Down 7
Ptarmigan* 1280 876 Down 404
Red g rouse 890 962 Up 72Wheatear 209 231 Up 22
Meadow pipit 23 82 Up 59
Ring ouzel 23 26 Up 3
Dotterel* 45 35 Down 10
8
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F212 Mark Scheme
Question Expected Answer Mark Addit ion3 (a) (ii)
1
2
3
4
5
climate change / global warming ;
(environmental) change too rapid for adaptation ;
change in, flora / plants / food supply / insects / prey /predators / human activity ;
disease (that affects sub-arctic species more than others) ;
sub-arctic species, less well-adapted than / have beenoutcompeted by, non sub-arctic species / AW ;
2 max
1 IGNORE greenhous1 DO NOT CREDITenough without referen
3 ACCEPT camouflareduction in size of hab
5 ACCEPT ora
3 (b) (i) the number of species present (in a habitat) ;
1
DO NOT CREDIT ra
9
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F212 Mark Scheme
Question Expected Answer Mark Addit ion3 (b) (ii)
1
2
3
4
5
6
idea of: unbiased method to selecting sampling area ;
sample many times / AW, and calculate mean / average ;
standardised sweeping procedure ;
ensure insects do not escape (before being identified) ;
method to prevent recounting ;
sample at different times of, day / month / year / weatherconditions ;
3 max
Mark the firs t three s1 ACCEPT e.g. randocoordinates OR use of t1 IGNORE random s
3 e.g. same type of mosame number of sweep3 ACCEPT sample at3 IGNORE same colle3 IGNORE refs to usitechniques in order to c
4 ACCEPT use of po
5 if ref to mark-releaseand recapture and lookrecounting
10
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F212 Mark Scheme
Question Expected Answer Mark Addit ion4 (a) 1
2
3
4
free from, disease / illness ;
physical and mental and social wellbeing / AW ;
good nutrition ;
suitably housed ; 2 max
1 ALLOW infectiondisease
2 DO NOT CREDIT
3 ACCEPT balanced
4 ACCEPT ref to eco
12
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F212 Mark Scheme
Question Expected Answer Mark Addit ion4 (c) (i)
1
2
3
4
5
lives, on / in / in contact with, and harms host ;
takes nutrition from / feeds on (host) ;
warmth ;
protection / safe place / AW ;
allows transmission / spread, to a new host / AW ;
4 max
1 living on / in must befeeding1 IGNORE live off
3 ACCEPT incubate
5 ACCEPT distributehost
4 (c) (ii) 1
2
3
wash / clean / disinfect / sterilize, hands ;
not, scratching / touching, of anus ;
drugs to, kill / remove, parasite / eggs ;
2 max
2 ACCEPT method tonails2 IGNORE wash anu
3 DO NOT CREDIT3 IGNORE anti-bact
Total 12
14
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F212 Mark Scheme
Question Expected Answer Mark Addit io5 (a)
statement
DNA only ( D)or
RNA only ( R)orboth DNA and RNA ( B)
contains thymine D
contains ribose R ;
consists of 2 chainsconnected to each other
with hydrogen bonds
D ;
has a sugar-phosphatebackbone B ;
has 4 different nitrogenousbases B ;
contains a pentose sugar B ;
is found in the nucleus andcytoplasm R ;
6
Award 1 mark for eaDO NOT CREDIT i
15
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F212 Mark Scheme
Question Expected Answer Mark Addit ion5 (d) (i)
1
2
no DNA from living specimens in Wales analysed ;
population (may have) evolved / mutations have occurred /genetic variation, (since 1948) ;
1 max
2 ACCEPT descriptio2 DO NOT CREDITof pine marten populati
5 (d) (ii)
1
2
3
4
5
(introduced) pine martens might not be adapted to localconditions / AW ;
(local) habitat, might have changed / is no longer suitable(for any pine martens) / AW ;
introduced, pine martens, might outcompete native,population / pine martens ; introduced pine martens might bring disease ;
Welsh pine marten would lose its, distinctiveness / identity,because of interbreeding ;
1 max
ACCEPT animals as Aanswer 1 ACCEPT not adapt1 DO NOT CREDIT
3 ACCEPT introduceWelsh pine martens3 IGNORE compete
Total 14
17
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F212 Mark Scheme
Question Expected Answer Mark Addit ion6 (a) (i)
genes / genetic / mutation ;
environment(al) ; 2
Mark the first answerIGNORE inherited / D
6 (a) (ii)1
2
3
4
no defined categories ;
range of values / intermediate values ;
influenced by, environment / many genes / genes andenvironment ;
quantitative / has to be measured / cannot be counted ; 3 max
2 ACCEPT ref to belldistribution 3 ACCEPT any ref to
4 ACCEPT metric
6 (a) (iii ) B ; 1
DO NOT CREDIT if
6 (a) (iv)1
2
3
4
growth too rapid ;
increased susceptibility to, disease / named abnormality ;
inbreeding ;
reduces gene pool / genetic variation / genetic diversity ; 2 max
2 e.g. bone / skeletal ab
3 DO NOT CREDITmutations
4 IGNORE refs to bio
18
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F212 Mark Scheme
Question Expected Answer Mark Addit ion6 (a) (v)
1
2
3
4
5
6
maintain biodiversity ;
aesthetic (reasons) / tourism ;
ethical (reasons) ;
part of a food chain / web ;
maintain / increase gene pool ;
genetic resource / availability to breed with domesticchickens ;
2 max
3 ACCEPT religious
4 ACCEPT food sour
6 CREDIT descriptionor source of genetic va6 ACCEPT specific ee.g. disease resistance /
heat tolerance / idea of
19
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F212 Mark Scheme
Question Expected Answer Mark Addit ion6 (b) (i)
1
2
3
4
5
reduces / prevents (infectious) disease ;
prevent, problems / named problem, with gut ;
digest food more, efficiently / easily / quickly ;
greater proportion of, food / energy,can contribute to growth ;
reduce risk of transmitting, pathogens / named pathogen, tohumans ;
2 max
Mark the firs t two an1 IGNORE illness
2 e.g. diarrhoea
4 ACCEPT faster grogrowth4 IGNORE larger chic
5 ACCEPT meat lesbacteria
6 (b) (ii)
1
2
3
(antibiotic) resistant, pathogens / bacteria ;
antibiotics kill useful, bacteria ;
idea of: antibiotic passing into human food ;1 max
1 ACCEPT microorg1 IGNORE germs1 DO NOT CREDIT
2 DO NOT CREDIT
Total 13
20
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F212 Mark Scheme
Question Expected Answer Mark Addit ion
sequence / chain, of amino acids ; (amino acids) joined by peptide bonds ;
secondaryalpha / , helix ;small regions of, beta / , pleated sheet / fold ; hydrogen / H, bonds ;
tertiarysecondary structure / helix / polypeptide chain, undergoes
further, coiling / folding ;
3 bonds / interactions from: disulfide / ionic / hydrogen /
hydrophobic or hydrophilic ;
hydrophilic R groups on outside (of molecule) / hydrophobicR groups on inside (of molecule) ;
quaternary4, polypeptides / subunits ;
2, alpha / , chains and 2, beta / , chains ;
1 haem (group) per polypeptide / 4 haems (per molecule) ;
prosthetic group (is) haem, (which) contains Fe 2+ ;
6 max
CREDIT marking poindiagram 1 IGNORE polypepti
S3 Must be in context
T1 ACCEPT polypep
T2 IGNORE if clearly
quaternary structuresT2 H bond must be in
contains 2 and 2Q2)Q3 IGNORE protein polypeptide
3 ACCEPT iron ion /3 DO NOT CREDIT
7 (a)
12
S1S2S3
T1
T2
T3
Q1
Q2
Q3
3
QWC - correct refs to secondary, tertiary and quaternarystructure ; 1 1 S mark and 1 T m
21
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F212 Mark Scheme
22
Question Expected Answer Mark Addit ion7 (b)
1
2
3
4
5
6
(collagen has)amino acid, chain / sequence ;
peptide bonds ;
helical / helix ;
3 bonds / interactions from: disulfide / ionic / hydrogen /hydrophobic or hydrophilic ;
quaternary structure ;
more than one polypeptide / subunit ;4 max
Assume answer refers tIf the answer mentions candidate thinks any fehaemoglobin.
1 IGNORE polypepti1 IGNORE repeating
3 DO NOT CREDIThaving an helix
5 IGNORE primary /s
6 ACCEPT polypeptipolypeptides if numberTotal 11
Question Expected Answer Mark Addit ion8 1
2
3
4
5
6
antibodies ;
natural ;
artificial ;
natural ;
antigen ;
vaccination ; 6
ACCEPT minor mis-sbe confused with anoth
Total 6
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