9700 May June 2010 All Mark Schemes

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary Level and GCE Advanced Level

MARK SCHEME for the May/June 2010 question paper

for the guidance of teachers

9700 BIOLOGY

9700/11 Paper 11 (Multiple Choice), maximum raw mark 40

Mark schemes must be read in conjunction with the question papers and the report on the examination.

• CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

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Page 2 Mark Scheme: Teachers’ version Syllabus Paper

GCE A/AS LEVEL – May/June 2010 9700 11

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Question Number

Key Question Number

Key

1 D 21 C

2 C 22 C

3 C 23 A

4 C 24 A

5 D 25 D

6 B 26 B

7 A 27 A

8 D 28 B

9 A 29 C

10 B 30 D

11 A 31 B

12 C 32 C

13 B 33 A

14 A 34 B

15 D 35 D

16 C 36 A

17 D 37 C

18 D 38 A

19 C 39 C

20 B 40 B

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9700 BIOLOGY




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Question Number

Key Question Number

Key

1 B 21 C

2 C 22 A

3 B 23 A

4 D 24 A

5 D 25 D

6 D 26 A

7 B 27 A

8 A 28 D

9 C 29 C

10 B 30 B

11 A 31 A

12 C 32 C

13 C 33 B

14 D 34 A

15 C 35 C

16 D 36 D

17 B 37 C

18 C 38 D

19 B 39 B

20 C 40 A

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9700 BIOLOGY




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Question Number

Key Question Number

Key

1 D 21 C

2 A 22 A

3 C 23 B

4 A 24 D

5 C 25 C

6 D 26 C

7 D 27 B

8 A 28 C

9 B 29 A

10 C 30 B

11 D 31 B

12 C 32 C

13 D 33 D

14 A 34 C

15 D 35 B

16 C 36 C

17 B 37 A

18 A 38 B

19 D 39 A

20 B 40 A

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9700 BIOLOGY

9700/21 Paper 2 (AS Structured Questions), maximum raw mark 60

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers.



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GCE AS/A LEVEL – May/June 2010 9700 21

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1 (a) (i) glycosidic ; [1] (ii) hydrolysis / hydrolytic ; [1] (iii) assume that the answer refers to within the cell unless told otherwise accept any two relevant examples, e.g.

solvent / medium for reactions ; transport medium ; maintaining turgidity / keeping firm / prevents flaccidity / AW ; (raw material / reactant for) photosynthesis / photolysis ; expansion / elongation / growth ; maintains, hydrostatic pressure / pressure potential ; maintains water potential (gradient) ; A maintains osmotic gradient / prevents plasmolysis stomatal opening ; hydrophilic interactions of membranes ; (in vacuole) pushes chloroplast to edge of cell ; R hydrogen bonding unqualified by ref. to membranes [2 max]

(b) spherical / ball-shaped / AW ;

has a tertiary structure ; ignore quaternary hydrophilic / polar, groups on outside ; water soluble ; ignore ‘more than one polypeptide’ [2 max]

(c) (i) active site ; ignore binding / catalytic [1] (ii) 1 (shape of) U / active site, gives specificity ; A ecf from (i)

2 substrate, fits into / binds with, active site / U ; A ecf from (i) 3 complementary (shape) / matching shape ; A ‘lock and key’ / induced fit R ‘same shape’ 4 further detail of substrate binding to active site ; 5 forms, enzyme-substrate / E-S, complex ; 6 causes stress in substrate / AW ; 7 lowers activation energy / reactions occur at low(er) temperatures ; 8 not used up in reaction / remain unchanged / reusable ; 9 high turnover number / catalyse many reactions per unit time ; [4 max]

[Total: 11]

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2 (a) award two marks if correct answer (29) or (28) is given allow +/– 1 mm in reading the line 100 000 µm / 3 500 = (28.57) or (28.29 if measured 99 mm) or (28.86 if measured 101 mm) 29 ;; A 28 only if 99 mm measured award one mark if correct measurement is divided by the magnification or if answer is given to one or more decimal places [2 max]

(b) (i) stretch / expand / lengthen, on inspiration and, recoil / shorten, on expiration ;

A alternatives for inspiration and expiration but R contract and relax (stretch) to increase, surface area / volume of air, for, diffusion / gas exchange ; (recoil) to (help), expel air / force air out ; ignore contract prevent alveoli, bursting / breaking / AW ; R collapsing [2 max]

(ii) ignore moist

correct ref. to diffusion of, carbon dioxide / oxygen ; A absorb / lose / AW (many alveoli) large surface area ; surrounded by, (many) capillaries / capillary network / AW ; short diffusion distance (between air and blood) ; blood maintains concentration gradient ; epithelium / alveolar wall / AW, thin / squamous ; A alveolus one cell thick A alveolus has a thin wall R cell wall e.g. alveolar cell wall is thin idea that very little between, epithelium and endothelium / AW ; e.g. alveolus and capillary are close together [4 max]

(c) (i) assume answers are about person with emphysema, accept ora if clear

fewer alveoli / (large) ‘holes’ ; A alveolar walls broken down / fewer air sacs / alveoli burst / destroyed less / destroyed / broken, elastic tissue / elastin ; ignore damaged R no, elastin / elastic fibres small(er) surface area ; fewer capillaries ; named change(s) to bronchial tissue ; e.g. enlarged goblet cells, more mucus, scar

tissue, scarred, narrow lumen in airways, inflammation, damaged / no, cilia ref. to tar deposits ; R collapsed lung tissue [2 max]

(ii) shortness of breath (when exercising) / breathlessness ;

A breathing difficulty wheezing / AW (on inspiration) ; rapid breathing rate / hyperventilation / decreased ability to hold breath ; R heavy breathing chest, tightness / pain ; cyanosis / bluish appearance to the skin / AW ; A pale fatigue / tiredness / lethargy / weakness / dizziness / AW ; coughing / coughing up blood ; lots of mucus produced / much phlegm ; expanded / barrel, chest ; R ref. to oxygen concentration of the blood R small vital capacity [2 max]

[Total: 12]

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3 (a) (i) right ventricle ; pulmonary vein ; [2] (ii) ignore close to prevent backflow – allow ref to one side only

valve opens to allow blood from atria to ventricles ; when ventricles contract, valves close (to stop backflow) ; A valves close when blood is pumped out of the ventricles ref. to pressure difference between chambers ; [2 max]

(b) 1 ; 5 ; 2 ; 4 ; [4] (c) 1 SAN sends out, wave of excitation / impulses ; A electrical (im)pulses

R once only - nervous impulse(s) / pulse(s) / signal(s) / wave(s) R if brain stimulates SAN to send out impulses 2 spreads across atria ; 3 atria contract / atrial systole ; 4 fibrous ring / non-conducting tissue / insulating tissue ; 5 prevents, it reaching the ventricles / ventricles contracting at the same time (as atria) ; 6 AVN sends on wave of excitation to ventricles ; A in context – impulse reaches AVN and is passed on to ventricles 7 (therefore) time delay to allow, atria to empty / atria to complete contraction / ventricles

to fill / atria and ventricles do not contract at the same time ; 8 time ref. 0.1–0.2 seconds ; 9 Purkyne tissue conducts, excitation / impulses, to base of, septum / ventricles ; A apex of heart 10 spreads upwards in ventricle (walls) ; 11 (so) ventricles contract from base upwards / ventricles force blood up from base ;

[5 max] [Total: 13]

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4 (a) caused by pathogen, transmissible / communicable / contagious / transferable / passed from one person to another ;

A for pathogen – microorganism / any two named types of microbe R parasite unqualified [1] (b) R virus or bacteria once in the answer

female, Anopheles (mosquito) ; takes blood (meal) from an (infected) person, feeds on an (uninfected) person ; R ‘bite’ unless qualified with blood Plasmodium / parasite, transmitted in (mosquito’s) saliva ; Plasmodium / parasite, blood transfusion / shared needles / across placenta / at birth ; [2 max]

(c) max 3 for malaria max 3 if pathogen(s) is virus or bacterium

1 Anopheles / mosquito / vector, survives / breeds / lives, within the tropics / in hot and

humid areas ; ora 2 Plasmodium / pathogen / parasite, needs to reproduce within the mosquito (at

temperatures above 20°C) ; 3 eradicated in some countries outside the tropics ; 4 ref. to LEDCs and, poor / non-existent, mosquito control programmes ; 5 mosquitoes resistant to, DDT / insecticides / pesticides ; 6 Plasmodium resistant to, drugs / chloroquine / other named drug ; 7 TB is transmitted, by, droplets / coughing / sneezing ; A in the air 8 no vector / no mosquito / no requirement for hot or humid conditions ; 9 ref. to, HIV infection / lower immunity / immunocompromised ; [4 max]

(d) 1 active immunity ;

2 vaccine contains, antigen(s) / pathogen / microorganism / named type ; 3 (primary) immune response ; 4 B lymphocytes / B cells / plasma cells, synthesise / produce / secrete / release,

antibodies ; 5 ref. to T helper cells (enhancing humoral response) ; 6 clonal selection / described ; 7 specific, (T / B) lymphocytes / antibodies ; A ‘particular’ / AW 8 memory cells, remain (in circulation) / give long-term immunity / give immunological

memory / AW ; 9 fast(er) second(ary) response ; 10 ref. to boosters / AW ; 11 immunised person cannot spread disease to others ; 12 herd immunity / unimmunised people are safe(r) ; 13 surveillance of population for signs of disease / when there is an outbreak ; 14 ref. to ring immunity / AW ; [5 max]

[Total: 12]

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5 (a) interphase / S phase / synthesis phase ; R G1/G2 unqualified by interphase [1] (b) (i) hydrogen ; [1] (ii) M = adenine and O = cytosine ; [1] (c) each strand, of DNA acts as a template (for the synthesis of a complementary strand) ;

A described in terms of base pairing new DNA (molecule) has one, old / parental / original, strand and one, new / daughter

strand ; R ‘half old and half new’ unless clearly referring to two strands [2]

(d) accept ora

(errors are) mutations / named type of mutation ; ora if corrected there are no mutations (may lead to) production of altered proteins, so, impaired / loss, of function ; A altered amino acid in, protein / primary structure (may lead to) different antigens, so cells are rejected (by immune system) ; idea that cells cannot function together / impaired coordination ; ref. to cancerous cells / cancer(s) / tumours / sickle cell anaemia or other named monogenic

condition ; further detail ; e.g. uncontrolled, division / mitosis / cell replication / cell growth e.g. lack of contact inhibition / no apoptosis or described / (proto)oncogene(s) [2 max]

[Total: 7] 6 (a) H nitrogen fixation ; J nitrification / oxidation ; K denitrification / reduction ; [3] (b) provide source of, fixed nitrogen / usable nitrogen / organic nitrogen / amino acids / ammonia

/ ammonium ions / AW ; R nitrate ref. to protein production in legume ; legume can, colonise / grow in, nitrogen / nitrate, deficient or poor soils ; A not dependent on nitrate in soil compete successfully with non-leguminous plants ; [2 max]

[Total: 5]

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9700 BIOLOGY





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1 (a) plant cell because presence of cell wall ; A cellulose cell wall R incorrect cell wall materials plasmodesma ; A plasmodesmata tonoplast ; A vacuolar membrane large/central, vacuole ; ignore permanent [2 max] (b)

name of organelle

diagram of organelle(s) as seen under the electron microscope (not to scale)

one function of organelle cell type(s) in which organelle is located

all 3 for one mark oval/circular shape and two membranes close together and inner membrane infolded as two or more cristae ;

aerobic respiration/ATP, production/synthesis ; A oxidative phosphorylation A ref. β oxidation fats A ref. urea/ornithine cycle R any answer that refers to synthesis/production, of energy

centrioles ; A centriole A centrosome

animal ;

both for one mark two membranes and ribosomes on external surface ; R if ribosomes are excessively large

animal and plant/both ;

processing/modification/AW/ packaging, of, proteins/ molecules ; A description of modification e.g. glycosylation A production of, secretory/ Golgi, vesicles A production of lysosomes R protein synthesis

chloroplast ;

[8] [Total: 10]

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2 (a) (i) right, atrium/auricle and left ventricle ; correctly labelled left hand side box right hand side box [1] (ii) right atrium has (ora for left atrium) lower, concentration/partial pressure/AW, of, oxygen ; R no oxygen A (right) deoxygenated blood (versus oxygenated blood) A higher saturation of haemoglobin with oxygen

higher concentration/AW of, hydrogen carbonate ions/carbon dioxide ; A more carbaminohaemoglobin higher concentration of water molecules/high(er) water potential/less negative water

potential ; higher concentration/AW, of glucose ; [2 max] (b) reject if more than one letter for each disease pulmonary stenosis = G ; coarctation of the aorta = D ; ventricular septal defect = F ; [3] (c) accept ora where relevant suggest 1 blood flows from aorta to pulmonary artery ; 2 increased volume of / more, blood to lungs ; A blood to lungs at higher pressure 3 oxygenated and deoxygenated mix ; 4 oxygenated blood / blood from aorta, to lungs ; explain (why blood flows from aorta to pulmonary artery) 5 left ventricle thicker wall (than right ventricle) ; 6 (so) contraction generates greater force (than right ventricle)/AW ; 7 higher pressure in aorta (than pulmonary artery) ; [3 max] [Total: 9] 3 (a) 53 % ;; 2 marks for correct answer max 1 mark for correct calculation but, no/incorrect, answer or not to nearest whole number 72.4 – 33.9 = 38.5 (38.5 / 72.4) x 100 = 53.18 / 53.2 [2]

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(b) R greater wealth unless linked to points below any two valid reasons e.g. accept answers written as ora 1 more educated population ; in context of health 2 better/greater access to, health care/AW ; 3 higher level of preventive medicine ; e.g. immunisation programmes 4 better diet ; A ref. to less malnourished A ref. to access to food supplies 5 greater access to, therapeutic medicines/drugs ; A antibiotics 6 better/less overcrowded, housing/living conditions ; 7 better, sanitation/sewage treatment ; 8 greater access to uncontaminated drinking water ; R clean water unqualified 9 fewer, fatal diseases/AW ; 10 ref. to effects of, civil war/war ; 11 ref. to natural disaster ; [2 max] (c) (i) rank of % positive (of countries) is different to rank of difference in decrease in life

expectancy ; data quote to support ; e.g. Kenya 6th highest % positive but 3rd highest decrease in life

expectancy S. Africa 4th highest % positive but 6th highest decrease in life expectancy countries with, similar/same, decrease (in life expectancy) have different % positive ; data quote to support ; e.g. Malawi 17.8 years decrease, 16%, cf South Africa 17.5 years, 19.9% Kenya 20.1 years, 14%, cf Zambia 20.1 years, 20% ; with ref. to decrease in life expectancy and % positive Kenya, does not fit general trend/AW ; South Africa, does not fit general trend/AW ; data quote to support ; e.g. Kenya larger decrease than, Malawi/South Africa, but lower % positive Kenya 20.1 years decrease but only 14.0 %, compared to, Malawi 17.8 with 16.0%/

South Africa 17.5 with 19.9 % ; [2 max] (ii) any two relevant factors e.g. 1 anti HIV drug therapy/AW ; 2 ref. to treatment of AIDS-related diseases ; 3 ref. to education to prevent, transmission/spread ; 4 use/provide free, condoms/femidoms ; A dental dams 5 avoid promiscuity ; A one sexual partner 6 HIV mothers avoid breast feeding ; 7 heat treat/screen, blood (for transfusion) ; 8 needle-exchange schemes/AW ; A ref. to sterile syringes 9 use of sterile equipment, qualified e.g. in surgery/tattooing/piercing ; 10 testing for HIV status/contact tracing ; 11 ref. to vaccine development ; [2 max]

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(d) 1 primary/immune, response ; 2 ref. specificity; in correct context 3 (HIV/virus) antigens ; 4 antigen presentation/antigen presenting cell/APC/described ; 5 clonal selection/described ; e.g. recognition of/binding to, antigen by, B-lymphocyte 6 sensitisation/activation/described ; e.g. cell growth or cellular changes 7 clonal proliferation/formation of clone/mitosis/cell division/AW ; 8 B-lymphocytes/B-cells/plasma cells, synthesise/produce/secrete/release, antibody ; 9 T(helper)-lymphocyte response described ; e.g. cytokine production ignore ref. to T killer cells [5 max]

[Total: 13]

4 (a) (i) (describes the) sequence of amino acids (in a polypeptide chain) ; A order/arrangement [1]

(ii) H2O/water, released ; (correct) bond formation between (lysine) carboxyl group and (valine) amino group ; dipeptide (of lysine and valine) and formed with correct structural formula ; [3]

(b) (i) secondary 1 regular order/pattern, based on H-bonds ; 2 between CO– group of one amino acid and NH– group of another ; 3 alpha-helix and β-pleated sheet ;

tertiary to max 4 1 folding coiling ; 2 interactions between, R groups side chains ; 3 two correctly named bonds ; e.g. hydrogen bonds, disulfide, bonds/bridges, ionic

bonds, hydrophobic interactions 4 further description of bonds ; e.g. disulfide between cysteine (S–H) groups hydrogen between polar groups (NH– and CO–) ionic between ionised amine and carboxylic acid groups hydrophobic interactions between non-polar side chains 5 ref. active site, specific/precise, shape ; 6 ref. globular/AW, shape ; A spherical/ball 7 ref. amino acids with, hydrophilic/polar, R groups facing to outside ; ora [5 max]

(ii) enables (protein to) function/AW ; A enables antimicrobial action/AW A biological catalyst, qualified provides active site ; qualified ref. to specificity ; [1 max]

(c) altered, (mRNA) codon(s)/triplet(s) ; A named type of mutation changed/AW, amino acid(s) ; ref. to effects of stop codon ; e.g. shortened polypeptide chain different, primary structure/described ; A ref. to differences in, transcription/translation ref. to different properties of, R group/side chain (of normal v replaced amino acid) ; altered tertiary structure/AW ; A different R group interactions A change/loss of, active site idea of globular to fibrous change/hydrophilic R groups no longer to outside ; [3 max]

[Total: 13]

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5 (a) one mark for each correct row ; ; ; ;

cartilage ciliated

epithelium elastic fibres goblet cells smooth muscle

A � � �

B � �

� �

C � � �

D

� � �

[4] (b) goblet cells to max 3 synthesise/produce/secrete/release, mucus ; mucus, sticky/AW ; (mucus) traps/AW, pathogens/AW , dust/particles/AW, pollen ; A named organism types/microorganisms R cilia traps increased secretion when, inflamed / infection ; qualified ref. to role of mucus ; e.g. increases distance (e.g. of pathogen) to reach (epithelial) cells acts as barrier/prevents, entry/attachment to, cells prevent, infections/pathogens reaching alveoli allow once only in either section cilia to max 3 waft/move/AW, mucus ; synchronous/metachronal, rhythm ; AW movement towards back of throat for, swallowing/coughing out ; qualified ref. to role of cilia in health ; e.g. ref. to, normal air flow/ventilation/keeping airways

clear [4 max] [Total: 8]

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6 (a) Galalapagos hawk land iguana marine iguana xerophyte kelp animals in correct boxes ; all five animals to hawk ; all animals except hawk to snake ;

(only) short-horned grasshopper to lava lizard xerophyte to short-horned grasshopper and land iguana ; kelp to marine iguana max 3 if all correct but one arrow head missing max 2 if arrow heads, mixed in incorrect direction/missing [4] (b) kelp and xerophytes ; allow ecf for next two mps if only one organism both, photosynthetic/autotrophic/fix carbon/AW ; A both have chlorophyll both are, at the start of the food web/at the first trophic level/the source of energy to rest of

food web/AW ; [3] [Total: 7]

Galapagos snake

lava lizard

short-horned grasshopper

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9700 BIOLOGY





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1 (a) A nucleus ; A (eu)chromatin R nucleolus B mitochondrion ; A mitochondria C (rough) endoplasmic reticulum ; A (R)ER R smooth/S [3] (b) (i) protein/polypeptide, synthesis/AW ; A protein, transport/modification A ecf if C is identified as Golgi or SERor ribosomes in 1 (a) [1] (ii) ignore refs to magnification resolution/resolving power, low(er) ; ora 200 nm compared to 0.5 nm ; A resolution quoted in range 100-300 to 0.2-1.0 nm ref. to visibility of structure C ; e.gs. wavelength of light longer than size of, ribosomes/membrane ribosomes/membrane, cannot be seen as less than 200nm diameter ribosomes only 20–30 nm diameter A 15–20 nm membranes 7–10 nm thick small size linked to explanation of resolution [2 max] (c) any one relevant disadvantage e.g. only dead specimens can be viewed ; mounted in vacuum/pre-treatment, may distort delicate structures ; A artefacts expensive, qualified ; e.g. to buy, maintain, increased cost electricity, costs associated with,

time/training requires, more electrical power ; requires stable, high voltage supplies/currents ; sensitive to external magnetic fields ; difficult to operate/requires technical training ; samples more difficult to prepare ; A examples e.g. thin sections lengthy preparation time ; monochrome/black and white only ; not portable/can only be used in specific locations (e.g. with voltage supplies) ; [1 max] (d) allow +/- 1 mm in reading the line award two marks if correct answer is given 20 000/6 µm = (3333.3) A 19 000/6 = (3 166.7) A 21 000/6 = (3 500.0) 3 333 (x);; A 3 167 (x) A 3 500n(x) award one mark if answer is given to one or more decimal places or award one mark if correctly measured and divided by 6 µm but incorrectly converted [2 max] [Total: 9]

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2 (a) semilunar valve ; A pulmonary valve prevents backflow (of blood) ; from the pulmonary artery/into the right ventricle ; or ensures one-way flow of blood ; from the right ventricle/into the pulmonary artery ; [3] (b) (Y/wall of left ventricle) contains more (cardiac) muscle ; ora left ventricle/ventricle beside Y, pumps blood to, whole body / further ; ora at higher pressure with more force (than right) ; ora resistance to blood flow is greater in systemic circulation ; ora [3 max] (c) any two of SAN, AVN, Purkyne tissue/Bundle of His in correct context ; SAN/(primary) pacemaker, sends out, waves of excitation/impulses ; A electrical (im)pulses R once only nervous impulse(s)/pulse(s)/signal(s) R if brain stimulates SAN to send out impulses spreads across atria ; atria contract/atrial systole ; fibrous ring/non-conducting tissue/insulating tissue ; prevents, it reaching the ventricles/ventricles contracting at the same time (as atria); atrio-ventricular node/AVN, acts as ‘relay station’/sends wave of excitation to ventricles; A in correct context – impulse reaches AVN and is passed on (therefore) time delay to allow, atria to empty/atria to complete contraction/ventricles to fill//

atria and ventricles do not contract at the same time ; time ref. 0.1 – 0.2 seconds ;

Purkyne tissue bundle of His, conducts, excitation/impulses, to base of, septum/ventricles ; A apex of heart spreads upwards in ventricle (walls) ; (so) ventricles contract from base upwards/ventricles force blood up from base ; [5 max] [Total: 11]

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3 (a) (i) primary ; A first quarternary ; A fourth [2] (ii) disulfide (bonds/bridges) ; [1] (b) peptide bond broken ; correct involvement of water ; free –COOH/–COO and free –NH2/–NH3

+ shown ; [3] [Total: 6] 4 (a) any one correct description (1 mark) with explanation (1 mark) e.g. any named biological control method e.g B. thuringiensis ; kills mosquito larvae ; use of insecticides ; kills (adult) mosquitoes ; elimination of standing water ; removes, mosquito breeding sites/egg-laying areas ; use of oil on water ; prevents maturation of/kills, mosquito larvae ; [2 max] (b) (malarial) parasite/pathogen/Plasmodium, has many antigens ; eukaryotic/many genes ; many different stages of life cycle ; ref. to more than one Plasmodium species/strain of each species ; mutation changes antigens (over time)/antigenic shift/antigenic drift ; parasite only vulnerable, at certain stages of life cycle/when free in plasma ; antigenic concealment/described ; AVP ; e.g. changes antigens which are expressed (through gene switching) [3 max]

(c) percentage of, parasites killed/growth inhibition, increases with drug concentration for both parasites ;

effect is greater on chloroquine-resistant parasites/AW ; chloroquine-sensitive parasites not affected until 1 µmol dm 3 ; further use of data from Fig. 4.1 to illustrate ; further detail of difference in trend(s) ; A descriptive or figures [3 max]

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(d) (i) (percentage) increase in malaria is high(er) in, countries in the, south/south and east ; ora A named countries R more malaria

ref. (percentage) increase correlates with countries where HIV incidence is higher ;

penalise once if no ref to increase data quote ; [2 max] (ii) HIV, infects/AW, T (helper)–lymphocytes/T-cells ; qualified ref. to immune system ; (HIV and) malaria may be contracted via blood transfusion ; ref. to reduced number of workers so malaria prevention not carried out ; [2 max] [Total: 12] 5 (a) conversion of/AW, nitrogen (gas)/N2 ; in context of atmospheric nitrogen (to) ammonium (ions/compounds)/NH4

+/amino acids ; further detail ; e.g. nitrogenase (enzyme)/ref. conversion from unreactive (nitrogen) to

reactive (compound)/reduction of nitrogen/ATP required/anaerobic conditions required for enzyme function [3]

(b) (i) ammonification/putrefaction/decomposition/decay ; [1] (ii) supplies, ammonia/ammonium ions, for, nitrifying bacteria/nitrification ;

ammonia/ammonium ions, converted/oxidised/AW ; to nitrite ; to nitrate ; Nitrosomonas/Nitrobacter ; in correct context ref. nitrate useable form for plants ; [2 max] (c) (i) to check that urea is not hydrolysed/broken down, without enzyme ; ora A there is no reaction without enzyme [1] (ii) hydrolysis reduces, substrate/urea, concentration ; urea, hydrolysed/broken down, more quickly in Tube A than in Tube B; A ref. to differences in reaction rates Tube A enzyme can bind with substrate normally/ES complexes forming (at fast rate) ;

ora Tube B shape of active site complementary to (shape of) substrate/AW ; Tube B (competitive) inhibitor, occupying/binding at/AW, active site ; ref. substrate unable to enter active site/AW ; correct data quote from either column to illustrate ; [4 max] [Total: 11]

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6 (a) 1 mark each correct row

lined with cilia

reinforced with cartilage

site of gas exchange

contains smooth muscle

trachea � � � ;

bronchus � � � � ;

bronchiole � � � ;

alveoli � � � � ;

[4] (b) good/circulating, blood supply ; good ventilation/breathing movements ; [2] (c) (i) stretch/expand/lengthen, on inspiration and, recoil/shorten, on expiration ; A alternatives for inspiration and expiration R contract and relax (stretch) to increase, surface area/volume of air, for, diffusion/gas exchange ; (recoil) to help, expel air/force air out ; ignore contract prevent alveoli, bursting/breaking/AW ; R collapsing [1 max] (ii) emphysema ; [1] (d) (cause) mutations ; uncontrollable, division/mitosis/cell replication/cell growth ; lack of contact inhibition/no apoptosis or described/(proto)oncogenes ; goblet cells secrete, excess/more/AW, mucus ; destroys/weakens/paralyses/AW, cilia ; development of scar tissue ; inflammation ; increased chance of infection/AW ; [3 max] [Total: 11]

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9700 BIOLOGY

9700/31 Paper 31 (Advanced Practical Skills 1), maximum raw mark 40




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Question Expected Answers Additional Guidance Marks

1 (a) (i) Decide how often you will take samples. You should not sample for longer than 20 minutes.

4 or more numbers; Ignore units.

[1] MMO decisions 2

even range of times;

Range: longest time must be 10 or more minutes

[1]

(ii) Prepare the space below to record: time you remove sample, time at which end-point is reached and time taken to reach the end-point.

1 table with all cells drawn no outer boundary

needed.

(heading top or left) AND sampling or sample time or time removed;

[1] PDO recording 2

2 (heading for one other column or row) time with units;

Reject units in body of table

[1]

3 (ignore headings on results columns) sample time plus result column = other result column;

Must be clear units Reject 1.24

[1] MMO collection 2

4 (trend correct) figure for last sample less than figure for first sample;

[1]

MMO decision 1

5 (end-point result column) whole seconds or whole minutes for at least three results;

[1]

(b) (i) Describe a suitable control for this investigation.

ACE interpretation 1

1 boil and cooled enzyme OR 2 no enzyme and replace with water;

[1]

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(c) (i) Identify two significant sources of error in this investigation

1 timing with reason why causes an error e.g. removal of samples AND adding to potassium permanganate OR timing end-point OR two lots of timing;

2 judging or detecting end-point or colour change;

[max 2] ACE interpretation 2

3 idea of volume of reaction mixture or AW decreasing with each sample;

Reject temperature Reject pH Reject evaporation

(ii) State one variable which was not controlled in this investigation and how it could be controlled.

ACE improvement 1

temperature AND use thermostatically-controlled water-bath or water-bath at constant temperature;

Reject if more than one variable [max 1]

pH AND use buffer;

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(d) (i) Plot a graph to show the results in Table 1.1.

O x-axis time (/) s or sec(ond)s

y-axis AND mass of (reducing) sugars (/) mg;

Must have units [1]

S scale as 100 s to 2 cm ECF if no labels for O. Allow at origin 50 as long as scale 100 s to 2 cm

AND 0.5 mg to 2 cm; Allow 0.25 at origin but must label origin.

Reject if awkward scale [1]

P correct plotting using crosses/dots in circle only;

Intersection of cross must be clear to show plot.

Reject plotting if scale is awkward Reject if only blobs/dots/blobs in circles

[1]

PDO layout 4

60 0.32

120 0.64

180 0.95

300 1.55

400 2.05

L straight line through points;

Quality – not thick, not feathery for the complete line. Joining plots –

• Ruled lines plot to plot

• Straight line through most plots

• Straight line extrapolated to 0 Extrapolation

• Not beyond x- or y-axis

Reject if not five plots

[1]

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(ii) Use the graph to find the rate of hydrolysis of the sucrose by finding the gradient of the line. Show on your graph where you took your readings.

MMO collection 1

shows on graph at least one time and mass; [1]

MMO decision 1

two masses and two times; [1]

shows mass up 2.05 mg

AND divided by time up to 400 s;

[1] PDO display 2

any answer rounded to maximum of three significant figures OR five decimal places OR standard form;

[1]

(iii) Explain why the mass of reducing sugars increased and then remained the same.

enzyme; Reject use of enzyme in incorrect biological context

[1] ACE conclusion 2

(context of increase or up to 400 s) idea that non-reducing sugar or sucrose being converted (context of remaining the same or after 400 s) AND idea that all substrate hydrolysed or broken down or used up;

Reject enzyme active sites full or enzyme used up

[1]

[Total: 21]

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2 TS oesophagus (a) (i) Draw a large plan diagram of a quarter of the tube as shown in Fig. 2.1

PDO layout 1

1 clear, sharp, unbroken lines

AND no shading

AND Allow only for 3 or more lines;

Reject if overlaps text of question [1]

MMO collection 1

2 no cells AND Drawn detail for only correct quarter; Minimum of one layer needed.

Reject if drawn incorrect quarter [1]

3 innermost layer is thinner (+ or – 1 mm) than outermost thick layer; [1] MMO decision 2

4 first two lines folded; [1]

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(b) (i) Calculate the actual length, shown by line X, of one of the structures.

measures line X correctly in mm or cm; Reject m

mm cm

54.(0) 5.4

54.5 5.45

55.(0) 5.5

55.5 5.55

56.(0) 5.6

56.5 5.65

57.(0) 5.7


shows their measurement divided by or / or ÷ 50 AND × 1000 or 103 (mm) or 10000 or 104 (cm) or × 10 × 1000;

Reject use or conversion to metres Reject if no units

[1]

(ii) Explain how you would find the mean length of the structures shown in Fig. 2.2

ACE improvements 2

measure all OR any number five or more;

Reject calculate [1]

add together and divide by the number measured; [1]

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(iii) Prepare the space below so that it is suitable for you to compare and contrast the cells in J1 and Fig. 2.2.

(organise) table/ venn diagram/ ruled connected boxes

(heading for differences) any appropriate heading e.g J1 and Fig. 2.2

all differences statements opposite each other;

J1 Fig. 2.2

[1] PDO recording 2

heading , similarities; [1]

feature: J1: Fig. 2.2:

D1. folds no. OR packing or gaps or spaces OR surface area (to volume ratio)

fewer loosely packed/widely spaced or large gaps small(er)

more densely packed/closely packed or small gaps larg(er);

D2. fold shape Ignore length or height

wider or thicker/flat at top or round(ed)

thinner or pointed end;

D3. number of layers more or larg(er) few(er);

D4. group of folds different shapes similar shapes;

D5. lumen/ hollow/ space

present absent;

Similarities/compare clear as ‘both are’

S1. lumen/hollow/ space

present;

S2. folds present;


S3. layers present or many/multi-;

Must have at least 1 similarity Allow D5 or S1 not both Ticks and crosses require a key

[max 3]

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(iv) Suggest how the structures in Fig. 2.2 are adapted for absorption.

ACE conclusion

large surface area or microvilli or brush border or good or extensive blood supply or capillary network or lacteals or lymph vessels or selectively permeable;

[1]

(c) Make a large, labelled drawing of the complete cells shown in the sector on Fig. 2.3.

PDO layout 1

1 clear, sharp, unbroken lines

AND no shading

AND large;

Reject if overlaps text of question

[1]

2 cells drawn as a group AND narrower at base than top; [1] MMO collection 2

3 nucleus to right hand side goblet cell

touching the membrane

AND nucleus tapers;

[1]

4 triangular shape (goblet cell); [1] MMO decision 2

5 Reject if any label is biologically incorrect e.g. cell wall one correct label with label line from nucleus nuclear membrane nucleolus cytoplasm cell membrane microvilli brush border goblet cell columnar epithelium cilia;

Reject if any writing on drawing Reject if drawn organelles other than nucleus or nucleolus

[1]

[Total: 19]

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9700 BIOLOGY





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1 (a) (i) Calculate the surface area of each bead and the mean surface area of beads.

MMO decision 1

1. 5 or more (bead radii/diameters); [1]

MMO collection 1

2. measures diameter or records radius

AND units mm; Reject any measurements not whole number of mm Reject 6 mm or more for diameter or 3 mm or more for radius

[1]


3. one correct calculation for one bead surface area; [1]

4. shows addition of bead measurements divided by number measured

or each surface area added together and divided by number;

[1] PDO display 2

5. answer no more than 3 sig. figs.; [1]

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(ii) Prepare the space below to record your observations.

1. table with all cells drawn (heading top/left) AND surface area (/)mm2 or no. of beads;

Reject if units in body of table [1] PDO recording 2

(heading) 2. colour/observation;

[1]

3. only records at 2, 4 and 6 (minutes); [1] MMO collection 2

(highest no. of beads) 4. yellow/green;

[1]

5. surface area recorded; [1]

6. use 20 beads in one tube and at least 3 different numbers of beads;

[1]

MMO decisions 3

7. even range; [1]

(iii) The student realised that there were two independent variables in this procedure. State the two independent variables.


surface area or number of beads

AND enzyme or yeast concentration/quantity;

Reject more than two variables [1]

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(iv) Suggest how you would make three improvements to the student’s procedure.

idea of cubes with equal volume of yeast; Reject amount [1]

idea of equal shaking;

repeat measurements AND mean or average;

colorimeter/white card or pH paper or meter;

separate beads using Petri dish/larger container;

use thermostatically-controlled water-bath;

ACE improvements 3

idea keep time the same e.g. stagger start or have separate experiments;

[max 2]

use more beads or more surface areas;

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(b) Describe and explain the results shown in Table 1.2.

1. (in context of data) stops increasing or levels off or stops or stays constant or no more carbon dioxide or reaction stops;

[1]

(in any correct context use of) 2. enzyme or catalase or active sites or ESCs;

ACE conclusions 3

3. glucose or substrate fits into active sites or forms ESCs or (slowing or stops) lack of glucose or substrate or glucose not high enough or build up of product or ethanol lack of oxygen build up of carbon dioxide change in pH carbon dioxide dissolves into glucose or substrate or

solution or water;

[max 2]

Total [19]

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2 (a) (i) Draw a large plan diagram of a half of the specimen as shown in Fig. 2.1. Label xylem and the cortex.

PDO layout 1

clear, sharp, (not thicker than grid line for whole line) unbroken lines

AND no shading AND large 5 cm or more from centre of stele to epidermis;

[1]

no cells AND drawn only half with detail (shown by epidermis line);

Reject if overlaps the text of question


endodermis shown by two lines

AND length between epidermis and endodermis is at least twice the diameter of stele;

[1]

draws region of xylem central; [1] MMO decision 2

Reject if any label is biologically incorrect. one correct label with label line from xylem or cortex;

Reject if any writing on drawing [1]

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(ii) Make a high-power drawing of a group of three complete touching xylem vessels and a group of three complete touching cortex cells. Reject all marks if only two cells drawn except label mark?

PDO layout 1

1. clear, sharp, (not thicker

than grid line for whole line)

unbroken lines

AND no shading AND smallest group of complete touching cells will not fit inside 6 × 6 cm grid;

[1]

only 6 complete cells drawn AND two groups of 3 touching cells;


cell wall in at least one cell drawn angular in one group of three

AND other group of cells rounded;

[1]

(xylem) thicker cell wall than (cortex) cell walls; Measure thickest on both.

Allow only if cell walls drawn as double lines for both groups of cells

[1] MMO decision 2

correct labels with label lines to lumen in xylem AND any cell wall;


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(b) (i) Calculate the magnification of the specimen shown in Fig. 2.2. Actual length of line X = 1900 µm.

MMO collection 1

measures line X correctly with mm or cm; [1]

show in last calculation before answer 52 or 52.5 or 53 or 53.5 or 54 with 1.9 OR 5.2 or 5.25 or 5.3 or 5.35 or 5.4 with 0.19 OR 52000 or 52500 or 53000 or 53500 or 54000 with 1900;

[1] ACE interpretation 2

correct calculation of any figure divided by 1900 or 1.9 or 0.19;

[1]

(ii) Prepare the space below so that it is suitable for you to record the observable differences between the specimens on slide M1 and in Fig. 2.2.

organise as a table/venn diagram/ruled connected boxes

AND headed M1 and Fig 2.2

AND all comparative statements opposite each other;

[1] PDO recording 2

only differences recorded; [1]

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feature M1 Fig. 2.2

1. xylem shape star-shape;

2. xylem position centre;

3. phloem clearer or can see or present

not clear or cannot see or absent;

4. pith absent present;

5. thickened cells under epidermis

absent thick ring/present;

6. epidermis layers

one or thin(ner) two or thick(er);


7. size cortex stele/xylem

larger/wider/thicker or more smaller/narrower/ thinner or less

smaller/narrower/ thinner or less larger/wider/thicker or more;

Reject all ticks with crosses unless have key

[max 2]

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(c) Plot a graph of the data shown in Table 2.1.

O x-axis time /hr(s) or hour(s)

y-axis AND vol(ume) /cm3 hr 1;

[1]

S scale as 1hr to 2 cm (allow no 0) Allow 1 at origin as long as 1hr to 2 cm must label origin.

AND 0.5 cm3 to 2 cm; Allow 0. 5 at origin must label origin if not 0

[1]

P correct plotting with crosses or dot in circle;

Intersection of cross must be clear to show plot

[1]

PDO layout 4

L straight line between all points or smooth curve through all points;

Quality – no thicker than on grid, not feathery for the complete line Joining plots


• Curve through all plots Extrapolation


• If in context of data correct to go to 0,0 must be within 2 mm of 0

If not correct in context of data then no extrapolation at either end of data

Must have units

Reject S if awkward scale

Reject P plotting if awkward scale Reject if only blobs or dots or blobs in circles Reject if not five plots [1]

Total [21]

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9700 BIOLOGY





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1 (a) Draw on Fig. 1.1 a line to show the level of water in the large test-tube.

MMO decision 1

line drawn above or at the same level as the line showing the contents in the Visking tubing;

[1]

(b) State the volume of Benedict’s solution and the volume of the solutions and the sample.

MMO decision 1

(volume of Benedict’s) equal to or greater than (volume of each solution and sample)

AND (volume of each solution and sample) equal;

Reject any other values e.g. 2.5 cm3 [1]

(c) State ONE variable, other than volume, which needs to be kept constant when you do the TESTS and describe how you will keep this variable constant.

temperature; Reject if in context of Visking tubing set up or experiment e.g. keep at room temperature Reject if more than one variable given

[1] MMO decisions 2

use of water-bath AND between 80oC and 100oC or boiling;

[1]

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(d) (i) Prepare the space below and record your results.

1. table with all cells drawn No outer boundary needed

(heading to left/ top) AND a heading to describe (sample, or solution or test-tube or glucose);

[1] PDO recording 2

2. (heading) time (/) s or sec(onds) or min(utes);

Reject if units in table [1]

MMO collection 2

3. time for 0.3%/S3 quicker than 0.2%/S2;

Must be clear units Reject 1.24

[1]

4. figures for 0.2%/S2 quicker than 0.1%/S1;

[1]

(ii) Estimate the concentration of glucose in the sample.


correct estimate from their results Reject if sample not recorded in results

AND percentage/%; • is 0.1% or 0.2% or 0.3%

• between 0.1% and 0.2%

• 0.15%

• between 0.2% and 0.3%

• 0.25%

• greater/more than 0.3%

• less than 0.1% Reject any other values Ignore use of S1,S2, S3

[1]

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(iii) Suggest how you might modify this investigation to find the effect of temperature on the rate of diffusion of glucose through Visking tubing.

ACE improvements 2

states 5 or more temperatures OR gives examples of 5 or more 1oC to 100oC;

[1]

(in context of readings) repeats or more than once or replicates AND mean or average OR take samples at same time interval or example of time with units OR same volumes or example of volume with units of samples removed OR rate calculated from time taken to change colour OR same concentration or volume of glucose or example of concentration or volume + units;

Reject if change another variable e.g. concentration of glucose Reject amount

[1]

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(e) (i) Plot a graph to show the results in Table 1.1.

O x-axis time (/) min(ute)s

y-axis AND distance (diffused from well by coloured solution /) mm;

[1]

S scale as 20 min to 2 cm ECF if no labels on axes for O Allow 5/10 at origin but must label origin

AND 5 mm to 2 cm; Allow 5/10 as long as scale 5 mm to 2 cm but must label origin


P correct plotting using crosses or dots in circle only;


Reject plotting if scale is awkward Reject if only blobs/dots/blobs in circles

[1]

PDO layout 4

0 0

15 14

30 22

45 26

60 28

75 29

L line joined point to point or smooth curve;

Quality – no thicker than on grid, not feathery for the complete line Joining plots –




Reject if no 0,0 plot [1]

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(ii) Use the graph to calculate the rate of diffusion of the solution between 10 mins and 20 mins. Show on your graph.

MMO collection 1

1. shows on graph at least one reading(s) between or at 10 and 20 minutes;

[1]

PDO display 1

2. shows distance divided by time (has to be clear) any number between 4 and 20 divided by or / or ÷ whole number (between 4 and 20) or shows subtraction of numbers;

Reject if not clear distance divided by time [1]


3. correct answer AND mm min 1

or mm per min or mm/min;

[1]

PDO display 1

4. any figure rounded to maximum of four significant figures;

[1]

(iii) Describe and explain the trend in the rate of diffusion shown in the graph you have drawn in (e) (i).

(description) rate or distance decreases or slows or levels off;


(in correct context of diffusion ref. to) Idea of concentration or diffusion gradient, getting less OR Idea of (high at beginning) concentration or diffusion gradient high OR Idea of (at end) evenly coloured;

[1]

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(f) State the uncertainty of the measurements using this ruler.


+/- 0.5 mm OR +/- 0.05 cm;

[1]

Total [22]

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2 (a) (i) Make a large, labelled drawings of two different types of cell from Fig. 2.1 and one cell from Fig. 2.2. Indicate on the photomicrographs the cells that you have drawn.

1. (only cells marked on Figs. and drawn) MMO collection 1

on Fig. 2.1 white blood cell

AND any one complete red blood cell

on Fig. 2.2 AND any one complete red blood cell;

Reject if shown more cells Reject if drawing overlaps text of question

[1]

PDO layout 1

2. clear, sharp, (not thicker

than grid line for whole line)

unbroken lines Allow 1 error in

three cells 0 error for two

or one cell

AND no shading

AND smallest cell drawn larger than 2 cm (+/- 1mm) at widest point;

Must draw at least TWO cells [1]

3. (wbc from Fig. 2.1) (nucleus position) nearer to one side

(nucleus size) AND (+ or – 1 mm) nucleus fills between 50 and 75 % of whole cell;

Reject if any additional organelles drawn in any cell

[1] MMO decision 2

4. Reject if any label is biologically incorrect e.g. cell wall any ref. to plants e.g. cell wall or named plant cell or named animal cell other than blood cells.

Ignore nucleolus and named blood cells One correct label with label line from nucleus nucleoplasm cytoplasm cell

membrane/AW;


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(ii) Prepare the space below so that it is suitable for you to compare and contrast the cells in Fig. 2.1 and Fig. 2.2.

(organise) table/ venn diagram/ ruled connected boxes

(heading for differences) Fig. 2.1 and Fig. 2.2, labelled cells from (a) (i), named cells linked to figs.

all differences statements opposite each other;

Fig 2.1 Fig. 2.2 [1] PDO recording 2

heading similarities; [1]


Mark with identification from (i) drawings even if incorrectly named cells Mark for any similarities or differences max 3 Must be clear which cells are being compared or contrasted Ticks and crosses requires a key (continued on next page)

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feature Fig. 2.1 Fig. 2.2

Only credit each number once.

rbc or label from (i) wbc or label from (i) rbc or label

(rbc) small(er) (wbc) larg(er) 1. size cells;

small(er) larg(er)

rbc or label and wbc or label and only rbc/label

wbc present no wbc

2. types of cells;

two one

many or more cells/rbcs few(er) cells/rbcs

many or more rbcs one or a Reject few/small no.

3. number OR degree of packing;

dens(er)/more overlapping rbcs less dense;

absent Allow cannot be seen

present

absent Allow cannot be seen

present

(no key) present present

4. nucleus OR nucleus shape;

lobed or irregular not lobed or oval or round or regular or smooth

circular or round irregular

circular or round oval

5. cell shape;

irregular oval Allow few or some roundReject round

not granular granular 6. cytoplasm;

granular not granular or normal

7. cytoplasm OR cell membrane;

(no key) present

Beware Fig 2.1 cells magnified 3+ more than Fig 2.2 so cells in Fig 2.1 smaller Reject nucleus Reject if just cells have nucleus present or absent Reject 3D , rugby or disc or spherical or biconcave or arbitrary or random Reject negatives e.g. not circular Reject opposites e.g. regular

[max 3]

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(iii) Calculate the actual diameter of the cell shown by the line X in Fig. 2.2.

measures line X correctly in mm or cm; Reject m

mm cm

26(.0) 2.6

26.5 2.65

27(.0) 2.7

27.5 2.75

28(.0) 2.8


shows (their measurement divided by or / or ÷ 700) AND × 1000 or 103 (mm) or 10000 or 104 (cm) or × 10 × 1000;


[1]

(iv) Suggest how you would obtain a mean diameter for cells of this type.

ACE improvement 1

idea of make more measurements Reject calculate

AND add together AND divide by the number of measurements;

[1]

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(b) (i) Draw a large plan diagram of two different blood vessels shown in K1. Reject if one line for each vessel.

PDO layout 1

1. clear, sharp,

(unbroken lines)

complete vessels only

AND no shading

AND large;

Reject if overlaps text of question [1]

2. no cells AND only two complete vessels drawn; Minimum of three lines between two vessels


3. different vessels; (more than one) at least two complete vessels

OR total size or shape; Minimum of three lines between two vessels

[1]

4. at least one complete vessel drawn with two or more layers; Minimum three lines

[1] MMO decision 2

5. one with wall thicker than other vessel wall; Reject if more than two vessels [1]

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(ii) Suggest one way in which these blood vessels are adapted for transport.

ACE conclusion 1

lumen/hollow OR smooth muscle OR tunica media OR elastic fibres/elastin OR collagen OR tunica externa;

Reject if more than one given [1]

Total [18]

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9700 BIOLOGY





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1 (a) (i) Prepare the space below to show concentrations of hydrogen peroxide; volumes of hydrogen peroxide; volumes of distilled water.

three or more concentrations; [1]

includes 10 % as highest; [1]

volumes to make up to 10 cm3 or 20 or 30

AND correct; [1]

MMO decisions 4

even range or serial dilution;

[1]

(ii) Prepare the space below to record your results.

table with all cells drawn (heading to left or top) AND concentration;

[1] PDO recording 2

(heading for one other column or row) time with units;

Reject if units in body of table [1]

collects times in whole seconds or whole minutes; [1] MMO collection 2

figures for time faster at highest concentration compared with lowest concentration recorded;

[1]

MMO decision 1

repeats/more than one bead recorded for a concentration or six concentrations;

[1]

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(iii) Identify three significant errors in your investigation. Mark for any correct.

(beads) not all same or damaged;

(test-tube) not vertical (measuring bead to surface);

(conditions for enzyme action) temperature not constant;

(measuring) beads stuck to sides of tube/stuck together with those already dropped/float up under each other;

test-tubes not all the same size;


hydrogen peroxide concentration changes or too high or too low;

[max 3]

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(iv) Suggest how you would make three improvements to this investigation.

(ref. to beads) describes selection of bead or passes through sieve with same size holes or mechanism to release or allow to drip from syringe or use spoon or method to prevent damage;

(ref. to method) (hydrogen peroxide/H) wider range or more concentrations or adjust the concentration or use fresh hydrogen peroxide/H each time or cover hydrogen peroxide or wash and dry beads or use same size of test-tube or use a large test-tube/measuring cylinder;

(ref to conditions) thermostatically-controlled waterbath or describes keeping water bath at constant temp;

(ref. to measuring) put test-tube in retort stand and make vertical or view at correct angle or use video/camera/light gate to record drop or stain beads or mark line at top;

ACE improvements 3

repeats and mean/average;

[max 3]

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(b) (i) Plot a graph of the data shown in Table 1.1.

O x-axis time/min

y-axis AND vol(ume/) cm3;

Must have units [1]

S scale as 1 min to 2 cm

0.5 cm3 to 2 cm; Reject S if awkward scale [1]

P correct plotting with crosses or dot in circle;


Reject P plotting if awkward scale Reject if only blobs or dots or blobs in circles

[1]

PDO layout 4

L ruled/straight line to all points or smooth curve;

Quality – no thicker than on grid, not feathery for the complete line Joining plots –



• Not beyond x- or y-axis If not correct in context of data then no extrapolation at either end of data

[1]

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(ii) Describe and explain the results of the student’s investigation.

in first minute or from 2.9 drops to 0.8 or fastest or largest increase or biggest volume;

[1]

hydrogen peroxide/H or substrate fits into or binds to enzyme or active sites or forms ESCs;

[1]

ACE conclusion 3

lack of hydrogen peroxide/H or substrate or hydrogen peroxide not high enough;

[1]

Total [22]

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2 (a) (i) Draw a large plan diagram of a sector to include three vascular bundles. Draw a circle around one of the vascular bundles on your plan diagram. Label the xylem.

PDO layout 1

clear, sharp, (not thicker than grid line for whole line) unbroken lines

AND no shading AND larger than 6 cm across widest point on sector drawn;

Reject if overlaps the text of question [1]

no cells AND only three vascular bundles

AND circle round one vascular bundle;

[1]

any one vascular bundle divided into at least three regions with at least one curved line

AND middle region of vascular bundle thicker than the epidermis;

[1]

MMO collection 3

one vascular bundle from three drawn or circled wider at outer edge than inner edge (apex);


MMO decision 1

Reject if any label is biologically incorrect. correct label with label line to inner half of vascular bundle xylem;

[1]

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(ii) Draw three complete cells from the epidermis which are touching. Draw three complete touching cells between the inner edge of vascular bundle and centre of the specimen. This drawing should show any difference in size observed between these cells and the ‘two’ epidermal cells.

PDO layout 1

clear, sharp, AND no shading

AND size of bottom group of cells;

[1]

two groups of only three cells drawn

AND each group of 3 cells touching;

[1]

(epidermis) all cell walls must have two lines

AND straight line between any two cells

AND one of these cells, cell wall obviously curved or domed;

[1]

MMO collection 3

(inner cells) all cells rounded

AND at least one cell larger than smallest epidermal cell;

[1]

(b) (i) Calculate the actual length, in µm, of the structure shown by line X.

PDO display 2

shows 27.5 or 28 or 28.5 or 29 or 29.5 or 2.75 or 2.8 or 2.85 or 2.9 or 2.95

AND multiplied by × 1000/103 or multiplied by or × 10000/104

divided by 110; [1]

any answer correctly rounded to no more than three sig. figs.;

[1]

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(ii) Using Fig. 2.1 find the mean actual length of these structures. Prepare the space below and record your results.

5 or more recorded; [1] PDO recording 2

0.0/0.5 mm or 0.00/0.05 cm

OR calculated data to same precision, same number of sig. figs.;

[1]

MMO decision 1

shows addition and division by number of measurements; [1]

(iii) Draw a large plan diagram of the specimen as shown in Fig. 2.1.

PDO layout 1

no cells AND five areas of thickening touching epidermis;

[1]

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(c) Annotate your plan diagram to show three differences between your diagram and the specimen on slide N1.

Any three annotated labels on plan features labelled: under epidermis patches thickening or present;

vascular bundles scattered or not in ring or in centre;

vascular bundle thickening or collenchyma on top and bottom/more;

vascular bundle shape longer/thinner;

pith or centre cells not completely stained cells OR cells relatively much smaller compared to vascular bundle OR no intercellular or air spaces between cells;

air space present or large;


whole shape or outer square or not wavy or has straight sides;

[max 3]

Total [18]

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9700 BIOLOGY





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1 (a) (i) Complete the sentences: If the plant tissue ….. water then the sucrose solution will become more dilute. This will change the solution so that it becomes ……dense.

ACE conclusion 1

loses and less; [1]

(ii) Show clearly on the diagrams below how you would expect to see the drop move.

(same concentration/middle tube) drop stays at same height/no movement;


(more concentrated/left tube) shows drops/sinks/falls

(less concentrated/right tube) AND rises;

[1]

(iii) Decide on the concentrations of sucrose solution. Prepare the space below to show concentrations of sucrose solution; volumes of 1.0 mol dm-3 sucrose solution; volumes of distilled water.

three concentrations; [1]

even range; [1]

MMO decisions 3

correct volumes to make 50 cm3

AND correct molarity; [1]

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(iv) Prepare the space below to record your observations.

table with cells drawn no outer boundary

(heading to top/left) AND conc(entration)/mol dm 3;

[1]

(headings) (syringe) A

AND (syringe) B;

[1]

PDO recording 3

(records) description or key to show movement; [1]

A (0.7 mol dm 3) moves up and down; [1] MMO collection 2

B (0.25 mol dm 3) moves up in molarities more than 3 and down in others;

[1]

MMO decision 1

records more than one drop for each concentration; [1]

(v) Use your results to estimate the sucrose concentration.

(A) correct with their results; [1] ACE interpretation

(B) correct with results; [1]

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(b) (i) Plot a graph of the data shown in Table 1.1.

O x-axis [sucrose] or conc mol dm 3/M/molar

y-axis

AND water potential/Ψ kPa x102;

Must have units [1]

S scale as 0.2 to 2 cm (allow no 0) ECF if no labels or incorrect on axes for O

AND negative 0 at top –10 to 2 cm;


P correct plotting using crosses or dot in circle;


Reject plotting if scale is awkward or if only blobs/dots/blobs in circles

[1]

PDO layout 4

0.15 –5.0

0.35 –12.0

0.55 –19.0

0.75 –26.0

1.00 –35.0 L ruled/straight line through

points; Quality – not thick, not feathery for the complete line Joining plots –


• Straight line through most plots

• Straight line extrapolated to 0

Extrapolation not beyond x- or y-axis

Reject if not five plots [1]

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(ii) Using your results and your graph estimate the water potential of sample A (0.70).

MMO collection 1

(using their result for A) shows clearly on graph how one water potential obtained;

Allow any indication but must be estimate of A

[1]


any correct reading of water potential(s)

AND kPa x102; If A between … and …. reads off two water potentials allow any correct Allow if correct with result and reading from graph

[1]

(iii) Describe how you would improve the investigation to obtain a more accurate estimate of the water potential of sample A.

more (sucrose) solutions of known water potential;

two further examples of concentration of sucrose or describes more around where drop drops and rises;

more sucrose solutions or concentrations to estimate A;

standardise the volume of the methylene blue dye OR suggests method for controlling volume of drop;

ACE improvement 3

method to introduce drop OR measure time to rise or sink;

[max 3]

Total [23]

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2 (a) (i) Draw a large plan diagram of half of the trachea showing the ends of the cartilage ring. Label the diagram. Reject all marks except label if only 1 line.

PDO layout 1

clear, sharp, unbroken lines

AND no shading AND large; Minimum of three lines

[1]

no cells AND drawn only half; Minimum of two lines.


(in half section) has at least two ends of cartilage ring; [1]

at least 6 lines for layers; [1] MMO decision 2

Reject if any label is biologically incorrect e.g. cell wall Reject if any labels from other tissues e.g. arteries, veins, plant tissues and named cells unless described as a layer Accept any one label with label line correct cartilage epithelium (smooth) muscle layer of Goblet/mucus cells lumen;

Reject if overlaps text in question Reject if any writing on drawing [1]

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(ii) Prepare the space below so that it is suitable for you to compare and contrast the specimens on slide L1 and in Fig. 2.1.

PDO recording 1

organised as AND table/venn diagram/ruled connected boxes

correctly headed AND

comparative statements opposite each other;

L1 Fig 2.2 [1]

MMO collection 1

lumen clearly identified as present in both; [1]

feature: L1 (trachea): Fig. 2.1: (bronchiole)

then three of:

1.lumen shape or lining

regular/circular not folded/no villi

irregular/not circular folded/villi;

2. cilia or brush border microvilli

present cilia/brush border

absent or not visible microvilli;

3. cartilage present absent;

4. surrounding cells/air sacs/spaces

absent or no(ne) present or have;

5. epithelium thinner/narrower thicker/wider;

6. goblet or mucus cells

present or visible absent or not visible;

7. size wider/larger narrower/smaller;


8. whole shape

similarities: smooth muscle

oval/triangular (whole shape) round/circular

round/circular;

Ticks and crosses requires a key Reject 3D, disc or spherical or arbitrary or random Reject negatives e.g. not circular Reject opposites e.g. regular

[max 3]

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(iii) Calculate the actual distance across the lumen of the structure shown by line X in Fig. 2.1.

MMO collection 1

measures line X correctly in mm or cm Reject m

[1]

shows their measurement divided by or / or ÷ 70 AND × 1000 or 103 (mm) or 10000 or 104 (cm) or × 10 × 1000;

[1] PDO display 2

figure to no more than three sig. figs.;

mm/cm

28/2.8

28.5/2.85

29/2.9

29.5/2.95

30/3


[1]

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(b) Make a large drawing of three of these structures, which must be complete, to show the differences between them. Draw a circle on Fig. 2.2 around each of the structures Z which you have drawn.

MMO collection 1

circles 3 complete Z structures on Fig 2.2

AND draws three; Reject if overlaps text of question [1]

PDO layout 1

clear, sharp, unbroken lines

AND no shading

large; [1]

two of six structures match those drawn for shape; [1] MMO decisions 2

one enclosure matches any one structure shape

AND

position;

Reject if more detail [1]

Total [17]

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9700 BIOLOGY

9700/41 Paper 4 (A2 Structured Questions), maximum raw mark 100




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1 (a) (275 – 90) or 185 or 1705 for 1 mark 10 10 10 18.5 ;; A 19 R 18 [2] (b) 1 avoid disturbance to, nest sites/nesting females ; R ref. to mating 2 protect, nest sites/young, from predators ; 3 avoid sea pollution ; 4 example of pollution ; e.g. do not throw rubbish into sea / avoid discharge from

boats/light pollution (beaches) 5 take care when fishing (with nets) ; 6 stop hunting of adults ; A trading ban on turtle products 7 captive breeding programmes/AW ; 8 conservation areas/zoos ; 9 education/ecotourism ; [5 max] [Total: 7] 2 (a) 1 hamster injected with, antigen/CD40 ; 2 B cells/plasma cells, with ability to make antibody taken ; 3 from spleen ; 4 (B cells/plasma cells) fused with, tumour/cancer/myeloma, cell ; 5 use of, fusogen/PEG ; 6 (hybrid) cells cultured/AW ; R use of fermenter 7 check cells for mAb production ;

8 (antibody making) cells mass produced/AW ; A use of fermenter [4 max]

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(b) (i) accept mouse survival for heart survival 1 in A, 100% hearts survive 10 days or no heart survives 20 days ; 2 in D, 100% hearts survive, 80 days/to end of investigation ; 3 in B, 100% hearts survive 30 days or 10% hearts survive, 80 days/to end of

investigation ; 4 in C, 100% hearts survive 30 days or 75% hearts survive, 80 days/to end of

investigation ; penalise once for no mention of percentage in mps 2, 3 and 4 [4] (ii) 1 in D, both pathways/CD28 and CD40, blocked ; 2 so T-cells cannot be cloned/no immune response ; 3 in B, CD40 pathway is not blocked/only CD28 is blocked ; 4 so T cells can still be cloned/immune response triggered ; [2 max] (c) 1 carry blood to, cardiac/heart, muscle/tissue/cells ; 2 supply oxygen ; 3 supply, nutrient/named nutrient ; 4 for, energy release/respiration ; R produce energy [3 max] (d) two of the following: 1 diagnosis of, disease/named disease ; e.g. gonorrhoea/HIV 2 treatment of disease ; e.g. directing drugs to cancerous cells A autoimmune

disease but not tissue or blood typing 3 pregnancy testing/drug testing ; 4 (passive) vaccine production ; [2 max] [Total: 15]

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3 (a) E – spermatogonium/germinal epithelial cell ; F – secondary spermatocyte ; G – spermatid ; R spermatozoa H – Sertoli cell/nurse cell ; [4] (b) Accept identification of cells from diagram. 1 cell E mitosis ; 2 (E / spermatogonia) increases in size/AW ; 3 becomes a primary spermatocyte ; 4 (primary spermatocyte) meiosis I ; 5 forms secondary spermatocyte(s) ; 6 2n to n/diploid to haploid/halving chromosome number ; [4 max] [Total: 8] 4 (a) (i) J – epidermis/epidermal cell ; K – mesophyll (cell) ; L – bundle sheath (cell) ; [3] (ii) 1 mesophyll cells tightly packed/AW ; 2 so O2 cannot reach bundle sheath cells ; 3 light independent stage/Calvin cycle or RuBP, in bundle sheath cells ; 4 ref. malate shunt ; 5 maintains high CO2 concentration (in bundle sheath cells) ; 6 PEP carboxylase, has high optimum temperature/has higher affinity for CO2 /doesn’t

accept O2 ; 7 (PEP carboxylase) not denatured ; 8 photorespiration is avoided ; [4 max] (b) 1 reduces water loss/AW ; 2 wax does not melt ; 3 shiny surface reflects radiation ; [2 max]

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(c) (i) greater reduction in sorghum than in soybean ; use of comparative figures ; e.g. sorghum 5.5 to 1.2 or by 4.3 soybean 5.2 to 1.6 or by 3.6 [2] (ii) reject ‘no’ for all points 1 less surface area ; 2 less absorption of light ; 3 less, photophosphorylation / light dependent reaction ; 4 less chemiosmosis ; 5 (due to) smaller thylakoid space or reduced proton gradient ; 6 less ATP (produced) ; 7 less reduced NADP (produced) ; 8 light-independent reaction / Calvin cycle, slows down ; 9 less carbon dioxide, fixed / combined with PEP ; R uptake [4 max] [Total: 15] 5 (a) (A.) porcatus ; [1] (b) 1 A. brunneus, A. smaragdinus and A. carolinensis have smaller differences with

A. porcatus (than with others)/AW ; 2 therefore more closely related to A. porcatus (than to each other) ; 3 use of figures ; 4 AVP ; e.g. comment about figures for A. brunneus with A. smaragdinus/

ref. different times of separation [3 max]

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(c) 1 allopatric speciation ; 2 (lizard populations) separated by water ; 3 geographical/physical, barrier ; 4 no, breeding/gene flow, between populations ; 5 mutations occur ; 6 different selection pressures/different (environmental) conditions ; 7 genetic change ; e.g. different alleles selected for/change in allele frequency/

change in gene pool/advantageous alleles passed on ; 8 (can result in) different chromosome numbers ; 9 genetic drift ; 10 ultimately, reproductively isolated/cannot interbreed ; [4 max] [Total: 8] 6 (a) change in, DNA/base sequence ; produces different allele ; ref. different, protein/polypeptide, produced ; [2 max] (b) 1 – XrXr ; 3 – XrY ; 9 – XRXr ; 10 – XRY ; [4] (c) answers must refer to phosphate ions 1 altered shape/non-functional/no, carrier protein ; 2 less/no, reabsorption of phosphate ions (into blood) ; 3 from, glomerular filtrate/lumen of/proximal convoluted tubule ; 4 more/all, phosphate ions excreted ; 5 low phosphate ion concentration in, blood/bones ; R no phosphate ion conc [2 max] [Total: 8]

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7 (a) (i) glycolysis ; [1] (ii) cytoplasm/cytosol ; [1] (iii) 4 ; A 4 – 2 = 2 [1] (b) (i) inner membrane/cristae/stalked particles ; [1] (ii) 1 reduced, NAD/FAD ; 2 dehydrogenase enzymes ; 3 release hydrogen ; A H R H2/H

+ 4 hydrogen splits into proton and electron ; 5 electrons flow down, ETC/AW ; 6 energy released ; 7 protons pumped (across inner membrane/from matrix) ; 8 into intermembrane space ; 9 proton gradient ; 10 protons pass through, ATP synthase/stalked particle ;

11 oxygen final, hydrogen/proton, acceptor ; [5 max] (c) (i) nuclei and ribosomes ; [1] (ii) 1 glycolysis, does not occur in mitochondrion/only occurs in cytosol or cytoplasm ; 2 pyruvate produced in glycolysis ; 3 pyruvate can enter mitochondrion/glucose cannot enter mitochondrion ;

4 carbon dioxide produced/decarboxylation, in, Krebs/link reaction ; [3 max] (iii) 1 cyanide, inhibits cytochrome oxidase is a non-competitive inhibitor ; 2 reduced NAD not oxidised/AW ; 3 Krebs cycle stops ; 4 alternative H acceptor needed/pyruvate is H acceptor/pyruvate is reduced ; R H+ 5 lactate produced in cytoplasm ;

6 by anaerobic respiration ; [3 max] [Total: 16]

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8 (a) (i) 1 parents, heterozygous/carriers ; 2 CF allele recessive ; 3 CF child homozygous recessive ; [2 max] (ii) 1 thick/sticky/dehydrated, mucus produced ; 2 mucus not moved effectively by cilia/mucus accumulates ; R mucus blocks airway 3 reduced gaseous exchange/longer diffusion pathway ; 4 difficulty in breathing/AW ; 5 infections/(mucus) traps bacteria ; 6 lungs are scarred ; [2 max] (b) (i) 1 alters genotype ; 2 insert, dominant/normal, allele ; R gene 3 into, affected/appropriate, cells ; 4 use of vector/named vector ; 5 ref. recombinant DNA ; [2 max] (ii) advantage 1 treats cause not symptoms ; 2 no, physiotherapy/antibiotics/etc, needed ; 3 less time consuming than others treatments ; max 1 disadvantage 4 effects only last for a few days (at present)/low uptake by target cells ; 5 only target lung cells (at present) ; 6 side effects ; max 1 [2 max] [Total: 8]

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9 (a) 1 closely packed to absorb maximum light ; 2 vertical/at right angles to surface of leaf to reduce number of cross walls ; 3 large vacuole pushes chloroplasts to edge of cell ; 4 chloroplasts at edge short diffusion path for carbon dioxide ; 5 chloroplasts at edge to absorb maximum light ; 6 large number of chloroplasts to absorb maximum light ; 7 cylindrical cells or air spaces to circulate gases/provide a reservoir of CO2 ; 8 large surface area for diffusion of gases ; 9 moist cell surfaces for diffusion of gases ; 10 cell walls thin for maximum light penetration/diffusion of gases ; 11 chloroplasts can move towards light ; 12 chloroplasts can move away from high light intensity to avoid damage ; [8 max] (b) 13 Calvin cycle/stroma ; 14 carbon dioxide fixed by RuBP ; 15 rubisco ; 16 2 molecules of GP formed ; A PGA 17 (GP) forms TP ; A GALP/PGAL 18 use of ATP ; 19 use of, reduced NADP/NADPH ; 20 from light dependent stage ; 21 some TP forms, hexose/sucrose/starch/cellulose/glycerol ; 22 some TP converted to acetyl CoA ; 23 some TP used to regenerate RuBP ; 24 using ATP ; allow either mp 18 or mp 24 marks can be awarded on a diagram [7 max] [Total: 15]

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10 (a) 1 renal/Bowman’s, capsule ; 2 ref. podocytes ; 3 (proximal convoluted tubule/distal convoluted tubule/capsule) in cortex ; 4 proximal convoluted tubule ; 5 loop of Henle ; 6 (loop) in medulla ; 7 distal convoluted tubule ; 8 afferent arteriole ; 9 glomerulus ; 10 efferent arteriole ; 11 capillary network around/proximal convoluted tubule/loop/distal convoluted tubule ; 12 collecting duct ; accept points on a labelled diagram [7 max] (b) 13 endothelium of, blood capillaries/glomerulus ; 14 more/large, gaps between endothelial cells ; 15 podocytes ; 16 large gaps between podocytes/filtration slits ; 17 basement membrane, selective barrier/acts as a filter ; 18 prevents, large protein/RMM > 68 000, passing through ; 19 no cells pass through ; 20 named molecule which is filtered ; e.g. urea/water/glucose/uric acid/creatinine/

Na+/K+/Cl ; 21 high, blood/hydrostatic, pressure in glomerulus ; 22 afferent arteriole wider than efferent arteriole ; 23 lower pressure in, renal/Bowman’s, capsule ; 24 fluid forced into capsule/ultrafiltration ; [8 max] [Total: 15]

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9700 BIOLOGY





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1 (a) 1 more nests in, areas of low salinity/less salty areas ; ora 2 comment about result for salinity 16-20 not following trend ; 3 2 paired figs with units ; linked to 1 [3] (b) (i) (31 – 8) (× 100) 8 287.5/288 ;; allow one mark for suitable working if incorrect answer [2] (ii) any two from 1 (ensure) low salinity or more freshwater ; 2 nest sites protected ; 3 education/ecotourism ; 4 assisted breeding ; 5 ban on hunting ; 6 preventing pollution ; [2 max] [Total: 7] 2 (a) 1 receptor or binding site not, complementary/specific, to FSH ; 2 FSH has shorter β chain than LH ; ora 3 FSH has different, primary structure/sequence of amino acids ; 4 FSH has different, tertiary structure/3D shape ; [3 max] (b) (i) follicle (cells) ; A granulosa (cells) [1] (ii) corpus luteal (cells) ; A granulosa (cells) [1] (c) 1 (binding to a receptor), acts as a signal to the cells/stimulates cells ; 2 to, start/increase, synthesis of hormone ; A cells start to divide 3 oestrogen secreted ; A mature follicle formed (oestrogen), 4 stimulates thickening of endometrium/inhibits FSH (production) ; [3 max] [Total: 8]

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3 (a) 1 penicillin inhibits enzyme ; ignore name of enzyme 2 peptidoglycan chains cannot link up/stops cross-links forming ; 3 cell wall becomes weaker/AW ; 4 turgor of cell not resisted (by cell wall)/AW ; 5 cell/wall, bursts ; [3 max] (b) (i) B has, an outer membrane/channel proteins ; B has thinner (peptidoglycan) wall ; accept ora for A [2] (ii) 1 penicillin V can reach the, wall/(cell surface) membrane, of A ; ora 2 outer membrane of B stops penicillin V getting through ; ora 3 penicillin V cannot get through pores of outer membrane of B ; [2 max] (iii) can penetrate outer membrane ; through pores/directly through as non-polar ; [2]

(c) batch culture

1 set up and allowed to proceed ; 2 nutrients not added or products removed, (during fermentation) ; 3 air allowed in/waste gas allowed out ; 4 at end of each process, product harvested/fermenter cleaned out ; max 2

continuous culture 5 nutrients added (all the time) ; 6 products removed (all the time) ; 7 no down time/AW ; max 2 [3 max] (d) 1 (Penicillium/fungus), does not make penicillin all the time/penicillin is made in the later

stages of growth ; 2 when beginning to run out of nutrients ; 3 (penicillin) is a secondary metabolite ; 4 continuous culture has no yield of penicillin ;

5 continuous culture, never reaches stationary phase of growth/always exponential growth ; [3 max]

[Total: 15]

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4 (a) 1 can be grown in many different environments/AW ; 2 (grains) contain variety of nutrients ; A list of 3+ nutrients 3 detail of nutrient content ; e.g. high in calcium/vitamin B/protein 4 (grains) have high, energy/fibre, content ; 5 (grains) store well ; [3 max] (b) (i) endosperm ; [1]

(ii) 1 both rise and then fall ; 2 sorghum (enzyme) has higher activity (at all temperatures) ; 3 sorghum (enzyme) has higher maximum activity ; 4 sorghum (enzyme) has higher optimum temperature ; A 70° and 60° 5 comparative figures to illustrate points 2 or 3 ; [3 max] (iii) 1 (rice) tertiary structure/active site, of amylase is altered more by high temperature ; 2 (therefore) fewer ES/enzyme-substrate complexes formed/AW ; 3 high temperatures affect H bonds (more than other bonds) ; 4 amylase in rice may have more H bonds ; ora 5 correct ref. to other named bond ; [3 max] (c) (i) 1 higher CO2 uptake at higher light intensity ; ora 2 comparative figures ; using columns 1 and 2 3 CO2 used in, Calvin cycle/light independent reaction ; 4 photophosphorylation/light dependent stage provides, ATP/reduced NADP ; 5 for use in, Calvin cycle/light independent reaction ; 6 light is a limiting factor ; [3 max] (ii) 1 survive better at low light intensities ; 2 comparative figures ; using columns 1 and 6 [2]

[Total: 15]

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5 (a) divergence values less for persimilis than for pseudoobscura (at all DNA regions) ; ora use of figures ; [2] (b) 1 some regions of DNA more prone to mutation than others ; 2 mutation in some regions likely to be fatal (so not seen in populations) ; 3 there tends to be less divergence if DNA is part of an important gene/ora ; 4 detail ; e.g. causes change in essential protein [2 max] (c) 1 allopatric speciation ; 2 geographical/physical, barrier ; 3 no, breeding/gene flow, between populations ; 4 mutations occur ; 5 different selection pressures/different (environmental) conditions ; 6 genetic change ; e.g. different alleles selected for/change in allele frequency/change in

gene pool/advantageous alleles passed on ; 7 genetic drift ; 8 (ultimately) cannot interbreed/reproductively isolated ; [4 max] [Total: 8]

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6 (a) 1 allele/gene, found on X chromosome ; 2 females have two copies of, allele/gene ; 3 males have only one copy of, allele/gene ; [2 max] (b) key to symbols recessive allele Xa (= allele for CI) dominant allele XA (= allele for normal iris) ; cross 1 parental phenotypes male with CI/cleft iris and normal female ; gametes Xa or Y all XA ;

offspring genotypes XAXa XAY ; offspring phenotypes normal female normal male ; ......................................................................................................................................

or ……………………………………………………...…………………………………………..

cross 2 parental phenotypes male with CI/cleft iris and normal female ; gametes Xa or Y XA or Xa ;

offspring genotypes XAXa XAY XaXa XaY ; offspring phenotypes normal normal cleft iris/CI cleft iris/CI female male female male ; [5] offspring phenotypes must be linked to genotypes (c) 1 in 4/25%/0.25 ; R ratios [1] [Total: 8]

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7 (a) (i) removal of, carbon dioxide/carboxyl group ; removal of hydrogen ; [2] (ii) P and Q ; [1] (b) (i) 3 ; [1] (ii) 1 inner mitochondrial membrane/cristae ; 2 dehydrogenase enzymes ; 3 release hydrogen ; 4 hydrogen splits into protons and electrons ; 5 electrons flow down, ETC/Electron Transfer Chain/AW ; 6 energy released ; 7 protons pumped across (inner membrane) ; 8 into intermembrane space ; 9 proton gradient ; 10 protons pass through, ATP synthase/stalked particles ; 11 ATP formed ; linked to 10 12 oxygen (final), hydrogen/proton and electron, acceptor ; max 4 [5 max] (c) 1 pyruvate converted to ethanal ; 2 ethanal reduced ; 3 by reduced NAD ; 4 NAD, oxidised/regenerated ; 5 allows glycolysis to continue ; 6 ethanal dehydrogenase ; 7 ethanol formed ; 8 prevents H+ from lowering pH ; [4 max]

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(d) 1 no, decarboxylation/carbon dioxide removed ; A ora 2 single step ; 3 lactate dehydrogenase ; 4 reversible ; [3 max] [Total: 16] 8 (a) (i) 1 change in, genetic material/DNA, (in cell) ; 2 (therefore) change product of cell ; 3 during protein synthesis ; [2 max] (ii) 1 identification of transformed, cells/organisms ; 2 avoid use of antibiotics ; 3 easy to detect ; 4 no known ill effect on GM organism ; [2 max] (b) (i) 1 reduces deficiency disease/AW ; 2 better quality food ; 3 assistance to developing nations/AW ; 4 cheap seed ; e.g. for golden rice [2 max] (ii) 1 high cost of GM seed ; 2 too much power held by multinational companies ; 3 change to ecosystem ; e.g. hybridisation 4 GM crops may be difficult to sell ; 5 GM plant varieties may be genetically unstable ; 6 no long term studies done on effects on human health ; 7 reduction in biodiversity/outcompetes natural variety or species ; [2 max] [Total: 8]

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9 (a) 1 arranged in light harvesting, clusters/system ; 2 primary pigments/chlorophyll a ; 3 at reaction centre ; 4 P700/P1, absorbs at 700(nm) ; 5 P680/P11, absorbs at 680(nm) ; 6 accessory pigments/chlorophyll b/carotenoids, surround, primary pigment/reaction

centre/ chlorophyll a ; 7 pass energy to, primary pigment/reaction centre/chlorophyll a ; 8 P700 / PI, involved in cyclic photophosphorylation ; 9 (light absorbed results in) electron excited/AW ; 10 emitted from, chlorophyll/photosystem ; 11 flows along, chain of electron carriers/ETC ; 12 ATP synthesis ; 13 electron returns to, P700/P1 ; [8 max] (b) 14 photolysis (of water) ; 15 releases H+ ; R H/hydrogen atoms 16 by, P680/PII ; 17 e released ; 18 by, P700/PI ; 19 both combine with NADP ; (reduced NADP) 20 reduces, GP ; A PGA 21 to TP ; A PGAL / GALP 22 ATP used ; 23 NADP, regenerated/oxidised ; [7 max] [Total: 15]

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10 (a) 1 nucleus in cell body ; 2 (long) dendron ; R plural 3 (shorter) axon ; 4 many mitochondria (in cell body) ; 5 many RER/nissl’s granules, (in cell body) ; 6 synaptic knobs ; 7 detail of synaptic knob ; 8 (terminal) dendrites ; 9 Schwann cells ; 10 detail of myelin sheath ; 11 nodes of Ranvier ; accept points on labelled diagram [7 max] (b) 12 Na+ channels open ; A sodium channels 13 Na+ enter cell ; R enter membrane 14 inside becomes, less negative/positive/+40mV or membrane depolarised ; 15 Na+ channels close ; A sodium channels 16 K+ channels open ; A potassium channels 17 K+ move out (of cell) ; R of membrane 18 inside becomes negative or membrane repolarised ; A negative figure max 5 19 local circuits/description ; 20 (myelin sheath/Schwann cells) insulate axon/does not allow movement of ions ; 21 action potential/depolarisation, only at nodes (of Ranvier)/gaps ; 22 saltatory conduction/AW ; 23 one-way transmission ; 24 AVP ; e.g. hyperpolarisation/refractory period [8 max] [Total: 15]

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9700 BIOLOGY





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1 (a) 1 more nests in, areas of low salinity/less salty areas ; ora 2 comment about result for salinity 16-20 not following trend ; 3 2 paired figs with units ; linked to 1 [3] (b) (i) (31 – 8) (× 100) 8 287.5/288 ;; allow one mark for suitable working if incorrect answer [2] (ii) any two from 1 (ensure) low salinity or more freshwater ; 2 nest sites protected ; 3 education/ecotourism ; 4 assisted breeding ; 5 ban on hunting ; 6 preventing pollution ; [2 max] [Total: 7] 2 (a) 1 receptor or binding site not, complementary/specific, to FSH ; 2 FSH has shorter β chain than LH ; ora 3 FSH has different, primary structure/sequence of amino acids ; 4 FSH has different, tertiary structure/3D shape ; [3 max] (b) (i) follicle (cells) ; A granulosa (cells) [1] (ii) corpus luteal (cells) ; A granulosa (cells) [1] (c) 1 (binding to a receptor), acts as a signal to the cells/stimulates cells ; 2 to, start/increase, synthesis of hormone ; A cells start to divide 3 oestrogen secreted ; A mature follicle formed (oestrogen), 4 stimulates thickening of endometrium/inhibits FSH (production) ; [3 max] [Total: 8]

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3 (a) 1 penicillin inhibits enzyme ; ignore name of enzyme 2 peptidoglycan chains cannot link up/stops cross-links forming ; 3 cell wall becomes weaker/AW ; 4 turgor of cell not resisted (by cell wall)/AW ; 5 cell/wall, bursts ; [3 max] (b) (i) B has, an outer membrane/channel proteins ; B has thinner (peptidoglycan) wall ; accept ora for A [2] (ii) 1 penicillin V can reach the, wall/(cell surface) membrane, of A ; ora 2 outer membrane of B stops penicillin V getting through ; ora 3 penicillin V cannot get through pores of outer membrane of B ; [2 max] (iii) can penetrate outer membrane ; through pores/directly through as non-polar ; [2]

(c) batch culture

1 set up and allowed to proceed ; 2 nutrients not added or products removed, (during fermentation) ; 3 air allowed in/waste gas allowed out ; 4 at end of each process, product harvested/fermenter cleaned out ; max 2

continuous culture 5 nutrients added (all the time) ; 6 products removed (all the time) ; 7 no down time/AW ; max 2 [3 max] (d) 1 (Penicillium/fungus), does not make penicillin all the time/penicillin is made in the later

stages of growth ; 2 when beginning to run out of nutrients ; 3 (penicillin) is a secondary metabolite ; 4 continuous culture has no yield of penicillin ;

5 continuous culture, never reaches stationary phase of growth/always exponential growth ; [3 max]

[Total: 15]

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4 (a) 1 can be grown in many different environments/AW ; 2 (grains) contain variety of nutrients ; A list of 3+ nutrients 3 detail of nutrient content ; e.g. high in calcium/vitamin B/protein 4 (grains) have high, energy/fibre, content ; 5 (grains) store well ; [3 max] (b) (i) endosperm ; [1]

(ii) 1 both rise and then fall ; 2 sorghum (enzyme) has higher activity (at all temperatures) ; 3 sorghum (enzyme) has higher maximum activity ; 4 sorghum (enzyme) has higher optimum temperature ; A 70° and 60° 5 comparative figures to illustrate points 2 or 3 ; [3 max] (iii) 1 (rice) tertiary structure/active site, of amylase is altered more by high temperature ; 2 (therefore) fewer ES/enzyme-substrate complexes formed/AW ; 3 high temperatures affect H bonds (more than other bonds) ; 4 amylase in rice may have more H bonds ; ora 5 correct ref. to other named bond ; [3 max] (c) (i) 1 higher CO2 uptake at higher light intensity ; ora 2 comparative figures ; using columns 1 and 2 3 CO2 used in, Calvin cycle/light independent reaction ; 4 photophosphorylation/light dependent stage provides, ATP/reduced NADP ; 5 for use in, Calvin cycle/light independent reaction ; 6 light is a limiting factor ; [3 max] (ii) 1 survive better at low light intensities ; 2 comparative figures ; using columns 1 and 6 [2]

[Total: 15]

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5 (a) divergence values less for persimilis than for pseudoobscura (at all DNA regions) ; ora use of figures ; [2] (b) 1 some regions of DNA more prone to mutation than others ; 2 mutation in some regions likely to be fatal (so not seen in populations) ; 3 there tends to be less divergence if DNA is part of an important gene/ora ; 4 detail ; e.g. causes change in essential protein [2 max] (c) 1 allopatric speciation ; 2 geographical/physical, barrier ; 3 no, breeding/gene flow, between populations ; 4 mutations occur ; 5 different selection pressures/different (environmental) conditions ; 6 genetic change ; e.g. different alleles selected for/change in allele frequency/change in

gene pool/advantageous alleles passed on ; 7 genetic drift ; 8 (ultimately) cannot interbreed/reproductively isolated ; [4 max] [Total: 8]

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6 (a) 1 allele/gene, found on X chromosome ; 2 females have two copies of, allele/gene ; 3 males have only one copy of, allele/gene ; [2 max] (b) key to symbols recessive allele Xa (= allele for CI) dominant allele XA (= allele for normal iris) ; cross 1 parental phenotypes male with CI/cleft iris and normal female ; gametes Xa or Y all XA ;

offspring genotypes XAXa XAY ; offspring phenotypes normal female normal male ; ......................................................................................................................................

or ……………………………………………………...…………………………………………..

cross 2 parental phenotypes male with CI/cleft iris and normal female ; gametes Xa or Y XA or Xa ;

offspring genotypes XAXa XAY XaXa XaY ; offspring phenotypes normal normal cleft iris/CI cleft iris/CI female male female male ; [5] offspring phenotypes must be linked to genotypes (c) 1 in 4/25%/0.25 ; R ratios [1] [Total: 8]

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7 (a) (i) removal of, carbon dioxide/carboxyl group ; removal of hydrogen ; [2] (ii) P and Q ; [1] (b) (i) 3 ; [1] (ii) 1 inner mitochondrial membrane/cristae ; 2 dehydrogenase enzymes ; 3 release hydrogen ; 4 hydrogen splits into protons and electrons ; 5 electrons flow down, ETC/Electron Transfer Chain/AW ; 6 energy released ; 7 protons pumped across (inner membrane) ; 8 into intermembrane space ; 9 proton gradient ; 10 protons pass through, ATP synthase/stalked particles ; 11 ATP formed ; linked to 10 12 oxygen (final), hydrogen/proton and electron, acceptor ; max 4 [5 max] (c) 1 pyruvate converted to ethanal ; 2 ethanal reduced ; 3 by reduced NAD ; 4 NAD, oxidised/regenerated ; 5 allows glycolysis to continue ; 6 ethanal dehydrogenase ; 7 ethanol formed ; 8 prevents H+ from lowering pH ; [4 max]

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(d) 1 no, decarboxylation/carbon dioxide removed ; A ora 2 single step ; 3 lactate dehydrogenase ; 4 reversible ; [3 max] [Total: 16] 8 (a) (i) 1 change in, genetic material/DNA, (in cell) ; 2 (therefore) change product of cell ; 3 during protein synthesis ; [2 max] (ii) 1 identification of transformed, cells/organisms ; 2 avoid use of antibiotics ; 3 easy to detect ; 4 no known ill effect on GM organism ; [2 max] (b) (i) 1 reduces deficiency disease/AW ; 2 better quality food ; 3 assistance to developing nations/AW ; 4 cheap seed ; e.g. for golden rice [2 max] (ii) 1 high cost of GM seed ; 2 too much power held by multinational companies ; 3 change to ecosystem ; e.g. hybridisation 4 GM crops may be difficult to sell ; 5 GM plant varieties may be genetically unstable ; 6 no long term studies done on effects on human health ; 7 reduction in biodiversity/outcompetes natural variety or species ; [2 max] [Total: 8]

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9 (a) 1 arranged in light harvesting, clusters/system ; 2 primary pigments/chlorophyll a ; 3 at reaction centre ; 4 P700/P1, absorbs at 700(nm) ; 5 P680/P11, absorbs at 680(nm) ; 6 accessory pigments/chlorophyll b/carotenoids, surround, primary pigment/reaction

centre/ chlorophyll a ; 7 pass energy to, primary pigment/reaction centre/chlorophyll a ; 8 P700 / PI, involved in cyclic photophosphorylation ; 9 (light absorbed results in) electron excited/AW ; 10 emitted from, chlorophyll/photosystem ; 11 flows along, chain of electron carriers/ETC ; 12 ATP synthesis ; 13 electron returns to, P700/P1 ; [8 max] (b) 14 photolysis (of water) ; 15 releases H+ ; R H/hydrogen atoms 16 by, P680/PII ; 17 e released ; 18 by, P700/PI ; 19 both combine with NADP ; (reduced NADP) 20 reduces, GP ; A PGA 21 to TP ; A PGAL / GALP 22 ATP used ; 23 NADP, regenerated/oxidised ; [7 max] [Total: 15]

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10 (a) 1 nucleus in cell body ; 2 (long) dendron ; R plural 3 (shorter) axon ; 4 many mitochondria (in cell body) ; 5 many RER/nissl’s granules, (in cell body) ; 6 synaptic knobs ; 7 detail of synaptic knob ; 8 (terminal) dendrites ; 9 Schwann cells ; 10 detail of myelin sheath ; 11 nodes of Ranvier ; accept points on labelled diagram [7 max] (b) 12 Na+ channels open ; A sodium channels 13 Na+ enter cell ; R enter membrane 14 inside becomes, less negative/positive/+40mV or membrane depolarised ; 15 Na+ channels close ; A sodium channels 16 K+ channels open ; A potassium channels 17 K+ move out (of cell) ; R of membrane 18 inside becomes negative or membrane repolarised ; A negative figure max 5 19 local circuits/description ; 20 (myelin sheath/Schwann cells) insulate axon/does not allow movement of ions ; 21 action potential/depolarisation, only at nodes (of Ranvier)/gaps ; 22 saltatory conduction/AW ; 23 one-way transmission ; 24 AVP ; e.g. hyperpolarisation/refractory period [8 max] [Total: 15]

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9700 BIOLOGY

9700/51 Paper 5 (Planning, Analysis and Evaluation), maximum raw mark 30




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Mark schemes abbreviations: � ; separates marking points � / alternative answers for the same point � R reject � A accept (for answers correctly cued by the question, or guidance for examiners) � AW alternative wording (where responses vary more than usual) � underline actual word given must be used by candidate (grammatical variants excepted) � max indicates the maximum number of marks that can be given

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Question Expected answer Extra guidance Mark AO

1 (a) (i) oxygen / gas / air, produced (by photosynthesis); Do not allow: use / production of carbon dioxide / respiration / bubbles Allow: losing / releasing oxygen, etc. [1] M

(ii) 7 of: independent variable 1. a method of varying light intensity or use low light intensity; 2. ref. to a method of measuring light intensity; 3. ref. to a method of eliminating other light sources; 4. ref. to testing leaf discs for the two locations separately; dependent variable 5. ref. to a method of measuring photosynthesis by rising of discs; 6. ref to time taken; standardising variables (max 3) 7. ref. to discs from more than one leaf (from each location); 8. ref. leaf discs all being same diameter / size / number / mass. 9. ref. to same volume of hydrogen carbonate solution (in syringe); 10. ref. to using fresh hydrogen carbonate solution for each measurement /

same concentration of H carbonate;

1. e.g. lamp (with standard bulb) and

vary distance / lamp at same distance and vary wattage / lamp at same distance and use filters of different thickness / AW

2. e.g. (light) meter / photodiode / light dependent resistor / photometer / low wattage / 60 or below

Allow ref. to using a camera meter 3. e.g. dark room or box for

measurement 4. often implied 5. Do not allow: counting bubbles /

leaves rising 6. e.g. time for (all or a specified

number of) discs to rise / specified time and count the number of discs floating / distance risen in stated time

Allow: ecf time for bubble counting 8. Allow: use same straw for cutting 9/10 Watch for confusion with

hydrogen carbonate indicator – but ecf

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11. ref. to method of standardising temperature; 12. ref. to acclimatising before measuring; Reliability 13. ref. to repeating at least three times and taking mean; safety: 14. ref. to low risk investigation / AW or any suitable safety concern + precaution;

11. water bath / incubator / controlled room

Do not allow: room temp Do not allow: pH for standardising variables 13. Allow: several or many Allow: to remove anomalies /

outliers 14. e.g. hydrogen carbonate + gloves /

eye protection dry hands to prevent electrical shock / AW Do not allow: be careful unqualified Do not allow: care with cutting [7] M

(b) (i) x – light intensity y – rate of photosynthesis; suitable unit on one axis; Ignore other units

light – e.g. arbitrary / lux / lumens / candela / 1/d2

allow, watts / kilowatts / voltage photosynthesis. e.g. 1/time / arbitrary Allow: ecf for unit mark if axes wrong [2] D

(ii) (rate of) photosynthesis / gas production / oxygen production for shade leaf (discs) is higher (than exposed discs) at low intensity / ref. figures; photosynthesis / gas production / oxygen production begins at lower light intensity in shade leaf discs; Allow: at high(er) light intensity shade leaves level off / AW, whilst sun leaves continue to rise / AW;

Allow: reverse arguments for sun leaves at low intensity Ignore: ‘initial’ if the answer is about rate Do not allow: answers that imply time e.g. starts sooner / before …. Ignore: idea that photosynthesis stops at higher light intensities assume that ‘it’ or ‘they’ is the shade leaves if not stated in the answer [2] E

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(c) (i) 0.2mm2; must have units. [1] D

(ii) 185;; two marks if some working shown look for working if answer wrong if 0.196..... used ecf and take 188 or 189 – whole nos. only if other values in (c) (i) ecf by checking the calculation

0.2

37 = 185 1/0.2 = 5 5 × 37 = 185

If calculation correct but answer not transferred to table allow both marks

[2] D

(iii) there is no difference in the, number / frequency, of stomata in, exposed / sun, leaves and, shaded / shade, leaves;

Allow: any variation on the basic idea e.g. the (observed) means / number, are the same there is no difference (between the two leaf types) Do not allow: the experimental hypothesis [1] D

(iv) t-test; comparing two means / means have a similar standard deviation / data has a normal distribution / is continuous / is not discrete;

Do not allow: 2 sets of data are being compared ecf if the test name is incorrect Allow: a correct reason for the t-test. [2] D

(d) 1 of: sun leaves have (fewer stomata) as more likely to lose water / transpire; ora shade leaves have (more stomata) to increase gas / CO2 diffusion / AW;

Do not allow: to increase photosynthesis unqualified Do not allow: – stomata related to light absorption Watch out for statements that there are more stomata in sun leaves without any qualification. Assume comment applies to shade leaves if not stated. Do not allow: oxygen is given out [1] C

Total: [19]

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2 (a) (i) 1 of: ref. to thickness / volume / consistency / concentration of, agar / depth of wells / volume of wells / distance of antigen wells from test organism wells; ref to temperature; ref. to volume serum / antigen volume;

Do not allow: amount for any quantitative answer Do not allow: pH

[1] P

(ii) the serum / antibody / antibodies (from the test organisms); Do not allow: if antigen also mentioned Allow: organism from which serum / antibody came Ignore amount / volume etc. [1] P

(iii) 2 lines / 1 thick line, between 2 and antigens; 1 line between 1 and antigens;

Allow: 2 marks if lines do not intersect If the lines are reversed / spread outside dish max. 1 Do not allow: if the lines are inverted / lines cross wells [2] C

(b) 2 of: 1. ref. to all antibodies not forming precipitates / AW; 2. ref. to sensitivity / AW; 3. ref. to more qualitative / difficult to quantify; 4. ref. to, slow rate / inability to diffuse of some antibodies; 5. ref to problem of identifying individual antigens / AW;

2. the idea test will not detect low

concentrations 4. Allow: – if ‘slow’ is in the context of

getting results of tests [2] E

antigen X + antigen Y

1 2 test organism 2

test organism 1

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(c) (i) group 1 ref. to the idea of a control; group 2 and 3 ref. to idea of finding how many organisms, give immunity / needed; group 4 ref. to idea of finding the number of, inoculations / boosters, needed;

Be careful they are not conclusions e.g. how many are needed (to make the vaccine work) e.g. to see if another booster is needed [3] P

(ii) 2 of: ref. to (information that mutant) Plasmodium breeds / develops / AW in mosquitoes; ref. to breeding mosquitoes / culturing in salivary gland tissue / AW; ref. to extracting (Plasmodium) from salivary glands / culture of salivary glands;

Allow: idea of a culture medium similar to salivary gland / saliva Ignore: from the liver of mice

[2] M

Total: [11]

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9700 BIOLOGY





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1 (a) (i) a mesophytic plant loses more water than a xerophytic plant; Allow: any variation on the basic idea, but it must include a plant and water loss. Do not allow: loss in xerophyte greater than mesophyte Ignore: any ref. to external conditions / water uptake [1] P

(ii) 8 of: independent variable: 1. ref. to shoots / leaves of different types of plant / xerophyte and

mesophyte / type of plant used; 2. ref. to similar surface area; dependent variable 3. ref. to measuring / recording the movement (of water) along the

capillary; 4. ref. to time (of water movement) / description of measuring time; control variables (max 3) 5. ref. to same (environmental) conditions; 6. ref. to inserting / cutting shoot under water / cutting shoot at an angle; 7. ref. to drying leaves before measuring; 8. ref. to airtight seal (around shoot) / airtight apparatus / no air locks; procedure 9. ref. to using syringe to set (water level) in capillary; 10. ref. to leaving until steady rate / equilibrate; reliability 11. ref. to repeats / replicates – min 3 and mean value; safety: 12. ref. to a low risk experiment;

1. Allow: named examples of

xerophyte / mesophyte 2. Ignore: mass Allow: same / similar number of

leaves 3. Do not allow: upwards movement Ignore: dye 4. Do not allow: if an inappropriate time

is specified e.g. seconds 5. Allow: for any example, light /

humidity / temperature 8. Ignore: watertight 9. Ignore: ref. to indicator 11. Allow: to remove anomalies 12. Allow: example of appropriate safety

e.g. care in cutting shoots / pushing capillary through a bung [8] M

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(iii) ref. to finding surface area of the capillary;

ref. to multiplying (surface area (πr2)) by distance moved; OR use syringe to push water back to original position; measure volume from the syringe: OR idea that the capillary is pre-calibrated; (and) find the volume from the distance moved / read from scale;

Allow: both marks if formula for volume of cylinder is shown – any of these is acceptable

πr2 l / d / h

π

4

d2

l / d / h;

π

2

d2

l / d / h; [2] D

(b) 2 of: axes correct orientation and labelled appropriately for type of graph; mesophyte shown as having higher water loss / rate of water loss; Allow: marks on a horizontal bar chart

Line Graphs and Bar Charts: y axis – rate / water loss / distance moved (by water or meniscus) / rate of transpiration Line Graph x axis – time Allow: lines that start at 0 Bar Charts x axis – type of leaf If the x axis is incorrect but y axis is related to water movement Allow: mark for the difference in water loss If axes reversed on a line graph, Allow: the mark for the lines if shown correctly Allow: marks on two graphs units are not required [2] P

rate

type of leaf

meso xero

water loss

time

meso xero

rate

type of leaf

xero

meso

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(c) (i) area =

410 / 000 10

36 / 0.0036 / 3.6 × 10 3 / 36 × 10 4 (m2);

water loss = 30

0.018 / 0.0006 / 6 × 10 4 (cm3 min 1);

rate = 3

4

10 3.6 / 0.0036

10 6 / 0.0006

×

×

)(m 10 36

min cm24

13

×

= 0.167 cm3 m 2 min 1;

Watch for area being halved or doubled 72 or 18 Allow: ecf for the calculation Look for the correct figures in the answer. This may be in a combined formula.

Allow: 0.17 / 610.& cm3 m 2 min 1

Allow: any other valid method of calculating rate Do not allow: fractions [3] D

(ii) t- test; the data has a normal distribution / continuous / not discrete / comparing two means / averages;

Allow: correct reason for t-test even if the name is incorrect Do not allow: to compare 2 sets of data [2] D

(d) 3 of: 1. mesophyte has greater mass loss / water loss / transpiration (than a

xerophyte); 2. less mass / less water is lost / less transpiration over time by (both)

leaves / lower side of leaves / upper side of leaves covered; 3. both leaves / xerophyte / mesophyte lose more mass / more water /

transpire more from the lower side of the leaf / when the upper surface is covered;

4. xerophyte loses almost no water from the upper side / loses most of its water from the lower side of the leaf;

Allow: reverse arguments for points 1–4 Allow: use of figures for points 1–4 1. Allow: if refer to upper and lower

surface of leaves Allow: 5. there are more stomata on the

lower surface (of both leaves); 6. xerophyte has fewer stomata on

lower side than the mesophyte / mesophyte has more stomata on lower side than a xerophyte;

7. mesophyte has stomata on both sides of the leaf;

8. xerophyte may not have any stomata on upper side;

9. xerophyte has thicker cuticle than mesophyte;

Do not allow: guard cells [3] C

Total: [21]

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2 (a) 2 of: ref. to culture medium / growth medium / nutrient; ref. to constant volume / concentration; ref. to amino acid; ref. to constant volume (of both types) added; ref. temperature; ref. to suitable method of providing constant temp. ref. to aeration; ref. to a method of supplying oxygen / air; ref. to pH; ref. to buffers / named buffers;

Do not allow: amount for any quantitative answer. Do not allow: ref. to cell numbers or time Allow: ref. to fermenter features – water jacket (+ monitor) water bath must refer to a constant / stated temperature Allow: ref. to fermenter features – sparger / air lift

[2]

[2]

P

M

(b) Increase in number of cells (after 6 days); number of cells at beginning / previous

Allow: ratio of increase in cells to the initial number of cells. Ignore: percentages [1] D

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(c) glutamine: Support 1. stimulates / shows an increase and ref to any figure or range between

0.1–10 (mmol dm 3); Not support 2. does not stimulate / inhibits / shows decrease at 20 / 40 (mmol dm 3); glutamic acid: Support 3. does not stimulate / inhibits / shows a decrease at 0.1 / 0.2 / 0.5 / 40

(mmol dm 3); Not support 4. shows little effect on growth / too inconsistent / does not show any

trend (to draw any conclusion); Not support 5. at 10 (mmol dm 3) / 20 (mmol dm 3) appears to increase growth; anywhere in answer: Support 6. results should be reliable as means of 50 counts (per culture) / large

number used; Not support 7. cell counting procedures are estimates / prone to error;

Cause and effect must be correct – watch for cell increase and amino acids concentrations being reversed. Allow: glutamate for glutamic acid 2. Allow: no cells / no growth / no

changes Do not allow: cells are dead / no

cells 5. Allow: may be anomalous results at

these concentrations For comparisons between figs. of glutamine and glutamic acid: for appropriate use of figures max 2. mark points 6 and 7 can also be awarded. Support 8. more growth with glutamine than

glutamic acid between 0–10 (mmol dm 3);

Not support 9. more growth with glutamic acid than

glutamine at 20 (mm dm 3) and 40 (mmol dm 3); [4] E

Total: [9]

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9700 BIOLOGY





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1 (a) (i) a mesophytic plant loses more water than a xerophytic plant; Allow: any variation on the basic idea, but it must include a plant and water loss. Do not allow: loss in xerophyte greater than mesophyte Ignore: any ref. to external conditions / water uptake [1] P

(ii) 8 of: independent variable: 1. ref. to shoots / leaves of different types of plant / xerophyte and

mesophyte / type of plant used; 2. ref. to similar surface area; dependent variable 3. ref. to measuring / recording the movement (of water) along the

capillary; 4. ref. to time (of water movement) / description of measuring time; control variables (max 3) 5. ref. to same (environmental) conditions; 6. ref. to inserting / cutting shoot under water / cutting shoot at an angle; 7. ref. to drying leaves before measuring; 8. ref. to airtight seal (around shoot) / airtight apparatus / no air locks; procedure 9. ref. to using syringe to set (water level) in capillary; 10. ref. to leaving until steady rate / equilibrate; reliability 11. ref. to repeats / replicates – min 3 and mean value; safety: 12. ref. to a low risk experiment;

1. Allow: named examples of

xerophyte / mesophyte 2. Ignore: mass Allow: same / similar number of

leaves 3. Do not allow: upwards movement Ignore: dye 4. Do not allow: if an inappropriate time

is specified e.g. seconds 5. Allow: for any example, light /

humidity / temperature 8. Ignore: watertight 9. Ignore: ref. to indicator 11. Allow: to remove anomalies 12. Allow: example of appropriate safety

e.g. care in cutting shoots / pushing capillary through a bung [8] M

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(iii) ref. to finding surface area of the capillary;

ref. to multiplying (surface area (πr2)) by distance moved; OR use syringe to push water back to original position; measure volume from the syringe: OR idea that the capillary is pre-calibrated; (and) find the volume from the distance moved / read from scale;

Allow: both marks if formula for volume of cylinder is shown – any of these is acceptable

πr2 l / d / h

π

4

d2

l / d / h;

π

2

d2

l / d / h; [2] D

(b) 2 of: axes correct orientation and labelled appropriately for type of graph; mesophyte shown as having higher water loss / rate of water loss; Allow: marks on a horizontal bar chart

Line Graphs and Bar Charts: y axis – rate / water loss / distance moved (by water or meniscus) / rate of transpiration Line Graph x axis – time Allow: lines that start at 0 Bar Charts x axis – type of leaf If the x axis is incorrect but y axis is related to water movement Allow: mark for the difference in water loss If axes reversed on a line graph, Allow: the mark for the lines if shown correctly Allow: marks on two graphs units are not required [2] P

rate

type of leaf

meso xero

water loss

time

meso xero

rate

type of leaf

xero

meso

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(c) (i) area =

410 / 000 10

36 / 0.0036 / 3.6 × 10 3 / 36 × 10 4 (m2);

water loss = 30

0.018 / 0.0006 / 6 × 10 4 (cm3 min 1);

rate = 3

4

10 3.6 / 0.0036

10 6 / 0.0006

×

×

)(m 10 36

min cm24

13

×

= 0.167 cm3 m 2 min 1;

Watch for area being halved or doubled 72 or 18 Allow: ecf for the calculation Look for the correct figures in the answer. This may be in a combined formula.

Allow: 0.17 / 610.& cm3 m 2 min 1

Allow: any other valid method of calculating rate Do not allow: fractions [3] D

(ii) t- test; the data has a normal distribution / continuous / not discrete / comparing two means / averages;

Allow: correct reason for t-test even if the name is incorrect Do not allow: to compare 2 sets of data [2] D

(d) 3 of: 1. mesophyte has greater mass loss / water loss / transpiration (than a

xerophyte); 2. less mass / less water is lost / less transpiration over time by (both)

leaves / lower side of leaves / upper side of leaves covered; 3. both leaves / xerophyte / mesophyte lose more mass / more water /

transpire more from the lower side of the leaf / when the upper surface is covered;

4. xerophyte loses almost no water from the upper side / loses most of its water from the lower side of the leaf;

Allow: reverse arguments for points 1–4 Allow: use of figures for points 1–4 1. Allow: if refer to upper and lower

surface of leaves Allow: 5. there are more stomata on the

lower surface (of both leaves); 6. xerophyte has fewer stomata on

lower side than the mesophyte / mesophyte has more stomata on lower side than a xerophyte;

7. mesophyte has stomata on both sides of the leaf;

8. xerophyte may not have any stomata on upper side;

9. xerophyte has thicker cuticle than mesophyte;

Do not allow: guard cells [3] C

Total: [21]

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2 (a) 2 of: ref. to culture medium / growth medium / nutrient; ref. to constant volume / concentration; ref. to amino acid; ref. to constant volume (of both types) added; ref. temperature; ref. to suitable method of providing constant temp. ref. to aeration; ref. to a method of supplying oxygen / air; ref. to pH; ref. to buffers / named buffers;

Do not allow: amount for any quantitative answer. Do not allow: ref. to cell numbers or time Allow: ref. to fermenter features – water jacket (+ monitor) water bath must refer to a constant / stated temperature Allow: ref. to fermenter features – sparger / air lift

[2]

[2]

P

M

(b) Increase in number of cells (after 6 days); number of cells at beginning / previous

Allow: ratio of increase in cells to the initial number of cells. Ignore: percentages [1] D

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(c) glutamine: Support 1. stimulates / shows an increase and ref to any figure or range between

0.1–10 (mmol dm-3); Not support 2. does not stimulate / inhibits / shows decrease at 20 / 40 (mmol dm-3); glutamic acid: Support 3. does not stimulate / inhibits / shows a decrease at 0.1 / 0.2 / 0.5 / 40

(mmol dm-3); Not support 4. shows little effect on growth / too inconsistent / does not show any

trend (to draw any conclusion); Not support 5. at 10 (mmol dm-3) / 20 (mmol dm-3) appears to increase growth; anywhere in answer: Support 6. results should be reliable as means of 50 counts (per culture) / large

number used; Not support 7. cell counting procedures are estimates / prone to error;

Cause and effect must be correct – watch for cell increase and amino acids concentrations being reversed. Allow: glutamate for glutamic acid 2. Allow: no cells / no growth / no

changes Do not allow: cells are dead / no

cells 5. Allow: may be anomalous results at

these concentrations For comparisons between figs. of glutamine and glutamic acid: for appropriate use of figures max 2. mark points 6 and 7 can also be awarded. Support 8. more growth with glutamine than

glutamic acid between 0–10 (mmol dm-3);

Not support 9. more growth with glutamic acid than

glutamine at 20 (mm dm-3) and 40 (mmol dm-3); [4] E

Total: [9]

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Documents

9700 May June 2010 All Mark Schemes