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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary Level and GCE Advanced Level

MARK SCHEME for the October/November 2010 question paper

for the guidance of teachers

9700 BIOLOGY

9700/11 Paper 1 (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 October/November 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

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Mark Scheme: Teachers’ version Syllabus Paper

GCE A/AS LEVEL – October/November 2010 9700 11

© UCLES 2010

Question Number

Key Question Number

Key

1 D 21 C

2 B 22 B

3 A 23 D

4 A 24 C

5 B 25 B

6 B 26 A

7 C 27 D

8 A 28 B

9 D 29 C

10 A 30 B

11 C 31 B

12 C 32 A

13 B 33 A

14 D 34 D

15 B 35 D

16 A 36 D

17 B 37 D

18 C 38 B

19 B 39 A

20 B 40 D

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9700 BIOLOGY




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Question Number

Key Question Number

Key

1 D 21 C

2 C 22 D

3 B 23 A

4 B 24 A

5 C 25 D

6 B 26 B

7 C 27 A

8 C 28 D

9 D 29 A

10 B 30 B

11 D 31 D

12 D 32 D

13 A 33 A

14 C 34 B

15 B 35 B

16 A 36 D

17 B 37 C

18 C 38 B

19 C 39 C

20 A 40 C

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9700 BIOLOGY




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© UCLES 2010

Question Number

Key Question Number

Key

1 B 21 D

2 D 22 D

3 C 23 A

4 A 24 B

5 A 25 A

6 C 26 B

7 B 27 B

8 B 28 D

9 A 29 D

10 B 30 C

11 B 31 C

12 A 32 B

13 D 33 B

14 C 34 B

15 C 35 A

16 C 36 B

17 D 37 B

18 D 38 A

19 A 39 D

20 D 40 B

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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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© UCLES 2010

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

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1 (a) community ; niche ; A role second trophic level / first level consumers / primary consumer level ; A other appropriate terms [3] (b) loss (of energy-containing food in producers or in grazers) in indigestible parts / not being absorbed / faeces / egestion ;; one mark for producer, one mark for grazer excretion (in, grazers / herbivores / primary consumers) ; respiration (in, grazers / herbivores / primary consumers) ; loss of energy in movement / AW (in, grazers / herbivores / primary consumers); AVP ; e.g. heat energy [max 2] [Total: 5] 2 (a)

structure trachea bronchus bronchiole alveolus

ciliated epithelium � � � �

goblet cells � � � / � �

cartilage � � � �

smooth muscle � � � �

one mark each row [4] (b) (i) athlete takes a deep breath and then breathes out as much air as possible / AW ; suitable method to record this, e.g. spirometer / breathing out into a bell jar of water ; [2] (ii) 0.5 dm3 / 500 cm3 ; [1] (c) reduced supply of blood to, heart / cardiac, muscle ; reduced supply of glucose (to cardiac muscle) ; R no reduced supply of oxygen (to cardiac muscle) ; R no less aerobic respiration / (more) anaerobic respiration (of cardiac muscle) ; build up of, lactate / carbon dioxide ; ref. limited cardiac output ; AVP ; e.g. ref. to consequences to (muscles of) body with reduced blood supply, ref. to

pain caused by angina R heart attack / AW [3]

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(d) damages, lining of arteries / endothelium ; accept once speeds up (atheromatous / fibrous) plaque development ; accept once increases chance of blood clotting / promotes thrombosis ; accept once nicotine increases heart rate / AW ; increases blood pressure ; makes platelets ‘sticky’ ; decreases blood flow to, extremities / AW ; constriction of blood vessels ; (max 2) carbon monoxide combines with haemoglobin / forms carboxyhaemoglobin / higher affinity for

haemoglobin (than oxygen) ; reduces oxygen-carrying capacity / AW (in context of, haemoglobin / blood) ; promotes release of damaging free radicals / peroxides / superoxides / oxidising agents ; causes, platelets and neutrophils to stick together / platelets to stick to endothelium ; ref. hypoxia damage to cardiovascular system ; (max 2) [max 3] [Total: 13] 3 (a) accept ora penalise once if refs. in context of rates e.g. faster no cells remaining, correct concentration value given (accept up to 0.26%) ; 100% / AW, cells remaining, ref. from 0.86%–0.9% / AW ; steep increase in percentage cells remaining between 0.5–0.8% ; A to 0.7% if next

marking point included steepest increase between 0.7–0.8% ; comparative data quote to support ref. to increase ; [max 3] (b) max 5 if no mention of water potential anywhere in the answer correct use of term osmosis linked to water potential (in context of high to low) ; 0% and 0.7% (net) water in (to red cells) ; 0%, all cells burst / (haemo)lysis of all cells ; general ref. to bursting at 0.7%, some cells burst ; ora either concentration ; cell membrane cannot withstand pressure ; (0.7%) (remaining) cells swollen / cell volume increases ; 0.7% water potential gradient not as steep as in, water / 0% ; 1.5% (net) loss of water from cells ; cells, shrink / AW or cell volume decreases ; A descriptions relative to biconcave disc shape [max 6]

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(c) 4, oxygen molecules / O2, per (molecule of) haemoglobin ; (forms) oxyhaemoglobin (in lungs) ; A marking points 1 and 2 as equation ref. oxygen remains bound until blood in area of low pO2 / high pCO2 / high(er)

temperature ; A in area of respiring tissues (max 3) carbon dioxide combines with haemoglobin ; terminal, amine / amino, group of haemoglobin ; A –NH2 carbamino-haemoglobin ; R carboxyhaemoglobin ref. to hydrogen ions from carbonic acid ; ref. carbon dioxide remains bound until blood in area of low pCO2 / high pO2 ; [max 4] (d) (i) 19.7 / 20 (%) ;; allow 1 mark if incorrect answer but correct working shown 7.3 – 6.1 / 6.1 × 100 / 1.2 / 6.1 × 100 [2] (ii) partial pressure / AW, of oxygen is, low / lower than at sea level ; haemoglobin less well saturated ; more red blood cells / more haemoglobin ; compensates for, smaller volume of oxygen absorbed (per red blood cell) / lower

saturation of haemoglobin ; A ref. to tissues receiving sufficient oxygen AVP ; e.g. ref to erythropoietin (EPO) [max 3] [Total: 18] 4 (a) (i) Vibrio cholerae ; [1] (ii) active transport / described as movement against concentration gradient ; A facilitated diffusion / described [1] (iii) (bacteria) leave infected person in faeces / AW ; (bacteria) enter water supply / AW ; A idea of contaminated, food / utensils (bacteria) ingested by uninfected person ; [3] (b) must be in context of B-lymphocytes / B-cells / plasma cells max 3 if T-cells secondary response A ora presence of memory cells / AW (giving larger numbers) ; ref. increased chance of, encountering antigen / antigen presentation / clonal selection ; ref. larger numbers cells following, clonal expansion / AW (cf primary response) ; (so) shorter duration for onset of antibody production ; (so) higher antibody concentration ; secondary response antibody production (by plasma cells) lasts longer ; AVP ; e.g. faster rate, plasma cell / antibody, production, ref. longer-life of cells

involved in secondary response [max 4]

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(c) 1 poor sanitation / no treatment of faecal waste / AW ; 2 contamination of (drinking) water supply ; 3 poverty, qualified / poor living conditions 4 poor hygiene ; 5 poor / lack of, (health) education about transmission ; 6 ref to natural disasters ; e.g. assistance / aid / medical help / AW, cannot arrive in

time 7 ref. refugees / displaced people ; 8 lack of, water purification equipment / bottled water / AW ; 9 no rehydration therapy available (at time when needed) ; 10 no (effective) vaccine ; 11 further detail ; (bacteria live in gut, where immune system is not effective) 12 AVP ; e.g. contamination of vegetable plots with faecal waste, ref. to different

strains [max 4] [Total: 13]

5 (a) (i) β glucose ; [1] (ii) glycosidic ; [1] (b) many hydrogen bonds within the molecule ; idea of parallel chains / AW ; hydrogen bonds between cellulose molecules ; to form microfibrils ; held together by more hydrogen bonds to form fibres ; [2 max] (c)

function letter from Fig. 5.1

organelle that contains DNA H

structure that transports cell wall material to the cell surface membrane A

site of transcription H

site of ribosome synthesis J

site of photosynthesis D

[4] (d) polypeptide / protein, in (cisternae of) RER ; to Golgi (apparatus / AW) ; modification / glycosylation / packaging ; vesicle(s) formed / transport in vesicle ; A vacuole membrane of vesicle fuses with cell surface membrane ; exocytosis / described ; [max 3] [Total: 11]

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9700 BIOLOGY





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

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1 (a) (i) transcription first process and exocytosis final process ; correct order for remaining three processes (3, 4, 2) ; [2] accept words and mixture of words and letters (ii) F ; A / D A ; C D ;

events order of events

cell location (letter)

exocytosis 5 F cell membrane ;

protein modification 3 A / D A+D

Golgi and/or RER ,

secretory vesicle formation 4 A Golgi ;

transcription 1 C nucleus ,

translation 2 D RER ;

[3] (b) 1 vesicle / vacuole, moves towards, cell, surface / membrane ; A plasma membrane R if lysosome 2 fusion / described, of vesicle with membrane ; R attach / bind / combine 3 ref. to (fluid nature of) phospholipids ; 4 contents / AW, secreted / released / exported / removed / emptied / excreted ; A waste material / digested material 5 active process / energy-requiring / ATP used / AW ; R ‘active transport’ R endocytosis [max 3] (c) (i) AUG ; [1]

(ii) 1 secondary structure / α-helix / β-(pleated) sheet ; 2 tertiary structure / description / folding / complex 3D shape ; 3 formation of named bond(s) ; R if peptide bond in list 4 quaternary structure / description (e.g. assembly of polypeptides) ; 5 glycosylation / formation of glycoproteins / addition of carbohydrate(s) or sugar(s) ;

R hydrocarbon chain 6 addition of, non-protein portion(s) / prosthetic group(s) / named example ; A haem / iron / Fe / copper / Cu / magnesium / Mg / AW 7 removal of some amino acids ; R one amino acid 8 polypeptide(s) cut into two or more pieces ; 9 AVP ; e.g. ref. to exposure to water molecules and folding R ref. to amino acids coded for by stop codons [max 2] [Total: 11]

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2 (a) communicable / transmissible / contagious / transferable / AW ; A passed from one (infected), host / organism / one person, to another A ‘passed on’ caused by, a pathogen / microorganism / at least two named types of pathogen ; A virus, bacterium, fungus, protoctist, worm ; R parasite unqualified by two types [max 2] (b) Plasmodium, falciparum / ovale / vivax / malariae ; A phonetic spellings for specific name, A plasmodium R if specific name first, [1] (c) (i) (only) female feeds on blood / male does not feed on blood ; female requires blood (protein) for (development of) eggs ; (only) female carries, pathogen / disease-causing organism / Plasmodium / parasite ; A (only) female transmits the disease (only) female is vector ; ora ignore female carries, the disease / malaria [max 1] (ii) anti-coagulant (in saliva) is passed when mosquito, sucks blood / feeds / bites / takes a

blood meal ; anti-coagulant prevents blood clotting when mosquito, sucks blood / feeds / bites / takes

a blood meal ; [max 1] (iii) in marking accept Plasmodium / pathogen / causative organism / malarial organism where parasite is given

below short time (in blood plasma) for exposure to cells of the immune system / AW ; next stage(s) of life cycle inside cells ; A sporozoites into merozoites in liver / merozoites into schizonts in red blood cells parasite gains, food / energy, from cells ; parasite, reproduces / multiplies, inside (liver / red blood) cells ; damage to / bursting of / lysis of / impaired function of, cells ; (antimalarial) drugs cannot penetrate (liver / red blood) cells ; parasite, concealed / ‘hides’, from host immune system ; A antigen concealment ; no symptoms, until parasite leaves cells / while parasite is in cells ; idea that people incubating disease are symptomless ; A symptomless carriers idea that treatment unlikely to prevent spread from infected person ; AVP ; examples different stages provide problems with drug / vaccine development AVP ; mode of action of potential drugs – block attachment sites on cells parasite in blood cells allows testing by taking blood samples further development of any idea given above [max 2]

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(d) if virus / bacterium / disease used instead mark to max 3 in marking accept Plasmodium / pathogen / causative organism / malarial organism where parasite is given

below distribution described for one mark either (mainly in) tropics / between the tropics or any two named, areas and/or countries, affected ; e.g. areas (sub-Saharan) Africa, Central America, South America, South Asia, Central

Asia, Middle East, Caribbean e.g. countries India, Sri Lanka, China, Vietnam, Cambodia, Brazil, Kenya discussion to max four 1 (areas where) both parasite, and, vector / mosquito / Anopheles, are present ; 2 Anopheles / mosquito / vector, survives / breeds / lives, in, hot and humid areas / moist

tropical areas ; ora A standing / stagnant, water 3 parasite, needs to reproduce within the mosquito (at temperatures above 20°C) ; 4 eradicated in some countries / any e.g. (USA, Italy) ; 5 ref to LEDCs and, poor / non-existent, control programmes ; A poor health facilities / poor drug supplies / AW 6 mosquitoes resistant to, DDT / insecticides / pesticides ; 7 parasite resistant to, chloroquine / drugs ; 8 link between human population density and Anopheles ; e.g. human activity provides (lots of) breeding sites for Anopheles 9 occurs where named high risk group(s) exist ; e.g. refugees, HIV-positive pregnant women (more likely to pass HIV to unborn

children), (young) children 10 (outside tropics) disease spread by, travellers / tourists / migrants / refugees ; 11 AVP ; most cases / over 90% cases, in (sub-Saharan) Africa not, at high altitude / in deserts different species of Plasmodium differ in geographical distribution / AW misdiagnosis (so not reported) changing pattern linked to, global warming / changes in land use / deforestation /

irrigation / other relevant named R references to sickle cell [max 4] [Total: 11]

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3 (a) spherical / ball-shaped / AW ; A round(ed) / circular has tertiary structure ; R 3D hydrophilic / polar, (R) group(s), on outside / face to watery exterior ; hydrophobic / non-polar, (R) group(s), in centre ; water soluble ; [max 3] (b) (i) idea that plant cell walls and fungal cell walls have different components fungal cell walls made of, glucans / chitins / fungal cellulose / different components to

plant cell walls ; A peptidoglycan / murein A plant cell walls contain cellulose, but fungi do not idea of specificity in context of question enzymes are specific ; A specificity explained e.g. both substrates not complementary / shape of active site

specific to one substrate [2] (ii) 1 (at optimum pH) maximum / peak, activity ; A most efficient / works best 2 above / below, optimum, activity declines ; A description / graph sketched with pH and rate / activity 3 changing pH changes hydrogen ion concentration ; 4 hydrogen / ionic, bonds (between amino acids), break / disrupted ; 5 hydrogen / ionic, bonds, important in maintaining shape of, tertiary structure / active

site ; R 4 and 5 if refer to disulfide, hydrophobic interactions, peptide at sub-optimum pH 6 active site / tertiary, shape altered ; A enzyme denatured 7 charges at the active site may be affected ; 8 further detail ; e.g. transfer of electrons may not be possible 9 the substrate may be altered by pH changes ; R cell wall unqualified 10 (therefore) substrate no longer fits / ES complexes not formed ; [max 3] (c) osmosis, defined in terms of water potential / used in correct context ; 0% and / or 0.4% higher / less negative, water potential outside so water enters ; 0%, higher / less negative, water potential than 0.4%, so cells burst ; ora 0.9% equal / same, water potential inside and outside cells, water in = water out ; A no net movement of water / ref. to isotonic / no water potential gradient R ‘no osmosis’ / no movement of water 1.5% and / or 3.0% lower / more negative, water potential outside so water moves out ; 3.0%, lower / more negative, water potential than 1.5% so cells, smaller / AW ; [max 4] (d) cells, increase in size / burst ; A vacuole increases in size R becomes turgid no cell wall to, prevent cell bursting / withstand (turgor) pressure ; A idea that cell membrane alone cannot withstand increase in size / bursting [2] [Total: 14]

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4 (a) vaccine

; macrophages

antigens lymphocytes

; mitosis

plasma cells and Th-lymphocytes ; [3] no ecf from (a) to (b) (b) 1 active (artificial) immunity ; 2 memory cells / immunological memory ; 3 idea that many specific, B-cells / T-cells / lymphocytes, in the body ; A large(r) clones of specific, B- / T-cells or lymphocytes actual invasion by the pathogen 4 fast secondary (immune) response ; 5 fast increase in antibodies / immediate production of antibodies ; ignore incorrect type of cell secreting antibodies 6 high(er) concentration of antibodies are produced ; A more antibodies produced 7 pathogen destroyed before person becomes ill / AW ; R antigen A pathogen do not, increase in number / infect cells / AW [max 3] (c) two points to look for (if) most / sufficient / many / AW, people / children, immunised / vaccinated ; A herd immunity reduces the pool of infected, people / children, in the, community / population ; A fewer people can catch disease and be source of infection A protects those unvaccinated as, disease / illness, does not spread A less chance of transmission A pathogen cannot develop in immunised people A reduced exposure to pathogen [max 2] [Total: 8]

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5 (a) glycogen ; [1] (b) xerophyte / xerophyllic ; A phonetic e.g. zerophyte [1] (c) haploid (cell) ; A monoploid [1] (d) (primary) producer ; R first ignore autotrophic [1] (e) (nitrogen) fixation ; A nitrogen fixing bacteria [1] [Total: 5] 6 (a) (i) squamous / pavement (epithelial) ; [1] (ii) stretch / expand, on inspiration and recoil on expiration ; R contraction (stretch) to increases, surface area / volume of air, for, diffusion / gas exchange ; (recoil) to help, expel air / force air out ; A carbon dioxide A if destroyed then cannot expel air prevent alveoli, bursting / breaking / AW ; ref. to emphysema if elastic fibres destroyed ; [max 2] (b) award two marks if correct answer (anything in range 336–346) allow +/– 1 mm in reading the line (74–76 mm)

75000 µm / 220 µm = 341 ;; if answer incorrect, award one mark for correct measurement with unit and division by 220 award one mark if correct answer given to one or more decimal places [2] (c) look for two ideas – follow usual rules for marking numbered answer lines thin, alveolar wall / epithelial lining / AW ; A short diffusion distance (between air in alveolus and blood in capillary) A squamous cells are thin R thin, membrane / cell membrane R large surface area surrounded by, capillaries / capillary network ; A close contact with, capillaries / blood (vessels / cells) A many capillaries A large area of alveolus in contact with, capillaries / blood [2]

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(d) max 3 if no ref. to diffusion (named) gas(es), diffuse down, pressure gradients / concentration gradient / AW ; A from high(er) partial pressure to low(er) partial pressure A high(er) concentration to low(er) concentration ignore ‘along a concentration gradient’ in the answers accept the following AWs capillaries / haemoglobin for blood lungs for alveoli body for tissues lungs valid statement linking information in table below – 1 mark for each row comparison in partial pressure may be ‘higher / lower’ not both or high and low, but if not

then figures have to be given

blood ref. to gas

blood partial pressure

alveolar air partial pressure

gas exchange

pO2 5.33 / lower 13.87 / higher into blood from alveolus

;

in pulmonary artery / entering alveolar capillaries

pCO2 6.00 / higher 5.33 / lower out of blood into alveolus

;

respiring tissue valid statement linking information in table below – 1 mark for each row

blood ref. to gas

blood partial pressure

tissue partial pressure

gas exchange

pO2 13.33 / higher < 5.33 / lower into tissue from blood

;

in systemic artery / entering tissue capillaries

pCO2 5.33 / lower > 6.00 / higher out of tissue into blood

;

[max 4] R differences between pO2 and pCO2 in the same place [Total: 11]

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9700 BIOLOGY





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

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1 (a) (i) A phospholipid ; (1) B protein ; ignore protein descriptions R glycoprotein R lipoprotein (1) [2] (ii) polar / hydrophilic, head / group ;

attracted to / AW, water / aqueous environment ; A water-loving ref. hydrogen bonding (polar head to water) ; non-polar / hydrophobic / hydrocarbon / fatty acid, tails / chains / groups ; repelled by / away from, water / aqueous environment ; AW R water-hating [max 3]

(b) C any one of

(channel) allows, ions / water / polar molecules / water-soluble molecules / hydrophilic molecules, to, pass through membrane / enter cell / leave cell ; R transport, without qualification e.g. across, through facilitated diffusion ; active transport ; (max 1)

D any one relevant e.g.

cellular recognition cell identification antigen cell signalling receptor binding site ref to hydrogen bonding with water / forms bond with water to stabilise membrane cell adhesion (max 1) [2]

(c) 1764 ;; if correct working (588 × 3) is shown, but no answer or incorrect answer, award one

mark [2] [Total: 9]

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2 (a) Mycobacterium tuberculosis / Mycobacterium bovis ; (1) (infected person) coughs / sneezes / spits / exhales / breathes out / aerosol (infection) / droplet (infection) / moist air (containing the pathogen) ; (uninfected person) inhales / breathes in / inspires ; ignore ref. to cattle treat ref. to virus etc as neutral (2) [3]

(b) 1 ref. patient does not complete course / takes inadequate dose / stops taking when

feels better ; 2 problems with continuing supply (of antibiotics) ; 3 not all bacteria killed ; 4 ref. mutation to become resistant ; R immune 5 likelihood of resistance increases if only one antibiotic used ; 6 ref. to changes in bacterium to enable resistance ; 7 ref. to changes in host cell (membrane structure) ; 8 AVP ; e.g. repeated exposure to different drug regimes (because of mp. 1) exposure to bacteria with different resistance [max 2]

(c) 1 ref. to, worldwide incidence of TB / TB found worldwide ; AW

2 highest, incidence / AW, (sub-Saharan) Africa / LEDC / developing countries ; 3 problem with, vaccine / BCG, qualified ; e.g. doesn’t work well, everywhere / in

Africa / in Far East doesn’t work well for all ethnic groups less efficient with age ref. cold chain / needs to be kept cold knowing when enough people vaccinated ref. to cost R vaccine doesn’t work 4 difficult to identify infected people / ref. symptomless carriers / AW ; 5 difficulty with, contact tracing / described ; 6 difficult to diagnose / time to diagnose (can infect others) ; 7 ref. to transmission from animals to humans ; 8 weakened immune systems / link with HIV/AIDS / TB is opportunistic ; 9 ref. social factor ; e.g. overcrowded living conditions, poor diet, remote areas 10 coordination of, vaccine / treatment ; 11 ref. to difficulty of administering, drugs / DOTS ; 12 lack / availability, of trained personnel ; 13 ref. to political problems ; e.g. war , unstable regimes, refugees, migration 14 cost, qualified with additional relevant point ; 15 AVP ; e.g. ref. to countries (e.g. Russia) with large area / low population density, 16 AVP ;ref. to quarantine problems, travel qualified, other social factor [max 5]

[Total: 10]

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3 (a) (i) glucose and fructose ; ignore monosaccharides [1] (ii) 1 active site, gives specificity ; A specific active site

ignore ref to specific substrate 2 substrate binds with active site or enzyme-substrate / E-S, complex forms ; 3 complementary (shape) / substrate fits into active site ; A ‘lock and key’ A matching shape R ‘same shape’ 4 induced fit / described ; 5 further detail of substrate and active site ; e.g. binding by hydrogen bonding,

e.g. transfer of electrons 6 lowers activation energy / described e.g. causes strain in substrate / AW ;

A Ea 7 breaks glycosidic bond ; 8 glucose and fructose / products, no longer fit / AW ; [max 4]

(iii) non-competitive (inhibition) ; irreversible (inhibition) ; [max 1] (b) (i) idea of, hydrolysis / product formation / further metabolism, lowering sucrose

concentration (in, companion cells / sink cells) ; maintains, concentration / diffusion, gradient (between phloem sieve tubes and, companion cells / sink cells) ; to remove sucrose from the phloem (sieve tubes) ; AVP ; e.g.ref. easier transport of, glucose / fructose, through membranes ; [max 2]

(ii) ref. facilitated diffusion out / may be lost from cells ;

products / glucose / fructose, are soluble / AW ; (so) will lower the water potential / water potential becomes more negative ; causes water to move into cells by osmosis ; A osmotic, problems / stress reactive / easily metabolised, qualified ; e.g. so interferes with, other metabolic processes / cell chemistry A more reactive than starch [max 3]

[Total: 11]

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4 (a) R if mark points are in context of secondary response sensitised / activated / AW, by (foreign) antigen / epitope ; accept once only correct ref. specificity ; accept once only production of memory cells ; accept once only T lymphocytes (T-helper / Th) secrete, cytokines / lymphokines ; (T-helper / Th) stimulate, B cells to divide ; A stimulate humoral response (T-killer / Tk / T-cytotoxic / Tc) secrete, perforin / hydrogen peroxide / AW ; A toxins R hormones (T-killer / Tk / T-cytotoxic / Tc) kill / destroy / AW, non-self cells / pathogens / infected cells ; (T-surpressor / Ts) ref., surpresses / reduces, response (on recovery) ; B lymphocytes formation of plasma cells ; antibody production ; [max 4]

(b) no more antigen / AW ;

(remaining) antibodies, removed from the blood / broken down (in the liver) ; R excreted plasma cells, are short-lived / begin to die / are not replaced ; no more antibody produced ; AVP ; e.g. detail of removal / macrophage engulfs, digested, peptide bonds broken [max 3]

(c) line drawn continuous with that provided ;

and rising more steeply before day 55 ; should start to rise from day 40 / should rise more steeply initially /should not remain as a plateau from day 40 reaches higher than primary response between day 45-55 and, peaks / plateaus ; must not go below the day 40 antibody concentration [3]

[Total: 10]

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5 (a) 1 thin (alveolar) walls / one cell thick / thin epithelium / squamous epithelium ; A pavement epithelium R thin cell wall R thin layer 2 short diffusion distance (between air and blood) ; 3 elastin / elastic fibres ; 4 stretch to increase surface area / increase surface area on inspiration / recoil to

expel air ; 5 ref. to maintaining, diffusion / concentration, gradient ; linked to marking points

above 6 large surface area for, diffusion / AW ; 7 some cells secrete surfactant ; 8 prevent collapse ; [max 3]

(b) (i) (cigarette / tobacco) smoking ;

infection ; inflammation / detail of inflammation ; (excessive) coughing ; [max 1]

(ii) max 1 for structure

fewer alveoli ; A alveolar walls broken down / fewer air sacs / alveoli burst / alveoli destroyed / reduced surface area R elastin broken down or fewer capillaries ; effect less gas exchange / less uptake oxygen / less removal carbon dioxide ; [2]

(c) look for symptoms

shortness of breath / breathlessness / AW ; A breathing difficulty wheezing (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 / reduced mobility / AW ; coughing / coughing up blood ; lots of / AW, mucus produced / much phlegm ; expanded / barrel, chest ; R refs to oxygen concentration of the blood R small vital capacity [max 3]

[Total: 9]

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6 (a) (i) (for) chlorophyll (structure / synthesis) ; (for) ATP functioning ; (for) enzyme functioning / enzyme cofactor ; signalling ion / regulates carbon fixation ; (for) DNA / RNA, synthesis ; stabilises, DNA / RNA, structure ; A required in translation (matrix of) bone ; [max 1]

(ii) mutualistic association / AW ; A ref. to mycorrhiza

qualified; e.g. further detail of relationship, named nutrients arrow from plant to fungi ref. (some) fungi are, parasitic / pathogenic (on plants) ; A pathogens leakage (from plants) of assimilates ; arrow from fungi to plant plants absorb nutrients, excreted by fungi / from decomposition by fungi ; [2]

(b) (i) 5th / 6th ; A top carnivore [1] (ii) idea of little energy available, at / towards, top / end, of food chain ;

too few organisms in level below ; expend much energy catching animals in trophic level below ; to obtain, a wider range of / varied, nutrients ; reduced competition ; [max 2]

(c) (i) community

all, populations of all species / organisms, living in a particular area, at one time / AW ; (1) habitat place / location / environment / AW, where, a population / an organism, lives ; A community (1) [2]

(ii) soil is source of nutrients for, plants / producers ;

plants / producers, provide energy for ecosystems ; ref. recycling nutrients (by soil organisms) ; ref. to importance of, carbon / nitrogen, in, organic / complex molecules ; AVP ; e.g. detail of nutrient cycling, maintains balance of nitrogen in air [max 3]

[Total: 11]

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9700 BIOLOGY

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




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GCE A LEVEL – October/November 2010 9700 31

© UCLES 2010

Question Expected Answers Marks Additional Guidance

1 (a) (i) Prepare the space below and record your results. [6]

1. table with all cells drawn

AND heading (top or left) surface area/cm2 or length/mm; [1]

Reject

• if units in body of table

• t or T

• additional columns details of method

PD

O r

ec

ord

ing

2

2.

(heading) time with units; [1]

3. collects data as times for all four pieces of potato; [1]

MM

O

co

lle

cti

on

2

4. (A) recorded time different from other pieces; [1]

Reject units must be clear so 1.2 or 1:2 must have min and s or secs

5.

records all times correctly as whole seconds or minutes with seconds; UNITS must be clear somewhere [1]

MM

O d

ec

isio

ns

2

6. replicate recorded; [1]

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© UCLES 2010

(ii) Identify two significant sources of error in your investigation. [2]

Reject temperature

Cause of error Error

1. 2. 3.

(dependent) timing /dropping/distance long pieces of potato ora shorter pieces (pieces of) potato

not accurate/delayed/different; different height to top there is shorter distance to surface longer distance to surface; stick to sides/bottom of tube don’t sink to bottom; [max 1]

4. 5. 6. 7.

(standardised variables) potato or position in potato or age or storage water left on potato (test)-tubes hydrogen peroxide

not same different/variety old; not same/different; not same size/height; concentration changes/decreases evaporates/degenerates/breaksdown; [max 1]

AC

E in

terp

reta

tio

n M

AX

2

8.

(independent variable) lengths/size/surface areas/volumes

not same different vary; [max 1] max 2 overall

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© UCLES 2010

(iii) Suggest how you would make three improvements to this investigation. [3]

1. same potato or position in same age or storage or fresh use micrometer/cork borer/vernier callipers; [1]

2. use same volume/mass/volume ratio more surface areas/sizes; [1]

3. use a wider container or smaller potato use deeper container use tubes of same size clamp tubes in vertical position; [1]

4. method to dry the potato lid to cover hydrogen peroxide; [1]

5. (collect oxygen) use a gas syringe or water displacement/oxygen sensor; [1]

AC

E i

mp

rov

em

en

ts

Ma

x 3

6. replicate/repeat; [1] max 3

(b) (i) Three of the values in table 1.1 are anomalous. Draw a circle around each of these values. [1]

MM

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n 1

all three figures circled;

[1]

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© UCLES 2010

(ii) Complete table 1.1. by calculating the missing value. [1]

AC

E

inte

rpre

tati

on

1

7; Allow 9.

[1]

(iii) Plot a graph of the data shown in Table 1.1. [4]

x-axis pH Reject t O

AND y-axis time/s or seconds; [1]

Must have units

Reject awkward scale S

scale as each pH to 2 cm AND 5 seconds to 2 cm; [1]

Must use more than half grid in x and y.

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

P

correct plotting using crosses/dots in circle only;

intersection of cross must be clear to show plot. NO cross must touch the line for the next square.

[1]

PD

O l

ay

ou

t 4

L straight line through points; error carried forward if scale or plotting incorrect

quality – no thicker than on grid, not feathery for the complete line. joining plots –

• ruled lines plot to plot

• curve through all plots extrapolation

• not beyond x- or y-axis [1]

Reject if any extrapolation

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© UCLES 2010

(iv) Explain the relationship between pH and the enzyme catalase shown in the data. [3]

(in correct context of pH and activity (below 7/acid or above 7/ alkali) effect on) structure of protein/enzyme/active site or bonds

changed/altered/destroyed/no longer complementary broken; [1]

(below 7 or above 7) do not accept collision(s)/react fewer ECSs (enzyme substrate complexes) or less/no substrate can bind/combine/attach fit into enzyme/active site; [1]

AC

E c

on

clu

sio

n 3

(below 7/above 7) (enzymes) denatured; [1]

[Total: 20]

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© UCLES 2010

2 Make a large, high-power drawing to show the details of five of the structures specialised for gas exchange (alveoli). The walls of one alveolus must be touching the walls of at least two other alveoli. Label where gas exchange takes place. [5]

Reject if drawn over the print of question

Reject

• thick lines

• feathery lines

• 2 ‘tails’ or overlaps or gaps

PD

O l

ay

ou

t 1

1.

clear, sharp, unbroken continuous lines

AND no shading

AND use most of the space provided; [1]

2. five structures drawn AND at least 3 structures touching; [1]

MM

O

co

lle

cti

on

2

3. at least three alveoli different shapes/sizes

AND thickness of one wall irregular; [1]

4. (walls with) at least 2 cells drawn

AND at least one nucleus drawn; [1]

MM

O d

ec

isio

ns

2

5. Reject

• if any label is biologically incorrect e.g. cell wall.

• label within drawn area

• into centre of alveolus correct label with label line to wall of alveolus; [1]

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© UCLES 2010

(b) (i) Draw a large plan diagram of the bronchiole shown in Fig. 2.1. Label the lumen. [5]

Reject if drawn over the print of question

Reject

• thick lines – than grid

• feathery lines

• 3 ’tails’ or overlaps or gaps P

DO

la

yo

ut

1

1.

clear, sharp, unbroken lines

AND no shading

AND use most of space provided; [1]

2. no cells drawn AND width of base of fold greater than width of tip of fold; [1] M

MO

co

lle

cti

on

2

3. 13 to 15 folds in lumen; [1]

4. shows indentation; [1]

MM

O d

ec

isio

ns

2

5. Reject

• if any label is biologically incorrect e.g. cell wall.

• label within drawn area correct label with label line to lumen;

[1]

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© UCLES 2010

(ii) Calculate the ratio of the mean thickness of the outer layer of the bronchiole compared to the mean thickness of the wall of the blood vessel shown in Fig. 2.1. [4]

Reject If lines not shown on both bronchiole and blood vessel

shows one measurement on each of bronchiole and blood vessel; [1]

Reject If no units If not both same units If metres or converted to metres or micrometres or standard form M

MO

co

lle

cti

on

2

(one bronchiole measured) to nearest 0.5 mm

AND mm; [1]

shows mean adds measurements

AND shows division by number of measurements; [1]

MM

O d

ec

isio

ns

2

Reject

• If given as decimal :1

• If smaller to larger number

• If include units answer is larger whole number to smaller whole number or leaves as fraction;

[1]

Either must be to lowest common denominator

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© UCLES 2010

(iii) Prepare the space below so that it is suitable for you to compare the observable features of the bronchiole and blood vessel in the photomicrograph Fig. 2.1. [6]

organise as a table/ Venn diagram/ ruled boxes

AND headed bronchiole and blood vessel

AND differences opposite each other;

[1]

bronchiole blood vessel

PD

O r

ec

ord

ing

2

heading for similarities/similarity/compare (with contrast)/same; [1]

MM

O

de

cis

ion

1

attempted one similarity ;

[1]

Do not accept

• tick and cross without a key

• diagrams

• 3-D description

• incorrect biological terms e.g. endodermis

bronchiole blood vessel

similarity

S max 1

lumen smooth muscle epithelium

feature

D1 lumen shape irregular/lobed/folded smooth/oval/not folded;

D2 lumen size small(er) larg(er);

D3 folds many/present none/absent;

D4 no. of layers more/2 less/1;

D5 outer/muscle layer/wall thick(er)/wid(er) thinn(er)/narrow(er);

AC

E i

nte

rpre

tati

on

3

D6 overall shape circular/round oval/squashed circle; [max 3]

If no organisation if in same sentence or following sentences.

[Total: 20]

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9700 BIOLOGY





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© UCLES 2010

Question Expected Answers Additional guidance

1 (a) (i) Decide on the concentrations of copper sulfate solution you will use in your investigation. [3]

[1] any 4 or more (volumes/concentrations);

[1] (highest concentration) 0.3 to 0.15;

MM

O d

ec

isio

ns

3

[1] any three consecutive concentrations (including 0 if present) with two intervals

• the same

• or serial dilution by half

• or serial dilution by ten;

(ii) State which variable you will need to control when preparing the plant tissue samples. [1]

MM

O

de

cis

ion

1 [1] length or surface area or size or dimensions or volume;

Allow methylene blue

(iii) Describe how you will control this variable and prepare the samples of plant tissue. [2]

[1] (control) measure cut (methylene) rinsing/washing

the same any example of length 3 cm or less/size; excess

MM

O d

ec

isio

ns

2

[1] (prepare samples) use of scalpel/knife or ruler; (methylene blue) water

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© UCLES 2010

(iv) Prepare the space below and record your observations. [5]

Reject

• if units for % in body of table

• other units e.g. mol dm 3

[1]

table with all cells drawn AND heading (top or left) percentage conc(entration);

Reject

• if headings/columns for method/volumes/time 5 mins or size/lengths PD

O r

ec

ord

ing

2

[1]

(heading) colour or observations or description;

[1] (records clear separate observations/colours) after/during 5 min/before mixing

AND after mixing (after/at 5 min);

MM

O

co

lle

cti

on

2

[1] difference in the strength of colour between the first and last test-tube observations; Key e.g. + = colour

MM

O

de

cis

ion

1

[1] 5 or more concentrations or observation for water or replicate recorded;

(v) Suggest how copper sulfate solution affects plant cell membranes. [1]

AC

E c

on

clu

sio

n 1

[1] In correct context of increasing or just copper sulfate Idea of damages or destroys or makes more denatures (increases copper sulfate) increases (decreases copper sulfate) decreases (increases copper sulfate) decreases (decreases copper sulfate) increases

it or ((cell) membrane(s)) phospholipid(s) fluid mosaic (model/structure) (fully) permeable protein fluidity permeability selective permeability;

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© UCLES 2010

(vi) Identify three significant sources of error in your investigation. [3]

Reject temperature pH evaporation any errors which affect all test-tubes equally

Cause of error Error

[1]

(dependent) qualitative;

[1] [1] [1]

colour/colour change/observations mixing

difficult judging seeing; qualitative; more difficult to judge colour/colours the same;

AC

E i

nte

rpre

tati

on

MA

X 3

[1] [1] [1] [1]

(standardised variables) potato or position in potato or age or storage lengths/size/surface areas/volumes Allow mass staining/washing/handling/forceps potato/samples (into test-tubes)

not same different/variety old; not same; not same loses stain damages potatoes ends not stained or middle more stain; time not same/delayed time/not at same time; max 3

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© UCLES 2010

(vii) Suggest how you would make three improvements to this investigation. [3]

[1] same potato or position in same age or storage or fresh use micrometer/cork borer/vernier callipers/ruler with smaller divisions;

[1] leave in methylene blue longer/stronger concentration/more than 5 minutes idea of wash more;

[1] more/wider/narrower/different/examples range of concentrations or use burette or graduated pipette or smaller syringe or with smaller divisions;

[1] stagger start or do individually or use more stop clocks or use help;

[1] colorimeter or datalogger with light sensor; Reject calorimeter

AC

E i

mp

rov

em

en

ts

MA

X 3

[1] repeat or replicate; max 3

[Total: 18]

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© UCLES 2010

2 (a) (i) Draw a large plan diagram of a quarter of the specimen as shown in Fig. 2.1. Label the endodermis and cortex. [5]

Reject

• if drawn over the print of question

Reject

• thick lines-than grid

• feathery lines

• 3 ’tails’ or overlaps or gaps

PD

O l

ay

ou

t 1

[1]


AND no shading

AND uses most of space provided;

[1] no additional cells drawn AND (epidermis shows) only the correct quarter;

[1] epidermis drawn with two lines 3 mm or closer for most of length;

MM

O c

oll

ec

tio

n

3

[1] innermost line is wavy/undulating line;

Reject

• if any label is biologically incorrect e.g. regions belonging to other organs or animals.


MM

O d

ec

isio

n 1

[1]

correct label with label lines to cortex and endodermis ;

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© UCLES 2010

(ii) Make a high-power drawing of one large xylem vessel and the single layer of cells touching a quarter of the vessel’s circumference. Labels are not required. [5]

Reject


Reject

• thick lines – than on grid

• feathery lines

• 4 ‘tails’ or overlaps or gaps if double lines for all cells

• 1 if single line for any cell

PD

O l

ay

ou

t 1

[1]


AND no shading


[1] one xylem vessel drawn Ignore band inside

AND only single layer of surrounding cells ;

Reject if layer of cells all round xylem vessel If xylem vessel not circular/polygonal

[1]

(surrounding cells) (single layer) three to eight cells in a layer only; Allow not touching.

Reject any spaces if single line for cell walls. any gaps between cell walls – floating cells

MM

O c

oll

ec

tio

n 3

[1]

(all cells including xylem vessel) no enclosed spaces more than 1mm between adjacent double cell walls;

PD

O

rec

ord

ing

1

[1] cell walls drawn as double lines with middle lamella between three adjacent cells from surrounding cells;

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© UCLES 2010

(b) Prepare the space below so that it is suitable for you to record the observable differences between the specimens on K1 and that in Fig. 2.2. [4]

PD

O

rec

ord

ing

1

[1] organise as a table/Venn diagram/ruled boxes

AND headed K1 and Fig 2.2

AND first difference opposite each other;

K1 Fig 2.2

feature K1 Fig.2.2

hairs/trichomes Ignore root

no hairs/trichomes; 1 epidermis

thick(er) or more/2 layers thin(ner) or few(er);

2 cortex yes/present/more no(one)absent/less;

3 endodermis yes/present no(one)/absent;

4 pericycle yes/present no(one)/absent;

5 vascular bundles xylem

ring/centre/no(one)/absent/fewer

scattered/AW/towards edge/yes/present/more;

either way round for present/absent/under epidermis;

6 thickened cells/ sclerenchyma Allow collenchymas bundle sheath/AW

no(one)/absent yes/present;

yes/present no(one)/absent; 7 pith pith/centre cells

rounded angular/pentagonal/AW;

AC

E i

nte

rpre

tati

on

3

[1]

[1]

[1]

[1]

[1]

[1]

[1]

[1]

[1]

[1]

[1] [1]

8 air spaces/lenticels stomata

yes/present no(one)/absent

no(one)/absent; yes/present;

Ignore


• ref. to non-observable features

• 3D shapes max 3

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© UCLES 2010

(c) (i) Plot a chart of the data shown in Table 2.1. [4] MAX 2 for O and S if line graph drawn

O [1]

x-axis content(s) AND y-axis conc(entration in) phloem or sieve tube/element (/)

µg cm 3;

Must have units

Reject scale on y-axis any other than 20 to 2 cm.

S [1]

scale as even widths to 2 cm

AND y-axis 20 to 2 cm;

Reject if y-axis scale is awkward if bars arranged differently from order of

table if horizontal lines are too thick – 1mm/half

square or not clear Allow bars if scale 20 to 2 cm. even if not 0 25 to 2 cm

P

[1] correct plotting of each bar;

horizontal top line must be clear, sharp and ruled to show plot line must be on horizontal line for sucrose line must be between two lines for all other contents

PD

O l

ay

ou

t 4

L [1]

each bar separate if vertical lines only then must be at least 1 cm apart.

AND quality – vertical lines no thicker than on grid, not feathery for the complete line; bars –

• ruled lines Reject irregular thickness

• labelled clearly with contents – any clear labels e.g. chemical formulae NH4, Ca, Mg, Na or mixture – underneath, must be directly below correct bar or inside bar or shaded with key.

Reject solid shading If line shading outside a bar

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© UCLES 2010

(ii) Calculate the percentage difference between the concentration of calcium ions in the xylem vessels and the concentration of calcium ions in the phloem sieve tube elements. [2]

[1] shows subtraction (190 – 85) divided by 190 multiplied by 100; (190/190 – 85/190) × 100 or (1 – 85/190) × 100

PD

O d

isp

lay

2

[1] Reject if no working Allow any answer less than 100 to no more than 3 significant figures 1 decimal place

AND percentage/%;

(d) Suggest why there is 120 µg cm–3 of sucrose in the phloem sieve tube elements. [2]

[1] (phloem sieve tube elements) (sucrose) transported leaf(ves)/allow type of leaf cell/source to roots/other tissues/sink(s);

AC

E c

on

clu

sio

ns

MA

X 2

[1]

(detail) load(ed) (in source) or (transported by) mass flow/bulk transport/translocation (sucrose) too large to move out of phloem or sieve tubes or xylem walls impermeable;

[Total: 22]

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9700 BIOLOGY





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GCE AS/A LEVEL – October/November 2010 9700 34

© UCLES 2010


1 (a) (i) Show clearly on Fig.1.1 what you would expect the contents of the test-tube to look like after 10 minutes. You will gain marks for clear labels. [2]

[1] line drawn level with half way mark AND more yeast drawn towards bottom of tube or another line to show a separate region;

AC

E

co

nc

lus

ion

s 2

[1] one label or description;

(ii) State the time intervals you will use and what you will use the graph paper scale to measure. [2]

uses 10 minutes AND at least three times (including 10) even time intervals between consecutive three;

[1]

Or one/two/two and a half minutes or two mins 30s intervals; Reject if does not divide into 10 e.g. 3 minutes

MM

O d

ec

isio

ns

2

[1] measures or describes measuring e.g. (use graph paper) to find distance/length

AND description of what is measured; e.g. from halfway mark to top of sediment or bottom of tube to top of sediment/or from Fig. 1.1/AW;

(iii) …decide on the volume of Y and the volume of each buffer solution to use. Describe all the steps you used to work out the volume. [1]

State the volume of Y and the volume of each buffer solution to use. [1]

[1] describes all following steps

• takes into account to (half-way) line

• takes into account 1 cm3 calcium chloride/C

• divides by half;

MM

O d

ec

isio

ns

2

[1] volume of Y equal to volume of buffer AND cm3 / ml on both;

Allow

• to 0.1 cm3

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© UCLES 2010


(iv) Prepare the space below and record your observations. [5]

[1] table with all cells drawn AND heading (top or left) pH;

Reject

• if units anywhere else except headings

• t or T

PD

O r

ec

ord

ing

2

[1]

(headings) time min(utes)

AND length/depth/height/AW with mm or cm;

[1] different results/observations for different pH minimum 2 pH;

MM

O

co

lle

cti

on

2

[1] recorded to 1 mm or 0.1 cm only; Reject if no units/if mixed units Allow as error carried forward whole or 0.5 units on graph paper

MM

O

de

cis

ion

1

[1] repeats recorded;

(v) Use your results to state the effect of pH on the yeast suspension. [1]

AC

E

co

nc

lus

ion

1

[1] (yeast settles) more / higher rate of

• at some pH

• or correct example of pH with results;

Reject activity

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© UCLES 2010


(vi) Identify one significant source of error in this experiment. [1]

cause of error error

(dependent variable) boundary/ top of layers or bubbles on surface or graph paper and test-tube

idea of finding measuring seeing determining judging; lining up;

AC

E i

nte

rpre

tati

on

ma

x 1

[1] [1]

[1]

(standardised variables) test-tubes sizes/ mixing/adding/readings

not constant not same/different/vary cannot be done at same time; max 1

(vi) State the degree of uncertainty of using the graph paper scale as a measure. [1]

AC

E

inte

rpre

tati

on

1

[1] +/– 2 mm; Reject % error Allow +/– 0.2 cm or +/– whole or 1 graph paper unit

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© UCLES 2010


(vii) Suggest how you could make this investigation as accurate as possible … as reliable as possible [3]

C control of any relevant variable; [1] [1]

(for volumes) use measuring cylinder/burette/graduated pipettes or tubes or smaller (divisions)syringes Or hold tube vertical in retort stand/attach graph paper to tubes;

A1 improving measurements to get a true value [1]

use ruler/graph paper, with smaller divisions/vernier calipers or colorimeter or collect and dry sediment or larger/more volumes so heights larger;

A2 [1]

set up each pH separately/stagger timing/longer time;

A3 [1]

more buffer solutions or examples of extra buffer/pH;

R1 improve method to get repeat data [1]

repeat or replicate;

AC

E i

mp

rov

em

en

ts m

ax

3

R2 [1]

weigh out (initial) mass of yeast ;

Allow for either accuracy or reliable

max 3

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© UCLES 2010


(b) (i) Plot a graph of the data shown in Table 1.1. [4]

Reject t/T O [1]

x-axis calcium chloride/CaCl(2) conc(entration)(/) m mol

AND y-axis time (/) min;

Must have units

Reject if awkward scale 0.25 to 2 cm S

[1] scale as 0.2 to 2 cm AND 20 to 2 cm;

error carried forward if incorrect O then must use more than half provided grid in x and y

Reject

• plotting if scale is awkward unless 0.25

• if only blobs/dots/blobs in circles.

P

[1] correct plotting using crosses/dots in circle only;

intersection of cross must be clear to show plot.

PD

O l

ay

ou

t 4

L [1]

straight line through points; error carried forward if scale or plotting incorrect

quality – no thicker than on grid, not feathery for the complete line. joining plots –

• ruled lines plot to plot extrapolation

• not beyond x- or y-axis Ignore

• 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.

Reject if any extrapolation beyond 0 or 1.0.

(ii) State the concentration of calcium chloride required for the yeast to sediment out at 40 minutes. [1]

MM

O

co

lle

cti

on

1

[1] correct reading of concentration to no more than 2 significant figures;

www.maxpapers.com



© UCLES 2010


[Total: 22]

2 (a) (i) Select a large vascular bundle and draw a large plan diagram of the vascular bundle. Label the xylem tissue. [5]

Reject if drawn over print of question

Reject thick lines

• feathery lines

• 4 ‘tails’ or overlaps or gaps PD

O l

ay

ou

t 1

[1]


AND no shading

AND uses most of the space provided;

[1] no cells drawn AND draws only one vascular bundle;

[1] (vascular bundle) shows an outline which encloses vascular bundle tissues;

MM

O c

oll

ec

tio

n 3

[1] (in one vascular bundle) wider at one end than the other (tapered) Or at least three regions shown;

Reject



MM

O d

ec

isio

n

1

[1]

correct label with label line xylem to region middle to tapered end;

www.maxpapers.com



© UCLES 2010


(ii) Make a high-power drawing of one trichome, with at least three cells, and one epidermal cell on each side touching the base of the trichome. Label the trichome. [5]


Reject

• thick lines – than on grid

• feathery lines

• 5 ‘tails’ or overlaps or gaps if double cell walls PD

O l

ay

ou

t 1

[1]

clear, sharp, unbroken lines in cell outlines

AND no shading


[1] 5, 6 or 7 cells;

MM

O

co

lle

cti

on

2

[1] cells drawn as a touching group AND cell walls as double lines with middle lamella in 3 adjacent (epidermal) cells;

[1] (cell or tip of trichome or broken) pointed or rounded Or (in trichome) one larger cell or large base cell;

Reject

• if any label is biologically incorrect e.g. labels belonging to other organs or animals.

• label within drawn area MM

O d

ec

isio

ns

2

[1]

correct label with label line to trichome;

www.maxpapers.com



© UCLES 2010


(b) (i) Calculate the ratio of the diameter of the vascular tissue labelled X to the total diameter of the plant organ labelled Y. [3]

PD

O

rec

ord

ing

1

[1] (measurements to same degree of precision) whole mm or 0.5 mm;

Allow 0.1 cm or 0.15 cm

[1] shows larger figure to or: smaller figure or larger figure divided by smaller figure;

PD

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2

[1] rounds to correct ratio e.g. 125:69 or leaves as fraction e.g. 125/69;

Reject if include units in answer Reject 1.86:1

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© UCLES 2010


(ii) Prepare the space below so that it suitable for you to describe the observable differences between M1 and Fig. 2.1. [5]

PD

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1

[1] organise as a table or Venn diagram or ruled connected boxes

headed M1 and Fig. 2.1

differences opposite each other;

M1 Fig. 2.1

Reject tick and cross without a key –

feature M1 Fig. 2.1

shape irregular/wavy/uneven/ starshape/swellings

oval/circular; Ignore regular

pith/hollow space/empty/ lumen/cavity Ignore vacuole

present/yes absent/no;

vascular tissue/bundle/ xylem

bundles/around edge/ scattered

stele/in centre;

number of vascular bundles/ tissue/xylem

(vascular bundles) more/(xylem)less

(vascular bundles) less/(xylem)lots/more;

thickened layer/stained layer/collenchyma/AW

present absent;

thick thin; outer epidermis

continuous/smooth rubbing off/flaky/AW;

trichomes/hairs present/yes/some/more Allow less

absent/no/none/fewer; Allow more

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[1]

[1]

[1]

[1]

[1]

[1]

[1]

[1]

[1] trichome shape hair-like/pointed irregular;

if no organisation then mark points only if in same sentence or following sentences. Allow differences even if not opposite each other. Allow difference on one side if e.g. use more or –er. max 4

[Total: 18]

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9700 BIOLOGY





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© UCLES 2010


1 (a) (i) Decide which other concentrations of ascorbic acid to make and complete Table 1.2, including the concentrations from Table 1.1. [3]

[1] 0.1% and 0.08%

AND any two other concentrations

AND all in ascending or descending order;

[1] for two other concentrations correct volumes to make 20 cm3

AND correct %;

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3

[1] any three consecutive concentrations with two even intervals the same e.g. 0.08, 0.06, 0.04 or serial dilution by half;

(ii) Prepare the space below to show the concentration of ascorbic acid and record your results including samples X and Y. [6]

Reject

• if units for % in the body of table

[1] table with all cells drawn AND heading (top or left) percentage conc(entration);

Reject

• if units for volume /drops in body of table

• if any additional headings for method e.g. volume of ascorbic acid

[1] (heading) volume/vol cm3;

PD

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3

[1] volumes recorded to 2 decimal places;

.

[1] volume or drops decrease from highest concentration to next highest;

[1] Reject if records less than 3 concentrations result for Y (water/0%) records lowest volume;

MM

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3

[1] replicate recorded;

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© UCLES 2010

(iii) Plot a graph of the results. [4]

Reject v O

[1]

x-axis percentage conc(entration)

AND y-axis vol(ume) cm3;

Must have units

Reject if awkward scale S

[1] scale as 0.02% to 2 cm AND sensible volume to 2 cm and uses more than half

grid;

Reject plotting if scale awkward if only blobs/dots/blobs in circles if extra plot for X value

P



PD

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ay

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L [1]

straight line through points; error carried forward if scale or plotting incorrect

quality – no thicker than on grid, not feathery for the complete line.

joining plots –


• line of best fit two plots plus even plots (+1) either side or even plots either side

• curve through all plots

line of best fit must end either at the horizontal line or the vertical line for each of the end plots i.e. highest and lowest concentration Reject if any extrapolation

(iv) Use your graph to estimate the ascorbic acid concentration of sample X. Show clearly on your graph how you obtained the ascorbic acid concentration. [3]

MM

O

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1

[1] shows clearly on graph result for X e.g. as single line from volume for X or as extra plot;

[1] correct reading of ascorbic acid concentration

AND answer to no more than 4 decimal places or three significant figures if 4 decimal places last figure must be 5 (or 0); A

CE

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2

[1] %;

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© UCLES 2010

(v) Identify two significant sources of error when finding the concentration of ascorbic acid in sample X. [2]


[1]

[1]

(dependent variables) drops stick to sides too many drops volume for Y colour change or same colour

idea of volume/number of drops/not counted/not included/too high/not accurate too many at once/end-point missed too small judging determining seeing when;;

[1]

[1]

[1]

(standardised variables) drop size/different pressure on syringe/syringe sticking/ mixing iodine evaporating/exposed to light

not same/vary/different;

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[1]

[1]

(independent variable) (ascorbic acid) evaporates or mixes with air concentrations

changes concentration/reacts; more/wider/narrower/different needed; max 2

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(vi) Suggest how you would make three improvements to this investigation. [3]

[1] more/wider/narrower/different/examples range of concentrations (ascorbic acid) use graduated pipette or smaller/more divisions/calibration syringe/burette;

[1] device/described for making drops/burette/titrate;

[1] (to identify the end-point) use colorimeter or have a standard colour to compare to or use white tile/paper;

[1] put drops in nearer to mixture or use a smaller test-tube/container or use a wider/larger test-tube/beaker/AW;

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3

[1] replicate/repeat/take more readings (each concentration); max 3

[Total: 21]

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© UCLES 2010


2 (a) (i) Draw a large plan diagram of the sector shown in Fig. 2.1 to include the outline of two vascular bundles. No details of the internal tissues of the vascular bundles are required. [5]

Reject


Reject

• thick lines

• feathery lines

• 3 ‘tails’ or overlaps or gaps PD

O l

ay

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t 1

[1] clear, sharp, unbroken lines

AND no shading


[1] no cells drawn AND only two vascular bundles drawn in outline only;

MM

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2

[1] rounded/pointed end;

[1] longest vascular bundle is less than half width at widest point of section;

Reject

• if any label is biologically incorrect e.g. cell wall or regions belonging to other organs or animals.

• additional label(s) within drawn area

MM

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2

[1] correct label C (can be within drawn area) to tissue below upper or lower epidermis;

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© UCLES 2010


(ii) Using high-power, draw a large plan diagram to show one large vascular bundle in detail. Label the phloem. [5]

Reject


Reject

• thick lines

• feathery lines

• 4 ‘tails’ or overlaps or gaps

PD

O l

ay

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t 1

[1]


AND no shading


PD

O

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ord

ing

1

[1] (details of) two regions separated from each other and from each cap;

MM

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1

[1] no cells two caps withdrawn;

[1] proportion of longest length of one cap is equal to or more than half the longest length between the caps;

Reject



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2

[1]

correct label with label line to phloem;

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© UCLES 2010


(b) Calculate the ratio of the thickness of the layer labelled B compared to the total thickness of the layer labelled A as shown in Fig. 2.2. [3]

Reject

• if no units

• metres.

MM

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[1] two measurements of A one between 17 to 19 mm and one between 12 to 14 mm or one combined measurement between 28 and 33 mm

AND one measurement between 38 to 40 mm;

[1] shows larger figure to smaller figure; Reject if converts to other units (than mm or cm) or standard form

PD

O

dis

pla

y 2

[1] (needs working) answer rounded to correct ratio e.g. 39 : 29; Reject if put units

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© UCLES 2010


(c) Prepare the space below so that it is suitable for you to record the observable differences between the specimens on slide L1 and in Fig. 2.2. [3]

MM

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1

[1] only observable differences;

Ignore


• ref.to non-observable features

• 3 D shapes

AC

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x 2

[1]

[1] [1] [1] [1] [1] [1] [1]

[1]

feature L1 Fig. 2.2

vascular bundles number arrangement relative sizes

lots/more chain different sizes or large and small

few/one/two centre same sizes;

semicircles /AW not semicircles or one end only;

caps shape cap

yes/present no/none/absent;

none/not visible or few(er) yes/more;

top/bottom/one side all round/sides;

stomata numbers position sunken no/none/absent yes/present;

tapered/pointed/elongated semicircle/rounded; leaf shape surface Reject regular irregular/rough smooth;

extra ring/inner layer/allow endodermis

no/none/absent yes/present;

max 2

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© UCLES 2010


(d) Describe how the observable features of Fig.2.2 support the conclusion that this is a leaf from a plant growing in a dry habitat. [3]

[1] sunken stomata or rolled/rounded to reduce the diffusion of water/decreases diffusion gradient;

[1] thick cuticle or thickened epidermis

to prevent or reduce evaporation of water;

[1] no spongy mesophyll layer or no air spaces

to prevent evaporation from cell walls;

AC

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AX

3

[1] rounder shape or rolled or fewer stomata smaller surface area to volume ratio

to increase humidity/decreases diffusion gradient;

[1] (in context of any of above) reduces transpiration (rate); max 3

[Total: 19]

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9700 BIOLOGY





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© UCLES 2010


1 (a) (i) Decide on the temperatures you plan to use in the range (between) 25°C to 45°C. Record the temperatures you have chosen in the space below. [2]

[1] at least 5 temperatures;

MM

O

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ion

s 2

[1] one temp. 25°C to 29°C AND one temp 40°C to 45°C

AND any three with two even intervals 3 or more degrees;

(ii) Prepare the space below and record your results. [4]

Reject

• if any units in body of table

• only t

[1]

table with all cells drawn AND heading (top or left) temperature °C; Must have units

PD

O r

ec

ord

ing

2

[1] Reject

• if units in body of table

• if headings for volumes or stages (heading) time with units;

[1] temperatures recorded highest to lowest

AND first set of times recorded in whole seconds;

MM

O

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on

2

[1] time at the lowest temperature is greater than the next temperature; Allow

• only if 3 or more results

(iii) From your results, state the temperature at which the activity of the enzyme is lowest. [1]

AC

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1

[1] temperature with longest time AND with units, °C;

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© UCLES 2010

(iv) Identify two significant sources of error in this investigation. [2]


[1] (dependent) stage 3 or end-point clots stick small clots coagulation milk drains back slowly

idea of seeing determining judging when;

[1] (standardised variables) rotation or angle;

[1] shaking or mixing or E/enzyme starts to react;

[1] E/enzyme temperature; (as milk)/AW

AND idea of not constant/different not same timing delayed;

AC

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x 2

[1] (independent variable) temperature or test-tube removed from water-bath

idea of not constant/not maintained decreasing cools down;

Max 2

(v) Describe a suitable control for this investigation. [1] Reject if give two.

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1

[1] boil enzyme;

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© UCLES 2010

(vi) Suggest how you could make this investigation as reliable as possible. [1]

C control of any relevant variable

[1]

equilibrate milk and enzyme to temp. separately then mix Or use thermostatically controlled water bath Or keep tube in water bath during rotation;

AC

E i

mp

rov

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en

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AX

1

R1 improve method to get repeat data [1]

repeat AND calculate or find mean/average;

max 1

(b) (i) Three of the values in Table 1.1 are anomalous. Draw a circle around each of these values. [1] (ii) Complete the Table 1.1 by calculating the missing value. [1]

[1]

MM

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1

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1

[1]

circles around 8.2, 4.9, 1.1;

8.8 Allow 8.7

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© UCLES 2010

(iii) Plot a graph of the data shown in Table 1.1. [4]

O [1]

x-axis pH AND y-axis activity (/) arbitrary units or au; Must have units

Reject if awkward scale S

[1] scale as 0.2 to 2 cm Origin must be labelled as 6 or 6.02

AND 2 to 2 cm;

error carried forward if incorrect O then scale x-axis 2 to 2 cm and y-axis 0.2 to 2 cm. must use more than half grid in x and y.

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

P



PD

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ay

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t 4

L [1]

straight line through points; error carried forward if scale or plotting incorrect 6.02 8.8 or 8.7 or ecf 6.22 6.8 6.40 4.4 6.64 1.0 6.70 0.6

quality – not thick, not feathery for the complete line. joining plots –


• line of best fit

• curve through all plots

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© UCLES 2010

(iv) Explain the relationship between pH and the enzyme shown in the data. [3]

[1] (in correct context of pH and effect on activity) structure of protein or substrate or enzyme or active site or bonds

changed/altered/destroyed/no longer complementary broken;

[1] (in correct context of increase in pH and decrease activity) so fewer enzyme-substrate complexes (ESCs) or less/no substrate can bind/combine/attach/fit into OR (in context of decrease in pH and increase in activity) more ESCs or more substrate binds/attaches;

AC

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3

[1] (in correct context of effect of pH on enzyme i.e. when pH higher/nearer 7/less acidic/more alkaline) denatured/denaturation;

[Total: 20]

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© UCLES 2010


2 (a) (i) Draw a large plan diagram showing the features of the wall of the organ. Label the position of the lumen. [4]


PD

O l

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[1]

Reject

• thick lines

• feathery lines

• one ‘tail’ or overlap or gap clear, sharp, unbroken lines

AND no shading


Reject if drawn two walls

[1]

no cells drawn AND three layers drawn include any circles as only one layer;

MM

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n 2

[1] Reject if only two layers drawn innermost layer is wider than outermost layer at same point;

MM

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ion

s 1

[1] Reject

• if any label is biologically incorrect e.g. regions belonging to other organs or plants.

• label within drawn area – e.g. between two walls correct label with label line to or in lumen on inside;

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© UCLES 2010

(ii) Annotate (make notes with label lines) your diagram to show one difference between the outside layers and the inside layers. [1]

MM

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1

[1]

[1]

[1]

[1]

Reject

• if written over lines of the diagram drawing.

• if written underneath, unless have labelled on diagram Allow ‘er’ for one label

max 1

(b) (i) Actual diameter of the nucleus in the cell labelled Y is 7.8 µm. Use this information to calculate the actual diameter of the largest nucleolus in cell Y. [4]

[1] correct measurement of one nucleus, 11 to 15 mm; Reject if no units

MM

O

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on

2

[1] correct measurement of one nucleolus, 2 to 4.5 mm; Reject if no units

[1] (mean) adds three measurements AND shows division by 3;

PD

O

dis

pla

y

2

[1] answer to no more than 2 significant figures, (1 decimal place) between 1.1 and 6.4; Reject standard form

outermost innermost

thickness Reject cell wall

thin)ner) think(er);

texture smooth rough;

cells/nuclei Not clear/densely packed/ visible

Clear/less densely packed/(air) spaces/lots

Colours/staining of l

Pink/red/grey/lighter/more Purple/darker/less;

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© UCLES 2010

(ii) Suggest how you would make the measurement of each nucleolus more accurate. [1]

AC

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[1] different dimensions/diameters or use vernier callipers or (eyepiece) graticule or increase magnification or high power (of microscope) or enlarging or increase resolution;

(iii) Make a large drawing of the cell labelled X with three complete cells touching cell X. [5]


Reject

• thick lines

• feathery lines

• 2 ’tails’ or overlaps or gaps

PD

O l

ay

ou

t 1

[1]


AND no shading


[1] only cell X and three correct complete touching cells;

MM

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n 2

[1] nucleus with at least two distinct nucleoli (other than cell X);

[1] chromosomes drawn as two areas (no details of chromosomes shown);

MM

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s 2

[1] blue region/spindle around chromosomes drawn in cell X;

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© UCLES 2010

(iv) Prepare the space below so that it suitable for you to compare the cells labelled X and Y. [5]

[1]

organise as a table or Venn diagram or ruled connected boxes

headed (cell) X and (cell) Y

differences opposite each other;

PD

O r

ec

ord

ing

2

[1] heading for similarities/similarity/compare (with contrast)/same;

MM

O

de

cis

ion

1

[1] has at least one correct similarity, cytoplasm or cell/plasma membrane or shape;

Reject tick and cross without a key

AC

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ma

x 2

[1]

[1]

[1] [1]

[1]

[1] [1]

feature (cell) X (cell) Y

1 nucleus/nuclear membrane absent/none/not clear

present/clear;

2 nucleoli absent/none/ present/clear;

3 cytoplasm less/not granular more/granular;

4 spindle fibres present/visible absent/none/not visible;

5 chromosomes/chromatid(s) present/visible not visible;

6 cytoskeleton absent/not clear present/clear/visible;

7 cell size small(er) larg(er);

Similarities

if no organisation then mark points only if in same sentence or following sentences. Allow two ticks for both present i.e. for cytoplasm and shape. Allow differences even if not opposite each other. Allow difference on one side if e.g. use more or –er. max 2

[Total: 20]

X Y

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9700 BIOLOGY

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




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© UCLES 2010

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

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1 (a) 1 2 3 4 5 6 7 8

mallard numbers have increased and the others have decreased ; decrease due to pesticides / pollution / fertilisers ; change in temperature or pH of water ; lack of named food source ; increased competition / AW ; direct human interference on lake ; e.g. fishing / sailing etc not related to marking point 2 mallard increase due to doesn’t eat, insects / molluscs / fish ; less other birds so less competition ; [4 max]

(b) 1 2 3 4 5 6 7 8 9 10

cultural / aesthetic / leisure, reasons ; moral / ethical, reasons ; e.g. right to exist / prevent extinction resource material ; e.g. wood for building / fibres for clothes / food for humans ecotourism ; economic benefits ; ref. resource / species, may have use in future / AW ; e.g. medical use maintains, food webs / food chains ; A description nutrient cycling / protection against erosion ; climate stability ; maintains, large gene pool / genetic variation ;

[4 max]

[Total: 8]

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© UCLES 2010

2 (a) (i) 1 penicillin inhibits, enzyme / peptidase ; 2 blocks / alters shape of, active site ; 3 peptidoglycan chains cannot link up / stops cross-links forming ; 4 cell wall weaker / AW ; 5 turgor of cell not resisted (by cell wall) / AW ; 6 cell / wall / bacterium, bursts ; [3 max]

(ii) any two from 1 viruses do not have cell wall ; 2 viruses do not have cytoplasm ; 3 viruses do not have peptidoglycan ; 4 viruses do not have peptidase ; [2 max]

(b) 1 2 3 4 5

without antibiotic numbers of both wild-type and mutant strains, increase / hardly changes ; with antibiotic numbers of both wild-type and mutant strains decrease ; mutant strains decrease more than wild-type ; A faster this subsumes marking point 2 after 24h, wild-type plateaus and mutant strain continues to decrease ; ref. comparative figures at any one time ; ignore units for bacteria blue with blue red with red red with blue – with antibiotic [4 max]

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(c) (i) 1 changes in, base / nucleotide, sequence ; A named change e.g. substitution 2 alters, triplet code / codon ; 3 enzyme has different, primary structure / amino acid sequence ; 4 enzyme has different, 3D structure / tertiary structure / active site ; [2 max]

(ii) red and blue with antibiotic 1 wild-type bacteria can produce glucans or mutant bacteria produce less glucans ; 2 glucans bind with antibiotic ; 3 wild-type more resistant to antibiotic or mutant bacteria less resistant to

antibiotic ; [2 max]

(d) 1 2 3 4

antibiotic, is selective agent / provides selective pressure ; resistant bacteria, survive / reproduce ; pass allele for resistance to offspring ; frequency of allele in population increases ; [3 max]

[Total: 16]

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© UCLES 2010

3 (a) 1 2 3

to give superovulation ; follicles or oocytes, mature or develop, at the same time ; ignore grow to prepare uterus for implantation ; [2 max]

(b) 1 2 3 4

germinal epithelial cell divides by mitosis ; giving oogonia ; primary oocyte divides by meiosis I (to give a secondary oocyte) ; idea of diploid to haploid [3 max]

(c) advantage ensure sperm enters oocyte / select (visibly) healthy sperm ; disadvantage unneeded parts of sperm enter producing unwanted effects or cannot tell whether a chosen sperm is genetically suitable ; [2]

[Total: 7]

4 (a) 1 2 3 4 5

binds to receptors (on liver cell membranes) ; conversion of glucose to glycogen / glycogenesis ; (because) insulin activates enzyme ; e.g. glucokinase / phosphofructokinase / glycogen synthase increased use of glucose in respiration ; increased uptake of glucose / increased permeability to glucose (of liver cells) ; [3 max]

(b) (i) 1 mRNA (found in β cells) is only from gene coding for insulin / AW ; 2 large numbers (of mRNA coding for insulin) ; 3 (whereas) DNA has all genes ; 4 (so) restriction enzymes needed ; [2 max]

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(ii) 1 cut plasmid (DNA) ; 2 at specific, base sequence / site ; 3 leaving sticky ends (that will join with insulin gene) ; [2 max]

(c) (i) all statements must be comparative inhaled (accept ora for injected) 1 insulin concentration rises more rapidly when inhaled ; 2 higher peak ; 3 falls, more rapidly / earlier ; 4 (after 150 mins) lower (than injected) ; 5 use of comparative figures ; figures for both at one time [3 max]

(ii) 1 glucose conc. is linked to insulin conc. ; inhaled (accept ora for injected) 2 (initially) glucose falls because insulin conc. rises ; this subsumes marking point 1 3 glucose conc. falls lower because insulin conc. is higher ; this subsumes marking point 1 4 (later) glucose rises higher because insulin conc. is lower ; this subsumes marking point 1 5 use of figures ; e.g. one glucose conc. for inhaled and one for injected at one time or one glucose conc. linked to an insulin conc. at one time (either inhaled or injected) [3 max]

(iii) advantages: 1 faster response time ; 2 less chance of, infection / contamination ; 3 good for people with needle phobia ; max 1 disadvantages : 4 could cause larger swings in blood glucose concentration ; 5 may need to taken more often / not long lasting ; 6 possible variability of dose / AW ; max 1 [2 max]

[Total:15]

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5 (a) 1 2 3 4

oxygen availability low (when soil is flooded) ; plants carry out anaerobic respiration ; ethanol produced ; roots can continue to respire ; [2 max]

(b) (i) (store of) nutrients ; A named nutrient ignore food / water / fibre for, germination / growth of embryo ; [2]

(ii) protein in aleurone layer ; which is removed in white rice ; ora [2]

(iii) endosperm makes up a greater proportion of the total mass in white rice ; or brown rice has more, lipid / fibre / protein, than white rice so less carbohydrates per gram ; [1 max]

(iv) 1 cheap source of food ; 2 high, energy value / fibre content ; 3 high in carbohydrate ; 4 contain wide range of nutrients or three named nutrients ; 5 cereal grains store well ; 6 because they contain very little water ; [2 max]

[Total: 9]

6 (a) variation / different form, of a gene ; [1]

(b) marks for reasons only HbA HbA

low – susceptible to / die from, malaria ; HbA HbS high – no (full blown) SCA / have SC trait ; not, susceptible to / likely to die from, malaria ; HbS HbS low – susceptible to / die from, SCA ; [4]

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(c) 1 2 3 4

USA malaria not selection pressure ; HbS no advantage ; due to outbreeding ; genetic testing can lead to termination of pregnancy or testing / counselling, leads to not having children ; [2 max]

[Total: 7]

7 (a) 1 2 3 4

apical bud is source of auxin ; auxin inhibits growth of side shoot ; remove bud and auxin conc falls ; this allows cell, division / elongation, to take place (in side shoots) ; [3 max]

(b) 267 ;; accept suitable working for one mark e.g. 110 – 30 (× 100) 30 or accept 266.7 for one mark [2]

(c) D1 E2 E3 D4 E5 D6

days 2 to 8 no increase in length with paste plus auxin (compared to control) ; auxin moves from paste into plants ; inhibits growth ; days 8 to 13 increase in length occurs (with paste and auxin) ; less auxin left ; supportive figs ; e.g. two blue points on two days plus units or one red and one blue point on same day plus units must have at least one D (description) and one E (explanation) to score 3 marks [3 max]

[Total: 8]

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© UCLES 2010

8 (a) 1 2

absorb light ; A harvest light / trap light R collect light pass energy to, primary pigment / chlorophyll / reaction centre ; [2 max]

(b) 1 2 3 4 5 6

cyclic photophosphorylation electron emitted returns to, PSI / same photosystem or same chlorophyll molecule ; non-cyclic photophosphorylation electron emitted from PSII absorbed by PSI ; reduced NADP produced ; photolysis occurs ; A splitting of water (photolysis) only involves PSII ; oxygen produced 3 max accept ora for cyclic for marking points 3, 4 and 6 mark to max 3 if cyclic and non-cyclic are described the wrong way round [4 max]

(c) (i) some other factor becomes limiting / temperature no longer limiting ; CO2 / light intensity ; [2]

(ii) line falls towards 70oC ; [1]

(iii) rate of photosynthesis falls enzyme / rubisco, denatured / AW ; substrates not able to fit active site / AW ; [2]

(d) adaptation how the adaptation helps photosynthesis

thin cell wall greater light penetration / short diffusion distance (for gases) ;

cylindrical shape air spaces ;

large vacuole chloroplasts near outside of cell for better light absorption / maintains turgor ;

chloroplasts can be moved within the cell

absorb maximum light / avoid excessive light intensities ;

[4]

[Total: 15]

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do not credit marking points out of sequence prophase 1

1 idea of condensation of chromosomes ;

2 homologous chromosomes pair up / bivalent formed ;

metaphase 1

3 homologous chromosomes / bivalents, line up on equator ;

4 of spindle ;

5 by centromeres ;

6 independent assortment / described ;

7 chiasmata / described ;

8 crossing over / described ;

anaphase 1

9 chromosomes move to poles ;

10 homologous chromosomes / bivalents, separate ;

11 pulled by microtubules ;

12 reduction division ;

metaphase 2

13 chromosomes line up on equator ;

14 of spindle ;

anaphase 2

15 centromeres divide ;

16 chromatids move to poles ;


9 (a)

18 ref. haploid number ;

allow 4 or 14 allow 11 or 17 [9 max]

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19 change in, base / nucleotide, sequence (in DNA) ;

20 during DNA replication ;

21 detail of change ; e.g. base, substitution / addition / deletion

22 frame shifts / AW ;

23 different / new, allele ;

24 random / spontaneous ;

25 mutagens ;

26 ionising radiation ;

(b)

27 UV radiation / mustard gas ; [6 max]

[Total: 15]

1 ATP as universal energy currency ;

2 light energy needed for photosynthesis ;

3 ATP used conversion of GP to TP ;

4 ATP used to regenerate RuBP ;

5 (energy needed for) anabolic reactions ;

6 protein synthesis / starch formation / triglyceride formation ;

7 activation energy ;

8 (activate) glucose in glycolysis ;

9 active transport ;

10 example ; e.g. sodium / potassium pump

11 movement / locomotion ;

12 example ; e.g. muscle contraction / cilia beating

13 endocytosis / exocytosis / pinocytosis / bulk transport ;

10 (a)

14 temperature regulation ; [9 max]

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(b) 15 16 17 18 19 20 21 22 23 24

idea of lipid > protein > carbohydrate / AW ; A lipid has more energy than either protein or carbohydrate comparative figures ; e.g. 39.4, 17.0 and 15.8 accept any two kJ g 1 / per unit mass ; more hydrogen atoms in molecule, more energy ; lipid have more, hydrogen atoms / C-H bonds ; (most) energy comes from oxidation of hydrogen to water ; using reduced, NAD / FAD ; in ETC ; detail of ETC ; ATP production

[6 max]

[Total: 15]

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9700 BIOLOGY





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© UCLES 2010


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