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INTRODUCTIONThe marking schemes which follow were those used by WJEC for the Summer 2012examination in GCE BIOLOGY/HUMAN BIOLOGY. They were finalised after detaileddiscussion at examiners' conferences by all the examiners involved in the assessment. Theconferences were held shortly after the papers were taken so that reference could be madeto the full range of candidates' responses, with photocopied scripts forming the basis ofdiscussion. The aim of the conferences was to ensure that the marking schemes wereinterpreted and applied in the same way by all examiners.It is hoped that this information will be of assistance to centres but it is recognised at thesame time that, without the benefit of participation in the examiners' conferences, teachersmay have different views on certain matters of detail or interpretation.WJEC regrets that it cannot enter into any discussion or correspondence about thesemarking schemes.BIOLOGY BY11BIOLOGY BY29HUMAN BIOLOGY HB219BIOLOGY BY427HUMAN BIOLOGY HB436BIOLOGY BY549

GCE BIOLOGY BY1MarksQuestionsMarking detailsAvailable1. (a)(b)(i)Biosensor;1(ii)Tissue;1(i)Prokaryotic has no nucleus vs eukaryotic has a nucleus / eukaryotic1has membrane bound organelles vs prokaryotic no membranebound organelles (Accept named membrane bound organelle) /prokaryotes smaller ribosomes (70S) vs Eukaryotes larger (80S) /DNA circular v DNA in chromosomes or strands [must refer to bothterms];Reject reference to cell wall;Reject reference to size;Reject reference to plasmid;(ii)Chloroplast contain chlorophyll vs mitochondria have no chlorophyll1(accept photosynthetic pigments) / grana vs no grana / stroma vsmatrix / cristae vs no cristae / thylakoid vs no thylakoids / cristae vsgrana / infolding of membrane in mitochondria not in chloroplasts[must refer to both structures];Question total14

MarksQuestionsMarking detailsAvailable2. (a)(i)α glucose OH on C1 down, H up β glucose OH on C1 up, H down;1Allow HO (both for 1 mark).(b)(i)Cellulose –Beta Starch – alpha; (both for 1 mark).1Allow symbols.(ii)Starch: any 22correct reference to amylose and/or amylopectin;glycosidic bonds (α 1-4);molecules coil/branch (in amylopectin); NOT compactNOT: amylopectin – coiled or amylase branchedeasy to add/remove {glucose / maltose} units;Cellulose: any 22alternate units rotate / head up, head down / 180 rotation;straight chain only / no branches; NOT parallelhydrogen bonds between / reference to cross linking;gives strength or stability / forming microfibrils;Question total26

MarksQuestionsMarking detailsAvailable3. (a)(i)Nucleotide;1(ii)Phosphate / phosphoric acid / PO4 / PO3-;1NOT phosphorus / P(b)(iii)Deoxyribose in DNA and ribose in RNA (both);1(iv)Adenine, Thymine, Cytosine, Guanine (1 if 1 error).2Any 44Pairing described A-T and C-G (both needed);Backbone / Chains / polynucleotide formed by alternating sugarphosphate groups;two chains connected / joined by base pairs;hydrogen bonding;two chains (twisted) to form a helix / double helix;NOT alpha helix.Accept labelled diagram.(c){forming template / code / instructions} for {protein synthesis / mRNA1/ amino acid sequence / primary structure of protein / transcription}(accept Replication in dividing cells) /NOT genetic material alone.Question total310

MarksQuestionsMarking detailsAvailable4. (a)2 chromosomes in female cell;21 chromosome in male cell;Diagrams must match each other.Accept ‘chromatids’ in each cell. Do not accept chromatid in malecell if chromosomes drawn in female cell or opposite.(b)(i)2 Chromosomes arranged on equator of spindle; (ignore orientation)22 V shaped {chromosomes / chromatids} with centrosomes towardseach centriole/pole;Ecf from one diagram to other.(ii)Labelling: chromatids, centromere, spindle, centrioles, equator, cell2membrane.2 marks for 4 correct labels on either diagram;1 mark for 3.(iii)To provide {genetically identical cells / clones};2Repair / replacement {of cells / tissue} / regeneration qualified;NOT growth.(iv)Making gametes / sperm cells / sex cells / produce haploid cells for1reproduction;(v)Meiosis / reduction division;1Spelling must be correct.(vi)Genetic variation (in the offspring) / restore diploid number (in1zygote) OWTTE;(c)Fertilised eggs will develop into females, unfertilised eggs into1males; (both for 1 mark);Accept: fertilised will give genetically varied ants, unfertilised wouldgive clones;IGNORE haploid / diploid.Question total412

MarksQuestionsMarking detailsAvailable5. (a)(i)OH and H removal shown on diagram;3formation of water (H2O) shown;dipeptide correctly drawn with C joined to N;(b)(ii)Condensation;1(iii)Peptide; NOT dipeptide;1(i)Mosaic: Proteins are scattered (in lipid layer);2Fluid: molecules / components / (phospho)lipids / proteins are free tomove around;(ii)B;1(iii)Drawing shows a lipid bilayer with A and B in the correct places, B1intrinsic (through the middle) A extrinsic (on top or bottom, outsidephosphate heads);Need not use N and P, but must be clear which is A and Bany 1 correct label from phospholipid / hydrophobic / hydrophilic /1cholesterol / phosphate (head) / lipid or fatty acid (tails);(iv)Cell {recognition / interaction / identification / cell to cell recognition /1adhesion / signalling} / receptor qualified e.g. {hormone receptor /antigens};(c)(i)Secondary;1(ii)Ribosomes / rough endoplasmic reticulum;1Accept nucleus;NOT golgi body / nucleolus.(d)(i)Endocytosis (accept phagocytosis / pinocytosis);1NOT exocytosis.(ii)Any 2:2Diffusion / osmosis;Facilitated diffusion;Active transport;5

MarksQuestionsMarking detailsAvailable6. (a)(i)0.4M; no units no marks.1(ii)-1052 (kPa);1allow ECF(b)correct reference to osmosis;4bathing solution {has a lower water potential / is more concentrated /is more negative / hypertonic} than the water potential of beetrootcells / ORA;water leaves / moved {out of / from} cells / into bathing solution;bathing solution became less dense / lighter than original sucrosesolution;REJECT reference to water moving into or out of the drop.-790 -1100 Ψp ;(c)2Ψp 310 kPa;2 marks for correct answer.(d)(i)Diagram shows cell plasmolysed (any stage);1Mark diagram using labels.No labels 0 marks.Any 2 correct labels fromcell wall; plasma / cell membrane (part or all of which must be away2from cell wall); tonoplast or vacuolar membrane; vacuole;IGNORE incorrect labels.(ii)Plasmolysed / plasmolysis;1Question total612

MarksQuestionsMarking detailsAvailable7. (a)ANucleus;1BContains DNA code for amino acid sequence;1NOT genetic information alone;CCarries out transcription / makes RNA copy;1DNucleolus;1EMakes ribosomes / organises transcription / makes rRNA;1F{Rough ER / Ribosomes} { translate mRNA / put amino acids1together / protein synthesis};GEndoplasmic reticulum;1HTransports protein;1I(To) Golgi;1JPackages protein into vesicle;1KModifies protein or description;1LSecretory vesicle;1MVesicle migrates towards plasma membrane; (can award M and N if1use vesicle instead of secretory vesicle)NVesicle fuses / merges with plasma membrane;1OContents of vesicle emptied by exocytosis;1Question total710

MarksQuestionsMarking detailsAvailable7. (b)ATemperature;1Bdescription of (exponential) increase to optimum / maximum / certain1temperature then (sudden) decline / sketch graph showing;CIncreasing temperature increases rate because of increased energy1/ moving molecules faster / kinetic energy / ORA;D{Increasing frequency of / more / more likely} successful collisions /1Enzyme Substrate Complexes forming / ORA;EpH;1Fdescription of optimum pH and declining activity further from1optimum in both directions / sketch graph / optimum pH and narrowrange;(Award G, H, I, J in context for Temp and/or pH )G(3D) shape of active site changes;1HChanging away from optimum affects bonds holding tertiary1structure / structure of enzyme molecules;ICorrect reference to hydrogen / covalent / ionic bonds; NOT1disulphide / peptideJSubstrates do not fit into active site / is not complementary (so rate1reduced);KSubstrate concentration; NOT amount;1LEnzyme concentration; NOT amount;1(Award M,N, O in context for Enzyme conc and/or Substrate conc)MActivity increases up to maximum when it levels off / sketch graph1showing / ORA;NIncreasing substrate / enzyme conc. increases number of active sites1occupied / Enzyme Substrate complexes / successful collisions / ORA;OMaximum rate when all active sites occupied / saturated correctreference to limiting factors;81

GCE BIOLOGY BY2MarksQuestionsMarking detailsAvailable1.Fungi;Animalia / animal;Protoctista; Accept Protists;Prokaryotae / Monera; NOT bacteria;Plantae/plant;Question total95

MarksQuestionsMarking detailsAvailable2. (a)(i)AAlveoli/alveolar sacs;BCapillary (network);1Both for 1 mark.(ii)CPulmonary artery;DPulmonary vein;1Both for 1 mark.(b)Any 22Thin alveolus (walls) /one cell thick;NOT membrane or thin alone.Large surface area / highly folded;(volume – neutral)Large number of capillaries (or implied);(c)Contraction of intercostal muscles and diaphragm OR ribcage2moves up and out and diaphragm flattens / contract;Increased volume and decreased pressure so air moves in(tolungs);Question total106

MarksQuestionsMarking detailsAvailable3.Parasites {live in / on a} host and obtain nourishment {at the2expense of / do harm to} the host; NOT feed (can be neutral)Tapeworm / ticks / leeches / fleas / headlice / roundworm /plasmodium / malaria parasite / any parasite;Autotrophs use {(simple) inorganic molecules / carbon dioxide and2water} to synthesise {(complex) organic compounds / named organiccompound / sugars}; NOT foodPlant / named Plant / Algae / Bacteria must be qualified bychemosynthetic;Saprobionts {secrete enzymes onto the food outside the body / feed2by extracellular digestion} and absorb ( or e.q.) the (soluble)products (by diffusion); NOT ingestBacteria / Fungi / or named;Question total116

MarksQuestionsMarking detailsAvailable4. (a)ARight atrio-ventricular / tricuspid.1BLeft AV valve / bicuspid / mitral1Award one mark for identifying both Atrioventricular Valves but notright and left.C(b)Semi lunar valves.1Coronary;2Supplies oxygen / blood to the heart muscle / wall / tissue / cells ORcorrect function for vein;(c)(i)Valve {exposed to / works at} a higher pressure (in left ventricle)/1{Right ventricle pumps blood at / valve A exposed to} lowerpressures (to lungs);(ii)Blood leaks back (from ventricle) to atrium;1(iii)Breathlessness / fluid retention / fatigue / rapid or irregular heartbeat1/ blue lips / oedema / lower bp / faint / heart murmur;Question total128

MarksQuestionsMarking detailsAvailable5. (a)(b)(Gill) lamellae / filaments / plates;1Any 33Large surface area (for diffusion); (volume neutral)Thin / short diffusion pathway;Permeable;Good blood supply or implied; NOT transport systemNOT moist.(c)Water is forced over the gill by {ventilation mechanisms / pressure4differences / continuous swimming};Unidirectionally / one way flow;Countercurrent flow of blood and water / or description of;{Diffusion / concentration} gradient is maintained or description of;over the entire gill surface;High affinity Hb;Question total138

MarksQuestionsMarking detailsAvailable6. (a)(b)(c)ACapillaries; NOT blood vessels;1BEpithelium / epithelial cells; NOT endothelium;1CLacteal; NOT lymph;1DArteriole;1EVenule;1Microvilli:1Increase SA for diffusion / uptake of molecule / digestion (of1molecules);(d)Mitochondria:1(Synthesis of) ATP for active transport;1Goblet cell / mucus secreting cell; NOT Brunner’s gland.1Secretes / makes mucus; Accept even if named incorrectly above.1Question total1411

MarksQuestionsMarking detailsAvailable7.(a)(i)Any 33Has a reduced surface area / surface area:volume ratio;Thick cuticle;Curled / rolled (downwards with the stomata inside);Hairs (to trap water vapour);(ii)Any scientifically correct explanation of their chosen feature /cuticle ‒ comment on waterproofing /curled – trapping water /SA – less area over which water can be lost /(b)(c)(i)stomata – trapping water vapour;1Xerophyte;1Xylem;2Transports water (and minerals);(ii)Phloem;2Transports carbohydrates / sugars / products of photosynthesis /sucrose / amino acids;Not glucose/nutrients(iii)Endodermis / starch sheath.1(iv)Decent diagram of endodermis cell;2Endodermis ‒ with Casparian strip/band clearly labelled;15

MarksQuestionsMarking detailsAvailable(v)Any 44Waterproof / Casparian strip / band / suberin;Blocks the apoplast pathway;Selective uptake / Active uptake / transport of minerals (byendodermis cells);Into symplast pathway;Active transport of minerals into pericycle;Water follows by osmosis;Water and minerals move into xylem vessels;Question Total1616

MarksQuestionMarking detailsAvailable8.(a)A.Reference to Asexual and sexual;B.Asexual produces offspring that are genetically identical /clones;C.By mitosis;D.Allows (rapid) colonisation in favourable / stable conditionsOR outcompetes (slower) sexual reproduction;E.But if conditions / or e.g. such as temp change / unstable ordisease occurs;F.All individuals may die / none may have resistance /species may not be able to adapt;G.Sexual reproduction produces offspring that are geneticallydifferent;H.(Gametes) produced by meiosis;I.Genetic variability allows a species to adapt toenvironmental change /evolution;J.Slower/needs a partner (usually) / asexual faster;7 MaxK. Relationship with animals / insects for pollination;L. Relationship with animals / insects for seed dispersal;M. Pollen can survive dessication / without water;N. Seed with stored food enables the embryo plant to growuntil leaves form / are exposed to sunlight;O. Seed has a resistant (coat) to withstand adverse conditions;3 MaxQuestion total1710

MarksQuestionMarking detailsAvailable8.(b)A.Transpiration is the loss/evaporation of water (vapour) from(inside) the leaves (and stem) of a plant;B.Through stomata;C.Down a water potential gradient;D.High TEMPERATURE increases (Rate of) Transpiration /ORA;E.Correct explanation of effect of temp / increased kineticenergy / rate of movement of water molecules;F.Increased AIR MOVEMENT / eq which increases (Rate of)Transpiration / ORA;G. Correct explanation of effect of wind / increasing diffusiongradient;H.High HUMIDITY which decreases (Rate of) Transpiration /ORA;I.Plus correct explanation / decreased diffusion gradient;J.High LIGHT INTENSITY which increases (Rate of)Transpiration / ORA;K.Because it causes stomatal opening;7 MaxL.Set up under water / with a continuous column of water / makesure air cannot get in / it is air tight / equilibration;M.Any description of how to change one factor / may beapparent on diagram;N.Volume of water / movement of bubble taken up per unit timeis measured;O. To give a (close) approximation of transpiration rate;3 MaxQuestion Total 1018

GCE HUMAN BIOLOGY HB2MarksQuestionMarking ose;Hydrolysis / hydrolytic;Question total WJEC CBAC Ltd.195

MarksQuestionMarking detailsAvailable2.(a)Protein / cell surface marker / polysaccharide;2Stimulates immune response / antibody production;(b)Recognised / detected by specific B cells / lymphocytes;4Ref. T helper cells;Antigen / binding receptor sites / immunoglobulins on B cells;Antigen presentation;Clonal selection;B cell clones itself / clonal expansion / proliferation;Ref plasma cells releasing antibody;(c)(i)Greater antibody concentration in the blood;2More rapid increase / response;Less decline in antibody concentration from the peak / remainslonger in the blood;Shorter latent period for second injection;(ii)Memory cells present from first injection;2Multiply rapidly;Produce large numbers of plasma / B cells;Leads to more rapid response / more antibody produced;Question total WJEC CBAC Ltd.2010

MarksQuestionMarking detailsAvailable3.(a)(i)A alveoli;2C ciliated epithelium;(ii)Large surface area;2Increases gaseous exchange / uptake of oxygen;(iii)Pressure changes in bronchioli / lung;2Prevents passageway from closing / collapsing / keeppassageways open;Which would prevent passage of air;(b)(i)Breathlessness / wheezing / shortness of breath;2Difficulty breathing out;Inability to move / confined to bed / lack of energy / tiredness;(ii)Walls broken down / coalesce;2Forming large spaces / decrease in surface area / larger alveoli;Thicker walls;(iii)Trace showing less tidal volume;2Longer exhalation trace;(iv)Age;2Sex;Weight;Question total WJEC CBAC Ltd.2114

MarksQuestionMarking detailsAvailable4.(a)Causes Bohr {shift/effect} / dissociation curve moves to right;Max 4CO2 combines with water to form carbonic acid / HCO3-;Dissociation to form H and HCO3;Hydrogen ions combine with haemoglobin;Haemoglobinic acid formed / haemoglobin reduced;Decreases affinity for oxygen;More oxygen released / cannot hold as much oxygen;NOT quicker / more easily.(b)(i)Foetal haemoglobin 54/55% and normal haemoglobin 35/36%.1Both for one mark;(ii)Greater affinity for oxygen;3More saturated than maternal / normal haemoglobin;At all partial pressures of oxygen;Oxygen will (always) pass from maternal to foetal haemoglobin;(iii)Oxygen store; OWTTE.1Question total WJEC CBAC Ltd.229

MarksQuestionMarking detailsAvailable5.Name of structure(a)Function in absorption6(Absorption of) glucose /BCapillary;amino acids;(Absorption) glycerol / fatty acidsCLacteal;/ fats / triglycerides;Large surface area /FMicrovillus;carrier proteins /increase rate of uptake;(b)(i)Epithelial;1(ii)Prevents digestion of surface by enzymes / autolysis / acid;2Neutralises acid / provides optimum pH for enzymes;Lubricates / reduces friction from the passage of food;(c)(d)(i) Lymphatic system;1(ii) Hepatic portal vein;1Blood clotting / colour change difficult to observe;1Question total WJEC CBAC Ltd.239

MarksQuestionMarking detailsAvailable6.(a)PositionTime from start of wave(s)2SANAVNBundle of his0.165;Base of ventricles0.205;Top of ventricles(b)Continues beating after removal from body;1(c)Allows atria to complete contraction / completely empty;3Before wave passes to ventricles/ before ventricles begin to contract;Otherwise ventricles would not completely fill;(d)All blood forced out / if contraction was from top some blood would2remain;Via aorta and pulmonary artery;All of muscle contracts with greater force/ pressure from base upwards;AV valves forced shut;(e)Cardiac controlAction of heart muscleECG activity2atria contract / systole;QRSwave/complex;Question total WJEC CBAC Ltd.2410

MarksQuestionMarking detailsAvailable7.(a)A Caused by a bacterium;B Airborne droplets / coughed out;C Breathed into lungs;D Easily spread in crowded places / close contact;E Pasteurisation of milk;F X-ray screening;G Isolation of patients;H Use of antibiotics;I Range of antibiotic used to prevent resistance;J BCG / BCQ tests / Heaf / skin tests for natural immunity;K BCG vaccine given (to non-resistant individuals);L Vaccine is attenuated form of bacterium;M Health checks at ports / airports OWTTE;N Disease notifiable;O Increase in number of cases linked to AIDS/HIV;Question total WJEC CBAC Ltd.2510

MarksQuestionMarking detailsAvailable7.(b)A Prokaryotes are unicellular organisms;B No cellulose cell wall / Murein;C No membrane bound internal structures / organelles /no nuclear membrane;D Protoctista possess membrane bound organelles;E No tissue differentiation;F Fungi consist of hyphae / mycelium;G Cell wall of chitin;H Reproduction is by spores;I Plants carry out photosynthesis/ autotrophic;J Possess chloroplasts / membrane bound organelles;K Cellulose cell walls;L Animals are heterotrophic;M Show nervous co-ordination;N cells lack a cell wall;O Names of five Kingdoms;Question total WJEC CBAC Ltd.2610

GCE BIOLOGY BY4MarksQuestionsMarking detailsAvailable1. (a)(i)28.0 - 13.8/13.8 OR14.2/13.8;2102.9 / 103%; (2 marks for correct answer)(1 mark for calculation if answer incorrect)(ii)Any 2 from:2Gene

GCE MARKING SCHEME BIOLOGY/HUMAN BIOLOGY AS/Advanced SUMMER 2012 . INTRODUCTION The marking schemes which follow were those used by WJEC for the Summer 2012 examination in GCE BIOLOGY/HUMAN BIOLOGY. They were finalised after detailed discussion at examiners' conferences by all the examiners involved in the assessment. The conferences were held shortly after the papers were taken so that .

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