Mark Scheme Summer 2007 - The Student Room

GCE

Mark Scheme Summer 2007

GCE

GCE Biology (8040/8042 / 9040/9042)

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Summer 2007

Publications Code UA018980

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i

Contents

General Introduction p ii Unit Codes and Unit Titles p iii General Information p iv

Mark Schemes

Unit 1 6101 Molecules and cells p 1

Unit 2B Unit 2H

6102 6112

Exchange, transport and reproduction Exchange, transport and reproduction in humans

p 11 p 20

Unit 3 6103/02* 6103/03

Written alternative to coursework* Energy and the environment

p 29 p 33

Unit 4 Core material Option A Option B Option C

Respiration and coordination Microbiology and biotechnology Food science Human health and fitness

p 38 p 44 p 48 p 52

Unit 5B Unit 5H

6105 6115

Genetics, evolution and biodiversity Genetics, human evolution and biodiversity

p 56 p 64

Unit 6 6106/02 6106/03

Written alternative to coursework Synoptic Paper

p 70 p 74

* 6103/02 W1 (written alternative to coursework) is only available to International centres

ii

GENERAL INTRODUCTION Mark schemes are prepared by the Principal Examiners and revised, together with the relevant questions, by a panel of senior examiners and subject teachers. The schemes are further amended at the Standardisation meetings attended by all examiners. The Standardisation meeting ensures as far as possible that the mark scheme covers the candidates' actual responses to questions and that every examiner understands and applies it in the same way. The schemes in this document are the final mark schemes used by the examiners in this examination and include the amendments made at the meeting. They do not include any details of the discussions that took place in the meeting, nor do they include all of the possible alternative answers or equivalent statements that were considered to be worthy of credit. It is emphasised that these mark schemes are working documents that apply to these papers in this examination. Every effort is made to ensure a consistent approach to marking from one examination to another but each marking point has to be judged in the context of the candidates' responses and in relation to the other questions in the paper. It should not be assumed that future mark schemes will adopt exactly the same marking points as this one. Edexcel cannot under any circumstances discuss or comment informally on the marking of individual scripts. Any enquiries about the marks awarded to individual candidates can be dealt with only through the official Enquiry about Results procedure.

iii

Unit Codes and Unit Titles These Mark Schemes cover the units offered in this examination for Advanced Subsidiary Biology and Biology (Human) (8040 and 8042) and Advanced Biology and Biology (Human) (9040 and 9042). The units available in this examination series for the complete qualifications are listed in the table below. Level Unit Biology Biology (Human)

1 6101 Molecules and cells 6101

2 6102 Exchange, transport and reproduction

Exchange, transport and reproduction in humans 6112

AS

3 6103 Energy and the environment and Practical Assessment 6103

4 6104 Respiration and coordination and Options 6104

5 6105 Genetics, evolution and biodiversity

Genetics, human evolution and biodiversity 6115

A2

6 6106 Synoptic and Practical Assessment 6106

Cashing in The following tables show the units that must be taken in order to obtain an award for AS or Advanced GCE Biology, or for AS or Advanced GCE Biology (Human). Advanced Subsidiary Level Unit 8040 Biology 8042 Biology (Human)

AS 1 2 3

6101 6102 6103

6101 6112 6103

Advanced GCE Level Unit 9040 Biology 9042 Biology (Human)

AS 1 2 3

6101 6102 6103

6101 6112 6103

A2 4 5 6

6104 6105* 6106*

6104 6115* 6106*

* Only available in Summer examination series.

iv

GENERAL INFORMATION The following symbols are used in the mark schemes for all questions:

Symbol Meaning of symbol

; semi colon Indicates the end of a marking point

eq Indicates that credit should be given for other correct alternatives to a word or statement, as discussed in the Standardisation meeting

/ oblique Words or phrases separated by an oblique are alternatives to each other

{} curly brackets Indicate the beginning and end of a list of alternatives (separated by obliques) where necessary to avoid confusion

() round brackets Words inside round brackets are to aid understanding of the marking point but are not required to award the point

[] square brackets Words inside square brackets are instructions or guidance for examiners

[CE] or [TE] Consecutive error / transferred error Crossed out work If a candidate has crossed out an answer and written new text, the crossed out work can be ignored. If the candidate has crossed out work but written no new text, the crossed out work for that question or part question should be marked, as far as it is possible to do so. Spelling and clarity In general, an error made in an early part of a question is penalised when it occurs but not subsequently. The candidate is penalised once only and can gain credit in later parts of the question by correct reasoning from the earlier incorrect answer. No marks are awarded specifically for quality of language in the written papers, except for the essays in the synoptic paper. Use of English is however taken into account as follows: • the spelling of technical terms must be sufficiently correct for the answer to be

unambiguous e.g. for amylase, ‘ammalase’ is acceptable whereas ‘amylose’ is not e.g. for glycogen, ‘glicojen’ is acceptable whereas ‘glucagen’ is not e.g. for ileum, ‘illeum’ is acceptable whereas ‘ilium’ is not e.g. for mitosis, ‘mytosis’ is acceptable whereas ‘meitosis’ is not • candidates must make their meaning clear to the examiner to gain the mark. • a correct statement that is contradicted by an incorrect statement in the same part

of an answer gains no mark – irrelevant material should be ignored.

June 2007 6101 Unit 1 Mark Scheme

1 6101 June 2007

Unit 1 (6101) Question 1 Maximum marks

Structure

Bacterial cell Liver cell

Ribosomes

Centrioles x

Starch grains x x

Nucleus x

(1 mark for two correct boxes) Blank spaces are incorrect. A tick which has been crossed through and is ambiguous is incorrect.

Total 4 marks


2 6101 June 2007

Question 2 Maximum marks 1. covalent; 2. fatty acid; 3. glycerol / propan-1,2,3-triol / propantriol; 4. condensation; 5. unsaturated;

Total 5 marks


3 6101 June 2007

Question 3 Maximum marks (a) A = cisterna / cisternae;

B = (Golgi / secretory) vesicle / lysosome;

2 marks

(b) 1. {modified / ref. to attachment (of another molecule)} (of protein);

2. carbohydrate / glycoside / (oligo)saccharide (chain) / to form glycoproteins;

3. (proteins) concentrated / eq;

4. idea that proteins end up in vesicles / within a membrane / lysosome;

3 marks

Total 5 marks


4 6101 June 2007

Question 4 Maximum marks

(a) 1. {both / eq} are reducing sugars / contain a reducing sugar;

2. B has a {lower concentration / eq} of reducing sugar than A / converse

statement;

2 marks

(b) 1. {heat / hydrolyse / eq} with {acid / named acid};

2. (then) neutralise / add {(sodium) hydrogencarbonate / alkali / sodium hydroxide /

potassium hydroxide};

3. (then) ref to Benedict’s test / add Benedict’s reagent; 4. red / orange / brown / yellow / green;

3 marks

Total 5 marks


5 6101 June 2007


(a) acetic orcein / Schiffs / Feulgens / acetocarmine / lactopropionic acid / toluidine blue;

1 mark

(b) prophase, telophase, metaphase and anaphase;

1 mark

(c) (i) 1. idea that P1 is earlier (in prophase) than P2 ;

2. {chromosomes / threads / chromatids} can be seen (more) clearly / eq;

3. because (chromosomes / DNA) {shorten / spiral / condense / coil};

4. idea of chromosomes spreading out more;

5. ref to effect of preparation technique;

3 marks

(ii) correctly labelled cell;

IF two cells are labelled, both must be correct

1 mark

(iii) 1. centromeres divide / split / separate / pulled apart;

2. {spindle fibres / microtubules} become {shorter / contract / condense};

3. chromatids {separate / pulled apart};

4. chromosomes / chromatids move towards (opposite) {poles / ends / sides /

centrioles};

2 marks

Total 8 marks


6 6101 June 2007

Question 6 Maximum marks (a) Facilitated diffusion :

1. (proteins provide) {channels / gates / pores / carriers / transporters} in membrane;

OR

{channels / gates / pores / carriers / transporters} carry molecules across the

membrane;

2. (channels / gates / pores) can open or close / (carriers / transporters) can change shape;

3. for ions / {large / polar} molecules / molecules insoluble in lipids to pass through;

4. down {concentration / diffusion} gradient / eq; (Max 3 marks)

Active transport :

5. molecule {binds to / fits into / attaches to / combines with} protein;

6. use of {ATP / energy};

7. up concentration gradient / eq;

8. for faster uptake / eq; (Max 3 marks)

5 marks


7 6101 June 2007

Question 6 (continued) Maximum marks (b) (i) 1. increase in concentration (in cytoplasm) for first {2.3 hours / 2.4 hrs /

2h 18 min / 2h 24 min /eq} ;

2. (then) concentration remains {constant / plateau / levels off};

3. calculation of rate of uptake e.g. (2.8 ÷ 2.3 = 1.22 µgcm-3h-1);

2 marks

(ii) 1. active transport cannot occur;

2. at first, X diffuses in / can enter down concentration gradient / eq;

3. idea that once concentration of X in cytoplasm equals concentration

outside, no more can be taken up;

4. correct reference to some ATP present at start, so some active transport

will occur;

2 marks

Total 9 marks


8 6101 June 2007

Question 7 Maximum marks (a) (i) Uracil and cytosine (or vice versa);

ACCEPT U and C

1 mark

(ii) C T A G C A C;

1 mark

(b) 200 x 3 / 600;

÷ 50;

12 seconds;

3 marks

(c) 1. The mRNA {attaches /eq} to a ribosome;

2. two tRNA molecules (held in ribosome) / eq;

3. tRNA carries one {specific / eq} amino acid;

4. ref to anticodons on tRNA;

5. (which bind to) {complementary bases / codons} on mRNA;

6. peptide bonds form between amino acids;

7. idea of ribosome moves relative to mRNA;

8. until a stop codon is reached;

5 marks

(d) 1. {DNA / bacterial chromosome} is in the cytoplasm / not in a nucleus;

2. idea of mRNA doesn’t have to travel / ribosomes bind straight away;

3. (because) {transcription / mRNA formed) in the cytoplasm;

2 marks

Total 12 marks


9 6101 June 2007

Question 8 Maximum marks (a) 1. {digest / breakdown / hydrolyse} {proteins / peptide bonds};

2. into (small) peptides / amino acids;

3. (which) {dissolve / are soluble} in (washing) water;

2 marks

(b)(i) 1. {optimum / peak} at same pH / pH 7;

2. max activity of P is greater than Q;

3. Q works over wider range of pHs;

4. activity of P is greater than Q at pH 6.8 - 7.2;

5. activity of P is less than Q at pH 5 - 6.8 and at 7.2 - 9;

6. correct manipulation of activity figures to compare;

e.g. P max 1 unit greater than Q

3 marks

(ii) 1. use (enzymes) R and Q;

2. protease R is needed to break down the egg;

NB references to other enzymes breaking down egg negates this point

3. {protease Q because it has the greatest overlap (with R) / converse} /

both work well at {pH 8 / similar pHs};

4. detergent can only be at one pH;

3 marks


10 6101 June 2007

Question 8 (continued) Maximum marks

(c) 1. idea of link between pH and {H+ / eq} concentration;

2. affects {ionisation / charge / eq} of {R groups / side groups};

3. {disruption /eq} of bonds;

4. {changes shape / distortion} of active site;

5. {fewer / no} enzyme-substrate complexes formed / substrate does not fit

{active site / enzyme} / eq;

6. idea of {decreasing activity / denaturing} of enzyme away from optimum

pH / {no activity / denatured} at extremes of pH;

4 marks

Total 12 marks

June 2007 6102 Unit 2B Mark Scheme

6102 June 2007 11

Unit 2B (6102) Question 1 Maximum mark salivary glands ; amylase / ptyalin ; epithelium / mucosa / epithelial cells ; glucose ; fructose ; [NB Last two (glucose and fructose) may be either way round]

5 marks


6102 June 2007 12

Question 2 Maximum marks (a)(i) spermatids ;

1 mark (a)(ii) spermatogonia / spermatogonium ; primary spermatocytes / primary spermatocyte ;

2 marks (b) 1 meiosis / reduction division ; 2 reference to halving the number of chromosomes ; 3 idea that {the diploid number / 2n } restored at fertilisation / eq;

3 marks

Total 6 marks


6102 June 2007 13

Question 3 Maximum marks (a) A right ventricle ; B aorta / aortic arch ; C (left) atrioventricular valve / mitral valve ;

3 marks

(b) 1 sequence of events each time the heart beats / eq ; 2 (starts with) atrial systole ; 3 (then) ventricular systole ; 4 (then) diastole ;

3 marks

(c) 1 ability of heart (muscle) to {contract / beat / pump } ; 2 spontaneously / on its own / without nervous stimulation / eq ;

2 marks

Total 8 marks


6102 June 2007 14

Question 4 Maximum marks (a) A ;

1 mark

(b) 1 ref to control by the {medulla / inspiratory control centre / nerve impulses} ;

2 diaphragm contracts ; 3 (and) {moves / pulls} downwards / flattens ; 4 external intercostal (muscles) contract ; 5 rib (cage) moves upwards / rib (cage) moves outwards / sternum

moves upwards / ribcage expands ;

[Treat each point independently]

4 marks (c) TWO OF:

1 exercise / increase in metabolic activity ; 2 increase in carbon dioxide concentration / drop in pH (of blood) /

increase in H+ / increase in acidity ;

3 adrenaline / shock / stress / fear / excitement / panic ; 4 high altitude / eq / low (partial pressure) of oxygen ;

5 rise in temperature ;

2 marks

Total 7 marks


6102 June 2007 15

Question 5 Maximum marks (a) P anther ; Q stigma ;

2 marks (b) wind ;

For the other marks, ACCEPT references to any three of the following: 1 no petals / reduced petals / no nectaries ; 2 {large / long / versatile / rocking} anthers ; 3 produce lots of pollen ; 4 {exposed / eq }{anthers / stamens / stigmas / styles} ; 5 pollen released into air / blown away by the wind ;

6 {feathery / hairy / eq} stigmas / stigmas have a larger surface area ;

7 idea that stigmas (are more likely to) catch pollen ;

4 marks (c) 1 protandrous / explanation ; 2 protogynous / explanation ;

3 ref to pollen incompatibility ; 4 dioecious / monoecious explanation ; 5 dichogamy ;

2 marks

Total 8 marks


6102 June 2007 16

Question 6 Maximum marks (a) adaptations that enable a plant to {live in dry conditions / eq } /

{reduce water loss / reduce transpiration } ; (b) 1 leaf is rolled / curled up / eq ; 2 to reduce (exposed) surface area ;

3 encloses stomata (on the inside) ; 4 presence of spines / hairs / spikes ; 5 to trap air / trap humid air / trap moisture ;

6 reduces the {diffusion / concentration} gradient ;

7 thick cuticle ; 8 any reference to reducing {transpiration / evaporation / water

loss} ; 9 presence of hinge cells ; 10 idea that hinge cells roll the leaf ;

4 marks

Total 5 marks


17 6102 June 2007

Question 7 Maximum marks (a) 1 reference to transpiration pull ; 2 cohesion of water molecules explained ; 3 adhesion explained ; 4 reference to water potential gradient ; 5 any reference to root pressure ;

3 marks (b)(i) 1 distance moved increases as time increases / eq ; 2 steady / (approximately) linear / constant ; 3 credit manipulated figure reference ;

2 marks (ii) 1 reference to increased movement / eq ; 2 due to increased uptake of water ; 3 increased {transpiration / evaporation / water loss} ; 4 stomata open wider / more stomata open (in bright light) ; 5 (at high light intensity there is) more photosynthesis ;

3 marks (iii) 1 reference to increased {transpiration / evaporation / water loss}; 2 reference to dry air / low water (vapour) ;

3 increased diffusion of water (vapour) / increased {diffusion / concentration gradient} for water (vapour) ;

4 reference to increased water potential gradient ;

3 marks (b)(iv) temperature / wind (speed) / air movement ;

1 mark

Total 12 marks


18 6102 June 2007

Question 8 Maximum marks (a) 1 appropriate reference to shape ; 2 increased surface area ; 3 cells are thin ; 4 for increased diffusion (of oxygen) / decreased diffusion distance ; 5 presence of haemoglobin ; 6 reference to haemoglobin carrying / picking up oxygen / eq; 7 no nucleus / no {organelles / named examples} ;

8 idea that this gives more space for haemoglobin ;

9 small / flexible ; 10 to allow cells to pass {along / through} capillaries ;

4 marks


19 6102 June 2007

Question 8 continued Maximum Marks (b) 1 carbon dioxide {diffuses / eq } into red blood cell ; 2 where it combines with water ;

3 to form carbonic acid ; 4 this dissociates into hydrogencarbonate (and proton) ;

5 reference to carbonic anhydrase ;

6 {proton / H+} {combines with / buffered by / mopped up by} haemoglobin ;

7 forming {haemoglobinic acid / HHB} ; 8 hydrogencarbonate (ions) diffuse {into plasma / out of red cell} ; 9 reference to attachment (of carbon dioxide) to haemoglobin ;

10 forming {carbaminohaemoglobin / carbamino compound} ; 11 ref to carbon dioxide {carried in solution / dissolved} in RBC;

5 marks

Total 9 marks

June 2007 6112 Unit 2H Mark Scheme

* Common with 6102, Unit 2B 20 6112 June 2007

Unit 2H (6112) Question 1 Maximum marks salivary glands ; amylase / ptyalin ; epithelium / mucosa / epithelial cells ; glucose ; fructose ; [NB Last two (glucose and fructose) may be either way round]

5 marks



Question 2 Maximum marks (a)(i) spermatids ;

1 mark (a)(ii) spermatogonia / spermatogonium ; primary spermatocytes / primary spermatocyte ;

2 marks (b) 1 meiosis / reduction division ; 2 reference to halving the number of chromosomes ; 3 idea that {the diploid number / 2n } restored at fertilisation / eq;

3 marks

Total 6 marks



Question 3 Maximum marks (a) A right ventricle ; B aorta / aortic arch ; C (left) atrioventricular valve / mitral valve / bicuspid valve ;

3 marks

(b) 1 sequence of events each time the heart beats / eq ; 2 (starts with) atrial systole ; 3 (then) ventricular systole ; 4 (then) diastole ;

3 marks

(c) 1 ability of heart (muscle) to {contract / beat / pump } ; 2 spontaneously / on its own / without nervous stimulation / eq ;

2 marks

Total 8 marks



Question 4 Maximum marks (a) A ;

1 mark

(b) 1 ref to control by the {medulla / inspiratory control centre / nerve impulses} ;

2 diaphragm contracts ; 3 (and) {moves / pulls} downwards / flattens ; 4 external intercostal (muscles) contract ; 5 rib (cage) moves upwards / rib (cage) moves outwards / sternum moves

upwards / ribcage expands ;

4 marks (c) TWO OF:

7 exercise / increase in metabolic activity ; 8 increase in carbon dioxide concentration / drop in pH (of blood) /

increase in H+ / increase in acidity ;

9 adrenaline / shock / stress / fear / excitement / panic ; 10 high altitude / eq / low (partial pressure) of oxygen ;

11 rise in temperature ;

2 marks

Total 7 marks



Question 5 Maximum marks (a) A seminal vesicle ; B prostate ;

C testis / testes / testicles ;

3 marks

(b) (fructose) to act as an {energy source/ nutrient /respiratory substrate} for sperm ;

(mucus) ref. to lubrication ;

2 marks

(c) ref. to {increased temperature / (electromagnetic) radiation}; 1 mark

(d) reduced fertility / eq ; 1 mark

Total 7 marks



Question 6 Maximum marks (a) physiological changes / eq ;

which occur over a period of time ;

2 marks

(b) 1 increased number of red blood cells ; 2 increased carrying capacity of blood / eq ;

3 increased haemoglobin ; 4 increased carrying capacity of blood /eq ; 5 increased cardiac output / eq ; 6 increased delivery of oxygen to tissues / eq ;

7 increased pulmonary capillaries / increased blood flow in pulmonary capillaries / eq ;

8 increased uptake of oxygen / increased oxygen diffusion capacity / eq ;

9 increased affinity of haemoglobin ; 10 increased uptake of oxygen / eq ; [For full marks the answer must include 3 circulatory adaptations]

3 x 2 = 6 marks

Total 8 marks



Question 7 Maximum marks (a) 1 {secrete / eq} {sweat / eq } ; 2 water (in sweat) evaporates ; 3 (evaporates and) has a cooling effect / eq ; 4 reference to latent heat ; 5 ref. to changes in rate of sweating in relation to temperature ;

3 marks

(b) (i) 1 as skin temperature decreases, internal heat production increases ; 2 steadily / linear / eq ; 3 credit a manipulated, quantitative comment ;

2 marks

(b) (ii) 1 as skin temperature decreases, internal heat production increases in both ;

2 Inuits’ heat production (always) higher than Europeans ;

3 ref. to greater change in heat production in Europeans ; 4 credit a manipulated quantitative comparative comment (e.g. 58 and 40 kJ) ;

3 marks

(b) (iii) 1 increased heat production ; 2 increased metabolism / eq ; 3 maintains body temperature / compensates for heat loss ; 4 more tolerant to temperature change ;

2 marks

Total 10 marks



Question 8 Maximum marks (a) 1 appropriate reference to shape ; 2 increased surface area ; 3 cells are thin ; 4 for increased diffusion (of oxygen) / decreased diffusion distance ; 5 presence of haemoglobin ; 6 reference to haemoglobin carrying / picking up oxygen / eq; 7 no nucleus / no {organelles / named examples} ;

8 idea that this gives more space for haemoglobin ;

9 small / flexible ; 10 to allow cells to pass {along / through} capillaries ;

4 marks



Question 8 continued Maximum Marks (b) 1 carbon dioxide {diffuses / eq } into red blood cell ; 2 where it combines with water ; 3 to form carbonic acid ; 4 this dissociates into hydrogencarbonate (and proton) ; 5 reference to carbonic anhydrase ;

6 {proton / H+} {combines with / buffered by / mopped up by} haemoglobin ;

7 forming {haemoglobinic acid / HHb} ; 8 hydrogencarbonate (ions) diffuse {into plasma / out of red cell} ; 9 reference to attachment (of carbon dioxide) to haemoglobin ;

10 forming {carbaminohaemoglobin / carbamino compound} ; 11 ref to carbon dioxide {carried in solution / dissolved} in RBC;

5 marks

Total 9 marks

June 2007 6103/02 Unit 3 W1 Mark Scheme

6103/02 W1 June 2007 29

Unit 3 W1 (6103/02) Question 1 Maximum mark (a)

Initial mass of shells / g

Final mass of shells (after immersing in 0.4 mol dm-3 for

5 minutes) / g

% change in mass

0.85 0.05 94.1 (94 / 94.12) 2.04 1.26 38.2 (38 / 38.24) 2.50 1.61 35.6 (36 / 35.60) 1.82 1.18 35.2 (35 / 35.16) 1.02 0.21 79.4 (79 / 79.41) 1.18 0.40 66.1 (66 / 66.10) 1.55 0.76 51.0 (51 / 50.97) 2.30 1.47 36.1 (36 / 36.09)

Suitable table format ;

Rows and columns with correct headings and units ; All percentages correct ; ; [1 error = 1 mark, 2 errors = 0 marks] 4 marks (b) F Format line graph / bar chart ; A Axes correct – scale, orientation and labelled with units ; P (All) points plotted correctly ; L Suitable line point to point / good curve / bars accurate ; 4 marks

(c) 1. Percentage decrease in mass falls as original shell mass increases ;

2. Values quoted to support main trend ;

3. Steepest fall in percentage change in mass for shell mass between 0.85 and 1.18 grams / fall less steep from shell mass of 1.18 g ; 4. Effect at higher (initial) shell mass decreases / above {1.82 / 2.04} g ; 5. Manipulation of data (simple subtraction of 2 data points is sufficient) ; 6. Anomaly at shell size of 1.82 grams /eq ; 4 marks


6103/02 W1 June 2007 30

Question 1 continued Maximum mark

(d) 1. Shells may have been exposed to the environment for different periods (before experiment) ;

2. Shells may be from different {types / species} of snail ; 3. Shells not dried / eq (before or after weighing) ; 4. Surface area may vary ; 2 marks

Total 14 marks


6103/02 W1 June 2007 31

Question 2 Maximum marks (a) 1. Suitable method of selecting identical seeds / seedlings ;

2. Seeds sown / seedlings grown with same density/equal distance apart ;

3. How two named abiotic conditions for growth controlled eg. temp, watering, growth medium ; 4. Method of controlling light intensity described ;

5. Use of light meter/probe to measure/monitor light intensity ;

6. At least 5 different intensities. ;

7. Allowed to grow for fixed time (min 1 week) ;

8. Details of standard method of selecting leaves ;

9. Use of clear nail varnish peels / epidermal peels ;

10. (Nail varnish applied) to fixed position on leaf ;

11. Use of graticule to measure area of field of view of microscope /eq ;

12. Numbers of stomata (in field of view) counted ;

13. At least 3 times ;

14. Method of measuring total leaf area ;

9 marks

(b) 1. Suitable table with units and correct rows and columns to include raw

data which matches suggested method ; 2. Mean numbers of stomata (per unit area calculated) ; 3. Correct graphical format matches method ; 4. Correct orientation of axes with labels and units ;

3 marks


6103/02 W1 June 2007 32

Question 2 continued Maximum marks (c) Limitations 1. Difficult to standardise plants ;

2. Difficult to ensure all leaves receive equal light intensity ; 3. Density of stomata can vary on different parts of the leaf ; 4. Nail varnish difficult to peel off some leaves / eq ; 5. Density of stomata can vary with age/size of leaf ; Further work 6. Investigate variation of stomata with age/size of leaf ; 7. Investigate other species of leaf ; 8. Investigate effect of different wavelengths of light ; 9. Measure transpiration rate / porosity of plants ;

6 marks

Total 18 marks

June 2007 6103/03 Unit 3 Mark Scheme

33 6103/03 June 2007

Unit 3 paper 3 (6103/03) Question 1 Maximum marks (a) parasitic / parasite ;

1 mark

(b) 1. hooks / scolex ;

2. {to attach to / to prevent the animal being carried along} {intestine / duodenum /

ileum} OR { resist muscular movements/resist peristalsis/eq;

3. suckers / scolex ;

4. {to attach to / to prevent the animal being carried along} {intestine / duodenum / ileum} OR { resist muscular movements/resist peristalsis/eq};

5. {segment(s) / proglottid(s) / thin / flat / ribbon-like / large surface area / eq ;

6. provides a large surface area / allow for absorption of food / ref to better diffusion /

prevent blockage ;

7. cuticle / tegument / coat / chitin / mucus ;

8. idea of resistance to {enzymes / digestion / eq} ;

6 marks

(c) 1. Rhizopus {secretes enzymes on to food source / digests food}, while

tapeworm does not ;

2. Rhizopus grows over the surface of its food, while tapeworms are

{endoparasites /description of endoparasitism / eq} ;

3. Rhizopus {feeds on dead material / eq}, while tapeworms do not ;

4. both have large surface area (to absorb food);

2 marks

Total 9 marks


6103/03 June 2007 34


(a) any two from:

1. overgrazing / excessive grazing / too much grazing ;

2. drought / low rainfall / lack of rain / poor irrigation ;

3. climate change / global warming ;

2 marks

(b) 1. loss of {vegetation / eq} due to {overgrazing / climate change / drought /

eq} ;

2. {trampling / eq} compacts soil / removes plants ;

3. soil exposed to {wind / water / heat} (from sun);

4. soil blown away / carried away by water ;

5. {water evaporates / evaporation} {from surface of soil} leading to {salinisation /brings

salts up / deposits salts on surface / eq} ;

6. poor irrigation leads to {change in water content of soil / eq} ;

7. idea of loss of roots loosens soils / eq ;

4 marks


6103/03 June 2007 35

Question 2 continued Maximum marks

(c) Any two from the following pairs of answers:

1. put in barrier e.g. planting wind breaks / hedges / trees / shelter belt / stones / walls

/ fence ;

2. to reduce wind speed / provide shelter to crops ;

3. use {plants that are drought resistant / native species / eq} ;

4. idea that plants can survive ;

5. plant fuel crop / eq ;

6. so no need to fell trees / ref to sustainability ;

7. rain water harvesting / irrigation ;

8. to supply water to livestock / plants / crops / agriculture / eq ;

9. control grazing by e.g. density / frequency / number / species ;

10. to prevent loss of vegetation cover / eq ;

11. laying {straw mats / stones / gravel / eq} over ground / add water-retaining material ;

12. to stabilise soil / prevent wind erosion / reduce water loss / retain moisture ;

4 marks

Total 10 marks


6103/03 June 2007 36


(a) rain that is {more acidic / lower pH} than usual / rain with a pH less than 5.6 ;

1 mark

(b) 1. use of {fossil fuels / named example} {in a power station / to make electricity / eq} ;

2. vehicle {exhaust / eq} / ref to vehicle using {petrol / eq} ;

2 marks

(c) 1. higher rainfall (on the hills) / more rain / eq ;

2. conifer trees grow on more acidic soils ;

3. {acidic / podsolic} soils more easily damaged by acid rain ;

4. soils tend to be {thinner / less depth / eq} on hills ;

5. more fog / more cloud / more mist ;

6. conifers {evergreen / retain leaves} ;

7. {leaves / needles} have larger surface area to volume ratio ;

8. conifer roots {shallow / near surface} ;

3 marks

(d) 1. {needles / leaves / spines} { turn yellow / turn brown / fall off / lose colour / die} ;

2. die-back of branches ;

3. {stunted / slow / less} growth ;

4. {stunted / fewer / shorter} roots ;

5. {damage to / fewer} root hairs / mycorrhiza ;

6. {fewer / lack / eq} lichens ;

3 marks

(e) 1. pH {ranged between 4.3 and 4.8 / averaged 4.5} before liming / January to April ;

2. {steep / large / sudden / rapid / eq} increase {after liming/May to June} ; 3. {decreases slightly / eq} for rest of year ; 4. credit manipulation of figures ;

2 marks


6103/03 June 2007 37


(f) 1. fall (in aluminium concentration) ;

2. {levels off / fluctuates} after June ;

3. calculation of fall / {0.20 / 0.16 / 0.12} mgdm-3 OR stated range of fluctuation / 0.13 to 0.07 mgdm-3 ;

4. {increase in the pH of the soil / eq} causes {less aluminium to be released / aluminium to be held by soil} ;

5. so not washed into the lake (in water) ;

4 marks

(g) 1. (aluminium) causes mucus production in gills ;

2. reduces {oxygen uptake / gas exchange} (in gills) ; 3. this causes suffocation of fish ; 4. reduces the growth rate of the fish ; 5. (aluminium in body of fish / eggs) causes metabolic disorders / enzyme inhibitors /

named metabolic process ; 2 marks

(h) 1. increase in the number of {primary consumers / herbivores} ;

2. decrease in the number of producers ; 3. increase in {other predators / secondary consumers / tertiary consumers / other

carnivores} ; 2 marks

Total 19 marks

June 2007 6104 CORE Unit 4 Mark Scheme

38 6104/01 June 2007

Unit 4 Core (6104) Question 1 Maximum marks

Stage Part of cell in which it occurs Two Products

cytoplasm / cytosol ; pyruvate / pyruvic acid,

NADH / eq and ATP / H+ ;

ATP, CO2, NADH / eq and

FADH2 / eq /H+ ;

cristae / inner membrane of mitochondrion;

Total 4 marks


6104/01 June 2007 39


(a) (i) liver ; (ii) ovary / testis;

2 marks (b) 1. ref to glucagons binding to receptor activating adenyl cyclase ;

2. (therefore) {several / many} ATP molecules are converted to cAMP / eq ;

3. cAMP activates an enzyme ;

4. (each activated) enzyme (molecule) {hydrolyses / eq} many glycogen

(molecules) ;

5. idea that glycogen is made up of many glucose (molecules) ;

6. ref to cascade effect / eq ;

3 marks

Total 5 marks


6104/01 June 2007 40


(a) 1. idea that anabolism builds up molecules and catabolism breaks them down ;

2. correct example of anabolism e.g. glucose by photosynthesis, proteins from amino

acids ;

3. correct example of catabolism e.g. carbon dioxide from respiration, glucose from

glycogen breakdown ;

3 marks

(b) (i) 1. {hydrogen / electrons} transferred from malate to NAD+ ;

2. ref to reduction of NAD+ ;

3. ref to oxidation of malate ;

2 marks

(ii) (enzyme) 1 ; 1 mark

(iii) 1. less fumarate produced ;

2. (therefore) less malate produced ;

3. (therefore) concentration of oxaloacetate decreases / eq ;

4. (so) {inhibition stops/ eq} / enzyme 2 becomes active again ;

5. ref to negative feedback ;

6. idea that succinate levels may rise ;

7. ref to more 2-oxoglutarate / hydroxyglutarate formed ;

8. ref to decreased {levels / production} of {NADH / FADH2 / H2O } eq ;

4 marks

Total 10 marks


6104/01 June 2007 41


(a) 1. increases ;

2. (because hydrostatic) pressure increases in {glomerulus / capillaries} ;

3. idea that volume of blood arriving is greater than that leaving ;

2 marks (b) 1. deamination / correct description ;

2. of excess amino acids ;

3. ref to production of ammonia ;

4. (followed by) ornithine cycle ;

5. in the liver ;

3 marks

(c)(i) 1. correct difference i.e. 15-8 (= 7) ;

2. correct division (by 15) ;

3. conversion to percentage ;

[correct answer = 46.7]

3 marks


6104/01 June 2007 42


(ii) 1. less protein in diet / eq (on day 2) ;

2. therefore fewer excess amino acids;

3. more water in diet (on day 2) ;

4. therefore more water in the urine ;

5. idea of dehydration (on day 1) ;

6. therefore less water in the urine ;

7. idea of greater demand for amino acids due to {training / growth / repair /

pregnancy} (on day 2) ;

8. therefore {less / no} excess amino acids ;

9. ref to liver malfunction / eq (on day 2) ;

10. less urea formed ;

11. urea loss through sweating (on day 2) ;

12. less urea in urine ;

3 marks

Total 11 marks


6104/01 June 2007 43

Question 5 Maximum mark

1. idea of resting potential {at start / returned to at end} (of post-synaptic membrane) ;

2. more Na+ outside axon and more K+ inside / eq ;

3. (imbalance maintained by) Na+ / K+ pump ;

4. ref to acetylcholine ;

5. diffuses across synaptic cleft ;

6. binds to receptors ;

7. on post-synaptic membrane ;

8. membrane becomes permeable to Na+ / Na+ gates open ;

9. Na+ enter (by diffusion) ;

10. causes more { Na+ channels / voltage gated channels} to open ;

11. result in depolarization (of membrane) / figures quoted;

12. idea of depolarization reaching threshold level;

13 (resulting in an) action potential / excitatory post-synaptic potential ;

14. propagation by local currents / eq ;

15. ref to {wave of depolarization / saltatory conduction / eq} ;

Total 10 marks

June 2007 6104/01 Unit 4 Option A Mark Scheme

6104/01 June 2007 44

Unit 4A (6104/01) Question 6 Maximum mark

(a) 1. (lactose converted into) lactic acid ;

2. causing a fall in pH ;

3. (low pH causes milk) proteins to coagulate;

4. causing yoghurt to thicken ;

5. ref to metabolites contributing to characteristic flavour /eq ;

3 marks

(b) 1. respiration (of glucose / maltose) produces carbon dioxide ;

2. (carbon dioxide) form spaces in the dough /eq ;

3. causing increase in volume of dough /eq ;

4. giving it its light texture /eq ;

3 marks

Total 6 marks


6104/01 June 2007 45

Question 7 Maximum mark

(a) (i) F /plasmid ;

(ii) D / ribosome ;

(iii) E / mesosome / membrane invagination ;

3 marks

(b) helical RNA

polyhedral / icosahedral RNA

complex DNA

3 marks

Total 6 marks


6104/01 June 2007 46

Question 8 Maximum marks (a) (i) 1. use (inoculating) loop / pipette ;

2. details of sterilisation of loop / pipette ;

3. cool (flamed loop / autoclaved pipette) before use ;

4. flame neck of bottle / test tubes OR open lid of Petri dish slightly ;

5. details of removing sample ;

6. idea that transfer must be done quickly ;

4 marks

(ii) B / D (or both) ;

idea that bacteria are not on the surface of the culture fluid ;

2 marks

(iii) C ;

1 mark (b) 250 x 5

(1250) x 10 000 ;

12 500 000 / 1.25 x 107 ;

3 marks

Total 9 marks


6104/01 June 2007 47

Question 9 Maximum marks (a) (i) thick /eq ;

consisting of murein / peptidoglycan / mucopolypeptide ;

2 marks

(ii) (Gram negative cell wall) thinner / outer membrane / lipopolysaccharide ;

1 mark

(b) 1. as the concentration of garlic increases up to 60 – 80% {the growth of bacteria

{decreases / inhibited} / more bacteria killed} ;

2. decrease in growth is proportional to increase in extract concentration between 20% and 60% ;

3. idea that a concentration of 60 - 80% (and over) has maximum effect /eq ;

2 marks

(c) (i) Gram negative bacteria are affected ;

1 mark

(ii) idea of extract affecting gram negative bacteria more than it affects positive

bacteria / eq ; 1 mark

(d) (because) bacteria are prokaryotes (and humans are eukaryotes) / differences in

{(bacterial) enzymes / protein synthesis / DNA synthesis / membrane / ribosomes / chromosome structure} OR Idea that human cells can break down the garlic extract whereas bacterial cells can not ;

1 mark

Total 8 marks

June 2007 6104/02 Unit 4 Option B Mark Scheme

6104/02 June 2007 48

Unit 4B (6104/02) Question 6 Maximum marks (a) 1. (results from a) lack of vitamin C ;

2. idea that it cannot be {synthesised / stored} in our bodies ;

3. needed for synthesis of {collagen / tissue proteins / connective tissue} ;

4. credit details of biochemistry ;

5. credit details of symptoms of scurvy ;

3 marks

(b) 1. fibre decreases transit time of stools / eq (through the colon) ;

2. decreasing time that {dangerous/carcinogenic} chemicals present ;

3. softens the stools / increases the bulk of faeces ;

4. reducing friction / trauma / eq;

3 marks

Total 6 marks


6104/02 June 2007 49

Question 7 Maximum marks (a) (skinfold) calliper ;

1 mark

(b) 1. pinch skin (between finger and thumb) ;

2. pull lever to open arms of calliper / eq ;

3. close calliper over skinfold / eq ;

4. read measurement from the scale ;

3 marks

(c) ANY TWO FROM:

waist

back / below shoulder blade

hip

front of upper arm

back of upper arm ;

1 mark

(d) (i) average skinfold calculated ;

percentage body fat: 17.4 – 18.4 ;

2 marks

(ii) measurements from one part of body only;

only three readings;

1 mark

Total 8 marks


6104/02 June 2007 50

Question 8 Maximum marks (a) 1. ethene released / produced ;

2. enzymes stimulated / ref to synthesis of enzymes ;

3. pectinase breaks down pectin ;

4. middle lamella / cell wall breaks down ;

5. starch broken down to sugar / eq ;

6. Chlorophyll broken down / lycopene produced ;

4 marks

(b) (i) 1. raise carbon dioxide level/lower oxygen content ;

2. store at low temperatures ;

3. use ethene inhibitor ;

1 mark

(ii) 1. reduce bruising / damage ;

2. ref to customer preference ;

3. less risk of microbial decay ;

4. adjusting time of sale / eq ;

5. increase shelf life / time of storage ;

2 marks

Total 7 marks


6104/02 June 2007 51

Question 9 Maximum marks (a) 1. fermentation of glucose/fructose/sucrose ;

2. in anaerobic conditions ;

3. (results in) the production of ethanol ;

2 marks

(b) (i) 1. up to 12 – 12.4 days both produce alcohol at similar rate / similar

volume ;

2. alcohol production by type B yeast stops before type A / eq ;

3. type A produces more alcohol overall / after day 12 than type B ;

4. correct manipulation of figures ; 3 marks

(ii) 1. alcohol toxic /eq ;

2. yeast died ;

3. sugar used up ;

2 marks

(c) 1. carbon dioxide is produced ;

2. by (either aerobic or anaerobic) respiration ; 3. alcohol levels will not become high enough to kill yeast / eq ;

2 marks

Total 9 marks

June 2007 6104/03 Unit 4 Option C Mark Scheme

52 6104 Option C June 2007

Unit 4C (6104/03) Question 6 Maximum mark (a) 1. by inhalation of bacteria in (droplets/dust) ;

2. called Mycobacterium tuberculosis ;

3. formation of {tubercles / plaques / lesions} ;

4. in the lungs ;

5. ref to invasion of other tissues / organs ;

3 marks

(b) 1. formation of atheroma / plaque ;

2. in artery walls ;

3. due to {lipid / eq} {deposits / eq} ;

4. narrowing the lumen (of the artery) / idea of restricting blood flow ;

5. ref to high (blood) cholesterol / high blood pressure / smoking / lack of

exercise ;

3 marks

Total 6 marks




(a) 1. reading 22 and 15 ;

2. correct numerator :{7 / 22-15} x 100% ;

3. correct denominator: 22 = correct answer ;

[correct answer 28.57: - 36.36%]

3 marks

(b) 1. ref to Ca2+ binding to muscle protein (troponin) ;

2. (this) results in {change in shape of muscle protein (troponin) / movement of

muscle protein (tropomyosin) / exposure of (myosin) binding site on actin} ;

3. ATP binds to myosin (head) ;

4. myosin attaches to actin (binding site) ;

5. ATP broken down to ADP and Pi / energy released from ATP / release of ADP

and Pi ;

6. head swivels / changes angle / idea of actin moving (over myosin) ;

4 marks

Total 7 marks



Question 8 Maximum marks (a) medulla / medulla oblongata ;

1 mark

(b) before diving / singing / sniffing / playing a musical instrument / peak flow

measurement / breathalyser / eq ;

1 mark

(c) 1. ref to baroreceptors / stretch receptors ;

2. detect degree of stretch in diaphragm and/or intercostals muscles ;

3. (and) feedback this to the {medulla /respiratory control centres} along

(sensory) neurones ;

4. idea of nervous link from {medulla / respiratory control centres}to muscles to

{alter / change} {ventilation (rate) / breathing rate / (depth of) breathing} ;

3 marks

(d) 1. idea that exercise {increases the {CO2 / H+} concentration / {decreases the pH

/ 02 concentration} ;

2. (this increase is) detected by chemoreceptors ;

3. (chemoreceptors) send impulse to medulla ;

4. (resulting in) increased {rate of ventilation / breathing rate / depth of

breathing / contraction of {respiratory / intercostals / diaphragm muscles} } ;

2 marks

Total 7 marks



Question 9 Maximum marks (a) 1. calcified connective tissue ;

2. {bone cells / osteocytes / eq} in {cavities in a matrix / lacunae} ;

3. cavities called lacunae ;

4. matrix consists of collagen fibres and {inorganic / eq} salts ;

5. salt called hydroxyapatite ;

6. ref to Haversian canals / description e.g. concentric rings idea ;

7. canals contain {blood vessels / nerves / lymphatic vessels} ;

8. ref to canaliculi ;

9. (canaliculi) contain cytoplasm ;

4 marks

(b) (i) 1. (overall) average bone mass density increases with length of exercise ;

2. ref to anomaly at 90 minutes of exercise ;

3. greatest increase in bone mass density seen between 0 and 30 mins of

exercise ;

4. (only) 120 minutes of exercise reduces range of bone mass densities

measured ;

5. manipulation of figures to compare two groups / bone densities or

ranges ;

3 marks

(ii) 1. idea that many other factors influence bone mass density ;

2. idea that factors were not controlled ; 3. any two factors named e.g. body weight / cigarette smoke / alcohol intake / intake of other drugs / genetics / contraceptive pill / gender / additional exercise taken / low calcium diet ;;

2 marks

(iii) exercise of this length is most significant contributing factor / eq / maximum bone density reached which cannot be exceeded ;

1 mark

Total 10 marks


6105 June 2007 56

Unit 5B (6105/01) Question 1 Maximum marks (a) ref. to (yeast is) genetically-modified / genetically-engineered / ref. to {vegetarians /

vegans / religious groups} concerned by use of {animal / calf / eq} ;

1 mark

(b) The points have to be within the context of the flow diagram.

1. cDNA produced by reverse transcriptase ;

2. using mRNA as {template / eq} ;

3. {vector / plasmid / (yeast) DNA} {opened / cut / eq} by {restriction enzyme /

endonuclease} ;

4. ref. to {sticky ends / eq} ;

5. cDNA and {vector / plasmid / (yeast) DNA} {joined / bonded / annealed / inserted /

eq} by ligase ;

6. ref. to polymerase used to {amplify multiply / eq} cDNA ;

4 marks

Total 5 marks


6105 June 2007 57

Question 2 Maximum marks (a) (i) codominance ;

1 mark

(ii) 1 chevron + 2 mixed + 1 patch ;

1 mark

(iii) 1. (genotypes of parents:) VPVC and VPVC ;

2. correct gametes shown for each ;

3. cross correct to give genotypes ;

4. genotypes matched with phenotypes ;

3 marks

(b) 1. both involve single {gene / allele pair / locus} ;

2. ref. to codominance in both / eq ; NOT just A and B, must use IA and IB

3. ref. to multiple alleles in blood groups / ABO involves three alleles, clover patterns

only two alleles / eq ;

4. ref. to dominance of { IA / IB } over Io / Io is recessive to {the others / IA / IB };

5. no {dominance shown / recessive allele} in clover patterns ;

6. the ABO blood group has 4 phenotypes, the clover pattern has 3 phenotypes ;

7. both show {discontinuous / discrete} variation ;

4 marks

Total 9 marks


6105 June 2007 58


(a) 1. shape and quality of diagram ;

ACCEPT round / oval clear diagram with a smooth, clear, complete outline.

2. double membrane i.e. has two lines clearly not cristae ;

3. grana / thylakoids shown as at least two stacks joined by one line;

4. correctly labelled position of light dependent and independent reactions ;

4 marks

(b) 1. {light absorbed / energy absorbed / electrons excited / eq} in {photosystem /PS I /

PS II / pigment system / P680 / P700} ;

2. (photosystems) {emit /eq} electrons ;

3. electron from PSII pass along {chain of electron carriers / eq} to PS I ;

4. ATP generated / eq ;

5. electron from PS1 to NADP to form NADPH + H / eq ;

6. using {H+ / eq} from {photolysis /eq} ;

7. oxygen formed ;

4 marks

(c) 1. oxygen {diffuses out (of leaf / photosynthetic tissue) / used in respiration} ;

2. ATP and NADPH + H {enter Calvin Cycle / enter light independent stage / used in

synthesis of carbohydrate / used to reduce CO2 / eq} ;

2 marks

Total 10 mark


6105 June 2007 59


(a) 1. made of C, H, O ;

2. glycerol / propan (1, 2, 3) triol ;

3. three fatty acids ;

4. correct location of ester {bond / link} ;

ACCEPT points 2, 3 and 4 made on a clearly labelled diagram

3 marks

(b) 1. rise in external temperature {causes / eq} the brown fat to be metabolised / eq ;

2. break down of {fat / bonds} ;

3. causes release of heat (energy) / ref to exothermic reaction ;

4. causes body temperature to rise ;

5. credit ref to detail of fatty acid break down / 2C / link reaction etc ;

6. {fats / fatty acids} respired {using oxygen / aerobically} ;

7. oxygen and temperature rises until 160 mins ;

8. (then) oxygen peaks at 160 min but temperature continues to rise until 180

mins / eq ;

9. body temperature levels off / eq at {normal body temperature / 37 °C} ;

10. {brown fat metabolism / eq} is reduced so {oxygen use falls / eq} ;

6 marks


6105 June 2007 60


(c) 1. provide (physical) protection to organs ;

2. idea of {thermal / eq} insulation ;

3. (combines with phosphate) to form phospholipids ;

4. buoyancy / eq ;

5. electrical insulation / myelin ;

6. waterproofing / eq ;

7. source of metabolic water ;

8. {solvent / storage} for vitamins ;

3 marks

Total 12 marks


6105 June 2007 61

Question 5 Maximum marks (a) 1. {proteins / amino acids / organic nitrogen compounds / eq} {broken down /

decomposed / converted} to {ammonium / ammonia} by {bacteria / fungi / putrifiers /

microorganisms / decomposers / eq} ;

2. {ammonium / ammonia} converted to nitrites by {Nitrosomonas / Nitrococcus /

nitrifying bacteria} ;

3. nitrites converted to nitrates by {Nitrobacter / Nitrobacillus / nitrifying bacteria} ;

4. ref. to oxidation in correct context ;

3 marks (b) 1. ref. to {absorbed / taken in / eq} by root hairs ;

2. by active transport and diffusion ;

3. used for {synthesis / eq} of {amino acid / protein / DNA / organic base / chlorophyll /

eq} ;

4. ref. to {proteins / DNA }required for {growth / cell division / specified part of plant} ;

3 marks (c) (i) 1. compost heap {warmer / higher temperature} than air ;

2. difference in range 15 – 25 oC / specified difference ;

3. both fluctuate in similar pattern / ref to both show a downward trend / eq ;

2 marks

(ii) 1. ref. to {respiration / metabolic activity} of microorganisms ;

2. (which) releases heat ;

3. ref. to insulation effect of {compost / container} ;

2 marks

(iii) ANY TWO FROM:

{reduced food / substrate / toxin / inhibitor / more waste product / competition

/ more anaerobic / less oxygen / cooling effect of rain / change in water / change

in pH} ;;

2 marks

Total 12 marks


6105 June 2007 62

Question 6 Maximum marks (a) biotic involve {other organisms / living / eq}, abiotic are {physical / non-living / chemical

/ eq} ;

1 mark

(b) 1. named organism appropriate to habitat ;

2. specified abiotic factor and means of measuring abiotic factor / named apparatus/eq ;

3. appropriate technique for measuring distribution of organism in the habitat e.g. {belt /

transect / systematic / stratified} sampling ;

3 marks

(c) (i) 1. stomatal {aperture / opening / pore / eq} {increases / eq} as temperature

increases {up to 30 oC / to 25 oC and levels off to 30 oC } ;

2. {aperture / opening / pore/eq} decreases as temperature increases from 30oC ;

[ref. to temperatures must be included]

2 marks

(ii) 1. more water lost when stomata open ;

2. plants in hot, dry conditions need to conserve water / eq ;

3. by reducing {evaporation / transpiration} rate ;

4. (cotton plants) during hottest part of day, % stomata opening is below

maximum / eq ;

5. ref to {time / figures} from graph ; ACCEPT ref to ‘early morning’ / ‘midday’ /

‘early evening’

6. idea of needing to have stomata open for {transpiration / gas exchange /

photosynthesis} ;

4 marks

(d) xeromorphic / xerophytic ;

1 marks

Total 11 marks


6105 June 2007 63


(a) 1. the rise in the (average) temperature of the Earth’s surface ;

NOT ‘air temperature’ / ‘atmosphere’

2. due to the increase in greenhouse gases ;

3. carbon dioxide / methane / CFCs / nitrogen oxides / water vapour ;

ACCEPT correct formula: CO2 / CH4 / NOx

IF ozone / sulphur dioxide mentioned, DO NOT AWARD this marking point

4. (which) {trap / reflect back / absorb } {heat / long wave / infra red / radiation} ;

5. reference to {enhanced / increased} greenhouse effect ;

3 marks

(b) (i) 1. overall trend generalists increased in abundance and specialists decreased ;

2. peaks and troughs in the abundance for both correspond ;

3. generalists always greater than specialists ;

2 marks

(ii) 1. specialists have lost their specific habitat ;

2. specialists have lost a food source ;

3. {weather /predation / common food} has effected both groups of butterflies ;

4. {climate change / temperature} has favoured generalists ;

5. generalists more able to {exploit new habitats / adapt / larger niche} ;

3 marks

(c) 1. comma once found only in the warmer south ;

2. (global warming) produces milder winters further north / eq ;

3. (global warming has) increased {food supply /egg plants / habitats} of the comma ;

4. other butterflies cannot survive so well so comma outcompetes them / moves to avoid

intraspecific competition / eq ;

5. (global warming) reduces the number of predators (so more commas survive) ;

3 marks

Total 11 marks


64 6115/01 June 2007

Unit 5H (6115/01) Question 1 Maximum marks

(a) ref. to (yeast is) genetically-modified / genetically-engineered / ref. to {vegetarians /

vegans / religious groups} concerned by use of {animal / calf / eq} ;

1 mark

(b) The points have to be within the context of the flow diagram.

1. cDNA produced by reverse transcriptase ;

2. using mRNA as {template / eq} ;

3. {vector / plasmid / (yeast) DNA} {opened / cut / eq} by {restriction enzyme /

endonuclease} ;

4. ref. to {sticky ends / eq} ;

5. cDNA and {vector / plasmid / (yeast) DNA} {joined / bonded / annealed / inserted /

eq} by ligase ;

6. ref. to polymerase used to {amplify / multiply / eq} cDNA ;

4 marks

Total 5 marks


6115 June 2007 65

Question 2 Maximum marks (a) (i) codominance ;

1 mark

(ii) 1 chevron + 2 mixed + 1 patch ;

1 mark

(iv) 1. (genotypes of parents:) VPVC and VPVC ;

2. correct gametes shown for each ;

3. cross correct to give genotypes ;

4. genotypes matched with phenotypes ;

3 marks

(b) 1. both involve single {gene / allele pair / locus} ;

2. ref. to codominance in both / eq ; NOT just A and B, must use IA and IB

3. ref. to multiple alleles in blood groups / ABO involves three alleles, clover patterns

only two alleles / eq ;

4. ref. to dominance of { IA / IB } over Io / Io is recessive to {the others / IA / IB };

5. no {dominance shown / recessive allele} in clover patterns ;

6. the ABO blood group has 4 phenotypes, the clover pattern has 3 phenotypes ;

7. both show {discontinuous / discrete} variation ;

4 marks

Total 9 marks


6115 June 2007 66


(a) (i) (human)

1. bipedal walking / walking on two {feet / legs} ;

2. idea of toes parallel ;

3. form a platform / ref. to arch ;

2 marks

(gorilla)

4. knuckle walking / eq ;

5. walks on side of foot / not on sole of foot / eq ;

6. (big) toe still opposable ;

7. uses foot for grasping ;

2 marks

(ii) 1. {hip bone / pelvis} has become {broader / more shallow / eq};

2. for attachment of muscles ;

3. pelvis lower in body ;

4. centre of gravity in pelvic area for standing upright / eq ;

5. more suited to bipedal walking;

6. legs longer than arms ;

7. femur at an angle / ref to valvus angle ;

8. knee in line with pelvis / eq ;

9. humans able to fully extend leg while walking ;

4 marks

(b) 1. to pick up {food / fruits / eq} ;

2. to carry {weapons / baby / eq} ;

3. to use {tools / eq} ;

2 marks

Total 10 marks


6115 June 2007 66

Question 4 Maximum marks (a) 1. made of C, H, O ;

2. glycerol / propan (1, 2, 3) triol ;

3. three fatty acids ;

4. correct location of ester {bond / link} ;

ACCEPT points 2, 3 and 4 made on a clearly labelled diagram

3 marks

(b) 1. rise in external temperature {causes / eq} the brown fat to be metabolised / eq ;

2. break down of {fat / bonds} ;

3. causes release of heat (energy) / ref to exothermic reaction ;

4. causes body temperature to rise ;

5. credit ref to detail of fatty acid break down / 2C / link reaction etc ;

6. {fats / fatty acids} respired {using oxygen / aerobically} ;

7. oxygen and temperature rises until 160 mins ;

8. (then) oxygen peaks at 160 min but temperature continues to rise until 180 mins / eq ;

9. body temperature levels off / eq at {normal body temperature / 37 °C} ;

10. {brown fat metabolism / eq} is reduced so {oxygen use falls / eq} ;

6 marks

(c) 1. provide (physical) protection to organs ;

2. idea of {thermal / eq} insulation ;

3. (combines with phosphate) to form phospholipids ;

4. buoyancy / eq ;

5. electrical insulation / myelin ;

6. waterproofing / eq ;

7. source of metabolic water ;

8. {solvent / storage} for vitamins ;

3 marks

Total 12 marks


6115 June 2007 67

Question 5 Maximum marks (a) 1. {proteins / amino acids / organic nitrogen compounds / eq} {broken down /

decomposed / converted} to {ammonium / ammonia} by {bacteria / fungi / putrifiers /

microorganisms / decomposers / eq} ;

2. {ammonium / ammonia} converted to nitrites by {Nitrosomonas / Nitrococcus /

nitrifying bacteria} ;

3. nitrites converted to nitrates by {Nitrobacter / Nitrobacillus / nitrifying bacteria} ;

4. ref. to oxidation in correct context ;

3 marks (b) 1. {nitrates / minerals / eq} can be {washed / eq} into stream ;

2. ref. to eutrophication / nutrient enrichment (in stream) ;

3. leads to {exercise plant growth / algal bloom};

4. relevant consequence ;

3 marks (c) (i) 1. compost heap {warmer / higher temperature} than air ;

2. difference in range 15 – 25 oC / specified difference ;

3. both fluctuate in similar pattern / ref to both show a downward trend / eq ;

2 marks

(ii) 1. ref. to {respiration / metabolic activity} of microorganisms ;

2. (which) releases heat ;

3. ref. to insulation effect of {compost / container} ;

2 marks

(iii) ANY TWO FROM:

{reduced food / substrate / toxin / inhibitor / more waste product / competition

/ more anaerobic / less oxygen / cooling effect of rain / change in water / change

in pH} ;; NOT death

2 marks

Total 12 marks


6115 June 2007 68


(a) biotic involve {other organisms / living / eq}, abiotic are {physical / non-living / chemical

/ eq} ;

1 mark

(b) 1. named organism appropriate to habitat ;

2. specified abiotic factor and means of measuring abiotic factor / named apparatus/eq ;

3. appropriate technique for measuring distribution of organism in the habitat e.g. {belt /

transect / systematic / stratified} sampling ;

3 marks

(c)(i) 1. {partial pressure / tension / eq} oxygen lower (at high altitudes) ;

2. diffusion gradient between air and blood {lower / eq} ; 3. diffusion of oxygen into blood {slower / less efficient/ eq} ;

2 marks

(ii) 1. ref. to Ethiopia, Andes and Tibet have high mean altitudes ;

2. Ethiopia seems to have adapted ;

3. (because) has {similar % saturation as USA / higher than USA} has high % saturation compared with Andes / Tibet ; 4. Andes / Tibet do not seem to be adapted ; 5. (because) lower % saturation than {Ethiopia / USA} ;

4 marks

(d) 1. increased red blood cell density / eq ;

2. ref. to increased haemoglobin density / changes in haemoglobin {structure / eq} / increased affinity for O2 in haemoglobin ; 3. increased lung {volume / (vital) capacity} ; 4. ref. to {more / denser} capillaries (around alveoli) ;

3 marks

Total 11 marks


6115 June 2007 69

Question 7 Maximum marks (a) 1. the rise in the (average) temperature of the Earth’s surface ;

NOT ‘air temperature’ / ‘atmosphere’

2. due to the increase in greenhouse gases ;

3. carbon dioxide / methane / CFCs / nitrogen oxides / water vapour ;

ACCEPT correct formula: CO2 / CH4 / NOx

IF ozone / sulphur dioxide mentioned, DO NOT AWARD this marking point

4. (which) {trap / reflect back / absorb } {heat / long wave / infra red} ;

5. reference to {enhanced / increased} greenhouse effect ;

3 marks

(b) (i) 1. overall trend generalists increased in abundance and specialists decreased ;

2. peaks and troughs in the abundance for both correspond ;

3. generalists always greater than specialists ;

2 marks

(ii) 1. specialists have lost their specific habitat ;

2. specialists have lost a food source ;

3. {weather /predation / common food} has effected both groups of butterflies ;

4. {climate change / temperature} has favoured generalists ;

5. generalists more able to {exploit new habitats / adapt / larger niche} ;

3 marks

(c) 1. comma once found only in the warmer south ;

2. (global warming) produces milder winters further north / eq ;

3. (global warming has) increased {food supply /egg plants / habitats} of the comma ;

4. other butterflies cannot survive so well so comma outcompetes them / moves to avoid

intraspecific competition / eq ;

5. (global warming) reduces the number of predators (so more commas survive) ;

3 marks

Total 11 mark


6106 W2 June 2007 70

Unit 6 W2 (6106/02) Question 1 Maximum marks (a)

[Tally columns are optional] Rows and columns with correct headings and units: Suitable size classes (9 mm min with no overlap) ; All windward tally totals correct ;

3 marks

(b) F Histogram format ; A Axes, scale, orientation and labelled with units ; P All plotted correctly ; L Sheltered/windward columns paired and clearly keyed ;

4 marks

(c) Any of the following:

Overlap between both data sets ; Sheltered range = 10-90 Windward range 50-115/Sheltered has greater range of data the windward ; Both have large range of data (showing other factors may affect length) ;

1 marks

First internode length mms

Sheltered side Windward side

10-29 // 2 0 30-49 ////// 6 0 50-69 //// 4 /// 3 70-89 // 2 /////// 7 90-109 // 2 //// 4 110-129 0 // 2

First internode length mms

Sheltered side Windward side

10-39 //// 5 0 40-69 /////// 7 /// 3 70-99 //// 4 ///////// 9 100-129 0 //// 4


6106 W2 June 2007 71


(d) The calculated value of t/4.09 is greater than the critical value/2.04 ;

At the 5% significant level / 0.05 probability level ; There is a significant difference between (the means of) the lengths of first internodes on the sheltered and windward sides of the dunes ;

3 marks

Total 11 marks


6106 W2 June 2007 72

Question 2 Maximum marks (a) 1 Different colours on same species of flower / size card ;

2 Sugar of {stated concentration / nectar from same source} ; 3 Standardise source / species of bees / eq ;

4 (Solutions put in) the same {shaped / sized} {dishes /flowers} ;

5 Method of controlling TWO other factors related to site (e.g. scent,

location, shade of/brightness of colours) OR stated physical condition standardised/controlled (e.g. time of day, sunny, warm, still , clear, equal distance apart) ;

6 Put {sugar / nectar) on one of colours ;

7 Leave dishes / flowers for fixed time after set-up ;

8 Rearrange dishes / coloured flowers / plots (to randomise) ;

9 Count number of honeybees visiting each colour over stated time

period/on each colour at specified time ;

10 Detail of what counts as a visit (e.g. only count bees that land on colour) ;

11 Repeat at least twice more ;

12 Ref. to humane treatment of bees / care of environment ;

8 marks

Account is concise and well-organised, there is good use of technical vocabulary and almost no spelling errors – 2 marks

There is some lack of organisation, limited vocabulary and a number of spelling errors – 1 mark The account lacks organisation, there is little or no technical vocabulary and many spelling errors – 0 marks

2 marks


6106/02 June 2007 73


(b) Table of raw data with suitable labelled rows and columns with units ; Calculation of means suggested/totals counted ;

Suitable graph format matching data & method, including correctly labelled axes ;

Graphical presentation allows comparison ;

Reference to suitable type of statistical test {(for significant difference)} between means/for association ;

Use of stated null hypothesis (ref. to significance required) ;

6 marks

(c) Limitations

1. Difficult to standardise environmental conditions ;

2. Difficult to {standardise a visit/record exact honeybees’ response (they may visit more than one colour) ;

3. Insufficient numbers of honeybees visit OR difficult to {train/attract/eq} honeybees ;

4. Honeybees do not recognise the colours used ;

5. Honey bees visiting (after training/eq) may be different (from those making original visit) ;

6. Despite control of variables, other sense(s) are attracting bees to colours ;

7. Interactions between bees and other insects may affect colour choice ;

Further work

Investigate:

8. The precision to which honeybees respond to colour ;

9. The range of colour vision in honeybees ;

10. Colour vision in different types of bee/wasps/hymenoptera ;

11. Time period over which attraction to colour (without sugar) continues ;

5 marks

Total 21 marks

June 2007 6106/03 Unit 6 Synoptic Mark Scheme

6106/03 June 2007 74

Unit 6 Synoptic (6106/03) Question 1 Maximum marks (a) 1 (blood glucose concentration) increases / eq ; 2 by 2.2 mmol per dm3 / by 44% / by 1.44 times ; 3 glucose is absorbed (into the blood) / eq ;

4 in the {ileum / duodenum / small intestine / stomach / jejunum} ;

3 marks (b) 1 they both increase up to (a maximum at) 30 minutes ; 2 (then) decrease /eq ;

2 marks (c) 1 reference to (glucose) transporter proteins ; 2 reference to phosphorylation of glucose ; 3 (glycogen synthesis) reduces the concentration of glucose in cell ;

4 this {maintains / increases} the {diffusion / concentration gradient} ;

3 marks


6106/03 June 2007 75

Question 1 continued Maximum marks (d) There are four possible named hormones:

1 glucagon ; 2 increases blood glucose {concentration / level / eq} ; 3 by (promoting) glycogenolysis / inhibiting glycogenesis /

(stimulating) gluconeogenesis / eq ; OR 1 adrenaline ; 2 increases blood glucose {concentration / level / eq} ; 3 by (promoting) glycogenolysis / (stimulating) gluconeogenesis / eq ; OR 1 thyroxine ; 2 decreases blood glucose {concentration / level / eq} ; 3 by increasing cell respiration / eq ; OR 1 cortisol ; 2 increases blood glucose {concentration / level / eq}; 3 by (increasing) gluconeogenesis / eq ;

3 marks

Total 11 marks


6106/03 June 2007 76

Question 2 Maximum marks (a) 1 they both decrease /eq ; 2 accept an accurate, manipulated, quantitative reference for both ;

2 marks (b) 1 calculation ;

2 18.3 ;

2 marks (c) 1 consists of (α) glucose + fructose ; 2 joined by a glycosidic bond / glycosidic link ;

2 marks (d) 1 acetylcholine is {a (chemical) transmitter substance / a neurotransmitter} ;

2 (insecticide X) will {stop / reduce / eq} the transmission of nerve impulses ;

3 across synapses / blocks the synapse / stops synaptic (transmission) ;

4 no post-synaptic potential generated / ref to permeability of post-synaptic membrane / eq ;

3 marks


6106/03 June 2007 77

Question 2 continued Maximum marks (e) 1 reference to toxicity to non-target species / insecticides are

non-specific ; 2 reference to (chemical) stability of insecticides ; 3 reference to bioaccumulation ; 4 reference to development of resistance / eq ; 5 reference to resurgence (of pests) / need to re-apply insecticides ; 6 reference to harmful effect on crop ;

3 marks

Total 12 marks


78 6106/03 June 2007

ESSAY MARK SCHEME

Outline scheme for marking essay questions 3, 4B and 5H 11 available for Scientific content (S) 2 available for Balance (B) 2 available for Coherence (C) Total maximum mark available: 15

Scientific content (S)

Scientific content (S)

Description

11

(good)

The essay demonstrates a sound understanding of the topic and contains a significant amount of material from most areas of the mark scheme, including A2 content. Suitable examples are included and the candidate has clearly and coherently linked together information from different parts of the specification.

9

(above average)

An above average essay, with accurate content. The essay includes a good balance of material from several areas of the mark scheme, including A2 content, and examples where appropriate. There may be some minor factual errors.

7

(average)

The essay includes relevant information from some areas of the mark scheme, including A2 content. The candidate links together some facts and principles. Some examples are included. There may be some minor factual errors.

5 (below

average)

The essay includes some generally factually accurate and relevant material, and there is some attempt to link material from more than one area of the mark scheme. The A2 content, in particular, lacks depth and accurate details.

3 (poor)

There are some correct facts, but the essay lacks depth and accuracy. The essay contains little or no relevant information from the A2 content.

1 (poor)

There are very few correct facts. The essay is generally superficial and inaccurate.

0 (poor)

No correct or relevant material is included.

Note: If a scientific content mark of 0, 1, or 3 is awarded, it is very unlikely that a balance mark of more than 1 is appropriate. An essay containing AS content only can be awarded a max of 3 for scientific content. An essay containing A2 content only can be awarded a max of 7 for scientific content.

S = 11 marks


79 6106/03 June 2007

Balance (B) 2 Most of the main topic areas outlined are covered

Some discussion of each of the areas chosen, illustrated with suitable examples where appropriate Material included is all relevant to the topic and the candidate has linked information from more than one area of the specification. Few, if any, errors

1 Some of the main topic areas outlined are covered. Some discussion of each of the areas chosen. Some irrelevant material included. There are some examples which link together different areas of the specification. Some errors

0 Very limited account, possibly only one aspect chosen

Material mostly irrelevant No examples of the candidate linking information from different topics Large number of errors

B = 2 marks Coherence (C) 2 Material logically presented, with little or no repetition

Essay has coherence, ideas are developed well; continuous prose used throughout Essay has an introduction and a conclusion, summing up the main points Technical terms have been used correctly Spelling, punctuation and grammar are sound

1 Material is presented in an orderly way and some ideas developed

Continuous prose used throughout The introduction and conclusion may be present, but brief Technical terms are used and generally in the correct context Spelling, punctuation and grammar are generally sound

0 Essay style not used Material in note form or numbered points Very poor standard of spelling, punctuation and grammar

C = 2 marks


80 6106/03 June 2007


[A2 content is in bold] Introduction could include ref to the importance of sexual reproduction giving rise to genetic variation – Gamete formation involves meiosis – independent assortment Crossing over – Random fertilisation – Mutations giving rise to genetic variation – Selection pressures act on the gene pool – Changes in allele frequency in populations – Stabilising, directional and disruptive selection – Natural selection giving rise to speciation – Allopatric speciation – Sympatric speciation -

Scientific content 11 marks Balance 2 marks

Coherence 2 marks

Total 15 marks


81 6106/03 June 2007

Question 4B Maximum marks

[A2 content is in bold] Introduction could include overview of pollination and chemical control of growth – Principal parts of an insect pollinated and a grass flower - Pollination – Adaptations to insect and wind pollination – Effects of:

auxins - cytokinins – gibberellins – abscisic acid – ethene –

Synergism and antagonism – Phytochrome -


Coherence 2 marks

Total 15 marks


82 6106/03 June 2007

Question 5H Maximum marks

[A2 content is in bold] Introduction could include reference to the significance of meiosis – Gamete formation involves meiosis – First and second divisions of meiosis – Chiasmata formation – Translocation - Non–disjunction – Polysomy and polyploidy – Specific reference to Down’s syndrome –

[Trisomy-21, or 14’21 translocation] Detection of chromosome mutations and karyotypes -


Coherence 2 marks

Total 15 marks

Further copies of this publication are available from Edexcel Publications, Adamsway, Mansfield, Notts, NG18 4LN Telephone 01623 467467 Fax 01623 450481 Order Code UA018980 June 2007 For more information on Edexcel qualifications please visit www.edexcel.org.uk/qualifications Alternatively, you can contact Customer Services at www.edexcel.org.uk/ask or on 0870 240 9800. Edexcel Limited. Registered in England and Wales no.4496750 Registered Office: One90 High Holborn, London, WC1V 7BH

Documents

Mark Scheme Summer 2007 - The Student Room