2005 January SN 1,4 Mark Scheme

Rewarding Learning

edexcelmes IN

GCEEdexcel GCE

Biology (Salters-Nuffield) (Pilot)(6131 and 6134)

1 -nuary 2005

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January 2005

Publications Code UA016155

All the material in this publication is copyrightC1 Edexcel Ltd 2005

Contents

General Introduction p

Unit Codes and Unit Titles p iii

General Information p iv

Mark Schemes

Unit SN1 6131 Lifestyle, Transport, Genes and Health

p1

Unit 5114 6134 Environment and Survival p 12

i

GENERAL INTRODUCTION

Mark schemes are prepared by the Principal Examiners and revised, together with the relevantquestions, by a panel of senior examiners and subject teachers. The schemes are furtheramended at the Standardisation meetings attended by all examiners. The Standardisationmeeting ensures as far as possible that the mark scheme covers the candidates actualresponses 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 thisexamination and include the amendments made at the meeting. They do not include anydetails of the discussions that took place in the meeting, nor do they include all of the possiblealternative 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 inthis examination. Every effort is made to ensure a consistent approach to marking from oneexamination to another but each marking point has to be judged in the context of thecandidates' responses and in relation to the other questions in the paper. It should not beassumed 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 ofindividual scripts. Any enquiries about the marks awarded to individual candidates can bedealt with only through the official Enquiry about Results procedure.

11

Unit Codes and Unit Titles

This Mark Scheme covers the units offered in this examination for Advanced Subsidiary Biology(Salters-Nuffield) (Pilot), 6131 and for Advanced GCE Biology (Salters-Nuffield) (Pilot), 6134.

The units available for the complete qualifications, Advanced Subsidiary and Advanced, arelisted in the table below.

Level Unit Code Unit TitleAS

1 6131 Lifestyle, Transport, Genes and Health

2 6132 Development, Plants and the Environment

3 6133 Report and Practical Review

A24 6134 Environment and Survival

5 6135 Energy, Exercise and Coordination; Coursework Investigation

6 6136 Synoptic Paper

Please note that Units 6132, 6133, 6135 and 6136 are only available in the Summer examinationseries.

Ill

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

eqIndicates that credit should be given for other correctalternatives to a word or statement, as discussed in theStandardisation meeting

/ oblique Words or phrases separated by an oblique are alternativesto each other

{) curly bracketsIndicate the beginning and end of a list of alternatives(separated by obliques) where necessary to avoidconfusion

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

[] square brackets Words inside square brackets are instructions or guidancefor 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—beignored. If the candidate has crossed out work but written no new text, the crossed out work forthat 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 notsubsequently. The candidate is penalised once only and can gain credit in later parts of thequestion by correct reasoning from the earlier incorrect answer.

No marks are awarded specifically for quality of language in the written papers, except for theessays in the synoptic paper. Use of English is however taken into account as follows:

• the spelling of technic-al terms must be sufficiently correct for the answer to beunambiguouse.g. for amylase, 'ammalase' is acceptable whereas 'amylose' is note.g. for glycogen, `glicojen' is acceptable whereas Iglucagen' is note.g. for ileum, 'illeum' is acceptable whereas 'ilium' is note.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 ananswer gains no mark-Irrelevant material should be ignored.

iv

January 2005 6131 Unit SN1 Mark Scheme

Unit SN1 (6131)

Question 1 Maximum mark

(a) {Sinoatrial / SA) node / SAN / pacemaker ;1 mark

(b) 1. [(Wave of electrical) impulses / depolarisation) from SA node ;

2. Passes over (both) atria / eq ;

3. Resulting in atrial [systole_tcontractionj ;

4. Slight delay at AV node ;

5. (Impulses) pass along bundle of His ;

6. (Up / along) Purkinje fibres / eq ;

7. Correct direction of impulse described / ventricles contract from the base up /eq ;

8. Resulting in ventricular (systole / contraction) ;4 marks

Total 5 marks

Page 1 6131 January 2005



(a) (i) 1. Copy of (normal / correct) [allele / gene} inserted into a (loop of DNA / plasmid /vector / (retro)virus)

2. Reference to [restriction enzyme / endonuctease} ;

3. Reference to DNA ligase ;

4. Forms Liposome-DNA complex / (gene) inserted into Liposome ;

5. CF patient breathes in (aerosol containing complexes / (retro)virus / DNA) /targeted to lungs,

6. Use of nebuliser ;

7. Liposome fuses with membrane and DNA released in cell / (retro)virus inserts DNAinto nucleus;

8. Normal (allele / gene) enters nucleus and CFTR protein is transcribed / eq ;

4 marks

(ii) 1. Effect is temporary / process has to be continually repeated / (Because) cellslining airways are continually replaced / low chance of success / eq ;

2. (Retrovirus) may cause [disease / toxic affects);

3. New gene may disrupt normal genes ;

4. Doesn't help other aspects (of CF) e.g. digestive problems / sterility etc.

5. Treatment at early stage of development / eq ;

6. [Cost / ethical} issue well qualified2 marks



Question 2 continued Maximum mark

(b)

Paired points

1. Physiotherapy ;

Helps (loosen / remove) mucus / improve airflow into and out of lungs / reducerisk of infection

2. Flutter device

Vibrations dislodge mucus and aid mucus movement ;

3. Digestive enzymes ;

Because pancreatic duct is blocked / eq ;

4. Bronchodilators ;

Relax muscles in airways resulting in them opening up

5. Antibiotics

Destroy bacteria trapped in the mucus ;

6. DNAase enzymes ;

Break down DNA which adds to sticky mucus ;

7. Steroids

Reduce inflammation of the lungs ;

8. Diet ;

Extra (protein / carbohydrate / fat) to overcome reduced uptake

9. (Heart and) lung transplant ;

New lungs function normally2 marks

Total 8 marks




(a) Concentration of sucrose in solution is higher than in the potato cylinder /converse / correct reference to water potential /eq ;

Water moves out of {the cells / potato} ;

By osmosis ;

Reference to {plasmolysis / loss of turgor}2 marks

(b) (i) 1. To the right of the original curve ;

2. Curve follows a similar shape to original Line;

3. Curve starts and finishes at the same values as the original curve ;

2 marks

(ii) 1. {Sucrose / sugar} {increases the solute concentration / ref-hires water potential} ofthe {cells / potato} / eq

2. More sucrose in the potato cells so cells reach {equilibrium / eq} at a higherconcentration of sucrose solution / eq

3. Concentration difference is {less / reduced} / eq ;

4. At the start {full turgor / eq} ;

5. At the end {full plasmolysis / eq} ;

6. Reference to starch having {no / little} effect on osmosis ;2 marks

Total 6 marks


Statement Starch Glycogen Monosaccharide

Is a polymer V x

Glycosidic bonds arepresent

V x

Is an energy store inanimal cells

x V

Has high solubility inwater

x I

January 2005

Question 4

(a)

6131 Unit SN1 Mark Scheme

Maximum mark

[One mark for every two correct]4 marks

(b) 30;1 mark

(c) 1. DNA {uncoils / separates / unzips} / hydrogen bonds break / eq ;

2. (Template) strand used to form {mRNA / complementary strand} / transcription ;

3. Reference to RNA polymerase ;

4. mRNA passes [to ribosome / out of nucleus / to the cytoplasm} ;

5. tRNA picks up specific amino acid ;

6. Codon and anticodon binding ;

7. Correct reference to {start / stop} codons ;

8. Peptide bonds forming between amino acids ;

9. Example of correct complementary base pairing ;5 marks




(d) (Different) R groups ;

Determine bonds formed between R groups of different amino acids ;

Named bond between R groups, e.g. 5=5 / H / etc ; [not peptide]

Reference to [secondary / tertiary) structure ;2 marks

Total 12 marks




(a) Suitable symbols used (dominant upper case, recessive same letter lower case) ;

Parent gamete shown ;

F1 genotype ;

F2 genotypes ;

F2 phenotypes related to genotypes ;

F2 genotypes related to 3:1 ratio ;

[Maximum of 3 marks if suitable symbols not used]4 marks

(b) (Back) cross to suitable recessive plant / self fertilise ;

Examine phenotypes of offspring ;

Suitable ratios e.g. if back cross then (phenotypes) offspring all dominant or 1:1dominant : recessive / if self fertilise all dominant or 3:1 dominant : recessive ;

Linked to explanation i.e. if all dominant then F2 plant is homozygous / if mix ofdominant and recessive then F2 plant is [heterozygous / carrier / eq} ;

2 marks

Total 6 marks


January 2005 6131 Unit 51,11 Mark Scheme


(a)

A Fatty add / hydrophobic [region / tail) / phospholipid tail

B Phosphate / glycerol / hydrophilic [region / head) / phospholipid head

C (Channel / transmembrane / intrinsic) protein

D Glycoprotein

[Half mark each, rounded down]2 marks

(b) Facilitated diffusion

Through [channel / carrier} protein ;

Down a concentration gradient / eq ;

Active transport

Using carrier protein ;

Energy from ATP;

Against concentration gradient ;

Exocytosis / endocytosis

Vesicle containing glucose fuses with membrane ;

Vesicle forms (from membrane enclosing glucose)

[Maximum 2 marks if only one process mentioned or described. Marks must be incontext of a correct process]

3 marks




(c) (i) 1. Discs cut from the same beetroot ;

2. Pre-treatment of beetroot / washing discs ;

3. Standardised method of obtaining beetroot discs / discs the same (mass / volume/ surface area) ;

4. Further detail of method e.g. way of keeping the discs from clumping in thewater ;

5. Use of water baths at fixed temperatures ;

6. Fixed time in water baths / fixed volume of water ;

7. Use of colorimeter / description af method of measuring intensity of colour ;

8. Detail of colorimeter e.g. use of (reference blank / filter) ;4 marks

(ii) 1. Membrane selectively permeable at lower temperatures ;

2. {Temperature increase above 40 °C / higher temperatures) / membrane breaksdown / eq ;

3. Increase of kinetic energy of (pigment molecules / phosphotipids in membrane /eq) ;

4_ Proteins are denatured ;

5. Membrane becomes (freely / more) permeable to (pigment molecules) withincreasing temperature ;

6. Reference to diffusion of pigment molecules out of the cells / reaches equilibriumat high temperatures ;

3 marks

Total 12 marks


January 2005

6131 Unit SN1 Mark Scheine


(a) (i) COON

0

\ OH

2 marks

(ii) Saturated

No double bonds in (hydrocarbon) chain ;2 marks

(b) (i) Anything that [affects / raises} the chance of harm / eq ;1 mark

(ii) 1. Strain on the heart ;

2. Raises blood pressure ;

3. Raises cholesterol / LDL (in the blood);

4. Increased risk of formation of [atheroma / plaques};

5. Atherosclerosis / atherosclerosis explained / eq ;

6. Increased risk of type 2 diabetes / explained3 marks

(c) 1. Glucose is [a monosaccharide / soluble / doesn't need to be digested} / eq ;

2. Glucose can be quickly absorbed into the blood stream ;

3. Can pass into muscle (cells)

4. Can be used for respiration ;

5. For (muscle) contraction3 marks

Total 11 marks


January 2005 6134 Unit 5N4 Mark scheme

Unit SN4 (6134)


(a) Skin is a physical barrier to bacteria /prevents entry / eq

Normal flora compete {better than / with} pathogens ;

Surface {too salty / too acidic} for pathogens ;

Antibacterial agents in {sweat / eq} ;

Reference to hygiene ;

Reference to lysozyme / tears / saliva;2 marks

(b) Clot formation ; [accept a description]

Histamine release / eq;

Vasodilation / increased blood flow / eq ;

Phagocytosis / (increased) phagocytes / eq ;

Mitosis / cell division / eq2 marks

Total 4 marks


January 2005 6134 Unit SN4 Mark scheme


(a)

(Diversity) [reduced / becomes Low};

Gene pool {smaller / now small};

Fewer alleles;

Reference to inbreeding ;

Reference to heterozygosity ;

Used to increase-/ maintain (diversity)2 marks

(b)

DNA passed unchanged from parent to offspring / eqORNo human error involved / less scope for recording errorsORDNA match with parents ;

1 mark

(c) • [DNA / genes / alleles } [more similar / fewer differences} (in racehorses) ;

DNA fingerprints Likely to be more similar;

Probability of DNA fingerprint being unique much smaller;

Most horses closely related / humans not ;2 marks

Total 5 marks




(a) Light (intensity / wavelength} / photoperiod / carbon dioxideconcentration / (soil / eq} / [watering / humidity} / temperature / (age /size / mass / eq} of plant

[Reject amount]1 mark

(b) Prevent [ reactions / respiration / photosynthesis / carbon fixing / uptakeof carbon dioxide} / eq ;

1 mark

(c) 1. ATP production requires electron flow / ATP production reduced ;

2. Reference to (light dependent reactions / photosystems / thylakoids} ;

3. CO2 fixation requires ATP / less CO 2 fixed ;

4. RuBP regeneration requires ATP / cannot regenerate RUBP ;

5. Correct reference to reduction of NADP ;

6. Production of carbohydrate requires ATP / less carbohydrate produced ;

7. Reduction of (PGA / GP / triose phosphate} requires reduced NADP ;

8. Conversion to_PGAL requires energy from ATP / reduced NADP ;

9. So less radioactive carbon fixed in products of photosynthesis / eq5 marks

Total 7 marks




(a) Number / range / variety of species ;

Range of taxa / eq ;

[Variety / diversity} within species ;

[Variety / diversity} of ecosystems ;2 marks

(b) [Identify / classify / name} organisms / eq ;

Recognise new species ;2 marks

(c) Correct working (56 250 - 53 820) (=2430)-÷ 56250 x 100;

Correct answer = 4.32 % / - 4.32 %

2 marks for correct answer with no working shown ;;2 marks




(d) 1. Loss (of rainforest) is not that bad

2. Main means of subsistence / e.g. [growing food / obtaining fuel / buildingmaterials} / eq

3. Can't afford reforestation

4. Can't afford fertilisers (to improve existing farmland)

5. Allows exploitation of resources for profit / benefit economy ;

6. Too difficult to enforce regulations ;

7. [Ancient / existing} land rights ;

[Maximum 4 marks from marking points 1-7]

8. Benefit tourism in Honduras ;

9. Rainforests help to [prevent [slow down} global warming / reference toCO2 Levels;

10. Reference to other environmental benefit of keeping forests ;

11. Prevent loss of [habitat / niches / shelter / eq} for wildlife;

12. Prevent loss of [species / biodiversity] ;

13. Provide means of sustainable-exploitation (of forest) ;

14. Prevents loss of potential medicine ;

15. Regulation would make government unpopular;

[Maximum 4 marks from marking points 8-15]

5 marks

Total 11 marks

Page 15.... 6134 January 2005



(a) 1. Agar {plates /dish]; [Reject agar with no qualification]

2. {Lawning / spreading / coating} with bacteria ;

3. Sterility of equipment ;

4. Aseptic technique ;

5. {Wells / discs / paper / container / eq] with antibiotic

6. Reference to different concentrations of antibiotic ;

7. Control of {solvent only / sterile water / disc alone / known antibiotic} ;

8. Incubation ;

9. Details of safe incubation e.g. temperature, taping plates closed;

10. {Measure / compare} a dimension of (area without bacteria) ;5 marks

(b) Resistance develops / bacteria not killed by existing antibiotics / diseasecannot be cured with existing antibiotics;

Alternative pathways / enzymes destroy antibiotic / eq ;

Explanation of how resistance develops;

Rapid {division / mutation / generations} of bacteria / high mutation rateof bacteria ;

[Reject immune]2 marks

(c) Ensure safe to use on {people / mammals) / not toxic ;

Mammalian cells similar to human cells / eq;1 mark




(d) (i) 10% = 20 (line on graph worth credit)

4.3(mg dm-3)2 marks

(ii) Some bacteria already resistant ;

Some (bacteria) {survive / are not all killed) at high concentrations / use offigures ;

Reference to inheritance of resistance alleles;2 marks

Total 12 marks

Page 17, — — 6134 January 200S

January 2005 6134 Unit 5144 Mark scheme


(a)

Measure {growth / height / number of leaves / mass / dry mass} ;

Growth with copper and {without copper / control / range of copperconcentrations ;

Reference to controlling variables;

Reference to {repeats / means / calculation of percentage growth];2 marks

(b) High tolerance plants grow on {site B / eq} ;

Tolerance genes from {mine site / site BI;

Carried by {pollen / seeds};

To {downwind site / site C} ;

Tolerance higher downwind than upwind-;3 marks

(c)

Plants compete / eq ;

For {ions / water / nutrients / nitrates / tight / space / eq)

Tolerant plants less well adapted / converse / eq ;

So tolerant plants {smaller / less dry mass} / converse / eq

Idea: Results are due to competition only because trays 1 and 3 growingthe same ;

Manipulated figures ;4 marks

(d)

Decreases / more non-tolerant;

No benefit ;

Competes less well;2 marks

Total 11 marks

Page I 3 6134 January 2005



(a) 1. Changes in temperature detected ;

2. (Peripheral) receptors / hypothalamus;

3. {Reference to / description of} negative feedback ;

4. Increased {muscular activity / shivering);

5. Less sweating ;

6. Livertiochemistry ;

7. Reference to behavioural mechanisms / eq ;

8. Increased {metabolic rate / respiration);

9. -Peripheral vasoconstriction / less blood flow to extremities / reducesradiation of heat to surroundings / less cold blood goes to core ;

10. Increased hydrolysis of {fat / brown fat);3 marks

(b) (i) In hypothalamus;1 mark

(ii) {Set point / norm} raised / thermostat reset higher / eq ;1 mark

(iii)1. Reduces bacterial growth / reproduction ;

2. Increases phagocytosis ;

3. Reference to denaturation of bacterial enzymes ;

4. Human enzymes work quicker ;

5. Faster immune response / eq ;2 marks

- Page 19s 6134 January 2005-

January 2005 6134 Unit 51,14 Mark scheme


(c) 1. Can no longer reduce temperature / uncontrolled (temperature) rise ;

2. Delirium

3. Positive feedback ;

4. Reference to critical temperature / {42 / 43} °C;

5. Enzymes denature ;

6. Death ;3 marks

Total 10 marks

-Page K 6134 January-2005

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Documents

2005 January SN 1,4 Mark Scheme