Mark Scheme January 2008 - Egypt IG Student Roomegyptigstudentroom.com/pastpapers/edexcel/alevel/gce/Biology/Jan...Mark Scheme January 2008 GCE GCE Biology (8040/9040) ... Level Unit

Mark Scheme January 2008

GCE

GCE Biology (8040/9040) GCE Biology (Human) (8042/9042)

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January 2008

Publications Code UA019777

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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 2 6102

6112 Exchange, transport and reproduction

Exchange, transport and reproduction in humans

p 10

p 18

Unit 3 6103/03 Energy and the environment p 26

Unit 4 Core material

Option A

Option B

Option C

Respiration and coordination

Microbiology and biotechnology

Food science

Human health and fitness

p 31

p 37

p 41

p 45


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 6103

A2 4 6104 Respiration and coordination and Options 6104

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


1

Unit 1 (6101)

Question Number

Answer Mark

1

Statement

Glycogen

Cellulose

Consists of ß glucose

X

Contains 1,4 glycosidic bonds

Is a branched molecule

X

Is a structural carbohydrate

X

Any two correct boxes for one mark

max 4

Question Number

Answer Mark

2

1. (simple ) diffusion ; 2. facilitated diffusion ;

3. active transport ;

4. ATP ;

4


2

Question Number

Answer Mark

3 (a)(i)

the {sequence / order} of amino acids ;

1

Question Number

Answer Mark

3 (a)(ii)

hydrolysis ;

1

Question Number

Answer Mark

3 (b)

CCNH

H H O

OHCH2

OH ;

1

Question Number

Answer Mark

3 (c)

Collagen Insulin

1. fibrous globular ;

2. three {polypeptide chains} / triple helix

two {polypeptide chains} / reference to A and B chains ;

3. chains not held together by disulphide bonds / chains held together by hydrogen bonds

chains held together by disulphide bonds / eq ;

4. large / about 1000 amino acids OR length can be variable

small / 51 amino acids OR fixed / precise length ;

5. repetitive / repeating sequence / eq

no repetitive sequence ;

max 3


3

Question Number

Answer Mark

4 (a)

1. reference to (same / similar) cells ;

2. of similar {structure / common origin / function} / eq ;

2

Question Number

Answer Mark

4 (b)

1. correct dimensions ;

2. folded inner lining ; 3. 5 or 6 tissues shown with no cell details ;

3


4

Question Number

Answer Mark

5 (a)(i)

cell in anaphase correctly identified ;

1

Question Number

Answer Mark

5 (a)(ii)

cell in telophase correctly identified ;

1

Question Number

Answer Mark

5 (a)(iii)

2 / 3 ;

1

Question Number

Answer Mark

5 (b)

1. idea that during prophase {chromosomes / chromatids} (becoming)

visible ;

2. idea of centrioles move to opposite poles ;

3. reference to formation of {spindle /spindle-fibres /

microtubules} ;

4. disappearance of nucleolus / nucleoli ;

5. breaking down of nuclear {envelope / membrane} (in prophase) or

nuclear envelope is broken down by metaphase / eq ;

6. (at metaphase) {chromosomes / centromeres} attached to spindle

(fibres) ;

7. idea of {chromosomes / chromatids} lined up at equator ;

max 5


5

Question Number

Answer Mark

6 (a)

1. {envelope / double membrane} clearly shown ;

2. granum clearly shown ; 3. {granum / thylakoid(s)} labelled ; 4. {stroma / ribosomes / starch grain / DNA / lipid droplet / {double

/ inner / outer} membrane / envelope / intergranal lamellae} correctly labelled ;

4

Question Number

Answer Mark

6 (b)(i)

1. correct length ;

2. divided by 50 000 ;

3. correct length in µm ;

3

Question Number

Answer Mark

6 (b)(ii)

vacuoles / vesicles / lysosomes / glycogen granules / ribosomes / lipid droplets / centrioles / spindle fibre / microtubules ;

1

Question Number

Answer Mark

6 (b)(iii)

{resolution not high enough / eq} / damage / {angle of section / eq} / {poor printing of photograph / eq} ;

1


6

Question Number

Answer Mark

7 (a)

1. reference to use of {iodine solution / iodine in potassium iodide} ;

2. {observation / colour change} described ;

3. credit any valid experimental details ;

3

Question Number

Answer Mark

7 (b)

1. overall decrease in activity ; 2. increasing concentration up to 4 au increases the activity of

amylase ; 3. increasing concentration from 4 au (to 32 au) reduces activity ; 4. reference to change in activity at 20 au ; 5. correct manipulation of data ;

max 3

Question Number

Answer Mark

7 (c)

1. {copper ions / inhibitor} block the active site / eq ; 2. idea that inhibitor is the same shape as substrate ;

3. preventing {starch / substrate} binding with {amylase / active site /

enzyme} ; 4. the more {copper ions / inhibitor} the more active sites are blocked ; 5. reduces enzyme activity / eq ;

max 3


7

Question Number

Answer Mark

7 (d)(i)

1. it allows a comparison to be made (with and without copper ions) ; 2. reference to {starch / substrate} concentration being the same (with

and without copper ions) ; 3. the rate of reaction changes with time /eq ;

4. because substrate is being used up / eq ;

max 2

Question Number

Answer Mark

7 (d)(ii)

idea that the {maximum rate/ Vmax} (with copper ions present) is lower (than without inhibitor) / if it was active site-directed it would take longer to reach same maximum rate ;

1


8

Question Number

Answer Mark

8 (a)

A phosphate B deoxyribose ;

1

Question Number

Answer Mark

8 (b)(i)

Adenine 29, Guanine 21, Cytosine 21 ;

1

Question Number

Answer Mark

8 (b)(ii)

1. a purine always bonds to a pyrimidine ;

2. % thymine must equal % adenine / eq ;

3. guanine and cytosine must make up rest of molecule / eq ;

4. % guanine = % cytosine / eq ;

max 3

Question Number

Answer Mark

8 (c)

1. DNA contains genetic information / eq ; 2. DNA codes for protein / eq ;

3. a change in DNA could produce a different {protein / mRNA} / eq ;

4. idea that it is required throughout life (or {cell / organism} ) ;

5. idea that it is needed to pass on to next generation (of {cell /

organism}) ;

max 2


9

PAPER TOTAL: 60 MARKS

Question Number

Answer Mark

8 (d)

1. part of the DNA (molecule) unwinds ; 2. DNA strands separate / {hydrogen / H} bonds break ; 3. idea only one strand acts as a template ; 4. (free) nucleotides line up against DNA ;

OR reference to complementary base pairing / correct description ;

5. correct reference to RNA polymerase ; 6. reference to {nucleotides joining together / formation of

phosphodiester bonds} ; 7. (to form) mRNA ; 8. exits through nuclear pore / from nucleus to cytoplasm / movement to

ribosomes ;

max 5


10

Unit 2B (6102)

Question Number

Answer Mark

1

1. monocytes ;

2. antibodies / immunoglobulins ;

3. eosinophils / basophils ;

4. nucleus ;

4


11

Question Number

Answer Mark

2 (a)

A red blood (cell) / erythrocyte ; B (alveolar) epithelial cell / epithelium / squamous epithelium / ;

2

Question Number

Answer Mark

2 (b)

1. {thin / eq} cells ;

2. decreases diffusion distance ;

3. permeable (to respiratory gases) ;

4. (collectively) have a large surface area ;

5. increases diffusion ;

6. of respiratory gases / oxygen / carbon dioxide ;

7. (surrounded by) capillaries ;

8. idea that movement of blood maintains {diffusion / concentration}

gradient ;

9. reference to {the presence of / a description of} surfactant ;

max 4

Question Number

Answer Mark

2 (c)

8.1 (dm3) ;

1


12

Question Number

Answer Mark

3 (a)

Carbohydrate Enzyme Products

amylase ;

glucose and galactose ;

sucrose ;

sucrase ;

4

Question Number

Answer Mark

3 (b)

1. reference to active uptake / active transport (of glucose) ;

2. reference to sodium-glucose co-transport ;

3. reference to (specific) glucose carrier proteins / fewer transport proteins for fructose / more transport proteins for glucose / fructose is absorbed by diffusion (only) ;

3


13

Question Number

Answer Mark

4 (a)

A aorta / aortic arch ; B (right) atrioventricular valve / tricuspid valve ;

2

Question Number

Answer Mark

4 (b)

1. reference to coronary circulation ;

2. reference to coronary artery / coronary arteries ;

3. reference to capillaries (in wall of heart) ;

4. oxygen {transported / eq} by {red cells / haemoglobin} ;

5. oxygen diffuses out of {blood / red cells / capillaries} (to heart

muscle) ;

max 3

Question Number

Answer Mark

4 (c)

1. pacemaker / SAN sends {impulse / eq} (to atria) ;

2. {causing/ eq} atria to contract ;

3. {impulse / eq} reaches AVN ;

4. reference to delay at the AVN ;

5. idea that the impulse travels to ventricles via {bundle of His /

Purkyne tissue / eq} ;

max 3

Question Number

Answer Mark

4 (d)

1. increased {demand for / eq} {oxygen / glucose} / increased

respiration ;

2. increased heart rate / heart beats faster / eq ;

3. increased stroke volume / cardiac output ;

4. increased production of carbon dioxide ;

5. reference to dilation of blood vessels in muscle ;

6. reference to adrenaline ;

max 3


14

Question Number

Answer Mark

5 (a)(i)

1. presence of gills ;

2. to increase surface area / increase uptake of oxygen ;

3. presence of haemoglobin / respiratory pigment ;

4. with high affinity for oxygen ;

5. presence of siphon / (breathing) tube / eq ;

6. to obtain oxygen (directly) from the air ; NB paired points

max 4

Question Number

Answer Mark

5 (a)(ii)

1. presence of claws / hooks / suckers ;

2. to attach to substrate / eq ;

3. {flattened / streamlined / eq} body /reference to burrowing ;

4. less resistance to water flow / less likely to be washed away ;

NB paired points

max 2

Question Number

Answer Mark

5 (b)

1. inverse relationship / eq ;

2. credit a manipulated quantitative comment ;

2


15

Question Number

Answer Mark

6 (a)

1. insect ;

2. large petals / coloured petals ;

3. scent / nectar / nectary ;

4. to attract insects ;

5. correct reference to position of anthers ;

6. correct reference to position of stigma ;

max 3

Question Number

Answer Mark

6 (b)

1. increased (from 30) to 90 minutes ;

2. decreased from 90 (to 180) minutes ;

3. reached a max. at 90 minutes / reached a peak at 90 minutes ;


max 3

16

Question Number

Answer Mark

7 (a)

xylem (vessel) ;

1

Question Number

Answer Mark

7 (b)

1. endodermal cells have Casparian strip ;

2. reference to {suberin / eq} ;

3. which is waterproof / eq ;

4. stops movement of water in apoplast pathway / description ;

5. water directed into symplast pathway / description ;

6. reference to {control of uptake / active transport of ions (into

xylem)} ;

max 3

Question Number

Answer Mark

7 (c)(i)

1. concentration increases as temperature increases / eq ;

2. credit a manipulated quantitative reference ;

2

Question Number

Answer Mark

7 (c)(ii)

1. uptake is active / eq ;

2. concentration in cells is higher than concentration in solution /

converse ;

3. ions are taken up against concentration gradient ;

3

17

Question Number

Answer Mark

8 (a)

E D C B A ;; NB All correct = 2 marks, 1 error (i.e. one letter out of sequence) = 1 mark

2

Question Number

Answer Mark

8 (b)

(i) 46 ; (ii) 23 ;

2

Question Number

Answer Mark

8 (c)

1. {primordial (germ) cells / oogonia} divide by mitosis ;

2. oogonia (develop to) form primary oocytes ;

3. primary oocytes divide by meiosis I ; 4. to form a secondary oocyte ;

5. and a polar body ;

6. secondary oocyte divides by meiosis II ;

7. to form an ovum ;

max 4


18

Unit 2H (6112)

Question Number

Answer Mark

1

1. monocytes ;

2. antibodies / immunoglobulins ;

3. eosinophils / basophils ;

4. nucleus ;

4

19

Question Number

Answer Mark

2 (a)

A red blood (cell) / erythrocyte ; B (alveolar) epithelial cell / epithelium / squamous epithelium / ;

2

Question Number

Answer Mark

2 (b)

1. {thin / eq} cells ;

2. decreases diffusion distance ;

3. permeable (to respiratory gases) ;

4. (collectively) have a large surface area ;

5. increases diffusion ;

6. of respiratory gases / oxygen / carbon dioxide ;

7. (surrounded by) capillaries ;

8. idea that movement of blood maintains {diffusion / concentration}

gradient ;

9. reference to {the presence of / a description of} surfactant ;

max 4

Question Number

Answer Mark

2 (c)

8.1 (dm3) ;

1

20

Question Number

Answer Mark

3 (a)

Carbohydrate Enzyme Products

amylase ;


sucrose ;

sucrase ;

4

Question Number

Answer Mark

3 (b)

1. reference to active uptake / active transport (of glucose) ;

2. reference to sodium-glucose co-transport ;

3. reference to (specific) glucose carrier proteins / fewer transport proteins for fructose / more transport proteins for glucose / fructose is absorbed by diffusion (only) ;

3

21

Question Number

Answer Mark

4 (a)

A aorta / aortic arch ; B (right) atrioventricular valve / tricuspid valve ;

2

Question Number

Answer Mark

4 (b)

1. reference to coronary circulation ;

2. reference to coronary artery / coronary arteries ;

3. reference to capillaries (in wall of heart) ;

4. oxygen {transported / eq} by {red cells / haemoglobin} ;

5. oxygen diffuses out of {blood / red cells / capillaries} (to heart

muscle) ;

max 3

Question Number

Answer Mark

4 (c)

1. pacemaker / SAN sends {impulse / eq} (to atria) ;

2. {causing/ eq} atria to contract ;

3. {impulse / eq} reaches AVN ;

4. reference to delay at the AVN ;

5. idea that the impulse travels to ventricles via {bundle of His /

Purkyne tissue / eq} ;

max 3

Question Number

Answer Mark

4 (d)

1. increased {demand for / eq} {oxygen / glucose} / increased

respiration ;

2. increased heart rate / heart beats faster / eq ;

3. increased stroke volume / cardiac output ;

4. increased production of carbon dioxide ;

5. reference to dilation of blood vessels in muscle ;

6. reference to adrenaline ;

max 3

22

Question Number

Answer Mark

5 (a)

Frostbite:

1. reference to tissue / skin damage ;

2. due to exposure to (dry) cold / freezing ; Trench foot:

1. damage to toes / feet ;

2. due to immersion in cold water ;

4

Question Number

Answer Mark

5 (b)(i)

1. increase in body temperature ;

2. credit manipulated quantitative comment ;

3. due to conduction of heat from water to body ;

max 2

Question Number

Answer Mark

5 (b)(ii)

1. reduction in body temperature ;

2. credit manipulated quantitative comment ;

3. heat lost by {radiation / conduction / evaporation of water /

convection / lower {air / room / chair} temperature} ;

max 2

23

Question Number

Answer Mark

6 (a)

1. colostrum contains antibodies / eq ;

2. reference to imparting (passive) immunity / eq ;

2

Question Number

Answer Mark

6 (b)(i)

1. colostrum has more protein (than human milk) ;

2. calculated difference (e.g. 5.7 times more protein) ;

3. colostrum has less lactose (than human milk) ;

4. calculated difference (e.g. half the concentration of lactose) ;

max 2

Question Number

Answer Mark

6(b)(ii)

1. cows’ milk has more protein ;

2. protein is required for (tissue) growth / eq ;

3. cows’ milk has less fat ;

4. appropriate reference to benefit of less fat in diet ;

max 2

24

Question Number

Answer Mark

7 (a)(i)

1. as altitude increases, partial pressure of oxygen in alveoli

decreases / eq ;


2

Question Number

Answer Mark

7 (a)(ii)

1. reference to low partial pressure of oxygen (at high altitudes) ;

2. haemoglobin poorly saturated with oxygen ;

3. insufficient {oxygen to maintain consciousness / oxygen reaching

the brain} ;

4. reference to hypoxia ;

max 2

Question Number

Answer Mark

7 (a)(iii)

1. wind speed ;

2. solar radiation ;

2

Question Number

Answer Mark

7 (b)

THREE of:

1. increased lung volume /eq ;

2. increased pulmonary capillaries / eq ;

3. increased cardiac output /eq ;

4. increased numbers of red cells / eq ;

5. increased haemoglobin ;

6. increased affinity of haemoglobin (for oxygen) ; 7. increased melanin / skin pigmentation ;

8. reference to short stature / eq ;

max 3

25

Question Number

Answer Mark

8 (a)

E D C B A ;; all correct = 2 marks, 1 error (i.e. one letter out of sequence) = 1 mark

2

Question Number

Answer Mark

8 (b)

(i) 46 ; (ii) 23 ;

2

Question Number

Answer Mark

8 (c)

1. {primordial (germ) cells / oogonia} divide by mitosis ;

2. oogonia (develop to) form primary oocytes ;

3. primary oocytes divide by meiosis I ;

4. to form a secondary oocyte ;

5. and a polar body ;

6. secondary oocyte divides by meiosis II ;

7. to form an ovum ;

max 4


26

Unit 3 Paper 3 (6103/03)

Question Number

Answer Mark

1 (a)(i)

1. reference to external digestion /eq ;

2. feed on organic material / both are heterotrophic /eq ;

3. reference to hypha(e) {secrete / eq} enzymes / absorb {digested

products / named product} / eq ;

max 2

Question Number

Answer Mark

1 (a)(ii)

1. (Rhizopus) is {saprobiontic / saprophytic} / eq ;

2. (Rhizopus) {feeds on / eq} {dead / eq } material ;

3. reference to importance of Rhizopus as {a decomposer / involved in

recycling of nutrients} and Phytophthora causing {harm / loss of crops / eq} ;

max 2

Question Number

Answer Mark

1 (b)

1. {less / eq} photosynthesis possible ;

2. (because) {leaves / palisade cells / photosynthetic cells /

chloroplasts} damaged / eq ;

3. less {glucose / starch / organic compounds} produced /eq / idea of fungus using up the plants’ organic material ;

4. reference to {blocked stomata / inefficient gas exchange / eq} ;

max 2

27

Question Number

Answer Mark

2 (a)

1. bacteria / fungi / saprophyte / saprobiont / decomposer / suitable,

correct organism ; 2. reference to respiration ;

2

Question Number

Answer Mark

2 (b)(i)

photosynthesis ;

1

Question Number

Answer Mark

2 (b)(ii)

1. reference to respiration (of some of the organic material) ;

2. idea that energy is required ; 3. for synthesis of {molecules / eq} / movement / active transport} ;

max 2

Question Number

Answer Mark

2 (c)

1. idea of {carbon / carbon dioxide} {locked away / stored} / eq ;

2. for {many years / a long time / eq} ;

2

Question Number

Answer Mark

2 (d)

24 391 ÷ 37.98 ;

642.2 x 106 ha ;

2

28

Question Number

Answer Mark

2 (e)

1. (different) {climates / rainfall / temperatures / eq} ; 2. (different) {species / types} of {tree / forest} ;

3. (different) {ages / maturity / size / eq} of forests ; 4. (different) tree density / number of trees ;

5. reference to (different) day lengths ; 6. reference to (different) light intensity ;

7. (different) carbon dioxide concentration / eq ;

8. any two other valid reasons ;;

max 2

Question Number

Answer Mark

2 (f)

1. idea of less carbon dioxide {fixed / taken up / eq} by photosynthesis ;

2. {respiration / combustion of {fossil fuels / trees}} continues to release

carbon dioxide ;

3. carbon dioxide builds up in {upper atmosphere / troposphere} ;

4. reference to carbon dioxide as greenhouse gas ;

5. description of the greenhouse effect ;

6. reference to {enhanced / eq} greenhouse effect ;

7. reference to global warming / increase in mean temperature (of Earth’s surface) ;

max 4

29

Question Number

Answer Mark

3 (a)(i)

{total biomass / eq} produced / {total energy / eq} taken in ;

by {plants / producers / photosynthesis / eq} ;

2

Question Number

Answer Mark

3 (a)(ii)

1. light intensity ; 2. light duration / eq ;

3. light wavelength ;

4. temperature ;

5. {carbon dioxide / carbonate} concentration ;

6. pH ;

7. named aquatic pollutant ;

max 2

Question Number

Answer Mark

3 (b)

1. (dead plant material) is decomposed / eq ;

2. by action of {bacteria / microoorganisms / eq} ;

3. idea that aerobic respiration involved ;

4. (more) dead material provides more nutrients which leads to an

increase in microorganisms / eq ;

max 3

Question Number

Answer Mark

3 (c)(i)

1. CR in winter {usually greater/eq} than in summer ;

2. both show increase as distance (from headwaters) increases ;

3. in winter CR increases {greatly / eq}, in summer only {slight increase /

eq} ;

4. use of manipulated data ;

max 2

30

Question Number

Answer Mark

3 (c)(ii)

1. idea that {more leaves / detritus / eq} added with distance from

source / more leaves shed in winter / (more dead material because) algae die down in winter ;

2. far increased {bacterial / eq} activity ;

2

Question Number

Answer Mark

3 (d)(i)

1. GPP {increases as distance (from headwaters) increases / higher in

Motueka River} ;

2. high GPP indicates {high algal population / eq} ;

3. (because) algae release oxygen by photosynthesis ;

4. more algae means more {grazing invertebrates / eq} ;

5. more food (for fish / trout) ;

max 3

Question Number

Answer Mark

3 (d)(ii)

1. CR {higher / increases} (in winter) ;

2. (higher CR indicates) more {detritus / eq} ;

3. {algae / eq} may die down in winter ;

4. reference to {decay / eq} (of detritus and/or algae) uses up oxygen ;

5. fish population {falls / eq} ;

max 3


31

Unit 4 Core (6104)

Question Number

Answer Mark

1 (a)

B = medulla (oblongata) ;

C = cerebellum ;

2

Question Number

Answer Mark

1 (b)

1. to receive sensory input / eq ; 2. idea of {interpretation/coordination} (of information) ; 3. {initiates / transmits} impulses to effector ; 4. idea of control of voluntary action / eq ;

5. reference to {thought / learning / intelligence / memory } ;

6. reference to speech ;

7. reference to {personality / emotion} ;

max 2

32

Question Number

Answer Mark

2 (a)

1. idea of a deviation from the {norm / normal level / eq } triggers

mechanism to eliminate the deviation ;

2. increase in level of cortisol inhibits {CRH secretion /hypothalamus} ;

3. (which) reduces secretion {of ACTH / from (anterior) pituitary} ;

4. this causes drop in level of cortisol ;

max 3

Question Number

Answer Mark

2 (b)

{follicle stimulating hormone / FSH / luteinising hormone / LH / thyroid stimulating hormone / TSH / growth hormone / prolactin } ;

1

Question Number

Answer Mark

2 (c)

1. effect is longer lasting / eq ;

2. effect is slower / eq ;

3. effect is (often) not reversible / eq ;

4. reference to involvement of transport in blood system ;

5. reference to {several target organs/diffuse effect / eq} ;

6. hormonal involves chemical control, nervous involves electrical (and

chemical) control ;

max 3

33

Question Number

Answer Mark

3 (a)

1. reference to influx of calcium ions(into pre-synaptic knob) / eq ;

2. vesicles move to pre-synaptic membrane / eq ;

3. fuse with pre-synaptic membrane / eq ; 4. (acetylcholine released) by exocytosis ;

max 3

Question Number

Answer Mark

3 (b)(i)

value between 0.85 and 1.95 (ms) ;

1

Question Number

Answer Mark

3 (b)(ii)

3.0 ± 0.05 (ms) ;

1

Question Number

Answer Mark

3 (b)(iii)

1. correct reading from graph of duration of one action potential ;

2. 1000 / reading from graph ;

2

Question Number

Answer Mark

3 (c)

1. idea that the inside of the (post-synaptic) membrane is becoming

{more negative / hyperpolarised} ;

2. therefore {more Na+ channels must open / more Na+ must enter} ;

3. to reach threshold level / eq ;

max 2

34

Question Number

Answer Mark

4 (a)(i)

carbon dioxide / CO2 ;

1

Question Number

Answer Mark

4 (a)(ii)

1. to regenerate the {hydrogen carriers / NAD+ } / oxidise reduced NAD ;

2. NAD+ does not become limiting / eq ;

3. so that glycolysis can continue ;

4. to allow ATP to be formed (during glycolysis) ;

max 2

Question Number

Answer Mark

4 (b)(i)

1. rate is {constant / steady / eq} for the first 6 minutes ;

2. rate {slows / decreases} from {6 to 14 minutes / for next 8 minutes} ;

3. no respiration from 14 – 20 minutes / eq ;

4. manipulation of figures e.g. calculation of rate for first 6 minutes ;

max 3

Question Number

Answer Mark

4 (b)(ii)

rate is constant (throughout the 20 minutes) / rate is slower in sucrose than in glucose (in first 6 to 8 minutes) / respiration does not stop ;

1

Question Number

Answer Mark

4 (b)(iii)

1. to prevent oxygen entering (solution) / keep conditions anaerobic ; 2. to prevent TTC being {oxidised / decolourised} / no TTC would be

reduced ;

2

35

Question Number

Answer Mark

4 (b)(iv)

1. maintain constant temperature / eq ;

2. respiration produces heat (energy) ;

3. change of temperature will affect rate of enzyme activity ;

4. idea that the experiment can be performed in 20 minutes ;

max 2

36

Question Number

Answer Mark

5 (a)

1. (ultrafiltration) occurs in {glomerulus / Bowman’s capsule / renal

capsule} ; 2. reference to high pressure {of blood / in glomerulus} ;

3. because afferent arteriole is wider than efferent arteriole ;

4. {small molecules / eq} forced out (through capillary wall) / {large

molecules / proteins} remain in blood ;

5. reference to {fenestrations / pores} in capillary walls ;

6. reference to basement membrane (acting as a filter) ; 7. reference to podocytes in (Bowman’s capsule) ;

max 4

Question Number

Answer Mark

5 (b)

1. all {glucose / amino acids} are reabsorbed ; 2. by (sodium) co-transport mechanism ;

3. {some / eq} urea is reabsorbed ; 4. by diffusion ;

5. sodium ions are {actively reabsorbed / co-transported} ;

6. {chloride ions / negatively charged ions} (follow) down electrochemical gradient ;

7. reference to microvilli (on epithelial cells) to increase surface area ;

8. reference to {many mitochondria for active transport /

mitochondria produce ATP (for active transport) ;

max 5

37

Unit 4A (6104/01)

Question Number

Answer Mark

6

Feature λ phage TMV HIV

Nucleic acid DNA ; RNA ; RNA ;

Shape of protein coat

complex ; helical ; polyhedral ;

6

38

Question Number

Answer Mark

7 (a)

1. overall the number of cases caused by Salmonella increased whereas

those caused by Staphylococcus decreased / eq ;

2. between 1985 and (some of) 1988 more cases were caused by Staphylococcus ;

3. after {1989 / second part of 1988} more cases were caused by Salmonella ;

4. there was a (very marked) increase in the number of cases caused by Salmonella from 1995 compared to {very little change / eq} in number of cases caused by Staphylococcus ;

5. credit correct manipulation of figures to compare numbers of cases in

a stated time period ;

max 3

Question Number

Answer Mark

7 (b)

Endotoxin

Exotoxin

Lipopolysaccharide protein ; Released from dead bacteria/damaged cell wall

released from living bacteria / eq ;

Delay in release immediate release ; Low toxicity / eq high toxicity ; Released from gram positive released from Gram negative and

Gram positive ;

max 2

39

Question Number

Answer Mark

8 (a)

1. Gram positive bacteria / S. aureus {more sensitive to /shows greater

effect / more susceptible to / shows less resistance} to ampicillin /eq ;

2. S. aureus / Gram positive have thick {cell wall / peptioglycan layer /

eq} ;

3. ampicillin affects cell wall synthesis ;

4. inhibits formation of {peptidoglycan bonds (in cell wall) / eq} ;

5. weakening of cell walls ;

6. reference to osmotic shock / cell lysis / eq ;

max 4

Question Number

Answer Mark

8 (b)

1. correct reason for existence of resistant bacteria ;

2. any resistant bacteria will multiply ;

3. (and) pass on {resistance gene/ plasmid} ;

max 2

Question Number

Answer Mark

8 (c)

(48-36) ; /36 x 100 = 33.33% ;

2

Question Number

Answer Mark

8 (d)

ampicillin doesn’t fit active site / allosteric effect / eq ;

1

40

Question Number

Answer Mark

9 (a)(i)

1. L. bulgaricus grew best at pH 5 ;

2. L. bulgaricus could grow at pHs 5, 6 and 7 (and 8) ;

3. E. coli grew best at pH 7 ;

4. E. coli could grow at pHs 6, 7 and 8 (and 5) ;

5. neither species could grow at pH 9 ;

max 3

Question Number

Answer Mark

9 (a)(ii)

1. idea that pH affects enzyme activity ;

2. enzymes can only work in narrow pH range ;

3. enzymes needed to {replicate DNA/make protein} ;

4. L. bulgaricus adapted to grow in acidic conditions due to lactic acid

production ;

5. E. coli adapted to live in alkaline conditions ;

max 3

Question Number

Answer Mark

9 (b)

1. use sterile conditions / eq ; 2. could have seen more colonies (on any one plate) as contaminants grew

too / could have seen colonies on plates where none were found before as the contaminants could grow at these pHs / could have seen fewer

colonies due to inhibition/competition ; 3. shake culture before sampling ; 4. fewer colonies, as bacteria would have settled to bottom of container ; 5. spread samples over agar thoroughly ; 6. fewer colonies seen due to bacteria on top of each other / inaccurate

counting due to overcrowding in one place ;

max 4

41

Unit 4B (6104/02)

Question Number

Answer Mark

6

Enzyme Enzyme

substrate Product(s)

of the reaction

Industrial use

Glucose isomerase

Glucose

fructose ;

confectionery / soft drinks ;

Amyloglucosidase

(liquid) starch ;

Glucose

brewing / bread making / fruit sorbets ;

Lactase

Lactose


{lactose free / low lactose} products / whey syrup /ice cream ;

6

42

Question Number

Answer Mark

7 (a)

1. between 16 and 34 diabetes is more common in women than men/eq ;

2. more common in men over 35 / eq ;

3. increase in prevalence in women with age / eq ;

4. increase in number of men with diabetes as age increase up to 74 /

eq;

5. credit correct manipulation of data ;

max 3

Question Number

Answer Mark

7 (b)

1. obesity ; 2. genetic ; 3. viral infection ; 4. high fat ; 5. high calorie ; 6. high sugar ; 7. reference to less insulin / inactivity of insulin ;

max 2

43

Question Number

Answer Mark

8 (a)

supplies respiratory substrate / eq ;

1

Question Number

Answer Mark

8 (b)

fungus / mould/ Aspergillus / Saccharomyces / yeast ;

bacteria / Lactobacillus /Bacillus / Pediococcus ;

2

Question Number

Answer Mark

8 (c)

1. changes due to activity of mould / eq ;

2. enzymes or named enzyme produced / eq ;

3. (amylases convert) carbohydrates into simple sugars / eq ;

4. (proteases convert) protein into amino acids / eq ;

5. reference to named product of fermentation ;

6. pH falls / eq ;

max 3

Question Number

Answer Mark

8 (d)(i)

0.73-0.07 ;

/0.07 x 100 ;

2

Question Number

Answer Mark

8 (d)(ii)

ethanoic / formic / acetic / lactic / methanoic / carbonic ;

1

44

Question Number

Answer Mark

9 (a)(i)

1. chilled vegetables have a higher vitamin C content throughout / eq ;

2. faster loss of vitamin C in vegetables at room temperature ;

3. both methods of storage result in a {greater / faster} loss of vitamin C

in the first 2 - 3 days ;

4. at 7 days there is no vitamin C left in the vegetables stored at room temperature, but some vitamin C still remains in the chilled ones ;

5. there is still some vitamin C left in the chilled vegetables at the end of

20 days ;

6. comparative manipulation of figures to give quantitative comparisons ;

max 3

Question Number

Answer Mark

9 (a)(ii)

1. vegetables should be chilled ;

2. because the vitamin C content stays higher ;

3. quantitative comparison of chilled with frozen ;

4. quantitative comparison of chilled with room temperature ;

5. freezing can result in damage to vegetables / or ref. to energy cost ;

max 3

Question Number

Answer Mark

9 (b)

1. vitamin C is a reducing agent ;

2. DCPIP is a dye ;

3. blue in oxidised & pale yellow / brown / colourless in reduced state ;

2

Question Number

Answer Mark

9 (c)

1. reference to use as antioxidant / eq ;

2. prevents oxidation of {fats / oils} ;

3. no rancid flavours develop /eq ;

4. correct description of prevention of rancidity ;

max 2

45

Unit 4C (6104/03)

Question Number

Answer Mark

6

White blood cells

Type of immune response

One role in the immune response

B-lymphocytes

humoral / antibody

mediated / specific ;

reference to antibody

production by plasma cells /

reference to plasma cells /

reference to of memory cells ;

T-lymphocytes

cell-mediated /

specific ;

act as memory cells / killer T

cells {destroy infected cells /

destroy cancer cells / attract

macrophages / activate

phagocytosis } /

/ T helper cells activate {B-

cells / antibody production} /

T suppressor cells suppress

{killer T cells /B-cells} ;

Macrophages

non-specific /

phagocytosis ;

phagocytosis / engulf bacteria

/ antigen presentation ;

6

46

Question Number

Answer Mark

7 (a)

1. both have a {heavier /eq} left ventricle ;

2. both have a {thicker / eq} wall ;

3. both have a larger volume (left ventricle) ;

4. manipulation of figures to quantify one of the comparisons ;

max 3

Question Number

Answer Mark

7 (b)

1. reference to {epicardium / pericardium}, myocardium and

endocardium ;

2. outer {epicardium / pericardium}, inner endocardium and myocardium in between / eq ;

3. reference to cardiac muscle ;

4. reference to {epithelial cells / connective tissue} ;

max 2

47

Question Number

Answer Mark

8 (a)

1. age; 2. gender; 3. level of fitness / eq ; 4. resting pulse rate ; 5. diet / weight ; 6. heart conditions / eq ; 7. high blood pressure ; 8. drugs ; 9. height / eq ;

max 2

Question Number

Answer Mark

8 (b)

1. 152 x 85, 142 x 96 ; 2. / 1000 ;

3. subtraction = 0.71 ;

3

Question Number

Answer Mark

8 (c)

1. description of systolic and diastolic ;

2. systolic increases ; 3. (after training programe) stroke volume increases / greater volume

of blood entering arteries / heart contracts with greater force ; 4. (due to) greater stretching of ventricles during filling / increased

filling / increased end diastolic volume ; 5. diastolic decreases ; 6. due to greater emptying ; 7. reference to Starling’s law ;

max 4

48

Question Number

Answer Mark

9 (a)

A alveolus B blood vessel C bronchiole ;; NB All correct for 2 marks, 2 correct for 1 mark

2

Question Number

Answer Mark

9 (b)(i)

1. number of deaths greater in men than women (in all years) ;

2. between 1930 and 1960 increase in death rate in men but {stayed

constant in women / only increased slightly} ;

3. between 1960 and 1980/1990 death rate increased in men and women ;

4. linear increase in women but not linear in men ;

5. after 1990 number of deaths fell in men but still rose in women ;

6. manipulated comparative quantitative comment ;

max 3

Question Number

Answer Mark

9 (b)(ii)

1. lung cancer caused by smoking ;

2. increase in lung cancer due to increase in smoking ;

3. men smoke more than women ;

4. women started to smoke about 1930 ;

5. reference to polluted work environment causing lung cancer ;

6. idea of women {smoking being more socially acceptable / having

money / going out to work} ;

max 3

Question Number

Answer Mark

9 (c)

1. removal of tumour / lung ; 2. radiotherapy ; 3. chemotherapy ;

max 2

49

Further copies of this publication are available from Edexcel Publications, Adamsway, Mansfield, Notts, NG18 4FN Telephone 01623 467467 Fax 01623 450481 Email [email protected] Order Code UA 019777 January 2008 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

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