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Mark Scheme (RESULTS)January 2008
GCE
GCE Biology (6101/01)
Edexcel Limited. Registered in England and Wales No. 4496750Registered Office: One90 High Holborn, London WC1V 7BH
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1
Statement Glycogen Cellulose
Consists of glucose X
Contains 1,4 glycosidic bonds
Is a branched molecule X
Is a structural carbohydrate X
Any two correct boxes for one mark
max4
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2 1. (simple ) diffusion ;
2. facilitated diffusion ;
3. active transport ;
4. ATP ; 4
1 Unit 1
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2
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3 (a)(i) the {sequence / order} of amino acids ; 1
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3 (a)(ii) hydrolysis ; 1
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3 (b)
CCNH
HH
O
OHCH 2
OH ; 1
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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 bydisulphide bonds / chains heldtogether by hydrogen bonds
chains held together bydisulphide bonds / eq ;
4. large / about 1000 aminoacids OR length can bevariable
small / 51 amino acidsOR fixed / precise length ;
5. repetitive / repeatingsequence / eq
no repetitive sequence ; max3
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4
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5 (a)(i) cell in anaphase correctly identified ; 1
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5 (a)(ii) cell in telophase correctly identified ; 1
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5 (a)(iii) 2 / 3 ; 1
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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 ; max5
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5
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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
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6 (b)(i) 1. correct length ;
2. divided by 50 000 ;
3. correct length in m ; 3
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6 (b)(ii) vacuoles / vesicles / lysosomes / glycogen granules / ribosomes / lipiddroplets / centrioles / spindle fibre / microtubules ; 1
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6 (b)(iii) {resolution not high enough / eq} / damage / {angle of section / eq} / {poorprinting of photograph / eq} ; 1
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6
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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
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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 ;max3
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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 ;max3
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7
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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 (withand without copper ions) ;
3. the rate of reaction changes with time /eq ;
4. because substrate is being used up / eq ;max2
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7 (d)(ii) idea that the {maximum rate/ V max } (with copper ions present) is lower (thanwithout inhibitor) / if it was active site-directed it would take longer to reachsame maximum rate ; 1
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8
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8 (a) A phosphateB deoxyribose ; 1
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8 (b)(i) Adenine 29, Guanine 21, Cytosine 21 ; 1
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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 ;max3
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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}) ;
max2
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1 1. monocytes ;
2. antibodies / immunoglobulins ;
3. eosinophils / basophils ;
4. nucleus ; 4
2 Unit 2
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2 (a) A red blood (cell) / erythrocyte ;
B (alveolar) epithelial cell / epithelium / squamous epithelium / ; 2
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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 ; max4
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2 (c) 8.1 (dm 3) ; 1
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3 (a) Carbohydrate Enzyme Products
amylase ;
glucose andgalactose ;
sucrose ; sucrase ;4
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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 transportproteins for fructose / more transport proteins for glucose /fructose is absorbed by diffusion (only) ; 3
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4 (a) A aorta / aortic arch ;
B (right) atrioventricular valve / tricuspid valve ; 2
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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 heartmuscle) ;
max3
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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} ;
max3
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4 (d) 1. increased {demand for / eq} {oxygen / glucose} / increasedrespiration ;
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 ;max3
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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
max4
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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
max2
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5 (b) 1. inverse relationship / eq ;
2. credit a manipulated quantitative comment ; 2
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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 ; max3
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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 ;
4. credit a manipulated quantitative comment ;max3
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7 (a) xylem (vessel) ; 1
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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 (intoxylem)} ;
max3
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7 (c)(i) 1. concentration increases as temperature increases / eq ;
2. credit a manipulated quantitative reference ; 2
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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
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8 (a) E D C B A ;;
NB All correct = 2 marks, 1 error (i.e. one letter out of sequence) = 1 mark 2
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8 (b) (i) 46 ;(ii) 23 ; 2
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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 ;max4
PAPER TOTAL: 60 MARKS
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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 {digestedproducts / named product} / eq ;
max2
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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 inrecycling of nutrients} and Phytophthora causing {harm / loss of crops/ eq} ;
max2
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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} ;max2
3 Unit 3
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2 (a) 1. bacteria / fungi / saprophyte / saprobiont / decomposer / suitable,correct organism ;
2. reference to respiration ; 2
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2 (b)(i) photosynthesis ; 1
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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} ;max2
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2 (c) 1. idea of {carbon / carbon dioxide} {locked away / stored} / eq ;
2. for {many years / a long time / eq} ; 2
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2 (d) 24 391 37.98 ;
642.2 x 10 6 ha ; 2
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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 ;;max2
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2 (f) 1. idea of less carbon dioxide {fixed / taken up / eq} by photosynthesis ;
2. {respiration / combustion of {fossil fuels / trees}} continues to releasecarbon 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 Earths surface) ;
max4
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3 (a)(i) {total biomass / eq} produced / {total energy / eq} taken in ;
by {plants / producers / photosynthesis / eq} ; 2
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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 ;max2
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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 anincrease in microorganisms / eq ;
max3
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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 ;max2
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3 (c)(ii) 1. idea that {more leaves / detritus / eq} added with distance fromsource / more leaves shed in winter / (more dead material because)algae die down in winter ;
2. far increased {bacterial / eq} activity ; 2
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3 (d)(i) 1. GPP {increases as distance (from headwaters) increases / higher inMotueka 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) ;max3
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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} ;max3
TOTAL FOR PAPER: 38 MARKS
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1 (a) Time of day Cushion temp./ 0C
Mean cushiontemp. / 0C
Air temp. / 0C
08.00 8,9,8 8.3 (8.33) 410.00 17,15,15 15.7 (15.67) 712.00 20,22,23 21.7(21.67) 914.00 21,21,22 21.3 (21.33) 1116.00 19,17,20 18.7 (18.67) 918.00 6,5,5 5.3 (5.33) 3
suitable table with time, mean cushion temp and air temp ;
correct rows and columns with headings and units ;
means correct to consistent sig. figs. (all correct = 2 marks, one error = 1mark);;
max4
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1 (b) F line graph format with both lines on same axes ;
A axes correct orientation and labelled with suitable scale ;
P points plotted correctly ;
L straight line joins points or good curve through all points ; 4
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1 (c) 1. cushion temperature always above air temperature ;
2. as air temperature increases ANDdecreases so cushion temp increasesANDdecreases ;
3. some relevant use of figures e.g. maximum cushion temp. 10.3 0Chigher than maximum air temp. ;
4. temp / max cushion temp. almost double max air temp. / eq ;max2
W1 Unit 3
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1 (d) 1. no evidence of any significant anomalies / cushion temp. falls eventhough air temp. continues to rise ;
2. random cushion readings do not vary by more than 3 0C / cushion airtemp. anomaly quantified ; 2
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1 (e) 1. reference to higher temperature promoting metabolism (e.g. enzymeactivity, photosynthesis) ;
2. growing points / meristems can be protected from temperatureextremes inside cushion ;
3. ref to reduction in surface area / eq ;max2
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2 (a) Points 1 & 2: reference to initial seeds/seedlings at start of study
Points 3 & 4: ex traction of root nodules material (from established plants)
Points 5 & 6: selection of seedlings for inoculation
Points 7 to 13 : design, growth parameters and measurement
1. use of stated leguminous plant / member of Papilionaceae forstudy (e.g. clover) ;
2. {germinate / grow} {seeds / seedlings} in two named standardconditions ;
3. remove nodules (from established plant of same species) ;
4. suitable method of extraction of constant concentration of inoculum (e.g. {grind / eq} stated mass of root nodules in statedvolume of water) ;
5. stated number (5 or more) of {seedlings / seeds} for each trial ;
6. seedlings / eq / seeds {same size / same mass / measuredparameter} at start ;
7. preparation of concentrations described (e.g. named nitrogensource / nitrate / ammonium salt / fertiliser e.g. 1 g in 100 cm 3) ;
8. same volume of nitrogen source (in every case) ;
9. 5 or more concentrations of nitrogen source used ;
10. suitable (control) with no nitrogen added (e.g. using distilledwater) ;
11. seedlings grown for stated period (minimum 1 week) ;
12. {count number / obtain {wet / dry} mass of root nodules} ;
13. minimum of 2 repeats (i.e. three trials in total) ; max9
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2 (b) 1. suitable table of raw data, with correctly labelled rows and columns,including units to match the method ;
2. line graph / bar chart ;
3. correctly orientated and labelled axes including units ;
4. calculation of means ; max3
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2 (c) Limitations: [Sub-maximum 4]
1. difficult to know if (original nodules / extract) contain living bacteria;
2. difficult to know if {seeds / growth medium} already containRhizobium ;
3. difficult to get {seeds / seedlings} {to take up bacteria to developnodules} ;
4. environmental conditions inhibit {formation of nodules (if notcontrolled) / enzymes (of Rhizobium ) ;
5. difficult to collect / count all root nodules ;
Further work: [Sub-maximum 4]
6. the effects of root nodules / leguminous plants on the growth of cropplants per se ;
7. test effect of different concentrations of inoculant ;
8. the effects of different species of legume and fertiliser on plantgrowth / crop production ;
9. the effect of root nodules and types of fertiliser on the growth of other legumes / eq ;
10. a named environmental condition on root nodule formation ;
11. undertaking field trials into the relationship between Rhizobium ,fertilisers and crop production ;
max6
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