WJEC

Photosynthesis

Mark Scheme

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Question Answer/Explanatory Notes Marks

Available

7. (b) A photosynthesis is affected by more than one factor/list given; 1

B rate will be limited by factors nearest its minimum value/in short

supply; 1

C if the value of this factor changes then so will rate (direction needed);

1

D increasing light intensity will increase rate; 1

E energy source for reaction; 1

F at low intensities light is limiting; 1

G at high intensities light is not limiting/other factors become 1

limiting;

H suitable graph of rate v light intensity/description; 1

I carbon dioxide concentration; 1

J carbon dioxide used in Calvin cycle/light independent reaction; 1

K temperature; 1

L influences enzymes activity in Calvin cycle; 1

M suitable graph of rate v carbon dioxide concentration/ 1

Description;

N suitable graph of rate v temperature/description/collision theory and

denaturation; 1

O Ref. to nutrients (e.g. Mg)/water qualified; 1

(not: reference to wavelength)

(A maximum of 10 marks may be awarded from the 15 available)

[10]

GCE M/S Biology (January 2005)/ME

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Question Answer/Explanatory Notes Marks Available

4. (a) (i) L adenine/nitrogenous base; M ribose/pentose/5C sugar 2 marks (ii) used in/needed for glycolysis; phosphorylation (of substrate)/activation; 2 marks (iii) proton/H+ gradient/conc higher in intermembrane space;

powered by energy from electron transport chain/electrons power pumps;

protons diffuse; through stalked particle; ATP synthetase; ATP produced from ADP + P; Max 4

(b) (i) NAD has 2 phosphates (v.3); 2 ribose/sugars (v.1); 2 adenine bases Max 2 or made up of 2 nucleotides (v.1); 1 mark or 2 adenosine and 2 phosphates 2 marks (ii) accepts hydrogen/electrons/becomes reduced; (action of) dehydrogenase; to cristae/inner membrane; passes electrons to electron transport chain; for ATP synthesis/oxidative phosphorylation; reoxidised to accept further hydrogen/electrons; Max 3

Question Total: 13

5. (a) Magnesium 1 mark

(b) (i) ����; all correct = 2, 1 mistake = 1, 2 or more mistakes = 0 2 marks

(ii) tube 2 transmission has increased; DCPIP has lost blue colour; DCPIP has been reduced; by electrons; Allow hydrogenreleased from chlorophyll/reaction centre when light absorbed; (not: chloroplast) tube 4 transmission remains the same;

no light for light dependent reaction; Max 5(not: photolysis)

(c) (i) between GP and TP; 1 mark (ii) between GP and TP; between TP and RuBP; 2 marks (iii) GP/TP; 1 mark (iv) RuBP; 1 mark

Question Answer/Explanatory Notes Marks Available

(d) loss of available RuBP/not bonding with CO2; less carbon dioxide fixed; less productivity/photosynthesis less efficient/rate limited;

does not take advantage of bright light/products of light dependent reaction; Max 3

Question Total: 16

6. (a) A. mechanical digestion in mouth and stomach; 1 mark B. chemical/enzyme digestion starts in stomach; 1 mark C. rennin in correct context 1 mark (not: breaks protein down) D. pepsinogen produced by chief cells/gastric glands; 1 mark E. activated to pepsin by HC1/pepsin; 1 mark F. endopeptidase; 1 mark G. proteases secreted by pancreas and ileum; 1 mark (not: small intestine) H. activated by alkaline conditions; 1 mark I. endopeptidase and exopeptidase 1 mark J. dipeptides to amino acids on surface of cells or inside cells; 1 mark K. absorption in ileum/villi; 1 mark L. into capillaries by diffusion/active transport; 1 mark

(not: blood/blood vessels) M. to liver by hepatic portal vein; 1 mark N. used in protein synthesis; 1 mark O. excess deaminated and stored; 1 mark P. AVP; e.g. enzymes on surface of epithelium of villi/ transamination etc 1 mark (A maximum of 10 marks may be awarded from the 16 available)

Question Total: 10

6. (b) A. batch culture; 1 mark B. all materials added at the start/not during process; 1 mark C. sterile apparatus/vessel; 1 mark D. pure (culture) of Penicillium (notatum); 1 mark E. sterile nutrient medium; 1 mark F. method of aeration; 1 mark G. oxygen for respiration; 1 mark H. filters for introduction of sterile oxygen; 1 mark I. method of mixing 1 mark J. temperature control by water jacket; 1 mark K. allow growth phase to take place; 1 mark L. penicillin produced after growth phase; 1 mark M. as glucose is depleted; 1 mark N. filtration of culture fluid; 1 mark O. antibiotic purified; 1 mark P. AVP; e.g. penicillin is produced in free living, possibly to reduce competition, when food sources are depleted 1 mark

(A maximum of 10 marks may be awarded from the 16 available) Question Total: 10

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Question Answers/Explanatory Notes MarksAvailable

3. (a) Process controlled by more than one factor;

final rate controlled by the factor closest to its minimum value. [2]

(b) (i) Carbon dioxide is limiting;

Temperature not high enough/limiting;

Rate of photosynthesis has reached maximum for the plant/

Not enough chlorophyll / enzymes/ owwte (not: ref. to area/water)

2 Max

(ii) C [1]

(iii) Reaches maximum rate of photosynthesis at low light intensities/normal light inside building [1]

(c) (i) (Carbon dioxide) produced by respiration. [1]

(ii) Fall / drop owtte. [1]

[8]

4. (a) (i) A = Triose phosphate TP/Glyceraldehyde phosphate/GALP/ Phosphoglyceraldehyde.

B = Pyruvate/pyruvic acid.

C = Acetyl Coenzyme A/ACoA. (not: CoA/Acetyl coenzyme)

D = Reduced NAD/NADH2 /NADH H+

E = Carbon dioxide

F = Oxygen. [6]

(ii) Convert glucose into glucose 6 phosphate/provide activation energy/provide energy for splitting glucose

(not: provide energy/activate glycolysis) [1]

(b) (i) Inner mitochondrial membrane / crista. [1]

(ii) Come from hydrogen(which is split into electrons and protons). [1]

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Question Answers/Explanatory Notes MarksAvailable

(b) A ATP, NADPH2 from light dependent;

B In stroma of chloroplast;

C 5C acceptor;

D ribulose bisphosphate RUBP;

E carbon dioxide fixed;

F Enzyme RuBisco/ref enzyme e.g. sequence of enzyme controlled reactions;

G (breaks down into 2 × 3C) glycerate 3 phosphate/PGA/GP;

H (converted into 2 × 3C) triose phosphate/TP/GALP;

I NADPH H+/reduced NADP;

J supplies hydrogen/used for reduction;

K ATP broken down into ADP and iP supplies energy. (not: ATP supplies energy)

L RuBP regenerated from TP.

M Phosphate from ATP needed for this.

N Glucose, lipids, amino acids, chlorophyll, cellulose, starch. Any 2 products.

O Fate of two products qualified, e.g. glucose respired for energy /amino acid make proteins

P AVP e.g. balancing 6 RUBP etc./most TP to RBP some to glucose.

[10]

16

Question Answers/Explanatory Notes Marks

Available

3. (a) (i) Chlorophyll a; chlorophyll b; xanthophyll, carotene, carotenoid

[1]

Any three of above (ii) Allows light of different wavelengths to be absorbed [1] (b) (i) Rate of photosynthesis; [1] at different wavelengths [1] (ii) Axis correctly labelled, - rate of photosynthesis [1] Line drawn to show peaks that coincide [1] (iii) The wavelengths of light most absorbed are the

wavelengths used in the biochemical reactions owtte. [1]

(c) (i) photosystems [1] (ii) photolysis [1] (iii) X - NADP [1] Y - water [1] Z - oxygen [1] (iv) p - electrons [1] q - protons [1] (v) Accepting or donating electrons [1]

(vi) XH2/NADPH2 [1]

(vii) Source of reducing power/to reduce CO2/adding hydrogen

to PGA (to form GALP). [1]

Total marks [17]

16

Question Answers/Explanatory Notes Marks Available

5. (a) (i) thylakoid/granum/lamellae/antenna complex/ light harvesting units; (not : reaction centre/photosystems)

1

(ii) chlorophyll a; 1

(iii) absorb light energy/photon; pass (energy) onto primary pigment/reaction centre/chlorophyll a; increase range of wavelength absorbed.

Max. 2

(b) (i) A reduced NADP;

B ATP; 2

(ii) oxygen; 1

(iii) C ribulose bisphosphate; D triose phosphate/GALP; 2

(iv) glucose/amino acids/lipids or other correct. 1

(c) (i) the factor in the shortest supply/nearest to its minimum

value (and therefore the most likely to determine the rate of photosynthesis); 1

(ii) photosynthesis/Calvin cycle uses enzymes; enzyme action is affected by temperature/ref. to enzyme kinetics; high temperature denatures enzymes/low temperature

slows enzyme action; Max. 2

(iii) X light; (intensity) Y carbon dioxide (concentration). 2

Total [14]

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Question Answers/Explanatory Notes Marks Available 7. (a) Photosynthesis produces oxygen (as a by-product); Aerobic bacteria are attracted to the oxygen; (not: bacteria need ooxygen unqual) Most bacteria [are in / move to] the [blue and red regions / stated wavelengths] of the spectrum / few bacteria in the green region; Most photosynthesis is in the blue / red region; [3 max] (b) action spectrum [1] (c) light absorbed by photosystems / chlorophyll a; they emit/give off electrons; electrons from PSII/P680 pass to PSI/P700 via series of carriers; (not: passed along electron transport chain) ATP synthesis; Electrons from PSI pass to NADP; Mention of photolysis of water; Electrons from photolysis replace those lost from PSII Formation of oxygen in context [4 max] (d) Oxygen used in respiration / diffuses out of leaf; (not: given off) ATP supplies energy and phosphate in Calvin cycle/eq.; NADPH2 / NADPH + H enter [Calvin Cycle / eq] / used to reduce CO2 / to synthesise glucose. [Any 2] Total 10 marks

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Q.5 (a) (i) mesophyll / palisade / guard (cell) ; 1

(ii) stroma (of chloroplast) ; 1

(b) (i) glycerate-(3)-phosphate / GP / triose phosphate / TP ; 1

(ii) ribulose bisphosphate / RuBP ; 1

(iii) triose phosphate / TP ; 1

(c) statement applies / rate (just about) doubles for increase from 5�C to 15�C ;

more energy for more collisions ;

comment on only small increase from 10�C to 20�C / decreases from 15� to 25� / 20� to 30�;

optimum (appears to be 15�C) ;

so would not expect increase above it or expect a decrease ;

30� / higher temperatures denature enzymes ; 3 max

(d) can absorb other / wider range of wavelengths /different colours;

less light penetrates into / intensity in deeper water ;

different wavelengths penetrate to different depths;

allows more / sufficient / maximum photosynthesis ; 2 max

[Total : 10]

Q.6 (a) (i) hybridoma ; (not : hybrid) 1

(ii) divide continuously / no cell death ; 1 (not : reference to speed)

(b) (i) specific (to one antigen) ; 1

(ii) pregnancy testing ; 1(not : HIV / tumours)

(iii) deliver drugs / magic bullets (to tumour cells) / during targetting ; 1(not : cancer treatment)

[Total : 5]

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7 (a) A. (photon of) light strikes chlorophyll / pigment / reaction centre / photosystem ; 1

B. chlorophyll a (molecule) loses electron ; 1

C. in photosystem II / P680 ; 1

D. passes down chain of electron carriers ; 1

E. converting ADP to ATP ; 1

F. reference non-cyclic (photo)phosphorylation in correct context; 1

G. electron passed on to photosystem I / P700 ; 1

H. electron lost from photosystem I / P700 ; 1

I. and then returned to photosystem I / P700 ; 1

J. reference cyclic photophosphorylation in correct context; 1

K. photolysis / splitting of water ; 1

L. provides electron to replace the one lost from photosystem II / P680 ; 1

M. produces oxygen ; 1

N. electron from photosystem I /P700 with H+ reduce NADP ; 1

O. ATP and redNADP available for light independent reaction / Calvin cycle ; 1

P. AVP ; e.g. ref to antenna complex / accessory pigments / sequence of electron carriers / detail of stalked particles / reaction centres. 1

Any 10 of the 16 available marks

[Total : 10]

(Points A, B, D, E could be in context of cyclic or non cyclic; K, L, M linked marks; F, J refer to ATP production and fate of electron)

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Question Answers/Explanatory Notes Marks Available

6. (b) (i) A When a chemical process is affected by more than one factor; [1] (allow: ref. photosynthesis)

B Its rate is limited by that factor which is nearest its minimum value;[1]

C If the value of this factor is increased then the rate will also increase until some other factor becomes limiting; [1]

(ii) D Increasing light intensity will increase rate; [1]

E Light acts as an energy source for the reaction / is involved; in the light dependent stage / photolysis of water. [1]

F At low light intensities light is limiting; [1]

G At high intensities light is not limiting / other factors become limiting; [1]

H Suitable graph with axes labelled of rate against light intensity or description showing levelling off; [1]

I Carbon dioxide concentration; [1]

J Carbon dioxide is used in the light independent reaction / Calvin cycle; [1]

K Suitable graph with axes labelled of rate against carbon dioxide concentration, levelling off or description; [1]

L Temperature change e.g. rate increases as temperature increases;[1] (not: temperature affects photosynthesis)

M Influences enzyme activity; [1] (linked with point L)

N Suitable graph of rate against temperature; [1]

O Graph showing two or more factors interrelated. [1]

[A maximum of 10 marks may be awarded from the 15 available]

(H, K, N – axes require: CO2 concentration; light and arrow or light intensity; temperature and arrow or temperature increasing or suitable scale / units)

GCE Biology (Legacy) Marking Scheme (January 2009)/ED 23 February 2009

15

Question Answers/Explanatory Notes Marks Available

5. (a) thylakoid membrane [1]

(b) photosystems / P680 and P700 [1] (not: PSI / PSII / antenna complex)

(c) photophosphorylation [1] (not: chemiosmosis)

(d) (i) photolysis [1]

(ii) replace electrons lost from photosystem II / PSII � [1] (not: raised to higher energy level / ref. to ‘going back to’)

(iii) accepted by NADP which is reduced to NADPH2eq. [1]

(iv) accepting (or donating) electrons [1] (not: catching electrons)

(e) (i) Calvin cycle [1]

(ii) stroma [1]

(f) (i) C / ribulose bisphosphate [1]

(ii) Between B and C (on line or slightly to right) [1]

(iii) glucose (not starch) [1]

[Total marks 12]