WJEC

Respiration

Mark Scheme

T John

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T John

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Tyrone

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T John

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16

Question Answer/Explanatory Notes Marks

Available

4. (a) (i) sugar + base + 3 phosphates or correct names;

ATP to ADP + Pi releases energy/exergonic or description;

ADP + Pi to ATP needs energy/endergonic or description;

easily reversible;

transfers energy from place of release/one molecule

to energy-requiring reactions;

provides energy in 'small packets'/figure e.g. 30.6 or 31. 4

(Max 4)

(ii) two of synthesis/muscle contraction/active transport/other

e.g. nerve impulses/photosynthesis etc.; 1

(not: movement/growth)

(b) (i) X H (atom)/reduce NAD/reduced FAD; 1

Y oxygen; (not water) 1

(ii) X chlorophyll/photosystem I or II; 1

Y chlorophyll/NADP/photosystem I; 1

(c) (electron) fuels proton pump;

across membrane/into intermembrane space;

H+/protons diffuse/flow down concentration gradient;

Through ATP synthetase/stalked particles (not: ATPase);

Chemiosmosis;

Membrane impermeable to protons;

(Max 4) 4

[13]

17

Question Answer/Explanatory Notes Marks

Available

5. (a)

Stage

Name of process

Precisely where it occurs

A

glycolysis

Cytoplasm

B

link reaction

matrix (of mitochondrion)

C

Krebs cycle

matrix (of mitochondrion)

One mark per box

(b) (i) carbon dioxide; 1

(ii) acetyl CoA; 1

(c) dehydrogenase; 1

(d) (i) 32 / 38 / 34 / 36 ; 1

(ii) C (allow: Krebs) 1

(iii) only glycolysis/no Krebs cycle/stops at link reaction;

so net production of 2 ATP/4 made and 2 used;

no electron transport chain;

no final electron acceptor/O2 to accept H+;

no recycling of NAD;

pyruvate/ethanal acts as H accepto/energy remains in

pyruvate; 3

(Max 3) [14]

T John

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12

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

15

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]

16

Question Answers/Explanatory Notes MarksAvailable

(iii) Used to pump protons into space between/across mitochondrial membranes (against conc gradient)/to produce proton gradient /proton motive force.

Protons move down electrochemical gradient/p gradient /proton gradient;

Through stalked particles / ATP synthetase /ATP synthase/ ATPase;

Provides energy to convert ADP + (i) P into ATP; (not: to produce ATP)

Chemiosmosis. 4 Max

(c) Why person lacking energy e.g. ATP used for muscle contraction/less absorption of food.

Food not enough to meet metabolic demands of body/named; i.e. food broken down but not making sufficient ATP

No excess food material to store;

therefore respiration using body tissues/fat/protein/food stores;

AVP e.g. heat production increases metabolic rate/body respires faster to produce ATP.

3 Max

[16]

17

Question Answers/Explanatory Notes Marks Available

6. (a) A acetyl CoA (enters/starting point); 1

B combines with 4C (acid) to produce 6C (acid); 1

C CoA regenerated/breaks off (not : reused); 1

D correct ref. to decarboxylation; 1

E correct ref. to dehydrogenation; 1

F correct ref. to carbon dioxide produced; 1

G correct ref. to reduced NAD and FAD; 1

H pass hydrogens to electron transport chain; 1

I correct ref. to ATP formed directly in Krebs; 1

J energy from electrons fuel proton pump; 1

K protons pumped/actively transported into inter-membrane space;

1

L diffuse/flow down concentration gradient; 1

M through ATP synthetase; 1

N stalked granules/particles; 1

O oxygen is the final acceptor; 1

P chemiosmosis; 1

Q ADP + P = ATP; 1

R correct ref. to no of ATP produced per NAD/FAD; 1

S AVP; e.g. no of pumps associated with NAD/FAD. 1

Any of the 12 of the 19 available marks

17

Question Answers/Explanatory Notes Marks

Available

4. (a) (i) ATP/adenosine triphosplate [1]

(ii) Purine base correctly circled on diagram

[1]

(iii) ADP/adenosine diphosphate AND phosphate

[1]

(iv) It occurs in all cells/ all organisms/ all metabolic reactions

[1]

(b) (i) A - intermembrane space [1] B - matrix

[1]

(ii) Glycolysis/Link reaction/Kreb's cycle [1] Any two - 1 mark each

[1]

(iii) P - pump protons from matrix into intermembrace space/ref. active transport

[1]

C - carry electrons (from pump to pump)/ electron transport

[1]

(iv) Provide energy for pumps

[1]

(v) ATP synthetase/synthase (accept ATP ase) (not: stalked particles)

[1]

(vi) converts ADP(+Pi) to ATP; [1] Using energy from protons moving down

(electrochemical) gradient chemiosmosis qualified

[1]

Total Marks [14]

5. (a) (i) I - humoral [1] II - cell mediated [1] (ii) X - B lymphocyte/cell [1] Y - T lymphocyte/cell [1] (iii) Bone marrow [1] (iv) Memory cell [1] Proliferate/produce antibodies (immediately) on next

contact with the specific antigen/ pathogen [1]

(v) Helper (cell), killer (cell), suppressor (cell), memory (cell) [2] Any 3 of above for 2 marks (2 for 1 mark)

(not: abbreviations)

(vi) Stimulate production of B cells/cytotoxicity/Switch off

cell mediated response at end of immune response/proliferate on next contact/ destroy pathogens by lysis

[1]

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Q.2stage of respiration main products where it takes place

Glycolysis pyruvate ; reduced NAD ; ATP ; 2 max

cytoplasm ;

Krebs cycle carbon dioxide ; reduced NAD ; reduced FAD ; ATP ; 3 max

matrix (of mitochondrion) ;

Electron transport chain

ATP ; water ; NAD / FAD ;

2 max

inner mitochondrialmembrane / crista ;

Incorrect answer negates correct answer. 10 max

[Total : 10]

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AS MODULE BI4

Question Answers/Explanatory Notes Marks Available

1. ATP

(a) A Phosphate(s)

B Adenine

C Ribose [3]

(b) Nucleotides [1]

(c) It is the major energy currency of the cell;

(provides energy) for cellular activities of the cell / protein synthesis / active transport / muscle contraction;

used for synthesising RNA / DNA (not: used for respiration/source of energy unqual) [Any 2]

(d) Cytoplasm

Mitochondria/specified region

Chloroplasts Mesosome [3]

Total 9 marks

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Question Answers/Explanatory Notes Marks Available 5. (a) A carbon dioxide B coenzyme A / Acetylcoenzyme A / Acetyl CoA C Oxygen D Water [4] (b) Box in correct place to include glucose and pyruvate [1] (c) Mitochondrial matrix [1] Cristae / inner mitochondrial membrane of mitochondrion [1] (d) E clearly between glucose and TP [1] ATP between TP and pyruvate between 5 and 4 acids [1 for both] (e) dehydrogenase; [1] (f) reduced NAD / eq; (used to) reduce pyruvate; to lactate; (not: lactate+ATP or energy) NAD regenerated [any 2] (g) glycerol enters at TP [1] Fatty acids enter at B [1] Total 14 marks

14

Question Answers/Explanatory Notes Marks Available

4. (a) A – substrate level [1] B – oxidative [1]

(b) (i) decarboxylase [1]

(ii) dehydrogenase [1]

(c) (i) X is NAD (not: NADH) [1] Y is FAD [1]

(ii) carrier system of FAD has two pumps / less pumps [1] (whereas NAD has three pumps)

(d)

Stage Number of ATP molecules formed from reduced hydrogen acceptors

Number of ATP moleculesformed directly

Total number of ATP molecules

Link reaction 6 / 3 × 2 0 6

Krebs cycle 22 2 24

[1 each – no marks for totals] [4]

(i) acetyl CoA / acetyl coenzyme A [1]

(ii) two [1]

(iii) pyruvate, (a 3 carbon molecule) is converted to acetyl group / acetate, (a 2 carbon molecule); by the removal of carbon dioxide / decarboxylation (and hydrogen) (hydrogen reduces NAD); The acetyl group combines with CoA (to form acetyl CoA) [2]

[Total marks 15]

17

Question Answers/Explanatory Notes Marks Available

4. (a) axes correct - colorimeter readings vertical, axis at 0, -ve below, +ve above [1]

axes both labelled, including units, over half page [1]

scale correct and same on both axes [1]

all plots correct, no tolerance [1]

(b) As light intensity increases the reading increases / eq (or converse) [1]

Some ref to slowing of rate of increase at high LI / correct use of figs [1]

(c) Compensation (point) [1]

(d) Rate of respiration = Rate of photosynthesis [1]

(e) Low Light Intensity

More CO2 is produced / CO2 is produced in respiration;

More respiration (than PS);

High Light Intensity

Less CO2 is present / CO2 is used up in PS;

More PS (than respiration);

Any correct use of data;

CO2 or Temp are limiting factors at high LI;

Any 4 points [4]

[Total 12 marks]

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Question Answers/Explanatory Notes Marks Available 6.

Oxidative phosphorylation

Cyclic photophosphorylation

Non cyclic photophosphorylation

Requires light NO YES YES

Requires oxygen YES NO NO

Produces oxygen NO NO YES

Number of proton pumps involved

3 1 1

Source of Electrons

Red NAD or Red FAD PS I Water / PSII

(not: chlorophyll)

Final electron acceptor

Oxygen PS I NADP /NADPH+

(allow: ticks and blanks for first three points)

[1 mark per row ] [6]

21

Question Answers/Explanatory Notes Marks Available 8. (a) A. Occurs in cytoplasm of (all cells) / Initial stage in the breakdown of glucose; B. Glucose is phosphorylated using 2 ATP C. Becoming hexose di phosphate D. This is spilt into 2 x triose phosphate E. TP is converted to Pyruvate F. Correct action of dehydrogenase G. Producing 2 x reduced NAD H. Explanation of net gain (4-2 used initially) I. 2 x ATP overall J. 2 x Pyruvate (8 max.) Anaerobic conditions yeast K. Pyruvate is converted to acetaldehyde / ethanal L. With the production of carbon dioxide M. Acetaldehyde / ethanal is reduced to ethanol using the reduced NAD Anaerobic conditions animal cell N. Pyruvate is reduced to lactate using the reduced NAD O. Regeneration of the oxidised NAD (animal or yeast) 10 max (out of 15) Max 7 marks total may be awarded from suitable well labelled / annotated diagrams for any of the sections. Any text to be marked first.