marking schemes for topic 1,2 stafford papers

Marking schemes for AS past papers by Stafford Valentine Redden, Head of Biology, VIHS. 1

SAQ 1 Annotate the diagram to show the polar charges on oxygen and hydrogen atoms, and hydrogen bonds between the molecules What would you say to make them realise they do not need to worry? Water warms up and cools down slowly, so the

fish will not experience rapid changes in water

temperature. For older or more able cousins

you might add that on a sunny day, a large

input of energy causes only a small increase in

water temperature. This is because a large

amount of energy is required to break

hydrogen bonds between the water molecules.

SNAB

SAQ 2 Solvent; dense; insulates; hydrogen

specific heat capacity; surface tension.

SAQ2. (a) Transport in blood and phloem / high specific heat capacity; (b) (i) Ice floats on water, forming a layer that insulates the water beneath with the result that large bodies of water rarely freeze entirely. So aquatic life can survive at the bottom of the lake. (ii) High latent heat of vaporisation helps to cool plants during transpiration and mammals during sweating. (1 mark) (iii) High specific heat capacity keeps temperature of aquatic habitats stable. (2) SAQ3. H2O; dipolar; hydrogen; solvent; specific heat capacity May 2002 Unit 1, Edexcel

SAQ4. Solvent; enter; insoluble; lipids;

glycogen; plant; (Total 6 marks) Edexcel

SAQ 5. a) Hydrogen bond. (1) b) Since oxygen is more electronegative than hydrogen, the oxygen side of the water molecule has a slight negative charge and the hydrogen side of the water molecule has a slight positive charge. (2) c) The high specific heat capacity of water ensures that the temperature of water bodies remains constant or fluctuates very slowly. This provides a thermo-stable habitat for

aquatic organisms. (2) (Total 5 marks) June 2004 Unit 1, Edexcel SAQ6. Feature / Explanation Helical/spiral/coiled (shape) – compact; Insoluble – osmotically inactive / does not leave cell; Large size– does not leave cell / many glucose/monomers; Branched – glucose/monomers easily/quickly removed; 2 max (Two features without explanations = one mark) Glycogen is a polysaccharide. It is a storage substance in humans. Suggest one advantage of

storing glycogen in muscle cells. (1 mark) Provides glucose for respiration/as energy source/for ATP production; 1 Jan08/BYB1 SAQ 7. (a) The statements in the table below refer to three biological molecules. If a statement is correct place a tick (J) in the appropriate box and if a statement is incorrect place a cross (x) in the

appropriate box. Four boxes have already been completed for you.

SNAB Unit 1 Jan 2005 SAQ7. (a) Loop of DNA; Non-cellulose cell wall; Plasmid; Capsule; Flagellum; Mesosome;

Accept small ribosomes (2) (b) (i) It turns blue-black/dark blue/black/purple with iodine; (1) (ii) Cellulose / pectin; (1) (c) Insoluble; Therefore will not wash out of cell / affect water potential / affect osmosis; OR

Statement

Starch

Glycogen

Monosaccharide

Is a polymer

J J X

Glycosidic bonds are present

J J X

Is an energy store in animal cells

X J X

Has high solubility in water

X X J


Molecule coiled/branched; Therefore large amount stored in small space / compact OR Does not affect water potential; So no effect on entry of water (into cell); (2) Jan 05 AQA BYA1 SAQ8.(a) The table below shows two types of breakfast.

Breakfast 1 Breakfast 2

Wholemeal toast Baked beans Tea Apple

Frosted flakes Milk White rolls and marmalade Tea

Breakfast 2, because these items are cooked and can digest easily. They also contain more sugars, which will be rapidly absorbed into the blood.

(b) Dietary carbohydrates are used to provide energy by respiration. Insoluble fibres reduce the risk of constipation.

(c) Adult people have variable metabolic rates and physical activity levels. So it is difficult to recommend a daily allowance.

(d)

(e) Why is this called a condensation reaction? Two monosaccharides are combined together to release one water molecule. (Total 7 marks) SNAB Specimen paper SAQ9. (a)(i) Condensation (ii)1, 4-glycosidic bond (iii) Water (b) (i) Starch is Compact - so it takes up less space in the cell. Starch is Insoluble – so it cannot leave the cell easily. Starch is Insoluble – so it does not have an osmotic effect. Starch is Insoluble and unreactive – so it does not get involved in chemical reactions in cell. (ii) Starch contains branches after every 20 to30 residues and glycogen contain branches after every 8 to 10 residues. Starch is made of

amylose and amylopectin, where as, glycogen is made up of a single component. (1) SNAB Unit 1 June 2006 SAQ10. (a) (i) lactose; 1 (ii) cellulose/chitin; 1 (b) they are not digested / hydrolysed / broken down in digestive system; as humans lack cellulase / the appropriate enzymes; not absorbed / passes straight through gut / energy not available; 2 max JUN05/AQA/BYA7 SAQ11. a) Starch is an efficient storage molecule in plant cells. The features that enable starch to function as an effective storage molecule are stated below. Starch is:

Compact: takes up less space in the cell.

Insoluble: cannot leave the cell easily.

Insoluble: No osmotic effect.

Insoluble and unreactive: does not get involved in chemical reactions in cell.

Easily hydrolyzed by enzymes into glucose and used for respiration when needed.

b) Ignore – not in syllabus

(i) Add 5 cm3 of Benedict’s solution to 5 cm3 of one sugar solution. Boil the mixture for 8 minutes in a water bath. Appearance of brick red precipitate confirms the presence of reducing sugar. (ii) Add 5 cm3 of Benedict’s solution to 5 cm3 of one sugar solution. Boil the mixture for 8 minutes in a water bath. Cool the mixture and filter it using a pre-weighed filter paper. Dry the filter paper and precipitate in a dessicator. Mass of ppt. = [(Mass of paper + ppt.) – mass of paper] The mass of precipitate is proportional to the concentration of reducing sugar in the solution. Repeat the procedure with the other sugar solution. The solution with the higher mass of precipitate will have a higher concentration of reducing sugar.


(Total 6 marks) Part of January 2001 Unit, Edexcel

SAQ 12. (a) Similar — allow valid similarities such as same number, carbon/ oxygen / hydrogen (atoms) I OH (groups): (A) hexose’ same formula; NOT similar NOT molecule ring / ring with O (atom) in it; NOT covalent correct ref. CH2OH; contain C, H and O; 1 max Different — allow valid differences such as- (assume referring to fructose) (fructose has) 5-membered ring I glucose has 6-membered ring; NOT pentose

(4 C in ring v 5C in ring I furanose v. pyranose in glucose) (in fructose) 2 CH2OH side chains/ 1 CH2OH side chain in glucose; different angles between C atoms; ref. alignment of H and OH groups (on carbon 3/ carbon 4); (in fructose) carbon 1 not in ring I carbon 1 in ring in glucose; 1 max

(b) (i) glycosidic ; NOT glucosidic 1 (ii) carbon positions 1 and 2 on glucose and fructose ; formation of , water / H2O , from 2 OH groups (plus separation) ; oxygen bridge / O , shown ; 2 max JUN 2005/2801/OCR SAQ 13. a) (i) 2[(CH2O)n] – H2O (1) (ii) Hydrolysis (1) (iii) Lactose is made up of glucose and galactose, but maltose is made up of two glucose residues. (1) b) Feed the baby ‗soya milk‘, as it does not contain lactose. (2) (Total 5 marks) January

1996, (B/HB1), Edexcel SAQ14. (i)

(ii) Condensation reaction. (iii) Six carbon atoms

b) The cellulose micro-fibril is made up of many parallel, unbranched chains of β – glucose residues linked to each other by hydrogen bonds. This arrangement provides high tensile strength to resist the stretching forces exerted by the movement of water into the cell. (Total 5 marks) Part of January 2001, Unit 1,AQA SAQ15.

Statement Sucrose Maltose

Contains glucose √ √

Is a reducing sugar X √

Contains glycosidic bonds

√ √

Is transported in the phloem of flowering plants

√ X

(Total 4 marks) May 2002 Unit 1, Edexcel

SAQ 16.a) Ignore – not in syllabus b) Ignore – not in syllabus c) Ignore – not in syllabus

June 2001 Unit 1/ Module Test B/HB1, Edexcel SAQ16. a) Maltose b) Disaccharide c) 1, 4 – Glycosidic bond (Total 3 marks) June 2000 Module Test B/HB1,

Edexcel SAQ17. a) (i) Ignore – not in syllabus (ii) The surface area to volume ratio is very low. So, rate of exudation of sugars is very low. b) Ignore – not in syllabus c) There will be reducing sugars in the solution, because boiling of the cells damages the cell membrane and allows the reducing sugars to easily diffuse out of the cells. d) During the spring, the polysaccharides are converted into reducing sugars to be transported and to provide energy for growth of the shoots. Thus, the concentration of reducing sugars increases. (Total 10 marks) BYB678 June 02AQA SAQ18. a)

Disaccharide Monosaccharides

Galactose Glucose Fructose

Sucrose √ √

Maltose √


Lactose √ √

b) Glycosidic bond

(Total 4 marks) May 2005 Unit 1, Edexcel SAQ 19. a)

Description of carbohydrate

Name of carbohydrate

A pentose found in transfer RNA

Ribose

A disaccharide consisting of glucose and galactose

Lactose

The carbohydrate transported in the phloem of plants

Sucrose

(Total 3 marks) June 2004 Unit 1, Edexcel SAQ20.

Carbohydrate One role in living organisms

Glucose Form in which carbohydrate is transported in mammals

Sucrose Form in which carbohydrate is transported in plants

Glycogen Form in which carbohydrate is stored in mammals

(Total 4 marks) January 2004 Unit 1, Edexcel

SAQ21. a) C12H22O11

b) (i) Ignore – not in syllabus (ii) Ignore – not in syllabus (Total 6 marks) January 2004 BYB1, AQA SAQ22. (a) (i) In first carbon H group is above the ring and OH group is below the ring. (1)

(ii)

(2)

(b)

Sugar Chemical formula

Type of sugar

Glucose C6H12O6

Monosaccharide formed by hydrolysis of Maltose

Fructose C6H12O6

Monosaccharide formed by hydrolysis of sucrose

Sucrose C12H22O11 Disaccharide formed by condensation of glucose and fructose

Maltose C12H22O11 Disaccharide formed by condensation of glucose

Jan 06 AQA BYA1

SAQ23. (a) (Molecules) with little (kinetic) energy; Move slowly; Few collisions (between enzyme and substrate)/fewer enzyme-substrate complexes formed; (3) (b) Heating would cause bonds (maintaining tertiary structure)/named bonds to break; Denaturing enzyme/ altering tertiary structure; Altering shape of active site (2)

Jan 03 AQA BYA1 SAQ24. (a) It is insoluble and does not have an osmotic effect. It can easily be reconverted into glucose and used for respiration. (b) (i)

(2)


(b) Due to enzyme specificity (1) SNAB Unit 1 Jan 2004

SAQ 25. a) Phospholipid b) A – Glycerol B – Ester linkage c) Hydrophobic means ‗water hating‘. This region of the phospholipids molecule is non-polar, hence it is not attracted to water molecules. d) The fluid nature of the cell membrane means that the proteins and phospholipids in the membrane can change places, within the membrane. The mosaic nature refers to the random arrangement of protein in the phospholipids bilayer. (Total 6 marks)

June 2001 Unit 1, Edexcel SAQ26. Glycerol; ester; condensation; thermal insulation; energy storage. (Total 5 marks)June

2001 Module Test B/HB1, Edexcel SAQ27. a) (i) 4 molecules. One glycerol and three fatty acids. (ii) The triglyceride molecule is NOT made of identical units or monomers. It is made of three fatty acids and one glycerol. b) (i) A - O(xygen) B - C(arbon) (ii) Saturated fatty acid means that there is no carbon – carbon double bonds in the fatty acid chain. Every carbon is joined to two hydrogens or to four other atoms. c) Volume = Area of film x height of film Height of film = volume / area of film Height of film = 1 / 400000 = 0.0000025 mm (ii) The phosphate head is polar, hence hydrophilic. So it is attracted to polar water molecules. The fatty acid tails are non polar, hence hydrophobic and have no affinity towards water. Thus it avoids or shuns polar water molecules. (Total 9 marks) AQA SAQ28. a) (i) Glycerol (ii) Ester linkage. b) Stearic acid has only Carbon – Carbon single bonds, where as oleic acid has at least one Carbon = Carbon double bond. Stearic acid has more number of carbon atoms than oleic acid.

The fatty acid chain in oleic acid will have kinks (bends) but the fatty acid chain in stearic acid is a straight chain. (2) c) Ignore – not in syllabus

(Total 8 marks) January 2004 Unit 1, Edexcel

SAQ29. a)

b) Explain why triglycerides are not considered to be polymers. The triglyceride molecule is NOT made of identical units or monomers. It is made of three fatty acids and one glycerol. (1)

SAQ30. (a) Glycerol (b) (i) Unsaturated fatty acid Eg. Oleic acid (ii) These fatty acids have at least one double bond between carbon atoms in the hydrocarbon chain.

(c)

(Total 5 marks) SNAB Unit one June 2003 SAQ31. (a) (i) Ester bond (ii) Hydrolysis (iii) Glycerol and Fatty acids (iv) unsaturated / eq are {liquid at room temperature / lower melting point} whilst saturated / eq solid at room temperature; MUST be a comparative point (b) Phosphate (ii) {hydrophilic / charged / polar / water attracting} {head/group} and {hydrophobic /not charged / non-polar / water repelling} {tail /group } ; to forming a bilayer; ref. to orientation in membrane;SNAB Unit 1 Jun 2007 SAQ32. (a) energy / glucose storage;


(b) (i)

(ii) ref to specificity / shape; correct ref to active site on enzyme; correct ref to enzyme-substrate complex / eq; lock and key concept / induced fit; ref to amino acids in proteins versus glucose in glycogen / peptide versus glycosidic bonds; (c) reduces activation energy / provides an alternative reaction pathway; (biological) catalyst / speeds up reaction without being used up; allows reactions to occur rapidly at body/lower temperature; SNAB June 07 unit 1 SAQ33. (a)

(b) (i) saturated (lipids) have no double bonds in the hydrocarbon chain / C = C / between carbon atoms and unsaturated have double bonds / C = C saturated (lipids) from animal sources and unsaturated from plant sources saturated (lipids) tend to be solid and unsaturated liquids at r.t. ; (ii) starch has {two components / amylose and amylopectin} and glycogen does not starch stored in plant cells and glycogen in animal cells glycogen has a branched structure but {starch / amylose} has a coiled structure glycogen has more branches than {starch / amylopectin}; (Total 8 marks) SNAB January 07 unit 1

SAQ34. (a) (i) 6 (ii) 11

(b) Water potential inside vesicle more negative/lower; Water moves into vesicle by osmosis/diffusion; (c) Mitochondria supply energy/ATP; For active transport / absorption against concentration gradient / synthesis / anabolism / exocytosis / pinocytosis; BYA1 AQA JAN 2004 SAQ35. (a) Ignore – not in syllabus (Banana + Benedict's solution) and heat; More reducing sugar produces redder colour/more precipitate/ description of relative colour change/turns red quicker; Standardise test/Same amount of banana and Benedict's solution; (b) More sugar/solute/soluble substances present; So concentration of water lower/less free water molecules; (c) (i) Process controlled by enzymes; Low temperature/cold means less (kinetic) energy; Fewer collisions/enzyme-substrate complexes formed; (ii) Chilling caused by time and temperature so if time long, temperature must be higher; (d) Starch 1 Coiled molecule; 2 Large quantity can be stored in small space/compact for storage; 3 Insoluble; 4 Not "washed" from cells/no osmotic effect; 5 Branched; 6 Easily broken down; 7 For respiration; SAQ36 a.) Terminal OH; Hydrogens on hydrocarbon chain with no double bonds; 2 Do not penalise references to C-O bond – ignore. b. Decrease in (percentage of) saturated fats / increase in unsaturated fats; Move towards healthy eating / less saturated fat / more unsaturated fat; 2 AQA/JUN02/BYA9/W SAQ37 (a) Cells all the same/similar structure/ function.


(ii) Condensation / esterification. 1 (c) (i) (Unsaturated fatty acids) lower the melting point. 1 (ii) Triglycerides are oils / melting point below body temperature; Explanation of advantage, e.g. prevents hard layer of fat forming under skin / mobility of lipid / deposition in arteries. 2 (d) (i) Lipase. (ii) Pancreas / tongue / stomach. (iii) IGNORE – OUT OF SYLLABUS Diffusion (of fatty acids & glycerol) into epithelial cells; (refs. to routes through membranes, e.g. proteins, neutral) Recombination as triglycerides; Chylomicrons formed / covered with proteins / lipoproteins formed; Pass into lacteals / lymph (vessels); Lymph vessels drain into blood vessels. max 3 (e) Bile emulsifies triglycerides/fats/lipids; Small droplets provide large surface / faster digestion; so gallstones reduce rate of digestion; (reject: 'stop' digestion) Acid not neutralised; so lipase inactivated. max 3 Total 15 AQA/JUN01/BYB1 SAQ38 (a) IGNORE – OUT OF SYLLABUS b)(i) Glycerol; (ii) Has a phosphate/ (only) two fatty acids;

Unqualified references refer to the phospholipids shown in the diagram

(iv) Hydrophobic/"hate" water/ non-polar; Attracted to tails of other phospholipids /

tails face inwards/away from water; 2 AQA/Jan07/BYA1

SAQ39 Lipid yields more H2O per gram / per unit mass; Lipid yields more ATP/energy per gram / per unit mass; (Reverse argument for

carbohydrate) For energy

For ATP

AQA/Jun07/BYA6 SAQ 40. Glycerol; ester; condensation; shock absorbance; energy storage; Edexcel SAQ 41. (a) (i) 1 glycerol molecule and 3 fatty acid molecules (ii) An ester bond (iii) Condensation (iv) Have double bonds between carbon atoms and between carbon and oxygen atoms (v) More hydrogen atoms than unsaturated lipids (i)

(ii) DNA polymerase (Total for Question 1 = 9 marks) SNAB SAQ42. (a) (i) 5:1; (ii) 7 [ x smaller] (b) 0.5

(c) Surface area relative to volume too smaller. Diffusion too slow; idea of speed needed Distance too great/some cells deep in body/not all cells in contact with Environment; Insufficient, oxygen, nutrient, supplied waste


removed; (May be) more (metabolically) active, homoeothermic (Total 6 marks) OCR JAN 07 UNIT 1 SAQ43. a) i) 6:1 ii) As the sphere size increases the diameter also increases so the volume and surface area also increases. So the surface area to volume ration decreases. b) Surface area relative to volume too smaller. Diffusion too slow; idea of speed needed Distance too great/some cells deep in body/not all cells in contact with Environment; Insufficient, oxygen, nutrient, supplied waste removed; (May be) more (metabolically) active, homoeothermic c) Villi and alveoli (Total 9 marks) OCR UNIT 1 Jan 06 SAQ44. (a)blood flows twice through the heart for one circuit/cycle of the whole body) A for one heart beat Ref pulmonary and systemic systems/to lungs and to (rest of) body; R systematic (ii) __ size __activity __ S.A;V ratio (mammals) larger; Cells deep in body; Regions requiring materials separated by a distance/ need to get materials to all parts Diffusion too slow; Activity (Mammals) more (metabolically) active Need more materials/ more rapid supply/ more removal of wastes; Diffusion alone not effective

(Total 4marks) OCR Jan 05 Unit 1 SAQ45. (a) (i) (field) mouse (ii) Many cell (layers) ; Cells deep in the body / diffusion too slow; (More metabolically) active Surface area to volume (ratio) low/lowest of the three (b) Oxygen; A oxygenated blood carbon dioxide; Urea / creatine; R urine Hormones/ named hormone; Vitamins/named vitamin; Ions / minerals / named ion / named mineral / salts; Sugars / monosaccharide‘ s / named monosaccharide; R carbohydrates/ sucrose Fatty acids / glycerol / lipids/ onoglycerides;

Amino acids / antibodies / proteins / named protein; R if dietary Protein implied; Lactate / lactic acid; Water;

[Total: 6] OCR Jan 03 Unit 1 SAQ46. a) ventricle systole b) Relaxation of atria and ventricles. Atria are being filled with blood from veins. Blood slowly oozes into ventricles from atria. c) Cardiac muscles are supplied with coronary artery from the aorta. Many capillaries are distributed in cardiac muscles. RBC which contains hemoglobin carries oxygen. (Total 6 marks) June 2005 Unit 2B, Edexcel

SAQ47. a) A. Semi lunar valve B. Aorta C. Atrio-ventricular valve. b) Artio-ventricular valves closed during ventricle systole to prevent the backflow of blood. Ventricles are made with thick muscles to provide high pressure. It pumps blood around the body. Aorta made with elastic muscles to accommodate blood expelled from ventricles. c)(i) Uterus is bigger and contains more tissue and muscle development. It helps in development and maintenance of placenta and also helps in baby development. (ii) Heart works harder to carry oxygen and nutrients through blood and sends to uterus, ;placenta, fetus and mothers body. (Total 10 marks) January 2005 Unit 2B,

Edexcel SAQ48. a) Both pressures rise and fall to 0 kPa in 0.5 seconds. However, the pressure change in the left ventricle is much greater than in the right ventricle. This is because the left ventricle has a thick layer of cardiac muscle tissue, to enable it to pump blood at high pressure to all parts of the body. The right ventricle has a thinner layer of cardiac muscle because it has to pump blood only to the lungs, which are close to the heart and are made up of delicate tissues. b) There is a rapid rise of pressure in both the left ventricle and aorta. However, the pressure in the aorta begins to rise a little later than in the left ventricle. This results in a slight time


delay for the blood to pass from the ventricle to the aorta. The pressure in the ventricle then falls steeply, but the pressure in the aorta remains relatively higher. This is because the elastic recoil of the aorta walls maintains the high pressure after the closure of the semilunar valve. c) On the graph. d) The impulse for heartbeat originates in the sino-atrial node (SAN). It then spreads into the atrial walls causing atrial systole. The wave of electrical excitation is then taken up by the atrio-ventricular node (AVN) and passed to the apex of the heart through the bundle of His. The impulse then spreads into the ventricular walls, through the Purkinje fibres, causing ventricular systole. The lack of conducting tissue between the SAN and AVN ensures that there is a time delay so that ventricular systole begins only after completion of atrial systole. (Total 12 marks) June 1998 Module Test B3, Edexcel SAQ49. (a) A= vena cava; B = aorta; C = left atrium; accept atria D = tricuspid / atrio ventricular (b) (i) Y= 10.6 – 10.7 (m): accept 11/ 11.0 (i.e. rounded up) (units not needed unless the answer has been changed into e.g. cm) (ii) left ventricle / Y, more muscular/ muscle or for X; (ie. A comparison) more pressure/ force (for Y) / or for X: (ie. A comparison) Left ventricle pumps to whole body / Right ventricle pumpls to the lungs; ( Y pumps a further distance

(c)

Statement T or F

cardiac muscle is myogenic T

contraction occurs in the diastolic phase

F

the left and right ventricles contract at the same time

T

when the left ventricle contracts, the semilunar valve in the aorta shuts

F

the semilunar valves have tendons to prevent inversion

F

OCR Jan 2002 unit 1

SAQ50. (a) F = Sino atrial node / SAN / pacemaker; G= pulmonary\ vein (b) (i) atrium / X, (only) has to pump, to ventricles/ short distance; or for ventricles A ref to gravity effect/ negative ventricle pressure Left ventricle/ Y, has to pump to body/ systemic circulation, and right ventricle/ Z has to pump to lungs pulmonary system; comparison of Y and Z. Left ventricle/ Y, pumps further/ great (er) pressure; Right ventricle / ZA to all/ whole body idea a distance Left ventricle / Y pumps against greater resistance; Right ventricle. (ii) (Purkynje fibres) conduct wave of excitation R impulse, signal pulse to the base/ apex of heart; So contraction occurs upwards both ventricles contract together. (c) blood passes to left atrium . Deoxygenated and oxygenated blood mixes in atria; R ‗between atria‘; Must imply direction in first alternative not the reverse (due to fap) So blood, in left ventricle / aorta, not full oxygenated/deoxygenated blood/ less oxygen, delivered to brain. A carbon dioxide builds up in brain. Reduce (aerobic) respiration in brain/ anaerobic respiration; R no respiration (possible link with ) lactic acid lactate, build up; R waste oxygen shortage in brain ( might ) lead to raised blood pressure (causing migraines) OCR June 2007 unit 1 SAQ51. (a) (i) left ventricle (ii) left ventricle (b) (i) 80 (60 divided by 0.75) (ii) Credit one use of pressure figures with units in X or Y: at X Ventricle is contracting / in systole; ventricle pressure, equals / exceed aortic pressure; lowsest aortic pressure / pressure in aorta starts to rise; R is rising semi lunar / aortic/ pocket valves, open; A blood passing through named valve Blood enters aorta (from ventricle) A blood leaves ventricle. At Y Ventricle is relaxing / in diastole; Ventricular pressure equals/ falls below atrial pressure/ or; atrium at highest pressure; Atrio ventricular mitral / bicuspid, valve opens; A blood passing through named valve R tricuspid/


cuspid blood, enters ventricle/ ;leaves atrium. [Total: 10] OCR June 2003 unit 1

SAQ52. (a) A. Coronary artery B. Right atrium C. Pulmonary artery D. Left ventricle (b) (i) oxygenated and deoxygenated blood / blood from two sides, would mix / AW; (so) less oxygen delivered (to the tissues) / AW; when the heart beats / AW; less blood leaves the heart / flow to body reduced / ref slower flow; ref to (possibly) lowering blood pressure; AVP; e.g. refs to double circulation altered Increase in heart rate (to compensate) (ii) ref to one way flow affected / general ref to flow back / wrong direction; less blood reaching destination / less blood leaves heart / AW; (when ventricles contract some) blood back to atria; (when ventricles relax some) blood back to ventricles (from arteries); ventricles not closed off / isolated / separated (from atria / arteries); drop in blood pressure; (c) M pressure in ventricle exceeds that in aorta / artery;

semi lunar / eq. valves, open; blood, enters aorta / leaves ventricle / pressure rises (in aorta / ventricle); ventricle, contracting / systole; R starting to contract N pressure in ventricle drops below that in atrium; atrio-ventricular / AV / mitral / bicuspid /, valves open; R tricuspid blood enters ventricle / leaves atrium / atrial pressure, starts to drop / peaks ; R if linked to atrial contraction / systole. ventricle relaxing / relaxed / in diastole; A one ref to figures in either M or N; M 8.1 – 8.5 N 0.8 – 1.2 (d) (ventricle has) more muscle / thick wall / AW ( ora for atrium); (high pressure) as ventricle pumps to body / a greater distance / AW; atrium only pumps to ventricle / through the atrio – ventricular valve / AW; less resistance; some filling by gravity; OCR June 2001 unit 1 SAQ53. (a) (i) arrows through correctly (ii) X = vena cava; Y = bicuspid / atrioventricular / AV / mitral (valve); (iii) when ventricle / heart, relaxes; A diastole; pressure lower (in ventricle implied); ora valves stop back flow. (b) (i)

chamber thickness/ mm

A 2

C 16

D 9

(ii) A / atrium, only pushes, to ventricle / short distance / AW; A effect of gravity C / left ventricle, pushes all round body / to systemic system / AW; D / right ventricle (only) pushes to lungs / to pulmonary system / AW; qualification for C or D e.g. greater distance / resistance or more, force / pressure; or for right ventricle. (c) 1. cardiac muscle is myogenic / description: 2 SAN / sinoatrial node / pacemaker: 3 .(in wall of) right atrium: 4 .wave of electrical activity/ impulse / depolarization/ excitation /AW: 5. spreads across atria / causes atria to contract; 6. stopped / AW (by, fibres/ septum), between atria and ventricles; 7. delay allows atrial systole to be completed (before ventricular systole): 8. atrioventricular node / AVN: 9. impulse passes down Ito, Purkyne (Purkinje) fibres/ bundle of His: 10. contraction from base upwards; 1I. both ventricles contract together : 12. AVP; e.g. external nervous control in response to, temp/ 002/ etc delay of 0.1hormone control.OCR June 2004 Unit 1 SAQ54. (a) (i) Tricuspid (ii) 1. Back flow of blood; 2. Oxygenated and deoxygenated blood will mix; 3. Volume of blood will increase. b) (i) 1. Deoxygenated blood will enter in to the left ventricle and it will pump to the complete body. 2. Oxygenated blood again enter into the lungs. 3. Less amount of blood enter into the body. (ii) If the hole only mended it will carry or supply only deoxygenated blood to all parts of the body. c) As the arteries are fixed in the correct position and the hole is mended the normal phases of systole and diastole will occur and oxygenated blood enter in to the carotid artery. So cheeks ae in pink colour. (Total 11 marks) SNAB Specimen paper SAQ55. (a) A. Right atrium


B. Left ventricle (b) Lung (c) Capillaries are extremely narrow and long; Oxygenated blood enter into the lungs; results loss of pressure blood emerges into the lungs; not enough pressure to get through capillary network; SNAB Jun 2003 Unit 1 SAQ56. (a) (i) Top two open ; Bottom two closed; (ii) X drawn anywhere in the right atrium (iii) Pacemaker / sets rhythm of heart / initiates cardiac cycle (c) Blood at high pressure; High concentration of oxygen ; High concentration of glucose. (Total 6 marks) SNAB Unit 1 June 2004

SAQ57. (a) Sino atrial node b) 1. [(Wave of electrical) impulses / depolarization) from SA node ; 2. Passes over (both) atria ; 3. Resulting in atrial [systole contraction ; 4. Slight delay at AV node ; 5. (Impulses) pass along bundle of His ; 6. (Up / along) Purkinje fibres ; 7. Correct direction of impulse described / ventricles contract from the base up ; 8. Resulting in ventricular (systole / contraction) (Total 5 marks) SNAB Unit 1 Jan 2005 SAQ58. (a) 1. Ventricle contracts / systole ; 2. Pressure in ventricles increases ; 3. Correct reference to pressure changes from graph 4. Pressure in ventricle exceeds pressure in aorta 5. Semilunar valve opens ; 6. Blood flows into aorta ; 7. Blood flows down a pressure gradient (b) (i) Sinoatrial (SA) node / pacemaker / SAN (ii) Right atrium (iii) 1. Reference to AV node ; 2. Delay at AV node 3. Reference to bundle of His ; 4. Reference to Purkinje fibres 5. (Electrical activity [impulse) travels from base up through cardiac muscle ;

6. Electrical activity / impulse stimulates contraction of cardiac muscle. (c) Lack of [oxygen / glucose} to the muscle (cells) Unable to respire / respires anaerobically [Insufficient / no} [energy / ATP} For (muscle) contraction (ii) (Injected into the bloodstream and) breaks down the clot / reference to use [streptokinase / TPA / tissue plasminogen activator / clot busting drugs); (Total 12 marks) SNAB Unit 1 Jun 2005 SAQ59. (a) (i) {semilunar / aortic} valve (ii) ventricular systole (iii) 1. ventricles contract ; 2. atrioventricular(AV) valves close ; 3. semilunar valves open /eq ; 4. due to higher pressure in ventricles ; 5. compared to {atria / artery} ; 6. blood passes into {aorta / artery} SNAB Unit 1 Jun 2006 SAQ60. (a) (i) arrows moving from direction of veins through the atria towards ventricles on both sides; (ii) sinoatrial node / SAN / pacemaker; (b) (i) some backflow of blood {(from ventricle) to atrium / through A-V valve}; during ventricular systole / eq; less blood (pressure) into the {aorta / artery}; less (efficient supply of) oxygen to the body / muscles / less aerobic respiration; (ii) ECG / electrocardiogram / MRI / magnetic resonance imaging / CT scan / CAT scan / blood pressure monitor / sphygmomanometer; (Total 5 marks) SNAB Unit 1 Jun 2007

SAQ61. (a) (i) X = aorta/ aortic arch ; Y = (left) ventricle / cardiac muscle ; Z = coronary artery (ii) second box down on the left (iii) SAN / sino atrial node / pacemaker (b) (i) 1. sequence of events from one beat to the next beat / eq ; 2. reference to {contraction / systole} and {relaxation / diastole} ; 3. correct detail of sequence e.g. atrial systole → ventricular systole → diastole / approx 30% of time spent in systole and 70% in diastole ;


4. correct detail of electrical regulation of cardiac cycle (ii) 1. left ventricle has {more / thicker} muscle / eq ; 2. blood from (left ventricle) has to divide between more capillaries / eq ; 3. left ventricle has to pump blood further (iii) 1. pressure increases as blood forced into ventricle during atrial systole ; 2. pressure increases during (initial) ventricular systole/eq ; 3. (due to) reducing volume of ventricle (causing pressure increase) ; 4. pressure starts to decrease due to blood into artery / loss of blood from ventricle ; 5. decreases during diastole / eq ; 6. (due to) increasing volume (of chamber) (c) 1. gender; 2. Smoking; 3. genes / inheritance; 4. stress 5. high LDL level / LDL to HDL ratio / high blood cholesterol 6. reference to inappropriate diet such as high {salt / fat } cholesterol / calorie} intake; 7. high alcohol intake; 8. Obesity; 9. lack of exercise. (Total 12 marks) SNAB Unit 1 Jan 2008 SAQ62. (a)

(b) Valves prevent backflow; muscles pushes blood/squeezes veins; large luman; little resistance; negative pressure in chest; gravity effect. (c) The capillaries are made up of a single layer of flattened squamous epithelial cells, which have intercellular pores to allow small molecules and ions to pass across the walls. (Total 6 marks) SNAB Unit 1 Jun 2008 SAQ63. (i) D. Artery E. Vein (ii) Thick wall and small lumen SNAB Jun 2003Unit 1 SAQ64. (a) A – Artery B – Vein

(b) thin wall / single cell layer / short pathway / ease of access to tissue fluid/ rapid / easy, diffusion ; smooth, (inner) surface / endothelium; (small) gaps / holes, between endothelial cells / in wall / AW ; allows nutrients / named nutrients / fluid / AW, out, / (most) cells / proteins cannot pass ; passing narrow / small (diameter) / figure quoted / AW ; idea of contact with many cells / short diffusion distance / rapid diffusion / reduced rate of flow qualified ; large, total surface area / cross-sectional area ; allows more exchange / slows flow for exchange / close to all the cells in the body; R easier / more efficient ideas unless qualified (c) transport medium between blood and the tissues (d) Blocked lymph vessels / high blood pressure / {low solute potential / high water potential} in blood / loss of plasma proteins / damage to tissue / histamine.

Edexcel SAQ65 (a)

Arteries Veins

More smooth muscle

Less smooth muscle

More elastic fibre tissue

Less elastic fibre tissue

Narrow lumen Wider lumen

(b) Higher (blood) pressure / more chance of damage to endothelium. (c) High {hydrostatic / blood) pressure ; Which is higher than {solute potential gradient / eq) / correct osmotic effect described; (Plasma forced out) through (pores / gaps) in capillary wall; The fluid is forced out of the capillary into the intercellular space (d) (i) Blocked lymph vessels / high blood pressure / {low solute potential / high water potential} in blood / loss of plasma proteins / damage to tissue / histamine. (ii) Oedema SNAB Jan 2004 Unit 1

SAQ66. (a) (Ventricular) systole / ventricular contraction (b) (As ventricle contracts) pressure increases ; From 2.0 -4.0 kPa Ito {14.0 /15.0) kPa ; (c) X Point when pressure in ventricle first exceeds pressure in atrium; Point when


pressure in aorta first exceeds pressure in ventricle ; (d) (60 ÷ 0.8) = 75 ; Beats per minute / bpm Total 7 marks SNAB Jan 2004 Unit 1

SAQ 67.

Feature animal plant

the contents of the vessels are pumped round the system

√ X

the vessels link to form a circulatory system

√ X

the vessels form a major nutrient transport system

√ √

(i) A= Artery B= Vein (ii) X= Tunica externa; Y= Tunica media; Z= Endothelium (iii) X= Collagen/ elastic fibers/ connective tissue; Y= Smooth muscle and elastic fibers; Z= Single cell layer/ smooth surface (b) (i) Pulsatile/ declining; amplitude declines. (ii) Reflects pumping of heart; elastic recoil effect; decrease/ amplitude changes, reflect distance from the heart. (iii) Slows rate; allows exchange in capillaries (c) Valves prevent backflow; muscles pushes blood/squeezes veins; large luman; little resistance; negative pressure in chest; gravity effect. (d) (i) Proteins too large to pass out. (ii) Red blood cells only in blood not in tissue fluid; more white blood cells in blood; platelets only in blood; hydrostatic pressure differences; dissolved gas levels qualified; blood in vessels. OCR Jan 2001 Paper1 SAQ 68. (a)

Feature Explanation of role

Narrow/small diameter

Contact with many cells

Thin wall/ single cell layer

Short pathway/rapid diffusion

Smooth surface Smooth flow

(b) (i) (-3.3+1.6)-(-1.3+1.1)=1.5 (ii) Out of capillary. (c) Water; urea; carbon dioxide ; proteins; lymphocytes; antibodies; hormones; fats; minerals and no plasma proteins and RBC. OCR Jan 2002 Paper1

SAQ 69. (a) (i) Y (ii) Thin wall; thin tunica media; less muscle and elastic tissue; wide lumen. (b) (i) 18.5-15.5=3kPa (ii) N (c) Action of skeletal surrounding/ arterial wall muscle; stop back flow; low pressure in thorax. OCR Jan 2003 Paper1

SAQ 70. (a) (i)

Tissue Fluid Blood

*no red blood cells

*no plasma proteins

*a few white blood

cells

*no platelets

*always low pressure

*red blood cells

*plasma proteins

*more white blood

cells

*platelets

*higher pressure

(ii) Lymphatic/lymph

(b) 1 pressure high at R / AW; ref to heart action causing (hydrostatic) pressure; greater than, osmotic effect / water potential effect / AW; A solute potential capillary wall, is leaky / has pores / AW; lets, fluid / water / plasma / liquid, through and dissolved substances / named substance(s); red blood cells / proteins / some WBC‘s, cannot get out because too large; pressure low(er) at S; ref to osmotic effect / water potential effect; A solute potential due to plasma proteins; return of fluid / AW, at S / AW; valves / pores, at T / lymph vessel / AW; R semi lunar valve allow, fluid / water / liquid, into lymph vessel / out of tissue fluid; allow proteins out of tissue fluid; (c) fluid / AW collects; R if suggests collection in cells (tissue) swells / AW; R turgid R if implies cells swell oedema; especial danger, in lungs / pulmonary oedema; ref to build up of proteins (from tissues); AVP e.g. loss of blood volume; OCR Jan 2004 Paper1

SAQ71. (a) (i) 15 (ii) qualified ref to distance from heart e.g. further ; friction / resistance (to flow) ; ref to increasing volume of e.g. capillaries; A surface area of capillaries idea of dissipation of energy in elastic recoil.


(iii) stop damage to, capillaries / arterioles / AW ; A stops bursting ref to, lack of (much) elasticity in these vessels / thin walls / AW ; ora for nature of artery wall max one mark if only veins mentioned slows flow rate ; to allow (time for) exchange (b) (i) C (ii) thin wall / single cell layer / AW ; R membrane / thin cell wall A statement which gives one cell thick, treating thin cell wall as neutral in this case short pathway / ease of access to tissue fluid AW, rapid / easy, diffusion ; smooth, (inner) surface / endothelium ; A epithelium R refs to smooth muscle reduced friction / smooth flow / reduced turbulence / reduced resistance / AW ; (small) gaps / pres / holes, between endothelial cells / in wall / AW ; allows nutrients / named nutrients / fluid / AW, out, / (most) cells / proteins cannot pass ; R refs to plasma A refs to, phagocytes / AW, passing narrow / small (diameter) / figure quoted / AW ; idea of contact with many cells / short diffusion distance / rapid diffusion / reduced rate of flow qualified ; large, total surface area / cross-sectional area ; allows more exchange / slows flow for exchange / close to all the cells in the body; R easier / more efficient ideas unless qualified OCR Jan 2005 Paper1 SAQ72. (a) Right ventricle to lungs (b) (i) Increased respiration; Carbon dioxide from muscles. (ii) B. AQA Jan 2002 BYA1

SAQ 73. (a) Pressure reaches highest value/ greatest range of pressure in ventricle. (b) (i) Pressure in ventricle/ B is higher than pressure in aorta (ii) 0.2 sec; Time when pressure in ventricles. (c) (i) Higher (ii) Thicker muscle in left ventricle. (d) 1µm (e) It is made up of different tissues like smooth muscle, endothelial cells and tunica media, tunica inerna. (f) Thick elastic layer in artery ; Even out flow/ associated with recoil; Link between pressure in artery and ventricle contraction/ systole; Arteriole with muscular layer; Muscle contraction results in smaller diameter/

vasoconstriction; Alerts blood supply to different organs; Endothelium provides smooth surface; Capillary wall thin/ only endothelium for exchange. AQA Jan 2002

BYA1 SAQ74. (a) (i) Arteries divide to form arterioles. (ii) Blood goes to (an organ) along an artery and leaves by a vein; (b) (i) multiply ( mean) length by total cross-sectional area; (ii) 60/930X100 = 6.45 (c) (i) Muscle/skin/lungs/heart (ii) muscle Contracts; vasoconstriction/ reduces diameter ( of arteriole supplying capillaries). AQA Jan 2003 BYA1

SAQ 75.

(Total 4 marks) EDEXCEL

SAQ76. (a) (i) simple nervous system / invertebrate; reduced awareness of pain/eq.; or transparent; heart visible without need for dissection/eq.; or abundant in nature; no threat to it or its dependent species (food chains); or bred for fish food; will thus die anyway; or may be clones; therefore no loss of genetic variation; (ii) lower temp leads to inactivity /freezing; higher temp leads to enzyme denaturation; (iii) controlling temperature/eq; (iv) accuracy;

(b) (i)


(ii) correct orientation of axes; axes correctly labelled including units with suitable scale (minimum half page); correct plotting of all points; sensible line; error bars/range bar to indicate variability/eq; (c) (i) sim: rise in temp leads to increase in heart rate (up to 30°C); diff: obvious peak in secondary data, none in Sam‘s / eq ; (ii) reference to kinetic effects on enzymes and the substrate; increase rate of respiration increases oxygen demand/increased rate of reaction increases heart muscle activity/eq; Above 30°C enzymes/proteins begin to denature; Reduced heart rate because of heart made of protein/eq;Daphnia become exhausted; SNAB SAM 2008 SAQ 77. (a) (i) daphnia is transparent and its heart is visible (ii) Temperature same species, same habitat, and same mass. (iii) Surface area : volume ratio is small; diffusion distance is large ; so they have heart to pump blood ; blood to carry vital substances around their body. (b) caffeine increases heart rate and blood pressure. High blood pressure exerts force on endothelial cells in the inner wall of artery. A slight damage to the endothelial cells leads to atherosclerosis. SNAB Unit 1 Jun 2005 SAQ 78. (a)

Statements about transport in

Daphnia

Tick or cross

(i) The movement of fluid through the heart is an example of mass transport

J

(ii) Daphnia uses diffusion to transport oxygen into muscle cells

J

(iii) Daphnia tends to lose water to the freshwater by osmosis

X

(iv) Daphnia can use active J

transport to move ions from the freshwater into its body

(b) (i) Daphnia A .........50..................... heart beats per 10 seconds Daphnia B ...........75................... heart beats per 10 seconds Daphnia C ...........100................... heart beats per 10 seconds (ii) 200 (iii) 1. only three Daphnia used / not enough {samples / repeats} to be representative / only one Daphnia used per concentration ; 2. different Daphnia used (for each caffeine concentration) / different Daphnia used for 35 au ; 3. range not large enough to make prediction; 4. Daphnia may respond differently at higher concentrations / OR they may die ; 5. taking readings for 10 seconds not sufficient ; 6. describe one environmental variable to be controlled / allow time for Daphnia to acclimatise ; 7. need for a control

(Total 9 marks) SNAB Unit 1 Jan 2008

SAQ 79. (a)Instant coffee: 36mg per 100 cm3 Filter coffee: 60mg per 100 cm3 Tea: 30mg per 100 cm3 (b) mass, species and habitat of daphnia (c) Caffeine increases the heart beat. Pond water temperature may be higher than 15 degree centigrade.(Total 8 marks)SNAB SAQ80. (a) A thromboplastin / thrombokinase / plasma enzymes / factor VIII); B thrombin; C & D fibrinogen and fibrin; (b) Calcium ions are (a cofactor) needed for (activity of) thromboplastin / thrombokinase / plasma enzymes / (factor VIII) / substance A; (Therefore) little thrombin formation / fibrin formation / calcium needed for fibrin or thrombin formation; (So) blood does not readily clot / blood more runny; Reject does not clot AQA BYA3 Jan 2002

SAQ81.(a) (i) A description to include four from: 1. white blood cells move into wall (of


artery) / inflammatory response ; 2. cholesterol deposited / reference to foam cells /eq ; 3. fibrous tissue develops / reference to plaque / atheroma ; 4. artery wall hardens / becomes less elastic / atherosclerosis ;5. narrowing of lumen / aneurysm ; 6. restricts {blood flow / oxygen} to the brain ; 7. detail of blood clotting process ; 8. correct reference to positive feedback ; 4 marks (ii) A suggestion to include two from: 1. monitor or treat high blood pressure; 2. avoid smoking ; 3. treat high blood cholesterol ; 4. correct reference to a specific dietary change ; 5. avoid air travel ; 6. use suitable drug treatment ; 7. more exercise ; 8. reduce stress in context ; 2 marks (b) Platelets; thromboplastin; prothrombin; fibrinogen; fibrin; red blood cells (Total 9 marks) SNAB Unit one June 2006

SAQ82. (a) Platelets / Prothrombin / Fibrinogen; (b) 1. Lack of blood to {cardiac / heart} muscle; 2. So lack of {oxygen / glucose} / ischaemic / anaerobic / eq ; 3. Muscle stops working / damaged / cells die ; 4. Pain / angina / lactic add build up ; 5. Myocardial infarction / heart attack / eq ; (c) (c) Warfarin / aspirin / streptokinase / adheparin / hirudin / clopidogrel ; (Total 7 marks) SNAB Unit one June 2004 SAQ83. (a) Calcium; Prothrombin and thrombin; Fibrinogen and fibrin; (b) (i) Blood vessels have broken/tissue damage (releasing thromboplastin); (ii) Blood clots may lead to thrombosis/MI/stroke; AQA BYA3 June 2003 SAQ84. (a) converts prothrombin to thrombin; (b) (i) (b) (i) fibrin formed from fibrinogen; by the action of thrombin; (ii) forms mesh of fibres which trap (platelets and blood) cells; (c) (i) warfarin prevents blood clotting which causes thrombosis in coronary arteries/may block c. arteries/ arteries supplying heart muscle; (ii) ( 36 ) = 17%; (210) (iii) (iii) (409) = 30%; (1334)

(iv) yes: smaller % age have thrombosis if already taking warfarin; substantial difference in figures/large sample; OR no: those taking warfarin obviously more likely to develop thrombosis; not matched with control group;

(2 marks)AQA BYA3 Jan 2004 SAQ85. (a) Calcium; Prothrombin + thrombin; Fibrinogen + fibrin; (b) (i) Antibodies/immunoglobulins; (ii) Memory (B)-cells (formed in previous attack already) present; (When bacteria recognised, they) divide rapidly to form plasma cells; (These) produce antibodies (more) quickly / in greater numbers (than first time); (2 marks)AQA BYA3 Jan 2005

SAQ86. P = prothrombin and Q = thrombin; R = fibrinogen and S = fibrin; T = calcium (ions); 3 (b) fewer clots form in blood; blockage of coronary arteries does not occur / less likely; AQA

SAQ87. High plasma cholesterol / hypertension cigarette smoking; Coronary; Plaques / atheroma; Clots/ thrombi; Oxygen / blood; Death / necrosis;

Edexcel

SAQ88. inner layer / tunica intima of Q much wider / thicker / converse for P; narrowing of / smaller lumen in Q./ converse for P; inner layer crinkled / roughened / not smooth in Q. Edexcel

SAQ88. coronary; plaques / atheroma; clots / thrombi; oxygen / blood; death / necrosis; Edexcel SAQ89.(a) Ignore – not in syllabus measured diameter (mm) = magnification; [Note: marks in this answer are awarded for explanation. The answer gains no marks]


(b) (i) Lumen narrower (in diseased artery); Wall thicker (in diseased artery); Cholesterol/ fatty tissue / plaque / lipids / atheroma/foam cells invading wall/ in wall(i.e. not on endothelium); Note: If answers start "it" assume this refers to the diseased artery] (ii) Atheroma/fatty material deposited in wall of artery; Causes turbulence/damage to endothelium/raises blood pressure; Blood clot formation; Atheroma/blood clot lodges in narrowed blood vessel/coronary artery; Reduces oxygen (supply) to (region of) heart muscle/heart cells; AQABYA3 June 03 SAQ90. (a) Lower blood pressure / less turbulence (in veins); Reject ‗no pressure‘. (b) (Collagen in) damaged blood vessel wall / platelets; (Activates) thrombokinase / thromboplastin; In presence of calcium (ions) / plasma enzymes / factor 8; Prothrombin converted to thrombin; (Thrombin causes) conversion of fibrinogen into fibrin; Latter two must be in correct sequence for both marks. (c) (i) (Greater blood) turbulence;

AQA BYA3 JUN 2002 SAQ91. (a) Lower blood pressure / less turbulence (in veins); Reject ‗no pressure‘. (b) (Collagen in) damaged blood vessel wall / platelets; (Activates) thrombokinase / thromboplastin; In presence of calcium (ions) / plasma enzymes / factor 8; Prothrombin converted to thrombin; (Thrombin causes) conversion of fibrinogen into fibrin; Latter two must be in correct sequence for both marks. (c) (i) (Greater blood) turbulence; (ii) Arrow at point of branch or just below in coronary artery; Reject ‗above branch‘. Total 7 marks AQA BYA3 JUN 2002 SAQ92. (a) (i) {semilunar / aortic} valve ; (ii) ventricular systole ; (iii) A description and an explanation to include three from:

1. ventricles contract ; 2. atrioventricular(AV) valves close ; 3. semilunar valves open /eq ; 4. due to higher pressure in ventricles ; 5. compared to {atria / artery} ; 6. blood passes into {aorta / artery} ; (b) (i) A suggestion to include three from: 1. reduced flow of blood to heart {muscle / cells} ; 2. lack of oxygen (to cells) / reference to anaerobic respiration / ischaemic / eq ; 3. cells / muscles damaged / die / eq ; 4. reference to lactic acid / angina ;

Edexcel SAQ93. (a) self-inflicted; social ; non-infectious (b) many factors contribute to risks / many risk factors / no one factor causes disease ; (c) (carbon monoxide / nicotine) increases heart rate; (nicotine) constricts arterioles / vasoconstriction ; R arteries / blood vessels (nicotine makes) platelets sticky; blood clot / thrombosis, more likely; increases blood pressure / hypertension; increases deposition of, fatty substances / cholesterol, in walls of arteries / formation of atheroma or plaque; increases (risk of), atherosclerosis / hardening of arteries; reduces lumen of artery; reduces, blood flow / oxygen supply, to heart, muscle / tissue ; AVP ; e.g. carbon monoxide damages, walls / lining, of artery 3 max (d) high in some places because more, animal / saturated fats, in diet ; less, linolenic / linoleic, acids (in diet) ; polyunsaturated more salt (in diet) ; high(er) incidence of obesity ; AW high(er) prevalence of smoking ; AW more alcohol abuse ; less exercise (is undertaken) ; high(er) stress levels ; high(er) blood pressure ; high(er), cholesterol / LDL, concentration in blood ; hereditary factors / ethnicity ; ‗at risk‘, gene / allele, may be more common ; A FHC gene ref to education ; AVP ; e.g. ref to differences in data collection AVP ; e.g. ref specific dietary differences red wine / antioxidants ref to cholesterol-reducing drug(s) / food(s) ref to life expectancy (if low do not develop CHD) ref to maternal diet during pregnancy ref to diabetes 4 max (e) benefits to society


fewer people have CHD / lower mortality due to CHD ; fewer drugs used ; fewer operations carried out / shorter waiting times ; e.g. by-pass surgery / heart transplant ; less, NHS / doctors‘, time taken up ; lower cost to NHS / more money to spend elsewhere ; fewer work days lost / less disability benefits paid out ; benefits to individual better quality of life ; live longer ; awareness of harm to body ; people eat, more healthily / less fatty food / less alcohol consumption ; people, exercise more / more active ; people do not smoke / less passive smoking ; AVP ; e.g. lower levels of obesity AVP ; e.g. stop people taking up smoking

OCR/2802/ Jun06 SAQ94. (a) 44.3%; (b) (i) metabolic rate / energy needed to maintain body‘s constant internal environment / to maintain life; rate when at rest; (ii) higher / greater / eq. in obese women; by 15% / 1.0 MJ day; greater body mass means more cells metabolising; more energy required for basic maintenance;

(c) (i) Lean women 0.1 MJ day -1;

Obese women 3.5 / 1.9 MJ day -1;

(ii) 1 more body mass to move about; more energy needed for same exercise; 2 less energy used in digestion;

(d) fed / eats measured quantity of food; of known calorific value; collect faeces; measure calorific value of food residue; calculate energy intake by difference between energy in food and energy in residue; ref to detail of use of calorimeter; Edexcel

SAQ95. (a) (i) all show a rise in blood pressure with increased sodium intake; blood pressure rises with age in developed and developing countries; each pair is parallel / eq; each is line of best fit / comment on scatter of results; the slope steepens as the age rises; lines for developing countries always below those for developed / mean BP higher in developed countries; difference between developed and developing increases with age / reference to figures / eq;

salt / sodium intake lower in developing countries; (ii) Any TWO from: differences in fibre / fat/ exercise / genetics / obesity / salt intake / stress;; [some qualification need eg more / less in one than the other] (b) (i) more resistance to blood flow; less blood flow to cardiac muscle / heart; reduced supply of oxygen / nutrients; may lead to death of heart muscle / heart attack; (ii) Any TWO from: high saturated fat intake / animal fat intake / high cholesterol; high trans-fat intake; low fibre intake; high / excess alcohol intake; Edexcel SAQ96. (a) steady / continuous fall in total energy; fat intake parallels total energy intake / eq; percentage of energy derived from fat unchanged; energy from saturated fatty acids unchanged; indicates no improvement in the diet; fall in energy intake should affect the obesity rate; (b)(i)

10010750

2890100

10750

7860–10750

Answer 26.88/26.9;

(ii) Any TWO from: qualified comment re. lifestyle change; reduction in total food eaten; less fried food / less fat eaten / less saturated fat eaten / less dairy products; greater awareness of high fat intake / overeating / eq; (c)reduction in fat intake as a percentage of diet; eat less animal / less saturated fats / OR replace animal fats with plant oils / unsaturated fats; increase percentage of carbohydrates in diet / replace fat with carbohydrate;

(d) Any Two from: no / less fat; less sugar; more fibre; more vitamins / contains vitamin C; Edexcel SAQ97.(a) France has a lower rate of heat disease than UK; The incidence of smoking is higher in France than UK; Drinking alcohol is higher in France than UK; Obtaining energy


intake of fat is higher in France than UK; If all these factors are considered likely to increase the risk of heart disease of CHD would be expected to be greater than in UK. (b) Quality response eg. Simple statement specifying more data that can be collected i.e., Data for same year for all factors; More detailed data is needed eg. All factors like fat/ consumption/ smoking/ drinking alcohol may not equally harmful; Detail of how data are changing with time are needed; appropriate specific examples of other factors that might be included; Equivalent data with respect to other similar regulating European countries to provide context. (c) By stabilizing/ neutralizing/ removing the free radicals by providing hydrogen ions. Free radicals damage biological molecules like endothelial cells in artery walls. (d) Vegetable oil is polyunsaturated/ animal fat is saturated; Vegetable oil forms HDLs/ animal fats form LDLs; Vegetable oil reduces cholesterol/ animal fats causes atherosclerosis. SNAB JAN 2003

SAQ98. (a) Similar in shape to noradrenaline/ adrenaline; Fit in (sympathetic) receptor sites; On cardiac muscle/heart; Prevent stimulation of cardiac muscle; (b) Dose (40-80mg)mg Explanation Higher doses produce no/ very little reduction in blood pressure; Risk of side-effects/ toxicity with higher doses; Saves wasting money on extra drug.

Total 5 Marks AQA Jan 2003 SAQ99. (a) (i) average number of admissions on ordinary day; when no football match being played; similar time of year / conditions (ii) experiencing a myocardial infarction over the six days; large / significant difference for three days; then small difference (b) increases heart rate; raises blood pressure / causes hypertension; blood supply to heart / oxygen use by heart increased; atheroma restricts blood / oxygen supply to heart muscle.

(c) reduces heart rate; beta-blocker fits receptor sites; on walls of heart / blood vessel; (receptor sites for) adrenaline / Noradrenaline / stops adrenaline /noradrenaline binding.

AQA June 2004 SAQ100.(a) (i) (Risk of): High blood pressure increases with age; Heart attack increases with age / no heart attacks before 35 years; (ii) Females (or reverse argument for males): More likely to develop high blood pressure; Have lower risk of heart attack (as they get older / post-55); (b) (Beta blocker) binds to receptor; Receptor on heart (muscle cells);(Therefore) adrenaline cannot bind; Blood pressure falls because heart rate reduced / force of contraction reduced; (c) Male is (700 – 378 = 322, 322 / 700 = ) 46%; Female because (480 – 252 = 228 / 480 = ) 47.5%; (d) Principle: CHD = heart muscle receives inadequate amount of blood or oxygen / (coronary) blood supply reduced; Smoking: Raises concentration of fibrinogen (in blood) / increased risk of clotting; Increases viscosity of blood; (Nicotine) causes platelets to stick together / causes vasoconstriction; Carbon monoxide associated with plaque formation; Reduces ability of arteries to dilate / reduces elasticity; Cholesterol: Fatty streaks / deposits adhere to wall of arteries; Atheroma / atherosclerosis / plaque; Narrows lumen of artery; Damages endothelium; Can lead to formation of thrombus / blood clot; Clots need to be in context Total 15 AQA-BYA3 JAN2002 SAQ101. (a) (i) reduce intake of fat / particularly saturated fat / correct examples / increase fibre / fresh fruit and vegetables / increase intake of foods containing sterols / stanols /include oily fish; (ii) 1. cholesterol synthesized by the body ; 2. further detail e.g. made in liver / cholesterol made from saturated fats; 3. genetic factors; 4. further detail e.g. hypercholesterolaemia / number of LDL receptors;


(b) (i) 39.9 / 40.0% (ii) (Statin) B;

(iii) The number of subjects involved ref to {validity / reliability /identification of anomalous results / allows for variation }; NOT accuracy / precision

The control group to confirm the drug was having the effect Total 8 marks SNAB Jan 2007 SAQ102. (a) Plaque/ fatty material/ cholesterol/ foam cells/ lipoprotein build up; In artery/ blood vessel wall; (b) Weakens artery wall; So that it swells/ bursts; (c) Slows/ prevents conversion of fibrinogen to fibrin/ fibrin formation; less chance of a blood clot/ thrombus being formed/ slows blood clot formation; which may block coronary artery/ artery supplying heart muscle; Total 7 marksAQA-BYA3 JAN2002 SAQ103. (a) Converts prothrombin to thrombin; (b) (i) fibrin formed from fibrinogen; by the action of thrombin; (ii) forms mesh of fibres which trap (platelets and blood) cells; (c) (i) warfarin prevents blood clotting which causes thrombosis in coronary arteries/may block c. arteries/ arteries supplying heart muscle; (ii) ( 36 ) = 17%; (210) (iii) (409) = 30%; (1334) (iv) yes: smaller % age have thrombosis if already taking warfarin; substantial difference in figures/large sample; OR no: those taking warfarin obviously more likely to develop thrombosis; not matched with control group; Total 9 marks AQA-BYA3 JAN2004 SAQ104. (a) 1. High fat diet/high salt diet/lack of exercise/age/gender;

TWO risk factors for one mark Not hypertension as this is given later 2. Atheroma forms under endothelium/in artery wall; 3. Atheroma may narrow lumen of artery; 4. Atheroma increases blood pressure; 5. Atheroma promotes clotting;

6. Details of effect of atheroma on clotting; 7. Blood clot lodges in coronary artery; 8. Reduced blood supply to heart muscle; 9. Reduced oxygen/glucose supply leading to cell death; (b) (i) 1. Reduces heart rate; 2. Keeps heart rate stable/reduces variation in heart rate; 3. Nullifies external stimulus; Individual points must be supported with information from the graph (ii) Similar shape to adrenaline/noradrenaline; Fits into receptors; On cardiac muscle/wall of artery; Preventing adrenaline/noradrenaline binding; (iii) To ensure change in heart rate due to beta blocker and not person‘s behaviour/knowing may affect heart rate; (c) (i) Beta blockers reduce mortality (following myocardial infarction)/ Greater reduction in the older group; (ii) ((Deaths with placebo – deaths with beta blocker) ÷ deaths with placebo) x 100 AQA-BYA3 JAN2006 SAQ105. (a) Similar (in shape) to adrenaline/noradrenaline/ β agonists; Reject same shape as receptor 2.(Fit into) receptors on heart muscle/lining of artery; 3.Stops adrenaline/noradrenaline/β agonists binding; 4.Slow down heart rate/relax muscles in artery walls / enlarge lumen of arteries (b) 1.(Reduced hypertension means) less turbulence; 2.Thrombus/blood clot less likely to form; Reject no blood clots 3. Which could block artery/ arteriole; 4. Less damage to artery wall; 5. Less atheroma formed/ less plaques formed; 6. Less likely to get aneurysm;

Accept converse for all points SAQ106. (a) 1. fatty material/foam cells/cholesterol in artery wall / under endothelium; 2. creates turbulence/damage to lining of artery;


3. formation of plaques/atherosclerosis/narrows lumen of artery; 4. (turbulence) increases risk of blood clot; 5. blood clot breaks off; 6. (blood clot) lodges in coronary artery; 7. reduces blood supply to heart muscle; 8. reduces oxygen supply; 9. results in death of heart muscle; (b) (i) equal chance of being assigned to either group; (ii) To compare with warfarin to see if it has any effect; (iii)(14/255) X 100 = 5.5% (37/253) X 100 = 14.6%; 14.6 - 5.5 = 9.1(%)/9.13(%); (c) (i) (Trend): as heparin concentration increases, clotting time increases; (Pattern): reference to change after 0.2 arbitrary units; (ii) blood clot from transfused blood could cause thrombosis /stroke / embolism/ heart attack/myocardial infarction; (iii) calcium ions needed to convert prothrombin to thrombin / fibrinogen to fibrin; less thrombin /fibrin formed; Total 15 AQABYA3 JUN 2005 SAQ107. (a) hepatic vein, vena cava, aorta;

inclusion of incorrect vessel negates mark pulmonary artery and pulmonary vein; 2 (b) (i) endocytosis / pinocytosis; 1 (ii) enzymes;

reject lysosomes are enzymes / lysosyme digest/break down/hydrolyse (lipo)proteins/envelope/membrane; 2 (c) produce faulty/different receptor protein; with different shape/tertiary structure; LDLs will not fit/bind to receptor site; LDLs not removed from blood / taken into cell / taken up;

OR does not produce receptor protein; no receptors in membrane; nowhere for LDLs to bind; LDLs not removed from blood / taken into cell / taken up; 3

do not penalise use of the term active site unless used in context of enzymes (d) increase; causes genes (controlling HMGCoA reductase/LDL receptors) to be switched off; no more synthesised / taken into cell;

continues to be used and therefore falls/returns to norm; 3 max (e) (i) adds hydrogen (ion)/proton to HMGCoA / mevalonic acid has extra hydrogen; ignore references to electrons 1 (ii) similar shape/structure to substrate /HMGCoA; fits active site of enzyme /acts as competitive inhibitor; prevents HMGCoA/substrate fitting / fewer enzyme-substrate complexes formed;

AQA/Jun06/BYA8/W SAQ108. (a) Bilayer / two molecules thick; ―Heads‖ / hydrophilic parts outwards / ―Tails‖ / hydrophobic parts inward; Credit information provided in a diagram, labelling essential for second marking point. Reject ‗water loving‘ / ‗water hating‘. (b) Only parts of membrane with receptors / molecules into which surface proteins will fit / recognition / binding sites; (c) Endocytosis / phagocytosis /pinocytosis; Reject ‗cytosis‘. (d) (i) Lysosome; (ii) Enzymes; Digests / breaks down/ hydrolyses (other molecules); Reject ‗cholesterol‘. AQA/0202/BYA1

SAQ109. a. Increasing the number of risk factors increases risk of CHD; Increase by one risk factor double incidence; Adding third risk factor has larger effect on incidence; smoking is the highest factor deaths are 620 in 100000 people. b. High blood cholesterol 1. Fatty deposition in artery walls / plaque formation; 2. Atheroma- formed; 3. Increased blood pressure 4. Lumen of (coronary) arteries narrowed I reduced elasticity of artery wall 5. Correct reference to LDIs; High blood pressure: 6. Damage to (lining of) arteries; 7. Risk of aneurysm / damaged Lining (of arteries) rupturing: 8. Increased risk of blood clot blocking coronary arteries-; 9. Correct reference to inflammatory response

Smoking: 10. Increases blood pressure 11. Increases risk of aneurysm 12. Less antioxidants / more free radicals-:t


13. Increases (number / activation of platelets: 14. (Leading to) increased risk of blood clot blocking coronary arteries Total 9 marks SNAB June 2005

SAQ110. (a) Increasing the number of risk factors increases risk of CHD; Increase by one risk factor double incidence / eq ; Adding third risk factor has larger effect on incidence ; Relevant use of manipulated figures ; (b) High blood cholesterol: 1. Fatty deposition in artery walls / plaque formation ; 2. Atheroma formed ; 3. Increased blood pressure ; 4. Lumen of (coronary) arteries narrowed / reduced elasticity of artery wall / eq ; 5. Correct reference to LDLs ;

High blood pressure: 6. Damage to (lining of) arteries ; 7. Risk of aneurysm / damaged lining (of arteries) rupturing ; 8. Increased risk of blood clot blocking coronary arteries ; 9. Correct reference to inflammatory response ;

Smoking: 10. Increases blood pressure ; 11. Increases risk of aneurysm ; 12. Less antioxidants / more free radicals ; 13. Increases {number / activation} of platelets ; 14. (Leading to) increased risk of blood clot blocking coronary arteries ; General points [allow in any section]: 15. Reduced blood supply to heart muscle ; 16. Angina / increased risk of heart attack ; 17. Reference to interactions between factors to increase risk ; 18. Correct reference to atherosclerosis ;

SNAB/SN1/2005 SAQ111. 1. (a) They differ in height and structure; Phil is taller than Andy. (b) They differ in BMR; Tara/ women has lower BMR than Phil/ men. Total 4 marks SNAB June 2003

SAQ112. (a) (i) ;(1.55)

58.802

Answer 24.47/24.5; (ii)person D; (iii) 1 coronary heart disease / atherosclerosis / high blood pressure / hypertension / stroke / angina; 2 increased danger of developing diabetes; increased likelihood of pulmonary problems / breathlessness; 3 damage to joints by carrying excess weight / eq; gall bladder disease; skin infection from skin folds; increased surgical risk / eq; (b)1 gender; age; general state of health; 2 lifestyle / level of physical activity; pregnancy; (c) any change in level of physical activity may affect body mass; increased physical activity increases energy expenditure / converse; more exercise and no increased energy intake reduces body mass / eq. increased exercise increases muscle bulk; this may increase body mass; Edexcel SAQ113. (a) (i) 0.14% (ii) 3.9 to 4 times (b) i. The greater the BMI the greater the chance of dying due to CHD. When BMI is increasing at 35 the death percent is 45. ii. BMI= Body mass in kg/ height2 in meters iii 1. Fatty deposits in arteries / atheroma / plaques / reference to atherosclerosis: 2. Higher cholesterol Levels: 3. Higher blood pressure: 4. Risk of damage to (coronary) arteries: 5. Risk of blood clot blocking coronary arteries: 6. Risk of type II diabetes. Total 8 marks SNAB Jan 2006

SAQ114. (a) (i) 33 Kg m2

(ii) 1.Increase Level of exercise; 2. (which) increases metabolic rate / uses more energy 3. (which) increases weight loss / 4. Reference to change in diet: 5. Decrease saturated fat intake: 6. (Therefore) reducing blood cholesterol Level;


7. Low carbohydrate diet / reduce alcohol intake / reduce sugars in diet: 8. To restrict calorie intake; 9. To reduce risk of type 2 diabetes; 10. Lowers blood pressure 11. Reduces risk of cardio vascular disease. (b) (i) EAR=BMR x PAL 10.6 MJ/day (ii)The PAL value for a man with a low level of physical activity is 1.4. Calculate the BMR for a 35 year old man with this level of physical activity. Show your working. (2) BMR = EAR/ PAL 10.6/1.4 = 7.6

Total 10 marks SNAB June 2005 SAQ115. (a) (i) kJ m-2 h-1 / in words; (ii) To calculate heat lost to water (jacket); (iii) To calculate heat lost to air; (b) Two marks for two of: 10-20 years – rapid decrease associated with adolescent growth spurt / eq / decrease in S.A. / mass; 20-35 years – no change as body same size / same composition / same level of activity; 30-70 years – slow decrease associated with loss of muscle / gain of fat /reduced activity; If none of the above scored, allow one mark for BMR decreases with age due to decrease in activity / high when young as more active; AQA/S02/BYA7

SAQ116. (a) Anything that affects the chance of harm (b)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 6. Increased risk of type 2 diabetes / explained (c) 1. Glucose is (a monosaccharide / soluble / doesn't need to be digested) 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) contraction. SNAB JAN 2005 SAQ117. (a) (cholesterol) deposited in, walls / lining, of arteries / 'in arteries / in blood vessels‘ atherosclerosis / atheroma; in coronary artery: forming plaques: roughens

lining: narrows lumen / narrows artery / reduces blood flow; R arteries become smaller / ‗blocks' increase in blood pressure: ref blood clotting / thrombosis; (b) less, (total) fat / saturated fat / animal fat: A increase (poly)unsaturated fat; less cholesterol; less salt; e.g. of a food to avoid - red meat, eggs, dairy products, full fat milk, ice cream, prawns, avocado, etc: eat, fruit / vegetables / fiber: increase intake of, antioxidants / named antioxidant; e.g. vitamin E / red wine. Eat, oily fish / named oily fish / Sushi / olive oil; eat, cholesterol-lowering foods / named example: (c) (heart / coronary) by-pass: described; e.g. carries blood around the blockage R replaces it source of blood vessel(s) used; A vein or artery or synthetic material heart transplant; from donor / from transgenic pig / artificial heart; immunosuppressant drugs: angioplasty: described (inflated balloon +/- laser): further detail; e.g. use of stents (wire mesh to hold open artery), use of catheter, insert in vessel in groin / leg / arm: ref to tissue matching / rejection (d) allows, early diagnosis: A ref to babies / children / young adults screen / test I check, for alleles / genes, that make them susceptible to disease / AW; advise parents on risks to children / counseling: provide check ups (at regular intervals) / ref monitoring: specific advice on, diet / exercise / obesity / smoking / alcohol; e.g. specific diet comment regular exercise; reduce weight; do not smoke; moderate intake of alcohol specific treatment; e.g. drugs to lower blood cholesterol / ref to gene therapy Total 12 marks OCR June 2003. SAQ118 (a) 1. Bronchitis 2. emphysema (b) damage to artery wall / lining / endothelium; scarring OR damage to artery/ damage in artery invasion by phagocytes; cholesterol / fat/ LDLs, deposited / accumulates / artery wall; growth / proliferation of, smooth muscle / fibrous tissue: wall thickens / lumen becomes narrow / reduces blood flow; rougher surface; platelets secrete clotting factor(s); endothelial


cells secrete less, anti-clotting factor(s) / prostaglandins; e.g. atheroma, breaks open /bursts through wall loss of elasticity/ walls do not stretch as much.

(c)nicotine increases, heart rate / blood pressure (possibly leading to damage to artery walls): decreases width of arteries / lumen smaller/ reduces blood flow; increases number of platelets / makes platelets more 'sticky; decreases antioxidants; damages walls of arteries: reduces oxygen carrying capacity of blood / binds with hemoglobin forms carboxyhaemoglobin: both increase development of, plaque / atheroma; stimulate production of, fibrinogen / clotting factors: reduces production of enzymes that remove clots: increase blood cholesterol (concentration). OCR June 2004

SAQ119 (a) eq.;10049

2049100

49

29

Answer 59.2 %;

(b)(i) DCPIP decolourised by vitamin C / blue colour disappears; use vitamin C solution of known concentration; determine volume needed to decolourise known volume of DCPIP; extract juices / eq. from vegetables / liquidise and filter / eq.; determine volume of each juice needed to decolourise same volume of DCPIP; any relevant calculation described; (ii) 1. same quantity / mass of each vegetable; same volume of water used; 2. DCPIP made freshly / kept covered; same / stated volume of DCPIP used each time; 3.add extracts to DCPIP drop by drop; same amount of mixing /shaking each time; (c) 1. chopping up / cutting / peeling / slicing / eq.; prepared fruit / vegetables kept in water; 2. bruising / tissue damage / freezing; long storage / ageing; exposure to air; exposure to light; Edexcel

SAQ120 No Marking scheme SAQ121 (a) (i) The diagrams below show three molecules P, Q and R. Choose a nutrient from the table above that would provide the baby with each molecule. Put your answer on the dotted line to the right of each molecule. (3)

Molecule P Protein Molecule Q Triglyceride/ fat Molecule R Maltose/ Carbohydrate

(ii) Calculate the difference in the mass of protein consumed per day by an average baby fed on formula milk compared with an average baby fed on human milk. Show your working. calculation (e.g. 3.3-1.0 or 2.3) x 8 (g) ; answer (18.4)

(b) Use your own knowledge and data from the table, to suggest and explain a reason why babies fed on formula milk are likely to put on weight more quickly than babies fed on breast milk. (2) 1. more protein (in formula milk) ; 2. protein needed for growth / muscle deposition ; 3. {protein / muscle} {heavier / more dense} than same amount of carbohydrate / fat

(c) There is concern that putting on weight in early life may be one cause of obesity in teenagers. Body mass index (BMI) can be used to identify people who are obese. Describe how BMI is calculated and used to judge whether somebody is obese or not. (2) 1. description of equation / body mass divided by height2 ; 2. look up on a chart to make judgment / over 30 (on BMI scale) Total 9 marks SNAB Jan 2008 SAQ122 (b) EAR = mean of the, population I sample; A ref. 50% need more, 50% less EAR is the only DRv for energy: RNI = two standard deviations, about I above and below, the mean or more than enough for most of the population I


(c) pregnancy: lactation / breast feeding: body building / training I exercise qualified; AVP;: re.g. heavy periods Irecovery from disease /high metabolic rate/ large size) R 'menstruation' unqualified (d) maintenance I repair / replacement; ref bones I organs / tissues: immune system: not able to store protein; AVP;: (e.g. any 2 protein functions) (e) individual needs (i.e. planning diets for individual): not generalised / related to specific groups / AW: ref advice I education I information, for general public / onsumers: analysing dietary surveys: use by dieticianns / constructing diets (i.e. for schools/hospitals/institutions): food labelling / selling / marketing: (f) measles is highly infectious: poor development of immune system I few lymphocytes / few T/B cells: weakened immune system; antibodies are proteins, fewer are made I AW; vitamin A deficiency: poor maintenance of epithelia (virus enters through nose I mouth etc); ref. to need for booster vaccination (as initial vaccination does not work): (g) (carbohydrate used) to provide energy: carbohydrate easily respwed: saves protein from being respired; high quality protein provides (all) essential amino acids: energy I protein, needed for growth I repair / replacement; OCR/JAN02/2802 SAQ123 (a) 95 / 95.4 / 95.44;

(b)(i) note that Q says ‘such as iron’ for haemoglobin / prevents anaemia / prevents deficiency; provides enough for most of the population / meets needs (of most people); data quote – 97.72 / 97.7%; allows enough to be stored (in the body); not enough to be harmful / guide to safe amount / ensure people do not take too much; ® idea that iron is harmless in large quantities AVP; e.g. people‘s requirements vary / difficult to know how much people require (ii) blood lost; at menstruation / during menstrual cycle / ref periods / at birth; females at higher risk of anaemia; ref to pregnancy;

OCR/JUN01/2802

SAQ124 (a) Mass in kg divided by height in metres squared / formula with units ; (b)BMI of 25 and over is overweight ; BMI of {more than / equal to} 30 is obese ; (c)1. 16-24 {no difference / slight difference} (between sexes) ; 2. Both increase with age ; 3. Men always higher than women / men rises faster than women / men percentage increases more than that for women ; 4. Greatest increase for both sexes between {24 / 25} and 34 ; 5. Men start to level off {before women / at 45, women at 55} ; (d) 1. BMR falls with (increasing) age ; 2. Need less {food / energy} as age increases ; 3.If {quantity / energy intake} of food not reduced the excess is stored as fat ; 4.Increase in fat leads to increase in BMI ; 5. Reference to steepest drop in BMR corresponds to biggest increase in overweight percentages / reference to age at which this occurs ; Edexcel

SAQ125 (a) 58.80 ÷ 1.552; 24.47 / 24.5; (b) Person D; 1 (c) Any three from: Gender; Age; Pregnancy; Lactation; General state of health; Lifestyle / level of activity;

Edexcel SAQ126 (a)(i)mass / weight in kg and height in m OR mass / weight divided by height squared (ii) adipose / fat

(b) (i) 2.2 - 1.08 [allow 1.075 to 1.1] = 1.12 arbitrary units / units [allow 1.1 to 1.125] /OR 100% to 104.7% rise 1 (ii)smokers risk always at least 2× that for

non–smokers /eq increase in risk as BMI increases 1 steep increase in risk for smokers at BMI 30 /

when obese /OR steep increase in risk for non–smokers at BMI 34 1 non–smokers with BMI 36 have higher risk than smokers at 26 1 between 32 – 34 little change / no change for

smokers /OR increases more for non–smokers (iii) raises blood pressure / raised pulse

rate/eq /OR reference. to carbon monoxide /


CO combining with Hb / reducing oxygen

carriage by Hb /OR decreases antioxidants (in

blood) /OR increases blood cholesterol /OR

constriction of coronary arteries /OR rise in

ratio of LDLP:HDLP /OR increased number of

platelets / OR platelets more sticky /OR increase risk of plaque formation in coronary arteries 1

(c) ref. to need to get energy expenditure

higher than energy intake /eq reduce carbohydrate /fat intake / ref. to low fat / low calorie diet / increase exercise / activity

Edexcel

SAQ127(a)(i)Maximum 72/73 kg; Minimum 57/58 kg.

(ii) BMI = 2)(Height

Mass

relates body mass to height / eq. / indicates amount of adipose tissue in the body. (b)(i) women have 3× the fat content */ eq.; men have almost 2x muscle content */eq.; men have 1¼ x non-muscle lean tissue */ eq.; men have 1¼ x skeletal tissue */ eq.; women more fat than muscle / men more muscle than fat; [* accept both figures quoted / difference / percentage age difference calculated]. (ii) 1.testosterone / androgens produce more muscle development in men 2.androgens increase skeletaldevelopment; women lay down greater fat stores / more fat qualified (c)1 reduction in mass of fat;increase in mass of muscle; 2 increase in mass of skeletal tissue. Edexcel

SAQ128. (a) Coronary artery ; (b)(i) (Increase in cholesterol level) gives increase in risk;

Slight / insignificant /eq increase between 5

and 6 (mmol dm-3)(not time reference so not faster / slower ); Increase in risk greater above 6.0-6.5 (mmol

dm-3) ; Risk at 8 (mmol dm-3) 2× that at 5

(mmol dm-3) / (sensible use of figures); max 2

(ii) Risk in both increases as cholesterol level

increases ; At low cholesterol /OR 5 mmol dm–

3 little difference between smokers and non-smokers (not time references so not faster / slower) As cholesterol level increases, risk increases more in smokers than in non-smokers / bigger difference at 8 than at 5 ; Credit use of figures ; Smokers always at

greater risk than non-smokers /eq ;

(iii)Age ;Weight / mass / BMI ;Reference to lifestyle, qualified / occupation / stress level ;Reference to exercise level / type / frequency of exercise ;Reference to genetic /family history ;Reference to other diseases / illnesses / e.g. diabetes ; Blood pressure ; max 2 (c)(i)Reference to absence of double bonds (in (hydro)carbon chains of constituent fatty

acids) /eq ; (ii) Japan ; (iii) As ratio / proportion of polyunsaturated to saturated fat increases, risk of heart disease seems to decrease; Edexcel

SAQ129. (a) 65/1.75 = 21kg m2

b. Less exercise/ Quantity: increased availability of food / people are wealthier / eq; Quality: more high (fat / sugar] foods / fast food / processed food c. i. 1. Reference to (Isolating / identifying normal (leptin) gene.: 2. Inserting normal (leptin) gene into (target cells / cells of adipose tissue]: 3. Reference to use of vectors: 4. Such as (virus / plasmids / Liposome; 5. Identify whether the normal gene is being expressed / has the treatment worked / gene is translated / correct protein made.(3)

(ii) 1. Reference to side effects / risk of diseases in the patient e.g. cancer 2. Reference to cost of treatment / resources diverted to thus from treatments for Life threatening diseases; 3. Reference to consent of patient / confidentiality issues; 4. Treatment not cure / genes stilt present to be passed on / reference to somatic as opposed to germ line; 5. Reference to counseling: 6. Reference to {animal / embryo testing:

Total 9 marks SNAB June 2004


SAQ130. (a) (i) A description to include three from: 1. increase in the percentage of {all / the population} classed as obese 2. increase in both males and females / females higher than males; 3. bigger difference between males and females in 1986; 4. 3 to 4 fold increase from 1980-2000 / correct manipulation of figures (ii) A suggestion to include two from: 1. inactivity / lack of exercise / high fat diet / eq ; 2. energy intake greater than energy loss ; 3. advertising and commercial pressures; 4. genetic reference to male and female differences / women {post-pregnancy / menopause} (b) (76 ÷ 1.702) / 26.29 / 26.3 / 26; ALLOW 76 ÷ 1.70 = 45 = yes / obese (c) An explanation to include three from: 1. increase in blood pressure; 2. increased risk of {damage to arteries / plaque / atheroma atherosclerosis}; 3. increased risk of stroke / blood clotting an artery / coronary heart disease / CVD 4. increase in blood cholesterol ; 5. increased risk of Type II diabetes; 6. Joint damage SNAB Jan 2007

SAQ131. SAME AS SAQ121

SAQ132. (a) minerals / salts / named mineral; fibre / roughage; water (b) (i) 23 (ii) Acceptable. (c) arthritis / joint problems; CHD / (coronary) heart disease / heart attack / heart failure / CVD; stroke; angina; thrombosis blood clotting; atherosclerosis; (named) cancer; high blood pressure / hypertension; breathlessness / shortness of breath diabetes; depression; varicose veins; gall stones; hernia; kidney failure; second named cancer cancers – breast, womb / cervical, ovary, gall bladder, colon / rectum / bowel, prostate, testicular

(d) 1.inducements / prizes / competitions; 2. clubs / local meetings / clinics / help lines; e.g. Well Woman clinics 3. target setting for weight reduction / target groups of people; 3. change diet, qualified with

ref to energy / nutrients; A ‗adopt a balanced diet‘ 4. accept refs to RDAs, RNIs, reduced alcohol intake 5. encourage people to exercise more / promote active lifestyle; 6. advertising / education, about health risks of obesity; A raise awareness 7. AVP; any other appropriate strategy to do with weight loss OCR June 2002 SAQ133. (a) eating too much; high, fat / sugar / carbohydrate/ alcohol (in diet): energy intake greater than use / insufficient exercise e.g. genetic predisposition underactive thyroid (b). decrease in % underweight: decrease in % acceptable; increase In % overweight: large / great / dramatic/ significant increase In % obese: use of figs to illustrate one change: (c) 1. high level of saturated fat in diet: 2 animal fat / red meat/ dairy products: 3. high cholesterol (in blood / body); 4. lack of, vit E / antioxidants; 5. high salt in diet: 6. obesity inked to high blood pressure / hypertension: 7. damage to artery, walls / endothelium: 8. cholesterol transported 9. cholesterol deposited in artery walls 10. in coronary arteries 11. atherosclerosis /atheroma 12. formation of, plaques / fatty streaks: 13. hardening / loss of elasticity (of artery wall): 14. roughens lining increases friction; 13. clot formation / thrombosis / thrombus: 16. narrows / restricts. lumen 17. reduced / restricted, blood fowl oxygen, to heart muscle 18. heart (muscle), under stress / works harder: 19. angina / heart attack / myocardial infarction / heart failure / hypertrophy; CHD 20. AVP; e.g. aneurism in aorta 21. low density lipoproteins (LDL) associated with deposition high density lipoproteins (HDL) associated with less deposition OCR June 2005 SAQ134. (a) 122: A if not in box (b) (i) (pulse rate) increases:


use of fig was to demonstrate increase: (ii) increased respiration in muscles: requires more, oxygen glucose: increased carbon dioxide production carbon dioxide removed in blood: cardiac output must increase lactate, produced / transported to liver: A lactic acid (c) Student D. high resting pulse rate: heart rate / pulse rate, goes higher than others / very high: A pulse rate always high figures to demonstrate pulse rate point: blood pressure higher at rest; blood pressure, rises to higher than others / highest: A blood pressure always higher use of figures to demonstrate blood pressure point: d. fat more likely to, compress / constrict, blood vessels / atherosclerosis more likely: greater friction: (therefore) blood pressure higher: more weight means more work done (by muscles during exercise): more oxygen needed (by respiring tissues) / more CO2 needs to be removed. OCR June 2005

SAQ135. (a) Cannot be made within the body; (b) 35% of 8830 = 3090.5 3090.5/37 = 83.53 or 84 (c) saturated fat, raises concentration of LDLs in the blood; raises (blood) cholesterol; (increases risk of) atherosclerosis / described: A atheroma / plaque / fat or cholesterol in wall of artery raises blood pressure: (increases risk of) blood clots / thrombosis: (coronary) heart disease / heart attack / heart failure / Ml / angina / CVD: stroke: overweight / obesity: increase body mass index (BMI); AVP;; e.g. obesity-related diseases such as arthritis, named cancer (R lung), gall stones, diabetes, hypertension, hernia, varicose veins, haemorrhoids, joint / knee damage, depression (R mental health problems) ref to surgery being difficultref to adipose tissue (d) 1 any two references to differences in quantities: A rich / richer / good source of 2 use of figures to make a comparison between quantities for any one nutrient; 3 protein needed for, repair / replacement / ref pregnancy / ref lactation / AW; 4 vitamin A, ref to function or deficiency:

rods / retina / night vision / xerophthalmia / ref epithelia / immune system 5 vitamin D, ref to function or deficiency: absorption or deposition of calcium / osteomalacia R rickets 6 calcium, ref to function or deficiency: skeleton / teeth / bones / fetal growth / muscles / nerves 7 iron, ref to function or deficiency: haemoglobin / anaemia / menstrual loss / red cells 8 other foods needed to provide iron or calcium / need to take supplements: 9 AVP consequences of deficiencies, e.g. osteoporosis, fatigue 10 AVP any ref to RNI for any one of these nutrients ref to polyunsaturated fatty acids in 'oily fish‘ idea that one food does not make a diet

Total 11 marks OCR Jan 2004 SAQ136. (a) brings no further benefit in fitness: may damage / put strain on, the heart / blood vessels: 1. (a) (i)men ……18.2 to 18.4…………….KPa women…17.7 to 17.9….. kpa (ii) 3.9/16.0 x 100 = 24% (iii) increase ; use of figures to show an increase: units to appear at least once (b) (all ages) higher % of men have hypertension; (40.8% men v 32.9% women) / higher % men with hypertension in groups from 16-64: (16.0 v 4.2%) men have higher (mean systolic) blood pressure (18.2 v 17.7 kPa) men have higher blood pressure in groups 16-64 (17.1 v 16.0 kPa, etc) women have higher % with hypertension >65; (72.8 v 69.9 %) women have higher blood pressure > 65: (19.9 v 19.7 kPa) A similar from 55 women's (systolic) blood pressure increases more between 16 — 75; idea that men and women reach (mean systolic) blood pressure of 18.7 kPa at same age: ref to

threshold for hypertension as given in the stem of the question use of figures to make a comparison: (figures quoted or ratio used) allow if no units given (c) Identifies people at risk of, disease / hypertension / AW; target, prevention / drug treatment / advice: identifies health, priorities / policies: check on progress of, health programmes /


health initiatives: public education / public awareness / patient awareness: ref to economics; OCR June 2003

SAQ 137. (a) Identify those at risk from developing cancer; So as to avoid relevant environmental factors / enable early diagnosis; Identify risk in families; (b) Mutation of suppressor gene 1. Mutation is a change in the DNA / sense strand; 2. Base sequence altered / e.g.; 3. Suppressor gene produces wrong instructions / has different code; 4. (Therefore) different amino acid sequence; 5. Different protein structure / non-functional protein; Malignant tumour 6. Cell division by mitosis; 7. Tumour cells growth abnormal / continuous / uncontrolled / rapid; 8. Tumour cells spread / invade other tissues / form secondary tumours / metastasis; 9. Via blood / lymph system; 6 max (c) (i) Most lung cancer occurs in smokers / non-smokers also develop lung cancer; Smoking increases the risk of lung cancer; Smoking is an environmental factor for lung cancer; Smokers‘ risk more than 4x that of non-smokers / correct ref to figures; (But) only a small proportion of smokers develop lung cancer; Smokers more likely to develop other lung disease than cancer; (ii) Do not know size of sample / might be small sample in study; Genetic differences / predisposition; Could be different age at which started to smoke; Could be different number of cigarettes smoked per day; Could be different tar levels in cigarettes smoked; Could be different sexes in sample; Other valid; (d) All exposed to same environmental conditions / factors / no regional variations; Same level of pollution / example; reject less pollution Similar diet / example; Same water supply; Easier to screen whole population; Easier to follow family history / people related; Identify genetic differences in those affected (since everything else the same) / less genetic diversity; Total 15 marks AQA BYA3JUN 2002

SAQ138.(a) high death rate: preventable / avoidable, deaths; premature deaths / younger than life expectancy / people of working age;

e.g. cost of care/ medical facilities (b) (i) supported or not supported / data support hypothesis explanation death rates (for both men and women) are lower; ref to any two figures from the table to show a comparison (e.g. Spain v Latvia) (ii)explanation support - all figures for men (in 35-74 )age range are higher than those for women; do not support - no data for men and women over 74! only applies to 35-74 age range / no data for men and women under 35! smoking- related not gender-related; ref to any two figures from the table to show a comparison (e.g. men and women In the same country); (iii) supported or not supported explanation prevalence of smoking is, higher/ no lower in Mediterranean countries, than in some countries with higher death rates from CHD; ref to men in Latvia and Russian Federation who show high prevalence of smoking and have high death rates from CHD: A no correlation between prevalence or smoking and mortality from CHD ref to any figures from the table to show a comparison. (c) lifestyle increases susceptibility to degenerative diseases: e.g. diabetes, CHD, atherosclerosis: smoking increases risk of developing, (lung) cancer / CHD; no signs of symptoms of disease, may be developing or increasing risk of developing (non-infectious) diseases; fathers heart attack, may mean that there is a genetic predisposition to heart disease: not a balanced diet: little fresh fruit and veg, little, dietary fibre / antioxidants / vitamins: little (aerobic)exercise; except on one occasion a week, may put strain on heart /AW: health risks associated with, binge drinking / alcohol. Total 9 marks OCR Jan 2004 SAQ139. (a) Nicotine (b) substance 1 carbon monoxide / CO; binds to haemoglobin / forms carboxyhaemoglobin; Hb has greater affinity or CO / CO binds more strongly than oxygen. A irreversibly reduces oxygen carrying ability / amount of oxygen that can be carried:


Substance 2 tar: accumulates, in lung / on alveolar surface increases, diffusion barrier/ thickness of barrier between air and blood / reduces rate of diffusion / gaseous exchange more difficult. causes cancer / carcinogenic: paralyses / damages cilia; skills / destroys, cilia increases mucus production / AW; increases chance of infection production of scar tissue: reduces elasticity of the airway / (oxidants) increase activity of elastase (emphysema) carcinogen (causes cancer) changes DNA / mutation. (c) (i) % heavy smokers rises from, professional / unskilled manual workers / A statements comparing groups 1 and 6 (ii) as % heavy smokers increases so does number of people suffering long-standing illness the relative increase if smoking is far greater than the relative increase in longs standing illness / not a proportional increase / use of figures to illustrate: e.g. smoking increases more than 6 fold while long-standing illness increases less than 2 fold smoking increases from 3% to 19% while long-standing illness increases from 290 to 420 (per 1000) (iii) medical services; working environment; living conditions; income; education (about diet/ possible relief from long-term illness); diet: work-related injury; alcohol intake: (work related) stress: (aerobic) exercise.

Total 11 marks OCR June 2005 SAQ140. (a) Enables comparison to be made; Since increase in incidence with age/ older people have had more exposure to cigarettes. (b) No/ incorrect response with some attempt at calculation based on 556 and 428 as numerators; = 1 mark No/ incorrect response with correct calculation; = 2 marks Correct response (non-smokers have greater risk than smokers) with calculation of 556/7316 × 100 = 7.6% and 428/4651 × 100 = 9.2% for smokers and non-smokers respectively. (c) (i) (Relative risk of) lung cancer decreases the longer it is since giving up smoking; (Relative risk of) lung cancer increases with the number of cigarettes smoked per day.

AQA Jan 2003

SAQ141. (a) smoking/obesity/genetics/lack of exercise/getting older/high blood pressure/stress/high salt/ high alcohol no marks for high fat diet (b) (i) 1000 × 0.2 = 200 (ii) 200 - (200 × 0.21) 200 × 0.79 = 158 (iii) 42 × 100/1000 (200 - 158 = 42) = 4.2% mark this consequential on answer to (ii), i.e. 200 – answer (ii) (c) (i) Two groups, one treatment, one control people assigned at random (to group) not selected from population at random (ii) E (iii) E (d) (i) far more people need to be given medicine to save one life / impossible to reduce any risk to zero / The increasing costs of reducing any risk to a very low level (ii) not cost effective/benefit not worth costs / very expensive/too expensive / takes money from other needs (e) less money for some other disease/care for elderly etc / side effects of statins / people might not take care of themselves in other ways OCR

SAQ142. Obesity is a factor that affects Coronary

Heart Disease (CHD). (a) being overweight; do not accept fat unqualified; allow BMI over 25 (b) (i) Rose / by 8% / from 16% to 24% / by 50% /rapidly then more slowly (ii) any two reasonable suggestions e.g. less active more food / take-aways / fast food accept e.g.s like fewer jobs / more cars / less physically demanding employment (c) (i) high (blood) cholesterol / do not accept combination of 2 labels / ignore references to LDL and HDL (ii) answer in range 8-17 inclusive (iii) some deaths related to more than one factor AQA-BLY1F-W-QP-JANO7 SAQ142. NO MARKING SCHEME SAQ144 (a) (i) Study involving the same people over a period of time (ii) Advantage: uses same individuals throughout / no participant variables / no variation in results due to genetic differences;


Disadvantage: time consuming / some individuals may be lost from the study;

AQA BYA7 JUN 2007 SAQ145. (a) minimum energy requirement per day / per hour / per .unit time. ; further qualification . at rest / recently woken / 12+ hours after a meal / warm environment / naked; (b) (i) warm environment; less heat loss / less energy loss / less energy needed to maintain body temperature;

OR Malaysians smaller / shorter / more rounded shape; lower SA to volume ratio for heat loss; OR this is a sub-set of the whole world population / an isolated population; local genetic variation; (ii) excess food changed to fat as lower metabolic rate / less energy used (than other populations / than average);

AQA BYA7JUNE 2006 SAQ146. (a) (i) quick / easy to monitor large numbers / do not lose track of individuals with time; (ii) more representative of the individual / do not lose detail by averaging; AQA BYA7 SAQ147. (a) (i) A study of) the same/ a group of people over a (long) period of time; (ii) Qualified reason why it is difficult to continue the measurement of all people e.g. migration/ death; OR Takes a long time to see a pattern/ conclusion; [Ignore: Takes long time to collect data] AQABYA7JAN2003

End of topic one

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Topic two (Genes and health)

SAQ148. (a) (i) X: phospholipid; Y: (channel) protein; Z: glycoprotein / carbohydrate; 3 marks (ii) P: (passive) diffusion; NOT facilitated diffusion Q: active transport; R: facilitated diffusion; 3 marks (b) 1. CFTR protein defective / eq; 2. chloride ions remain in cells / eq; 3. mucus lacks water/is very sticky / eq; 4. mucus blocks pancreatic (duct); 5. {fewer enzymes / correctly named enzyme} released into the small intestine; 6. lower concentration of enzymes / fewer active sites; 7. fewer collisions between substrate and the active site of the enzymes / named substrate and enzyme; 4 marks SNAB/JUNE 2007 SAQ149.a. A. fatty acid / hydrophobic / phospholipids tall B . Phosphate / glycerol / hydrophilic / phospholipids head C. (Channel / transmembrane / intrinsic) protein D . Glycoprotein b. Facilitated diffusion Through (channel /carrier) protein: Down a concentration gradient

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). c. i. 1. Discs cut from the same beetroot: 2. Pre-treatment of beetroot I washing discs: 3. Standardized method of obtaining beetroot discs I discs the same (mass/I volume / surface area): 4. Further detail of method e.g. way of keeping the discs from clumping In the water. 5. Use of water baths at fixed temperatures; 6. Fixed time in water baths / fixed volume of water; 7. Use of colorimeter / description of method of measuring intensity of color;


8. Detail of colorimeter e.g. e of (reference blank / filter). ii. 1. Membrane selectively permeable at lower temperature 2. (Temperature increase above 40 C / higher temperatures)/ membrane breaks down 3. Increase of kinetic energy of (pigment molecules/ phospholipids in membrane! eq); 4. Proteins are denatured: 5. Membrane becomes (freely/ more) permeable to pigment molecules) with increasing temperature: 6. Reference to diffusion of pigment molecules of the cells reaches equilibrium at high temperatures. SAQ150.a.

b. unsaturated contain one or more (C=C) double bonds . c. Diagram showing a bilayer of phospholipids; Heads on outside and tails on inside [Must have two tails]: Proteins included in the diagram: [distinguishable from the phospholipids, can be intrinsic, extrinsic or transmembrane with suitable Label]. SAQ151 a. A. protein B. Fatty acid / {hydrophobic / phospholipids} tail C.phosphate / glycerol / {hydrophilic / phospholipids} head b. 1. small (molecular size) ; 2. recognized by protein receptors 3. lipid soluble/non-polar/hydrophobic. c. i. both involve (carrier) proteins / both transport hydrophilic molecules / named molecule / selective ii. active transport requires energy / ATP, facilitated transport does not / active transport moves molecules against a concentration gradient, facilitated diffusion

allows molecules to move down a concentration gradient. 152.a. 1. fluid – (phospholipid) molecules can move within the phospholipid bilayer / monolayer; 2. mosaic – {proteins / glycoproteins / eq} dotted throughout the membrane / bilayer b. i. act as receptors / antigens ii. 1. two {fatty acid / eq} ‗tails‘ ; 2. glycerol ; 3. phosphate. c. 1. charged region (of cholesterol) only in line with hydrophilic phospholipid head /non-charged region only in line with hydrophobic phospholipid tails ; 2. all within 1 monolayer d. 1. LDLs carry most cholesterol / HDLs more protein; 2. LDLs bind to receptors on cell membranes ; 3. if in high concentration, they overload receptors ; 4. results in high blood cholesterol ; 5. high risk of atheroma / atherosclerosis ; 6. HDLs transport cholesterol to liver ; 7. cholesterol broken down therefore less risk of atherosclerosis. SAQ153. a.i. A – Glycoprotein B – Phospholipid. ii. A acts as a receptor for hormones and also helps in cell to cell recognition . iii. The phospholipid molecules have a hydrophilic phosphate head which is attreactes to water molecules in the membrane surface. The fattyacis tails are non-polar and hydrophobic so they face away from the water molecules on the membrane surface and form a barrier to polar molecules. b. The cell surface membrane is made up of a fluid mosaic model. Fluid means that the proteins can change places within the membrane. Mosaic means that the proteins are randomly embedded in the phospholipid bilayer. So when the two membranes are fused together , the proteins change places and arrange themselves randomly. SAQ154.a. Phospholipids are made up of two fatty acid tails and a phosphate head. The fatty acid tails are non polar and hydrophobic


(water hating), while the phosphate heads are polar and hydrophilic (water loving). So the polar phosphate heads are attracted to water molecules on the membrane surfaces and the fatty acid tails face away from the water on the membrane surfaces, forming a bilayer. b. Magnification = measured length / actual

length 3 x 106 = 18000 / X [18mm is same as

18000 µm] X = 18000 / 3 x 106 = 0.006 μm c. Carbohydrate : The carbohydrates may help in cell recognition, as in the case of antigens. They also play a role in adhesion of cells to each other. Protein: Some proteins may act as carriers or channels for the transport of specific substances across the cell membrane; some proteins may serve as receptors for hormones, helping hormones to recognize and affect only target cells; other proteins may serve as enzymes, as in the epithelial cells in the ileum of humans. SAQ155.a.i. The receptor molecule that binds with glucagon will have a particular shape(tertiary structure). This makes it specific so that it can bind only with glucagon. ii. The glucagon receptors are found only on the liver cells. Cells in other parts of the body do not have these receptors. b. Buffers keep pH constant. So that proteins and enzymes in mitochondria are not denatured. c. The proteins are embedded into the phospholipid bilayer of the cell membrane. Some proteins pass right through membrane – these are called as trans-membrane or intrinsic proteins. Some proteins associated with one layer – these proteins are called as extrinsic or peripheral proteins. The proteins are involved in facilitated diffusion, active transport or may be enzymes. The carrier proteins change shape to transport substances across the membrane. The channel proteins form channels or pores to allow the passage of water soluble molecules or ions, like glucose and sodium respectively.

SAQ156.(A) a. A – Glycoprotein or carbohydrate chain. B – Phospholipid b. i. The rate of uptake with ATP is much greater than without ATP. With ATP the ion uptake continues to for the entire five minutes, however without ATP the ion uptake stops after a few minute. With ATP the rate of uptake is about 10 times greater than without ATP. ii. These results indicate that sodium ions are taken up against the concentration gradient by active transport. The ATP is used for the sodium-potassium pump to change shape. Some sodium ions are absorbed by diffusion, without ATP. c. So that the movement of particles is not affected by temperature and the permeability of the membrane remains unchanged. SAQ157. (a) B; D; (b) idea of molecules/named molecules moving = Fluid; idea of both proteins and phospholipids = Mosaic; (c) slow rise, sharp rise, levelling off (reject.becomes constant.); diffusion rate increases / description of diffusion rate, e.g. increase in kinetic energy increases loss of ions; sharp rise / above 50oC proteins are denatured; levelling off due to concentration of chloride ions in water becoming equal / maximum loss of Cl- ions; 2 max Total 7 AQA/BYB1/JAN2005

SAQ158. a. Concentration of sucrose in solution is higher than in the potato cylinder / converse / correct reference to water potential ; Water moves out of {the cells / potato} By osmosis ;Reference to {plasmolysis / loss of turgor} 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 ii. 1. {Sucrose / sugar} {increases the solute concentration / ref-hires water potential} of the {cells / potato}


2. More sucrose in the potato cells so cells reach {equilibrium } at a higher concentration of sucrose solution 3. Concentration difference is {less / reduced} 4. At the start {full turgor} ; 5. At the end {full plasmolysis } . 6. Reference to starch having {no / little} effect on osmosis ; SAQ159.a. i. Water ii. Active site iii. Glycosidic bond b.i. Sucrase (has a (specific) tertiary structure / is a protein. Reference to specific shape of active site: Only sucrose will fit (the active site of sucrase) / enzymes are specific to substrate / correct reference to ―lock and key‖. Form an enzyme-substrate complex: Correct reference to induced fit theory. ii. Facilitated diffusion; Use of (specific carrier) proteins / moves molecule down a concentration gradient / correct reference to kinetic theory/: OR Active transport; Use of (specific) carrier proteins / moves molecules against a gradient / uses (ATP I energy]: OR Endocytosis; Description of endocytosis e.g. formation of vesicle / use of ATP. SAQ160. a. Both move through the

phospholipid bilayer. Both move down their concentration gradient. b. Curve Y shows absorption by active transport, as the ion uptake occurs continuously at all concentration and uses oxygen. This is evident from the fact that ion uptake is greater when oxygen is present. c. Since oxygen is absent, the ions can only be absorbed by diffusion. The concentration of ions inside the cells may be greater than concentration of ions in the solution. So diffusion cannot occur against a concentration gradient. d. The concentration gradient increases as the magnesium ions accumulate in the solution, so rate of diffusion and ion uptake increases. SAQ161. a.i. The solution is hypotonic and the cell cytoplasm is hypertonic. The cell has a

more negative water potential than the solution. So water enters the cells by osmosis, causing the cell to swell. ii. The solution is isotonic, which means that the cell and the solution have the same water potential. So, there is no net movement of water across the membrane. b. Excess water entered the cells causing it to

burst. SAQ162. (a) (i) As lipid solubility increases the rate increases; (Membrane) consists of (double layer) of lipid / phospholipids; (ii) Small molecules diffuse faster; Higher kinetic energy / easier to pass through pores / between phospholipid molecules; (b) Concentration/diffusion gradient; Number of carriers/channel/proteins; Temperature;

AQA/BYB1/JUN2007 SAQ163. a.i.A.Protein B. Glycoprotein ii. Fatty acid tails are hydrophobic and non polar; so away from waterPhosphate heads are hydrophilic and polar; so they attract the water. b. Difference Facilitated diffusion occurs though channel proteins; Active transport occurs with the energy ATP. Similarity Both are selective and involves with proteins. SAQ164.a.

b. 1.Largesurfacearea; due to Many alveoli / eq; 3. Large number / networks of capillaries 4. Small diffusion path / thin exchange surface / eq; 5. (Flattened / thin / squamous) alveolar (epithelial) cells / walls: 6, Capillary (endothelial) cells / walls: 7. Large difference in concentration: due to . 8. Ventilating the Lungs 9. Circulation of blood.


SAQ165. a. diffusion; facilitated diffusion; active transport / uptake; energy / ATP; carrier / channel; endocytosis b. i. similarity: both passive / do not require energy /eq /move (molecules) down a concentration gradient; Deference: osmosis involves transport of water only / converse /osmosis always involves movement of molecules through a partially permeable membrane / converse. ii. Similarity both involve the use of vesicles to move contents / eq /both involved in bulk transport both require energy / ATP. Difference endocytosis involves transport of substances into the cell, exocytosis transports substances out of the cell; SAQ166. a. i. 62 / 10 = 6.2 times ii. Active transport or active uptake b. All ions enter the cell through specific carrier or channel proteins in the cell surface membrane. So, the uptake of a particular ion will depend upon the number of specific proteins in the cell membrane. e. g. If there are more glucose transporter proteins in a cell membrane, then it will absorb more glucose than other substances. The activity of proteins can also affect the rate of ion uptake. e. g. some carrier proteins transport more than one particle at a time. The sodium potassium pump transports 3 sodium ions but only 2 potassium ions across the membrane with every cycle. Thus, it transports sodium more rapidly than potassium. c. Active transport requires ATP, which is produced by aerobic respiration. Thus, oxygen is needed. SAQ167.a.

Function Phospholipids Protein

May act as receptors

X √

May act as enzymes

X √

Involved in active transport

X √

b. Active transport, because the ions are absorbed against their concentration gradients. SAQ168.a. Diffusion is the net movement of particles from a region of its higher concentration to a region of its lower concentration, until the molecules are evenly distributed. b. Concentration gradient, temperature, thickness of the membrane, surface area of the membrane, size of the molecules and nature of molecules or ions (whether lipid soluble or not) c. active transport occurs against the concentration gradient, but diffusion occurs down the concentration gradient. Active transport uses ATP but diffusion does not. SAQ169. curve description:

1 Curve goes down when the poison is added and rises when ATP added; explanation: 2 Ion movement is by active transport; 3 ATP / energy needed for active transport; 4 respiration provides ATP / energy; 5 poison inhibits/stops respiration / ATP production; 3 max

AQA/BYB1/JAN2006 SAQ170.

Process

Take place against a

concentration gradient

Requires energy in the form of ATP

Diffusion X X

Facilitated diffusion

X X

Osmosis X X

Active transport

√ √

SAQ171.a.i. Facilitated diffusion is the movement of substances down their concentration gradient through channel and carrier proteins in the cell surface membrane, without using ATP. ii. Active transport requires ATP but facilitated diffusion does not. Active transport occurs against


the concentration gradient but facilitated diffusion occurs down a concentration gradient. b. i. (0.05 mol dm-3 = 90% and 0.07 mol dm-3 =

15%) Difference = 90 – 15 = 75% ii. The water potential of the solution is greater than the water potential of the cell cytoplasm, so water enters the cells by osmosis and causes the volume of cytoplasm to increase. This causes the cell membrane to stretch and the cell bursts. iii. Most of the cells would shrivel up (shrink or crenate) as water would move out by osmosis (exosmosis) c. The plant cells have a cell wall which resists expansion of the cell. SAQ172.a. Facilitated diffusion involves movement of ions or large polar molecules, but osmosis involves the movement of water. Facilitated diffusion occurs through membrane channel or carrier proteins, but osmosis occurs through the phospholipid bilayer. b. Organelle A is the mitochondria. it is the site of aerobic respiration, which provides energy in the form of ATP for active transport. c. The cell membrane is highly folded to form microvilli, which increases the surface area for absorption. It also has a large number of channel and carrier proteins for facilitated diffusion and active transport. Large numbers of mitochondria ensure that there is plenty of ATP for active transport. SAQ173.a. The cell membrane is made up of a phospholipid bilayer with proteins and glycoproteins embedded in the bilayer. It is said to be fluid because the proteins and phospholipids can move about within the membrane. It is mosaic because the proteins and glycoproteins are randomly embedded in the bilayer. b. To remove the red pigment released by the cells when the beetroot is cut open. c. As the concentration of bile salts increases from 0 to 0.6% there is a linear and rapid increase in the intensity of red coloration. Between a bile salt concentration of 0.6 to 1.6% the intensity of red coloration continues

to increase at a slower rate, until it reaches a maximum intensity of 1.9 arbitrary units at a concentration beyond 1.6%. d. Disruption of the membrane by the bile salts increases its permeability. The bile salts may emulsify the lipids in the membrane and may also affect the tertiary structure of the proteins. This causes the red pigment to diffuse out of the cell and vacuole. As the bile salt concentration increases, more cells become permeable and the pigments leak out until the concentration gradient becomes zero. e. Age, storage conditions like temperature, duration of storage, concentration of pigments may be different for beetroot 2. SAQ174.a. Uptake of A increases throughout the 6 hour period at a constant rate, where as the rate of uptake of B decreases with time. The rate of uptake of A is always greater than the rate of uptake of B. b. The initial rate of uptake is maximum as the initial concentration gradient is maximum. As substance B accumulates in the cell, the concentration gradient decreases and the rate of diffusion decreases. When the concentration of substance B in the cell becomes equal to the concentration in the solution, then diffusion stops. c. The molecules have more kinetic energy at 250C, so they move faster across the membrane. d. Active transport is the transport of substances against the concentration gradient. It uses ATP and takes place through carrier proteins which span the cell membrane. The substance binds with a specific carrier protein and the protein uses ATP to change its shape. This change in shape enables the protein to transport the substance across the membrane. The protein then regains its shape and the process continues. The transport of these substances always takes place in one direction only, unlike diffusion. For example the sodium-potassium pump transports two potassium ions into the cell and three sodium ions out of the cell with every transfer. SAQ175. (a) (i) nucleus / nuclear envelope /

nuclear membrane ;


(ii) (made up of) one type of / (squamous) epithelium, cell(s) ; (group of) cells performing the same function(s) ; (iii) large surface area ; permeable ; thin / short, diffusion path ; moist ; good blood supply / close to blood ; well ventilated / in contact with respiratory medium ; OCR/2801/JUN2006 SAQ176.a.

Structure Letter on diagram

Bronchiole Y

Branch of pulmonary artery X

Branch of pulmonary vein Z

b. 1. walls of alveoli one cell. thick / thin (epithelium) : 2. walls of (blood capillaries / endothelium {one cell thick / thin} 3. Alveoli covered with a dense network of capillaries/eq 4. Concentration gradients maintained by (blood flow / ventilation mechanism) 5. Large surface area provided by alveoli 6. Oxygen combines rapidly with haemoglobin; 7. Correct reference to diffusion. SAQ177.a. 1. Oxygen (from alveoli) to capillary and carbon dioxide (from capillary) to alveoli: 2. By diffusion / movement of molecules from area of high concentration to an area of Low concentration. b.1. Large surface area / lots of alveoli: 2. Large surface area of capillaries/ eq; 3. Thin alveoli walls; 4. Thin capillary walls: 5. (Circulation of blood / ventilation of lungs} to maintain concentration difference: 6. Short diffusion pathway. SAQ178.a.

b.30 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. 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 ; SAQ179 .a.i.Refer the notes ii. Peptide bond b. An explanation to include two from: 1. chain folds into secondary structure / reference to a-helix or f3 pleated sheets: 2. then folds into tertiary structure 3. (bonds / Interactions) between R groups: 4. reference to named bond; Reject peptide. c.i. An explanation to include: 1. substrate concentration limiting the rate/ or converse: 2. correct reference to not all active sites occupied by substrate. ii. An outline to include four from: 1. identify Independent variable and dependent variable: 2. select suitable range of concentrations (at least 5): 3. fixed volumes of enzyme I substrate: 4. control of named variable(s): 5. description of apparatus used: 6. correct method of obtaining quantitative results: 7. reference to replication / calculation of rate / mean values. SAQ180. Insulin is made up of two polypeptide chains, but collagen is made up of three polypeptide chains. Insulin has a tertiary structure, but collagen does not have a tertiary structure.


SAQ181. sequence; peptide; condensation; hydrogen; disulphide / covalent; residual groups / R groups SAQ182. amino acids; peptide; condensation; alpha helix; hydrogen. SAQ183. IGNORE - NOT IN SYLLABUS SAQ184.a.i. P – Amino acid Q – Triglyceride R – Alpha glucose ii. Nitrogen iii. Polypeptide / protein iv. Peptide bond v. Polysaccharide b.

SAQ185.a. IGNORE NOT IN SYLLABUS Add 5 cm3 of biuret reagent to a 5 cm3 of the protein solution. If the solution turns purple, violet or lilac then proteins are present. b. i. Nitrogen ii. Condensation reaction iii. Refer to notes SAQ186. nitrogen; peptide; alpha helix; hydrogen; residual groups / R groups SAQ187. Name of biological molecule

Smaller molecules from which it is made

Name of bond joining the smaller molecules

Triglycerides FATTY ACIDS AND GLYCEROL

ESTER

CELLULOSE β Glucose GLYCOSIDIC

Polypeptides Amino acids PEPTIDE

SAQ188.a.i. Ionic bond, covalent bond, hydrogen bond. ii. Two polypeptide chains are linked to each other.

b.i. The sequence of amino acids in a polypeptide chain. ii. The primary structure is always the same. So, the same types of bonds form and the molecule flods into the same shape. SAQ189.a.i.

ii. Condensation reaction SAQ190.a. Allows process to be run continuous or enzyme more stable or enzyme does not contaminate product. b. Smaller beads means greater surface area so more active sites are exposed to substrate for reaction. c.i. More lactose left in milk / not enough time to breakdown all lactose. ii. Not making full use of available enzyme. SAQ191. a. 1. Prepare a range of concentrations of amylase; 2. Known concentration/ excess substrate/ starch 3. Temperature is controlled; 4. Detail of measuring method; 5. Calculation of rate reference to timing. b. Increased rate with increased concentration; More active sites; More collisions with substrate molecules; More enzyme substrate complex per unit time. c. Inaccurate measurements/ experimental error/ small number of readings. Specific reference to difficulty of measuring end point. Explanation of curve eg. Substrate becomes limiting/ not a directly proportional relations. Reference to other variable. d. Enzyme specificity/ Cellulase will not break down starch; Shape of active site; reference to deferent bonds in cellulose and starch/ alpha and beta glucose.


SAQ192.a.i. Entrapment in {alginate /gel} {beads / matrix) ii. Enzyme more stable; Product not contaminated with enzyme / less down stream processing to remove enzyme; Enzyme can be reused; Allows a continuous process: b. Sucrose/ other disaccharide {doesn't fit / is the wrong shape/ different structure}; only lactose can fit; Reference to lactase active site: SAQ193. a.i. Water ii. Active site iii. Glycosidic bond b. i.Sucrase [has a (specific) tertiary structure / is a protein} Reference to specific shape of active site Only sucrose will fit (the active site of sucrase) / enzymes are specific to substrate / correct reference to "lock and key" Form an enzyme-substrate complex (iiFacilitated diffusion Use of (specific carrier) proteins / moves molecule down a concentration gradient / correct reference to kinetic theory ; OR Active transport ; Use of (specific) carrier proteins / moves molecules against a gradient / uses (ATP / energy}; OR Endocytosis Description of endocytosis e.g. formation of vesicle / use of ATP SAQ194.a.i. 1. (waxy layer) is waterproof ; 2. {enzyme / pectinase} in (aqueous) solution ; 3. (therefore) {enzyme / pectinase} unable to pass through(waxy layer) / unable to get to {pectin / polysaccharide /carbohydrate} / eq ; 4. pectinase is specific and will not digest lipid / waxy surface . ii. 1. shape of (enzyme / pectinase) active site ; 2. fits pectin / does not fit cellulose / reference to specificity of enzymes . b.i. 1. increases the surface area ; 2. more {substrate /pectin} available / increases the number of {enzyme-substrate

complexes / collisions between enzyme / eq and substrate / eq} ii. 1. hydrolysis uses up water ; 2. evaporation of water /eq ; 3. idea of same number of the {enzyme / pectinase} molecules but in less {solvent/water} ; 4. pectinase released from orange tissues/eq ; 5. correct reference to osmosis (into orange) . SAQ195. (a) 6 /0.5 OR 6/30(seconds); 12;

(b) assume candidates are referring to the

initial rate unless otherwise stated.

substrate = H2O2 (concentration of) substrate molecules , high at the start / higher than later; all / most / many, active sites occupied; more chance of substrate / fewer substrate molecules, entering active site ; more product made per unit time ; (c) increased enzyme concentration increases rate of reaction ; more active sites available ; more / greater chance that , substrate molecules enter / collide with, active site ; more product produced (per unit time) ; linear increase as long as plenty of substrate available ; slow reaction at low temperatures ; suitable ref movement / energy, of, molecules / enzyme / substrate, related to temperature ; few (cold) / more frequent (warmer) , collisions (between enzyme and substrate) / ESC formed ; (in warm temp) collisions (occur with more energy) to break bonds ; at high temperatures enzymes are denatured ; molecule vibrates breaking bonds (within enzyme molecule) ; change of pH from optimum reduces rate of reaction ; H ions interact with R groups (of amino acids) ; affect bonding within, enzyme / active site ; pH that is very different from optimum will denature enzyme ; tertiary structure / 3D shape, altered ; active site loses (precise) structure ; substrate no longer fits into active site inhibitor reduces rate of reaction ; bind to enzyme ; (binds) at active site and blocks it ; (binds) at another site and distorts shape of active site ; substrate unable to bind


with active site ; correct description competitive and non-competitive ; correct description reversible and non-reversible ; correct description end product inhibition ; OCR/2801/JAN2003/Q3 SAQ196. (a) 0.26 (mg dm-3 minute-1); (b) (i) Low kinetic energy; Fewer collisions/enzyme substrate complexes; (ii) Denaturation / alteration in tertiary/3D structure; Breaking of specifically named bonds; (not peptide bonds) Change in active site, substrate cannot bind; BYB1/JUN2008/Q5

SAQ197. a) pH, enzyme concentration, volume of enzyme solution, volume of substrate solution and total volume of reaction mixture are factors that must be kept constant for accurate results. b) As the substrate concentration increases there will be more substrate molecules to bind with the active sites. The collisions between substrate molecules and active sites become more frequent. So the rate of enzyme substrate complex formation increases and the rate of enzyme action increases. c) The curve levels off because all the active sites are occupied. There are no free active sites to bind with the substrate molecules. This is the point of maximum enzyme action which is called as Vmax (maximum velocity). The substrate concentration is no longer limiting the rate of reaction. However, the enzyme concentration is acting as a limiting factor. d) The line on the graph should begin at zero and must be below the original line. Lower temperature results in less kinetic energy and slower movement of molecules. So there are fewer and less energetic collisions between enzyme and substrate molecules per unit time. (Total 9 marks) January 2002 Unit 1, Edexcel SAQ198. a) The activation energy of the enzyme. b)

c) The pH of the mixture will decrease due to the formation of fatty acids formed by hydrolysis of the triglyceride. AQA SAQ199. (a) (i) Rate= mass of product / time (ii) higher kinetic energy at 650C; More frequent collisions/enzyme substrate complexes; (b) at 650C reaction is faster, so reaction is complete between 4 to 6 hours; at 550C reaction is slower, so reaction is still not complete but proceeds at a low rate; (c) buffer maintains a constant optimum pH for enzyme action;

SAQ200. (a) pH ; enzyme concentration ; enzyme (solution) volume ; substrate (solution) volume ; total volume ; 2

(b) more collisions / complexes ; with, enzyme / active site (and substrate) ; in unit time / eq ; 2

(c) enzymes are working as fast as they can / reference to Vmax ; all active sites occupied /

eq ; substrate concentration is no longer a limiting factor ; enzyme concentration is limiting ; 2

(d) line on graph begins at zero and is below original line ; less kinetic energy / molecules moving more slowly ; fewer collisions (between enzyme and substrate) ; less energetic collisions ; in unit time / eq ; 3

EDEXCEL/1A121


SAQ201. (a)

(b) F Line graph drawn; A Axes correct orientation and (abetted with units and using haLf paper: P ALL points plotted correctly: L Line joins points or good tine of best fit through the points: 4 marks c. (Initial) rate increases until a concentration of 190.2 mmol dm-3; Rate increases at (constant / almost constant) rate to a concentration of 158.5 mmol dm-3 / rate of increase is less between 158.5 - 190.2 mmol dm-3; Rate (doubles / almost doubles) as concentration doubles between (31.7 and 63.4 / 63.4 and 126.8) mmol dm-3 / manipulation of figures: Rate remains constant after 190.2 mmol dm-3; d.) Hypothesis correct at Lower concentrations / eqs: Reference to need to modify hypothesis at higher concentrations (e.g. rate of increase decreases at higher concentrations): Reference to active sites becoming saturated at higher concentrations / eq 2 marks e.) one variable not controlled e.g. (temperature / pH / lack of temperature equilibration}; (concentration / volume) of enzyme not standardised: Hydrogen peroxide not renewed for second run: (At high concentrations) time Is too short to- measure accurately: End point difficult to determine accurately: f.) core practical method more reliable because it directly measures the concentration of oxygen released; more accurately; g.) double the volume by usinmg distilled water; EDEXCEL/W1/MAY2004 SAQ202. (a) nucleotide; (b) (i) 21.4, 21.4; 28.6;

(ii) amounts of A and T / C and G / complementary bases different; therefore no base-pairing; (iii) both contain phosphate; pentose / 5C sugar; both have nucleotides/are polymers; both have purines / pyrimidines /bases /A/C/G;

Total 7 AQA/BYA2/JUN05/Q5 SAQ203. (a) appropriately placed box; (b) (i) B; (ii) A; (c) (i) determines (sequence of) amino acids / specific protein produced / mRNA formation; (ii) hydrogen bonds; (iii) stability / protects bases / replication; Total 6 AQA/BYB2/JAN05/Q1 SAQ204. A . Phosphate B. Organic base C. Deoxy ribose sugar B)i) T T T G T G ii) U U U GUG SAQ205. (a) R first reference to 15N being

radioactive semi-conservative replication would give one, template / original / old / parent, strand and one, new / daughter, strand ; complementary base pairing / joining of new nucleotides / two isotopes in molecule / molecule contains both 14N and 15N ; one strand with, ‗heavy‘ N / 15N ; R molecule one strand with, ‗light‘ N / 14N ; Rmolecule no molecules with only, 1 isotope / 14N / 15N (b) A ; C ; C and E ; (c)band drawn for 14N and 14N/15N only ; thick for 14N and thin for 14N/15N; OCR/JUN06 SAQ206. (a) (i) base / named bases; reject

nucleotide or uracil (ii) it has been produced by semi-conservative replication / one old strand and one new; one strand has 15N bases and the other 14N; Accept light / heavy N (therefore) it is less dense / lighter; (iii) one band is in same position as generation; one band higher; (b) (i) A = 31 and T = 31; C = 19; (ii) viral DNA single-stranded / not double-stranded; evidence from table e.g. not equal amount of A and T / C and G / all different;


(c) 1. DNA splits / separates / hydrogen bonds break; accept DNA unzips 2. to make mRNA; 3. using RNA nucleotides; 4. via RNA polymerase; 5. complementary pairing / eq.; 6. introns/non-coding DNA spliced out; accept junk DNA spliced out 7. mRNA joins to ribosome (accept travels to ribosome); 8. tRNA carries a specific amino acid; 9. codon-anticodon relationship / explained; 10. peptide bonds form between amino acids; 6 max AQA/BYA2/JUN06/Q9

SAQ207. (a) (i) A phosphate: NOT molecule B pentose I 5-carbon sugar / deoxyribose: C base / adenine / thymine / cytosine / guanine; (A) purine / pyrimidine (ii) base/C: (b) 1, template / original / old , and 1 new.: AW complementary base pairing: 2 isotopes in molecule: half/ 1 (original) strand with, 'heavy‘ N I 15N: half / 1 (new) strand with . 'light‘ N / 14N; no molecules with only 1 isotope: (c) A; C; B and C; (d) bar drawn in 14N column and ‗14N/15N‘ column:‘ 75% for ‗14N‘: 25% for ‗14N/15N‘: OCR/JAN02/Q7 SAQ208. (a) each strand copied/acts as a template; (daughter) DNA one new strand and one original/parent strand;

(b) (i) 15

N/ tube B (DNA), more/greater density; (ii) DNA with one heavy and one light strand;

new/synthesised strand, made with 14

N/ light strand; (c) 32; 28 32 26; AQA/BYB2/JUN06/Q4 SAQ209. (a) (i) A = phosphate and B = Deoxyribose/ pentose/5-carbon sugar; (ii) (Nitrogenous/organic) base(s); Both bonds formed with the same base; (b) Prevents DNA replication/being copied; Prevents production of proteins needed (for cell division); Prevents transcription or a description e.g. forming mRNA; Blocks (complementary) base pairing/hydrogen bonding; Blocks (DNA/RNA) polymerase;

Prevents strands separating/helix or DNA unwinding/unzipping/prevents H bonds breaking (if binds across helix);

AQA/BYB2/JAN08/Q2 SAQ210.a.i. Adenine ii. Uracil iii. Phosphate b. A description to include two from: 1. double (stranded / helix): 2. base pairing / A-T,C-G; 3. hydrogen bonds (easily broken): c. Any two from: 1. DNA replication - both strands copied / transcription only one strand copied; 2. DNA replication uses T, transcription uses U: 3. Reference to DNA polymerase / RNA polymerase: 4. DIIA replication copies whole strand / transcription only copies part of the strand / eq-:n 5. mRNA synthesised in transcription, not in DNA; SAQ211 .a. (nitrogenous / organic) base / named base b. Draw 8 pairs of lines, on that two lines are heavy. c. DNA polymerase / helicase / DNA ligase / primase d. T C G A A T G G T e. 1. correct reference to description of gene mutation ; 2. change {mRNA / codon / eq} ; 3. {different / wrong / no} amino acid included /stop codon ; 4. different / eq {sequence of amino acids / primary structure of protein} ; 5. different R groups ; 6. change bonding in protein / correctly named bond(s) ; 7. protein forms different {secondary / tertiary / quaternary}structure ; 8. different (3D) shape. SAQ212 .a.i. A – Transcription B – Translation ii. D is the Golgi body. It is the site of modification of proteins / polypeptide chains. iii. Exocytosis.


b. The transfer RNA binds to specific amino acids in the cytoplasm, using ATP and the enzyme tRNA-aminoacyl synthetase. The tRNA then carries the amino acid into the ribosome and matches the amino acid to its specific codon within the ribosome, by complementary base pairing between the codon and anticodon. This enables two specific amino acids to lie adjacent to each other in the ribosome. The enzyme peptidyl transferase then catalyses the formation of a peptide bond between the amino acids. The process continues until a stop codon is reached and a complete polypeptide chain is formed. SAQ213.

Feature DNA RNA

Cytosine present √ √

Uracil Present X √

Pentose sugar present

√ √

Is single stranded X √

JAN2003/UNIT1/EDEXCEL SAQ214.a. During transcription, the genetic information from the sense strand of DNA is copied by the formation of a single stranded mRNA molecule. The sense strand serves as a template for the free ribonucleotides to pair up with complementary bases on the sense strand, following the base pairing rule: DNA to mRNA Adenine with Uracil; Thymine with Adenine; Guanine with Cytosine; Cytosine with Guanine; The enzyme RNA polymerase joins the individual nucleotides by the formation of phosphodiester bonds. A single gene is copied during this process and will be used to form a single polypeptide chain. The genetic information is then carried out of the nucleus in the form of mRNA. b) (3) During translation, the genetic information on mRNA is used to determine the sequence of amino acids in a polypeptide chain. The mRNA attaches to the ribosome and tRNA molecules carrying specific amino acids enter the ribosome and match the amino acids to their specific codons within the ribosome, by

complementary base pairing between the codon and anticodon. The amino acids are linked by peptide bonds and a polypeptide chains with a specific sequence of amino acids is built up, until a stop codon is reached SAQ215.a. A – Phosphate group (Inorganic) B – Pentose sugar C – Nitrogenous base b. U C G G C A G G G C A G c. During semi-conservative replication of DNA, the enzyme helicase, causes the two parent strands to unzip by breaking hydrogen bonds between the base pirs. Each unzipped strand of parent DNA serves as a template for free nucleotides to pair up with complementary nitrogenous bases, following the base pairing rule: Adenine with Thymine Guanine with Cytosine The individual nucleotides are then linked up by the formation of phosphodiester bonds, using the enzyme DNA polymerase. DNA ligase joins the fragments of DNA formed during this process. Finally, each daughter DNA consists of one complete parent strand and one complete new strand of polynucleotides. d. 12.5 % of the final mass of DNA will be radioactive. In the first replication, 50 % of DNA is radioactive – one strand in each daughter molecule. In the second replication, 25 % is radioactive – two completely non radioactive molecules and two molecules with one complete radioactive strand. In the third replication, also only two molecules are half radioactive and the remaining are non radioactive. e. DNA replication takes place during the S – Phase of interphase. SAQ216. condensation, deoxyribose sugar, Thymine, helix, hydrogen


SAQ217.a. The enzyme helicase separates the two DNA strands by breaking the hydrogen bonds between the nitrogenous bases. b. The nucleotides are joined up by condensation reactions, using DNA polymerase enzyme. c. DNA replication takes place during the S – Phase of interphase. d.

SAQ218.a. J – Inorganic phosphate group K – Deoxyribose sugar L – Nitrogenous base M – Nucleotide b. The dotted lines represent Hydrogen bonds between the base pairs. c.

DNA mRNA

Double stranded molecule

Single stranded molecule

Contains Adenine, Thymine, Guanine and cytosine, but no Uracil.

Contains Adenine, Uracil, Guanine and cytosine, but no Thymine.

Contains Deoxyribose sugar

Contains Ribose sugar

d. The DNA controls all the genetic information that is needed for proteins synthesis. If the DNA is not replicated exactly, it will result in genetic changes, which will form defective proteins and adversely affect metabolic activities of the daughter cells. e.i

ii. DNA polymerase is used in DNA replication.

SAQ219.a.

Statements True False Correct word

During the formation of new DNA molecule, the base pairing is followed by bonding between deoxyribose and bases

X

√

Phosphate group

Synthesis of mRNA takes place in the nucleus

√

X

mRNA consists of many codons, each consisting of a base, ribose and phosphate

X

√

Nucleotides

b.i. AGC and AGU ii. The triplet TAC on DNA will code for methionine. iii. Leucine SAQ220.a.

DNA Nucleotide RNA Nucleotide



Does not contain Uracil

Does not contain Thymine

b.i. No. of nucleotides in chromosome = 125000000 x 10

= 125 000 0000 125 000 0000 nucleotides = 1 m 1 nucleotide = X X = 8 x 10-10 m = 8 nm Length = 8 nm ii. Protein synthesis takes place in two stages,

namely transcription and translation. During transcription, the genetic information from the sense strand of DNA is copied by the formation of a single stranded mRNA molecule. The sense strand serves as a


template for the free ribonucleotides to pair up with complementary bases on the sense strand, following the base pairing rule: DNA to mRNA Adenine with Uracil; Thymine with Adenine; Guanine with Cytosine; Cytosine with Guanine; The enzyme RNA polymerase joins the individual nucleotides by the formation of phosphodiester bonds. A single gene is copied during this process and will be used to form a single polypeptide chain. The genetic information is then carried out of the nucleus in the form of mRNA. During translation, the genetic information on mRNA is used to determine the sequence of amino acids in a polypeptide chain. The mRNA attaches to the ribosome and tRNA molecules carrying specific amino acids enter the ribosome and match the amino acids to their specific codons within the ribosome, by complementary base pairing between the codon and anticodon. The amino acids are linked by peptide bonds and a polypeptide chains with a specific sequence of amino acids is built up, unitl a stop codon is reached. c. During semi-conservative replication of DNA, each parent strand of DNA serves as a template for the formation of a complementary strand of DNA, using nucleotides from the medium. The free nucleotides pair up with complementary bases on the coding strand, following the base pairing rule: Free nucleotide with Parent strand

Adenine with Thymine Guanine with Cytosine Thymine with Adenine Cytosine with Guanine

Thus, the adenine bases on the parent strand will pair up with radioactive thymine nucleotides from the medium to form a component of the new DNA molecule. SAQ221.a.i. A – Deoxyribose sugar and inorganic phosphate (sugar phosphate backbone) B – Nitrogenous bases (Adenine, guanine, cytosine or thymine)

ii. Hydrogen bond b. 1 kilobase = 0.00034 mm (As, 1000 μm = 1 mm) 2900000 kilobase = X X = 986 mm c. The DNA is double stranded – this allows it to remain uncontaminated and unreactive. The double strand prevents the nitrogenous bases from reacting with chemicals in the cell or nucleus. The Hydrogen bonds between the base pairs can be broken by enzymes, causing the two strands to unzip. This makes it possible for the bases to be exposed during transcription and translation. The DNA is coiled and wound into a double helix, when not in use. This makes it compact and enables it to be transferred easily during cell division. SAQ222.a. Inorganic phosphate and deoxyribose sugar b.

Number of bases

A T G C

Strand A 6 4 5 2 Strand B 4 6 2 5

c. Every cell has a specific function and structure. This is called differentiation or specialization. This is brought about by activation of specific genes in different cells. The type of genes that are active in the liver cells will be different from the genes that are active in the liver cells. This means that both cells will have different types of proteins and enzymes, which determines and controls the structure and functions of the cells. SAQ223. a.i. P – Adenine Q - Guanine R - Thymine S – Cytosine ii. Every base on the DNA sense strand pairs with a complementary base on the anti sense strand. Thus, the number of bases will be the same. iii. This is due to post transcriptional modification of mRNA. The introns are the non coding region and are removed by splicing before the mRNA is released from the nucleus. Also the poly adenine tail and guanine cap are added to mRNA, which again alter the number of bases.


b. 1824 ÷ 3 = 608 amino acids c. The antisense strand pairs with bases on the sense strand. This prevents the genetic code from being exposed to chemicals in the cell. It makes the DNA less reactive. However, it can unzip when needed and expose the sense strand for transcription or replication. SAQ224. a. During semi-conservative replication of DNA, the DNA is unwound by the enzyme helicase by the breaking of hydrogen bonds between the base pairs. This exposes each parent strand of DNA, which can now serve as a template for the formation of a complementary strand of DNA, using nucleotides from the medium. The free nucleotides pair up with complementary bases on the template (parent) strand, following the base pairing rule: Free nucleotide with Parent strand

Adenine with Thymine Guanine with Cytosine Thymine with Adenine Cytosine with Guanine

This gives rise to the formation of two identical molecules of daughter DNA. Each daughter DNA molecule has one complete old strand and one complete new strand of nucleotides. b. i. DNA in batch B is lighter than DNA from batch A. This is because DNA from batch A contains all heavy nitrogen, where as the DNA from batch B will contain both heavy and light nitrogen (One strand of old radioactive heavy nucleotides and one complete strand of new light nucleotides from the medium). ii. In batch C, every DNA molecule will contain one complete strand of light DNA. The DNA in the lower band will contain one complete old heavy strand and one complete new strand of light DNA. This is called intermediate DNA. The DNA in the upper band will contain light DNA only, in both strands. This is light DNA. Both bands have equal thickness as light and intermediate DNA are found in equal proportion. iii.

SAQ225.a. i. w. Guanine x. Nucleotide Y. Phosphate z. Ribose sugar ii Hydrogen b.i. Transcription ii. Aspartic acid, Arginine, Cysteine, Lysine iii. 1. Incorrect amino acid inserted into polypeptide chain / (chain / sequence) or amino acids changed: 2. Named (Gly / glycine): 3. Different (side group / R group ); 4. Different bonds formed 5. Different (3D) shape when folded.

OCR/JUN07 SAQ226. (a) (i) U A C C G G A U U C A C ; ; (ii) transcription / transcribed ; R transcriptase (b) (i) J anticodon ; R anticodons K transfer RNA / tRNA ; L ribosome / rRNA ; M codon ; R codons (ii) DNA triplet / codon / M / mRNA triplet, Codes for specific amino acid; order of, triplets / bases , determines the order of amino acids; tRNA / K , has , corresponding /complementary , triplet / anticodon; (tRNA / K) attached to specific amino acid; activation of amino acid ; (tRNA) binding sites on the ribosome; codon and anticodon bind ; match A to U and C to G ; adjacent amino acids join ; peptide bond (b) attaches to ribosome; removes , base / portion , of ribosome; A stops ribosome assembling / changes shape of ribosome prevents ribosome , attaching to / reading , mRNA; prevents codons being exposed; prevents , tRNA / anticodon , attaching to , mRNA / codon; prevents / inhibits enzyme responsible for , formation of peptide linkages; [Total: 13] OCR/JUNE07/Q3 SAQ227.AQA/BYA2/JAN06


SAQ228. (a) GCAAUG; ; (b) (i) DNA is edited/introns present in DNA; 1

Allow reference to .junk.or non-coding DNA (ii) 220; allow 218 or 219-allow Three bases/nucleotides code for one amino acid; Correct explanation for 218 or 219; (c) mRNA has no base-pairing, tRNA has base-pairing/ mRNA linear, tRNA cloverleaf shape; mRNA has no binding site for amino acids, tRNA has; mRNA different for each gene/many kinds, only few/20/64 kinds of tRNA; accept mRNA longer/larger/more nucleotides than tRNA AQA/BYA2/JAN06 SAQ229. (a) (i) C → B → E → F → A →D (ii) nucleus; (iii) A, D, F; (ignore E if evident) (b) (i) Isoleucine; (ii) TGG; AQA/BYA2/JUN04 SAQ230. (a) (i) join/attach nucleotides, to form a strand/along backbone/phosphodiester bonds; (ii) ribosome/RER; (b) (i) CGTTACCAA; (ii) CGU UAC CAA; (c) substitution; (d) (i) alanine; (ii) (mutation 1) no change (to sequence of amino acids); codon for alanine/degenerate codon/same amino acid coded for; (mutation 2) (change in sequence) valine replaced by alanine/codon for alanine; folding /shape / tertiary structure / position of bonds may change; AQA/BYA2/JUN06 SAQ231. a. C C U U b. Anti codon c.

1. About 20 amino acids; 2. Triplet gives 64 permutations/ 43 3. Presence of 4 bases 4. Lowest number of bases enough

permutations/ 1 or 2 bases no enough permutation/ more codes than needed

5. Code is degenerate/ some amino acids have more than one code.

d. Ensure that the collect amino acid coded to polypeptide for given anticodon. The correct

sequence of amino acids to correct polypeptide structure. Presence of complementary base pairing. e.i. 1. Radioactivity in protein notes sharply; and falls more slowly. 2. Protein peaks between 5-7 mins; 3. Radioactivity in RNA falls through out; 4. Compare rate before and after about 5 mints; 5. Reference to a relationship between protein and RNA. ii. 1. Amino acids had been taken up by tRNA; 2. tRNA released amino acid at ribosome‘s; 3. Became part of protein during translation SAQ232.a. P. mRNA Q. tRNA R. Amino acid S. Anticodon b. .DNA, transcription, mRNA, translation, Complementary, Uracil, Guanine, peptide. SAQ233.a. Plasma proteins are too large to pass out during formation of tissue fluid {Soluble / plasma} proteins {decrease the water potential / increase the solute potential} of blood . Water is drawn back into blood By osmosis b.i. Sequence of {bases / nucleotides} on DNA / section of DNA which codes for a (specific) {protein /polypeptide} ii. 1. mRNA lines up at the ribosome 2. tRNA picks up specific amino adds ; 3. Codon-anticodon bonding (at the ribosome) / tRNA-mRNA complementary base pairing 4. Formation of peptide bonds (between adjacent amino acids) 5. Ribosome moves along the mRNA strand 6. Use of {start / stop} codon 7. Polypeptide released and folds into tertiary structure. iii. Hydrogen; Disulphide ;Ionic / electrovalent ; Peptide ; SAQ234.a.i. Relates to the sequence or amino acids ii. 1. Reference to R groups; 2. Reference to (specific) folding of the chain / tertiary structure / eq; 3. Reference to named bonds [not peptide]


b. 1. Enzymes have a (specific) active site 2. will only fit substrate with the correct shape / eq: 3. Reference to Lock ft key / enzyme-substrate complexes / induced fit: c. 1. Correct reference to translation: 2. mRNA Lines at the ribosome / eq: 3. tRNA attaches to specific amino acids) eq: 4. Codon- anticodon binding complementary base pairing between mRNA and tRNA; 5. Peptide bond: 6. Correct reference to start-) stop codons; SAQ235. a.i. ii. An explanation to include three from: 1. appropriate reference to {secondary structure / α-helix or β-pleated sheet}; 2. polypeptide chain folded in a specific shape / reference to tertiary structure; 3. reference to R groups; 4. bonding between R groups determines the shape; 5. named bond ie. hydrogen, disulphide, ionic b. i. 6 ii. transcription iii. AUG CCA UAC GGU UGG AAG SAQ236. (a) AGC; TTC; (b) anticodon complementary to codon/reads message on mRNA; specific amino acid; carried/transferred (to ribosome); correct sequence of amino acids along polypeptide; (c)

AQA/BYB2/JAN06

SAQ237.a. i.E: phosphate; F: ribose; G: uracil; ii. nucleus b.i. Tyr, Val, Glu, Arg; ii. Transalation iii. 1. change in amino acid sequence / primary structure of the protein; 2. Tyr replaced by a stop codon / UAG; 3. {polypeptide chain/protein} would be shorter / eq; 4. protein would have a different shape/structure / fold differently / eq; 5. protein would not function (normally);

6. RNA polymerase not functioning would mean that {no/less} transcription could take place; 7. {no/less} RNA could be synthesised by this cell; 8. {no/less} proteins could be made by this cell. SAQ238. Translation: Using the genetic information (sequence of bases) on mRNA to form a polypeptide chain with a specific sequence of amino acids is called translation. It occurs on the ribosomes in the cytoplasm. A ribosome attaches to the mRNA at an initiation codon (AUG). The ribosome encloses two codons. met-tRNA diffuses to the ribosome and attaches to the mRNA initiation codon by complementary base pairing. The next amino acid-tRNA attaches to the adjacent mRNA codon (ala in this case). The bond between the amino acid and the tRNA is cut and a peptide bond is formed between the two amino acids. The ribosome moves along one codon so that a new amino acid-tRNA can attach. The free tRNA molecule leaves to collect another amino acid. The polypeptide chain elongates one amino acid at a time, and peels away from the ribosome, folding up into a protein as it goes. This continues for hundreds of amino acids until a stop codon is reached. A single piece of mRNA can be translated by many ribosomes simultaneously. A group of ribosomes all attached to one piece of mRNA is called a polysome.

SAQ239. a. Ribosomes b.i. Amino acid ii. A sequence of three bases on tRNA which pairs with complementary codons on the mRNA iii. tRNA is folded into a clover leaf structure due to hydrogen bonds between the bases, where as mRNA bases do not pair or bond with each other.


SAQ240. a. P – Inorganic phosphate Q – Deoxyribose sugar R – Adenine S – Nucleotide b. DNA Polymerase c. S phase of interphase SAQ241.a.

b.i. There are 123 amino acids in the chain. Each amino acid is coded for by three nucleotides (one codon). Thus, 123 amino acids will be coded for by 369 nucleotides (123 x 6). ii. CGA – AAT – TCA – CTC c.i. On the ribosomes ii. During translation, the genetic information on mRNA is used to determine the sequence of amino acids in a polypeptide chain. The mRNA attaches to the ribosome and tRNA molecules carrying specific amino acids enter the ribosome and match the amino acids to their specific codons within the ribosome, by complementary base pairing between the codon and anticodon. The amino acids are linked by peptide bonds and a polypeptide chains with a specific sequence of amino acids is built up, until a stop codon is reached. d. The DNA is double stranded – this allows it to remain uncontaminated and unreactive. The double strand prevents the nitrogenous bases from reacting with chemicals in the cell or nucleus. The Hydrogen bonds between the base pairs can be broken by enzymes, causing the two strands to unzip. This makes it possible for the bases to be exposed during transcription and translation. The DNA is coiled and wound into a double helix, when not in use. This makes it compact and enables it to be transferred easily during cell division.

SAQ242.a.

DNA RNA

Double stranded molecule

Single stranded molecule

Contains Adenine, Thymine, Guanine and cytosine, but no Uracil.

Contains Adenine, Uracil, Guanine and cytosine, but no Thymine.



b.i. The part X is the amino acid attachment site. ii. Part Y is the anti codon. It is a sequence of three bases, which pairs with the codons on DNA and matches the amino acids to their respective codons during translation. c.i. Because a sequence of three bases codes for a single amino acids along the DNA. These triplets do not overlap and can code only for a specific sequence of amino acids. ii. A single amino acid may be coded for by more than one codon. SAQ243.a.i. transfer RNA or tRNA Ii. UAG (anticodon) b. During translation, the genetic information on mRNA is used to determine the sequence of amino acids in a polypeptide chain. The mRNA attaches to the ribosome and tRNA molecules carrying specific amino acids enter the ribosome and match the amino acids to their specific codons within the ribosome, by complementary base pairing between the codon and anticodon. The amino acids are linked by peptide bonds and a polypeptide chains with a specific sequence of amino acids is built up, until a stop codon is reached. SAQ244.a.i. In the nucleus ii. Condensation reactions b.i. Six amino acids ii. GCT – TGG – CGG – GCT – TAG – TGG c. This is because of the occurrence of the start codon and stop codon on the mRNA. Some of the nucleotides from the mRNA may also be removed before it moves out of the


nucleus. This is referred to as post transcriptional modification. d. During translation, the genetic information on mRNA is used to determine the sequence of amino acids in a polypeptide chain. The mRNA attaches to the ribosome and tRNA molecules carrying specific amino acids enter the ribosome and match the amino acids to their specific codons within the ribosome, by complementary base pairing between the codon and anticodon. The amino acids are linked by peptide bonds and a polypeptide chains with a specific sequence of amino acids is built up, until a stop codon is reached. SAQ244. a. On the diagram b. During transcription, the genetic information from the sense strand of DNA is copied by the formation of a single stranded mRNA molecule. The sense strand serves as a template for the free ribonucleotides to pair up with complementary bases on the sense strand, following the base pairing rule: DNA to mRNA Adenine with Uracil; Thymine with Adenine; Guanine with Cytosine; Cytosine with Guanine; The enzyme RNA polymerase joins the individual nucleotides by the formation of phosphodiester bonds. A single gene is copied during this process and will be used to form a single polypeptide chain. The genetic information is then carried out of the nucleus in the form of mRNA. c.i. In the ribosomes saq246. a. Ribosomes are made up of two subunits – a larger subunit and a smaller subunit. The larger subunit is made up of two rRNA and proteins, while the smaller subunit is made up of one rRNA molecule and proteins. b. Amino acids 2 and 3 are Glycine and lysine respectively. SAQ247. (a) EITHER 1. amniocentesis ; 2. amniotic fluid removed (from amniotic sac of mother) / eq ; 3. {fetal / embryonic} cells present in amniotic fluid /{fetal / embryonic} cells needed ;

4. DNA can be analysed / eq ; 5. to detect {defective / eq} gene(s) (in sample) / eq ; OR 1. chorionic villus sampling ; 2. placental tissue removed (from womb of mother) / eq ; 3. fetal cells present in {placenta / placental tissue / chorionic tissue} / fetal cells needed ; 4. DNA can be analysed / eq ; 5. to detect {defective / eq} gene(s) (in sample) / eq ; (b) Benefit: 1. gives information about abnormalities (in fetus) / eq ; 2. {opportunity for choice / eq} / {consider termination / eq} / time for {preparation / treatment / eq } / {peace of mind / eq} ; Risk: 3. possibility of miscarriage (due to procedure) / eq ; 4. {potentially a healthy baby would be lost / eq} / {risk to mother / eq} ; OR 3. idea of {false positive / false negative} result 4. wrong decision made / description of wrong decision ; OR

3. {damage / harm} to fetus ; 4. subsequent health issues / miscarriages / eq (c) 1. idea that a fetus is living ; 2. abortion is {wrong / murder} / eq ; OR 1. who has right to decide if tests should be performed / eq ; 2. implications of medical costs / disagreements over next step ; OR 1. issues relating to confidentiality of {parents / child} / eq ; 2. idea that {some other abnormality may be found / paternal DNA does not match / other family members have right to know results} ; OR 1. that or some other abnormality may be found ; 2. comment on possible problems with {future employment / insurance / what constitutes a serious condition} / eq ; OR


1. not fully understanding possible risks of prenatal testing; 2. possibility of {miscarriage / harm to child} / OR 1. {who has the right to make the decision for the fetus / fetus has decision rights} (if the test is positive) ; 2. {denying them the opportunity to live / fetus should be allowed to live / fetus has a right to live} ; Edexcel/June2009/unit1 SAQ248. (a) (i)

(ii) arg-met-leu-arg (c) (i) No effect/still codes for arg(inine); Important part of triplet is beginning/any triplet starting GC gives Arg(inine)/code is degenerate/3rd base does not matter; (ii) Met(hionine) replaced by iso(leucine); As TA/ first two bases followed by any other letter is iso(lucine); 2 (d) Deletion causes frame shift/alters base/nucleotide sequence (from point of mutation); Changes many amino acids/sequence of amino acids (from this point); 2

AQA/BYB2/JUN08

SAQ249. (a) Two suitable mutagenic agents;; e.g. High energy radiation / High energy particles; X-rays/cosmic rays; Gamma rays; UV light; Alpha particles; Beta particles; Nitrous oxide; Benzene; Tar from cigarettes; Mustard gas; Phenols; Colchicines; (b) 1 (Defective)CFTR/ carrier / intrinsic protein / channel in membrane / epithelial cells; 2 Blocks outward passage of chloride ions; 3 Water retained in cell/prevents water leaving / water enters the cells; 4 Unable to remove mucus in lungs so infection / coughing more likely; 5 Narrowing/blocking of air passages so reduced air flow / breathing more difficult; 6 Increased diffusion distance / reduced surface area for gas exchange reduced / reduced surface area so insufficient oxygen received; 7 Pancreatic duct blocked so less enzymes present / less efficient

digestion; 8 Damage to pancreas can cause diabetes; 9 Mucus in intestines so poor absorption of nutrients/undernourished; 10 Blocked ducts (in reproductive organs) causes fertility problems / sterility; (c) 1 Use liposomes (as vector); 2 Fuse with cell membrane; 3 Applied by aerosol/sprayed/inhaled; 4 Use (harmless) viruses; 5 These enter epithelial cells/inject DNA; 6 (Healthy) CFTR gene attaches to cell‘s DNA; 7 (Healthy) CFR gene expressed/normal CFTR produced; AQA/BYB2/JUN08

SAQ250. (a) One e.g. from; Ionising radiation High energy radiation High energy particles Example of radiation Named mutagenic agent; (b) Methionine: Substitution (always) gives different amino acids; Substitution of C gives isoleucine;; Glycine or isoleucine: Substitution of either of first two bases gives different amino acid; In glycine, substitution of third base still codes for glycine; AQA/BYB2/JAN07 SAQ251. (a) 387; (b) (i) CCAG; (ii) 5; (c) high energy radiation / X rays / ultraviolet light / gamma rays; high energy particles / alpha particles / beta particles; named chemical mutagens e.g. benzene / caffeine / pesticide / mustard gas / tobacco tar / free radicals; length of time of exposure (to a mutagen); dosage (of mutagen); (d) (i) UAC UUA UGG; (ii) addition and deletion (of Bases / nucleotides ); thymine added; adenine deleted; (addition of thymine and deletion of adenine = 3 marks) (allow addition of adenine (RNA) and deletion of uracil (RNA) = 2 marks) AQA/BYB2/JAN05

SAQ252. (a) high energy radiation /ionising particles; named particles/α, β, γ; colchicine; x rays/cosmic rays; uv (light); carcinogen / named carcinogen; mustard gas / phenols / tar (qualified);


(b)(i) removal of one or more Bases/nucleotide; frameshift/(from point of mutation) base sequence change; (ii) sequence of bases in mRNA would change; (sequence of) amino acids different / different primary structure; (active site / enzyme 1) changed tertiary shape / changed active sites; white pigment does not bind; lilac pigment not produced / white pigment remains unchanged/ enzyme 1 does not function; AQA/BYB2/JAN06 SAQ253. blue and lilac; white;

AQA/BYB2/JAN06

SAQ254. (a) (i) allele; (b) (i) reduced/blocked/stopped/slower; (CFTR) protein(one)amino acid missing / changed tertiary/3D shape; (reject irregular shape) (ii) water potential gradient reduced/water potential less negative/ higher in mucus (accept ref to concentration differences) reduced/no movement of water out of the cell / water moves into the cell, by osmosis; (must be in context) (c) transfer of healthy/normal gene; viral / liposome transfer / vector; (reject plasmids) gene transcribed and translated; (or description) gene expressed/functional / normal protein/CFTR produced; AQA/BYB2/JAN06

SAQ255. a. Tryptophan - glycine - lysine - valine - glycine; b.i. Substitution / point mutation; ii. Codes for a different amino acid / could be a stop codon / changes sequence of amino acids, affects primary structure of protein; reference to different bonding in protein; this affects the tertiary structure; changes shape of protein / active site / changes activity in protein; ref. to redundancy explained / possibly has no effect;

SAQ256. a. Sequence: mutant allele leads to formation/ref. transcription of mRNA; with incorrect base(s)/incorrect codon; Order of amino acids: therefore translation/arrangement of/order of amino acids is incorrect; so protein has wrong secondary/tertiary structure/shape; b. pancreatic enzymes/amylase/lipase found in blood; where not normally present; OR low levels of pancreatic enzymes found in faeces; where not normally so low. c. (i) Glucose oxidase (glucose oxidase) catalyses oxidation / breakdown of glucose (ii) Peroxidase H2O2 reduced/broken down (by peroxidase enzyme). SAQ257. Not in syllabus – ignore (a) is always expressed (in the phenotype) / produces (functional) proteins; (b) codominance; (c)

AQA/BYB4/JAN06

SAQ258. (a) Expressed (in the phenotype); In the absence of the dominant allele/ only when homozymous/not when heterozygous; (b)

AQA/BYB4/JAN07

SAQ259.a. Parents Hh and hh; Gametes of each parent shown: Correct genotypes of offspring Hh and hh: Probability 50% 11 in 2/0.5 b.i. 1. Reduce risk of heart disease: 2. Allows early medical intervention / prenatal testing / abortion /decision not to have children; 3. Allows a change in lifestyle:


4. Able to reduce risk factors: 5. Named risk factor; 6. Able to monitor cholesterol levels: 7. Take diuretic drugs / sympathetic nerve inhibitors — lowers blood pressure; 8. Use beta-blockers — reduces heart rate and blood pressure. 9. Use (anticoagulant /platelet inhibiting drugs/ dot busting drugs) — reduces the risk of a clot forming 10. Eat less salt to reduce blood pressure 11. Have a low fat diet/ reduce Intake of cholesterol/ have a more balanced diet /eat less saturated fat / eat more fibre - prevents the build up of (fatty plaques / atheromas/ atherosclerosis / narrowing arteries): 12. Eat five portions of fruit or vegetables a day / take vitamin supplements /take antioxidants — prevents cellular damage duo to free radicals. 13. Exercise more - to increase strength of cardiac muscle /make heart stronger / help prevent build up of (atheroma / fatty plaques) reduce fat (bums fat) / reduce BMI/ reduce risk of obesity 14. Stop smoking — to reduce (nicotine / free radical) levels: 15. Reduce stress - lowers blood pressure; 16. Avoid heavy drinking - avoid risk of damaging (heart tissue / liver tissue) / reduce production; ii. Depression or stress or problems with life insurance companies. SNAB/JAN/2004 SAQ260.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. 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 1:1 dominant : recessive / if self fertilize all dominant or 3:1 dominant : recessive ; Linked to explanation i.e. if all dominant then F2 plant is homozygous / if mix of dominant

and recessive then F2 plant is [heterozygous / carrier]. SNAB/JAN/2005 SAQ261.a. A change or damage to a gene / DNA / chromosome / allele / change in base sequence (on DNA); b.i. Parents‘ phenotypes: normal / unaffected and normal I unaffected: [Reject carrier] Parents' genotypes: Tt and Tt: iii. 3 in 4 / / 75% / 0.75: iv. Genetic screening / amniocentesis / chorionic villus sampling / embryo screening: [Altow genetic testing] SAQ262. a. change in code / base sequence; detail e.g. substitution / addition / deletion; of base(s); different amino acid(s) inserted into protein / polypeptide; role of tRNA b. protein has different shape; tyrosine no longer fits into active site SAQ263.a. gene is a specific sequence / length / eq. of DNA / occurs at a locus on a chromosome; with a specific function / codes for a particular polypeptide / protein responsible for a characteristic; alleles are alternative / different forms of a gene; only one allele present at a locus / alleles are separated in melosis;

b.i. 1IO IO;

2IA IB;

4IA IO;

5IB IO;

6IB IO;

ii. could be either A or B / IA IO or IB IO / AO or BO;

would inherit either (I)A or (I)B from mother / female / one parent;

but (I)O only from father / male / other parent / OR father is homozygous O; SAQ264. a. One form of a / the same gene; b. Probability = . Probability (girl with cystic fibrosis) = 1 in 8 / 1/8 / 0.125 / 12.5%; Prob. Of cystic fibrosis = 1/4/ 0.25/ 25% and P girl = 1/2 / 0.5/ 50%;


c. 1.Chiasma formation / crossing over; Random / independent assortment / segregation SAQ265.a. Restriction endonuclease b. 1. Gel electrophoresis is Use of (agarose / polyacrylamide) gel: 2. DNA loaded into wells / description: 3. Use of a buffer; 4. (Negatively charged) DNA moves to (positive) electrode: 5. DNA fragments move according to {charge / size) / (smaller go further or faster / converse) 6. Transfer DNA to (nylon / nitrocellulose) (paper) / southern blotting: 7. DNA strands separate (exposing base sequences) /single stranded / use of alkali: A gene probe 1. Gene probe with complementary sequence: 2. (Binds ) to faulty genes: 3. Use of (radioactive fluorescent) labelling: 4. Use of imaging technique (e.g. X-ray, UV, laser) c.i. 1. Chloride (ions) (cannot leave / retained by) cell; 2. Correct reference to sodium ions: 3. (Decreases water potential I increases solute concentration) inside cell / eq: 4. Water (diffuses /moves) into cell / water leaves the mucus; 5. By osmosis: 6. Therefore less water in mucus. ii. (Bacteria /pathogen / microorganism) trapped in sticky mucus / antibodies inactivated; SAQ266. SAQ267. a. 1. Test is inexpensive: 2. Test is reliable / no false Positives 3. Test is (simple / painless 4. Quick turnaround of results; 5. Counseling follow up; 6. Education about the test / advertise the test: 7. Confidentiality: b.i. Amniocentesis / chorionic villus sampling; ii. 1. Reference to extraction of DNA (from cells) 2. Use of restriction enzymes 3. Gel electrophoresis; 4. Any detail of gel electrophoresis e.g. (large

and small sections / positive and negatively charged sections) separate; 5. Southern blotting /use of nylon sheet 6. Correct reference to use of gene probe; 7. Detail of (gene probe) e.g. (complementary/ radioactive): 8. Reference to comparison to identify the gene. c.i. 4440 ii. 1. change in amino acid sequence / primary structure. 2. Affects the (specific) shape /tertiary structure of the protein; 3. channel does not allow passage of chloride ions: 4. Does not allow chloride (ions) to leave epithelial cells: iii. 1. chloride (ion concentration) builds up in the cell.: 2. Causes water to move into the cell; 3. By osmosis: 4. Loss of water from mucus makes it sticky. SAQ268.

SAQ269. SAQ270. SAQ271. a.i. 1. Copy of (normal / correct) (allele / gene) inserted into a Loop of DNA / plasmid / vector- / (retro)virus}; 2. Reference to (restriction enzyme / endonuclease): 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) I targeted to lungs: 6. Use of nebuliser: 7. Liposome fuses with membrane and DNA released in cell / (retro)virus inserts DNA into nucleus: 8. Normal (allele / gene] enters nucleus and CFTR protein is transcribed ii. 1. Effect is temporary / process has to be continually repeated / (Because) cells lining airways are continually replaced now chance of success 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 or development. b. 1. Physiotherapy ; Helps (loosen / remove) mucus / improve airflow into and out of lungs / reduce risk of infection 2. Flutter device Vibrations dislodge mucus and aid mucus movement ; 3. Digestive enzymes ;Because pancreatic duct is blocked 4. Bronchodilators Relax muscles in airways resulting in them opening up. SAQ272. a. 1. Correct reference to vector 2. Reference to functional gene codes for (CFTR) protein ; 3. CFTR protein (in cell membrane) 4. Allows chloride ions to leave the cells ; 5. Sodium ions (diffuse) out of cells 6. Lowers water potential in the [lumen / airways} ; 7. Draws water out of the cells by osmosis ; 8. Mucus is kept runny b. 1. (Regular) physiotherapy / rhythmical tapping of the chest cavity Loosens mucus ; 2. Flutter device ; Alters air pressure in respiratory passages Loosens mucus ; 3. Digestive enzyme supplements / other suitable example of dietary change ; Replaces enzymes missing due to blocked pancreatic duct / explained 4. Antibiotics Prevent infections; Due to build up of mucus Cells (lining the Lung die and) need to be replaced /replacement cells do not contain the new gene. SAQ273. a. 4,1,6,2,3,5 b. Somatic gene therapy c.i.

Somatic gene therapy

Germ line gene therapy

1. Alteration in somatic cell genes. 2. The changes won‘t pass to

1. Alteration in gamete cell genes. 2. The changes will pass to future generations.

future generations

ii. SAQ274. IGNORE – NOT IN SYLLABUS. A description to include five from: 1. correct reference to use of restriction enzymes; 2. use of agarose gel / DNA loaded into wells in the gel; 3. pass current through the gel / ref. to electrophoresis / negatively charged DNA moves to positive electrode / anode; 4. smaller fragments travel faster / further (in a given time); 5. reference to (use of alkali) to make DNA single stranded / reference to southern blotting / use of nylon membrane / eq; 6. reference to probe with complementary bases to faulty gene; 7. probe contains radioactive or fluorescent markers SAQ275. SAQ276. i. amniocentesis / chorionic villus sampling / CVS / pre-implantation genetic diagnosis / PIGD. ii. 1. extract DNA from cells; 2. cut DNA using a restriction enzyme; 3. gel electrophoresis; 4. credit one further correct detail of gel electrophoresis; 5. treat with alkali / make DNA single stranded; 6. southern blotting / transfer to a {nylon/nitrocelluose} membrane; 7. use of a gene probe; 8. further detail of a gene probe (complementary sequence /radioactively labelled / fluorescent marker. 9. disclosure {x-ray film / UV light / laser}; 10. comparison with marker gene; SAQ277. 1. CFTR protein defective / eq; 2. chloride ions remain in cells / eq; 3. mucus lacks water/is very sticky / eq; 4. mucus blocks pancreatic (duct);


5. {fewer enzymes / correctly named enzyme} released into the small intestine; 6. lower concentration of enzymes / fewer active sites; 7. fewer collisions between substrate and the active site of the enzymes /named substrate and enzyme; SAQ278. a. Mother and father both heterozygotes / Tt / carriers; Probability of thalassaemia 1/4 and female 1/2; Probability of both 1/8; b.i. Cut at same base sequence as same enzyme used; Fragments are same length / size / have same charge; Only differs by a single base; ii. Single base occurs many times; Sequence of 20 unlikely to occur elsewhere; SAQ279. a. High chloride concentration inside cells lining of lungs because lack of protein CFTR, it prevents chloride ions from escaping; Water removed from mucus lining by osmosis. b. By increasing the thickness of the (gas exchange) surface and diffusion distance or blocks bronchioles and prevents ventilation. c. Chorionic villus sampling can be carried out (earlier / at 8-12weeks) instead of 15-17 weeks. If an abortion is to be carried out the earlier it is done the earlier it is for the mother. SAQ280. a. DNA strands separated; Complementary base sequence/ DNA; Probe base sequence bind to mutant sequence DNA; Marker shows position. b. Test genotype of offspring during early pregnancy; Choice of termination of homozygous/ embryo selection; Preparation fo early treatment or of parents; Peace of mind if normal; Particular risk for these parents. c. 1. Gene copied to all cells of individuals/ cell division/ transfer gene; 2. Normal allele is dominant will be expressed; 3. All cells have normal allele produce normal protein. SAQ281. i. 1. CFTR (protein channel) does not work / eq; 2. Lack of CU ions transported into mucus / eq;

3. water does not move into mucus by osmosis / eq; ii. 1. Mucus blocks airways/bronchioles/alveoli. 2. Reduces surface area for gas exchange / diffusion: 3. Less oxygen (diffuses) into blood. 4. Long diffusion pathway: SAQ282.a. parents‘ genotypes shown (Nn and Nn): parents' gametes shown (N and n for both): son NN and daughter nn b. A description to include four from: 1. cells obtained by cheek (cell) swab / blood test. 2. DNA extracted (from cells) 3. reference to use of restriction enzymes 4. any detail or get electrophoresis method, for example, reference to pipetting Into wells / use of agarose gel / electrodes /electric current / use of buffer /correct reference to fragment size and speed. 5. reference to use of alkali /eq; 6. transferred to {nylon / nitrocellulose) membrane / southern blotting. 7. reference to use of gene probe; 8. further detail of gene probe, for example, radioactive/complementary. 9. reference to use of X ray film. c.i. amniocentesis / chononic villus sampling ii. peace of mind if result is negative / can consider abortion / can prepare for another child with cystic fibrosis: SAQ283.a. 1 genetic, testing / screening: 2 for inherited disease 3 (test to see if) individual is carrier: 4 premarital testing / predict if (potential) offspring may inherit the disease: 5 antenatal testing: 6 ref to termination: 7 embryo selection (to ensure embryo healthy); R selection of sex 8 (test for genes that contribute to) diseases that develop later in life: 9 those with genes given, advice to limit effects / counseling: 10 faster! earlier, diagnosis; 11 develop more, effective / efficient, drugs (to combat disease):


12 drugs have direct effect, on genes / protein made from specific gene code: 13 gene therapy! correct the base sequence of faulty gene:;c 14 economic implications / Aw: 15 AVP: e.g. ref. to method used / use of gene probes / biopsy 16 AVP: allows targeting of drug treatment b. anxiety about (future) health / may not want to know / Aw: many diseases we can test for have no treatments: discrimination by employers: discrimination by, insurance companies / banks: reliability of tests in question: A false, positive/ negative, result example of disease given in context: cost to. NHs / government: rich people can benefit poor will not benefit: e.g. moral issues associated with embryo selection eugenics parents feelings towards child presence of allele may not cause disease / ref to multifactorial diseases ref to storage of data and freedom or information / invasion of privacy question of paternity R 'playing God‘/ cloning.

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marking schemes for topic 1,2 stafford papers

Documents

water temperature

water molecules

large bodies of water

temperature of water

water x x j marking

present j j x

hydrogen bonds

water potential affect