Mark Scheme IGCSE Biology (4325)

Transcription

1 Mark Scheme IGCSE Biology (45) June 006 delivered locally, recognised globally Mark Scheme

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3 IGCSE BIOLOGY 45, MARK SCHEME Symbols used in marking points ; indicates separate mark points / indicates alternatives eq means allow any correct equivalent Paper F. (a) D; A; B; (d) C; (e) B; (f) D; (g) D; (h) C; C; (j) D; Total 0 marks. (a) A B C trachea; bronchus; diaphragm; coronary; fat / cholesterol; oxygen; glucose; Total 7 marks. (a) rice/plant insects/named insect spiders correct order; arrows; stop it eating rice / increases yield / stop damaging crop / eq; spider is a living organism / spider is a predator; reduces insect numbers / eq; Total 5 marks

4 4. warmth / temperature / heat; oxygen / air; water / moisture / humidity; light; Total marks 5. (a) tick in bacterium box; kill microorganisms (in milk) / no microorganisms; don t spoil yoghurt / don t compete with Lactobacillus / safe to eat; tick in lactose box; A; B; D; Total 7 marks 6. (a) plants would not grow / disease passed on to other plants; no microorganisms / eq; would harm plants / infect plants / cause disease; amino acids / protein; chlorophyll / chloroplasts; (d) root; shoot / stem / stalk / leaves; grows into carrot plant / cell division; Total 7 marks 7. (a) 8 64; 5; 9;; () for 5 4 growing more/faster; milk contains protein; protein for baby; baby growing; (e) lines joining: carbohydrate to energy; vitamin A to good sight; iron to make haemoglobin; calcium to healthy bones; 4 Total marks

5 8. diffusion; osmosis; active transport; Total marks 9. (a) arrow (with arrowhead) from plants to animals; arrow (with arrowhead) from plants to decomposers; K; J, L and N; carbon dioxide; glucose / cellulose / starch / sucrose / acceptable alternative; bacteria / fungus / microorganisms / named decomposer; Total 7 marks 0. (a) P cytoplasm; Q nucleoid / DNA / chromosome / genetic material; R cell wall / (slime) capsule / slime layer; S (cell) membrane; 4 (iv) 00%;; () for: 4 OR a number divided by x 00 = phagocytes; ingest / digest / engulf / swallow / eat; microorganisms / bacteria / pathogens / parasite / eq; lymphocytes; antibodies / antitoxins; plasma; (combines with / transports) oxygen; haemoglobin; biconcave (or described e.g. doughnut) / large surface area; no nucleus / more space for oxygen; thin / flexible; Total marks. (a) X hepatic vein; Y hepatic artery; Z hepatic portal vein; Y / hepatic artery / the one from the heart; stored; glycogen; insulin; respiration; energy / ATP; Total 6 marks

6 .. named gases;; e.g. carbon dioxide / nitrogen oxides / methane / CFCs. (from) combustion / deforestation / cars / decomposition / aerosols / eq;;. traps heat/energy / (long) wavelengths / infrared cannot escape / are reflected; 4. ice caps melt; 5. raised sea levels / flooding; 6. loss / change of habitat / loss of food; 7. loss of species / extinction / genes / change in distribution; 5. (a) st week / nd week; oestrogen; ovary; Total 5 marks progesterone; ovulation / egg release; 4. (a) Total 5 marks digests / breaks down; protein; amino acids; lower / reduce / decrease (gas exchange) / less oxygen absorbed; alveoli; less surface; join / fuse / combine with sperm / male nucleus; mitosis; egg / ovum; embryo; uterus / womb; milk; clones; 5 Total marks PAPER TOTAL 00 MARKS

7 Paper H. diffusion; osmosis; active transport; Total marks. (a) arrow (with arrowhead) from plants to animals; arrow (with arrowhead) from plants to decomposers; K; J, L and N; carbon dioxide; glucose / cellulose / starch / sucrose / acceptable alternative; bacteria / fungus / microorganisms / named decomposer; Total 7 marks. (a) P cytoplasm; Q nucleoid / DNA / chromosome / genetic material; R cell wall / (slime) capsule / slime layer; S (cell) membrane; 4 (iv) 00%;; () for: 4 OR a number divided by x 00 = phagocytes; ingest / digest / engulf / swallow / eat; microorganisms / bacteria / pathogens / parasite / eq; lymphocytes; antibodies / antitoxins; plasma; (combines with / transports) oxygen; haemoglobin; biconcave (or described e.g. doughnut) / large surface area; no nucleus / more space for oxygen; thin / flexible; Total marks 4. (a) X hepatic vein; Y hepatic artery; Z hepatic portal vein; Y / hepatic artery / the one from the heart; stored; glycogen; insulin; respiration; energy / ATP; Total 6 marks

8 5.. named gases;; e.g. carbon dioxide / nitrogen oxides / methane / CFCs. (from) combustion / deforestation / cars / decomposition / aerosols / eq;;. traps heat/energy / (long) wavelengths / infrared cannot escape / are reflected; 4. ice caps melt; 5. raised sea levels / flooding; 6. loss / change of habitat / loss of food; 7. loss of species / extinction / genes / change in distribution; 5 6. (a) st week / nd week; oestrogen; ovary; Total 5 marks progesterone; ovulation / egg release; Total 5 marks 7. (a) digests / breaks down; protein; amino acids; lower / reduce / decrease (gas exchange) / less oxygen absorbed; alveoli; less surface; join / fuse / combine with sperm / male nucleus; mitosis; egg / ovum; embryo; uterus / womb; milk; clones; 5 Total marks 8. (a) secondary consumers / carnivores; level and level ; energy is lost / used (up) / wasted; respiration / excretion / faeces / movement / heat / not eaten; Total 4 marks

9 9. (a) contents mixed or circulated / do not lie on the bottom; microorganisms (in contact with) nutrients / oxygen / air; even temperature / eq; cools down fermenter / removes heat / stops it getting too warm; microorganisms or enzymes need optimum temperature / cannot survive if too hot / stop denaturing; air / pipe (at bottom of fermenter); (aerobic) respiration; (d) (e) kills microorganisms / sterilises; hot / high temperature; stops contamination / competition from other microbes; no chemical contamination / cools to water; made more quickly / in larger amounts; less chance of side effects; more effective or suitable or compatible; no animals killed; Total 9 marks 0. (a) A DNA / RNA / genetic material / gene; B protein (coat) / capsid; inside cells / host / organisms / bacteria; influenza / HIV / measles / other correct virus; Total 4 marks. (a) parent genotypes: male + Hh female + hh; gametes: H h (h) h; offspring genotypes: Hh and hh; offspring phenotypes: Huntington s disease, normal; 50% / 0.5 / ½ / : / in ; 4 would have children already / gene already passed on; didn t know they had Huntington s; spinal cord; receptors; sensory / afferent neurones; relay neurones / spinal cord; motor / efferent neurones; muscles / effector; contracts; synapse; no brain involved; quicker; 5 Total marks

10 . (a) high in winter; decreases in spring; falls / low / rises in summer; high / rises in autumn; less light in winter / more light in spring; colder in winter / warmer in spring; less light means less photosynthesis; lower temperature means less photosynthesis; more photosynthesis means more numbers/growth; starch is a large molecule; insoluble / does not dissolve; less space needed; water is not taken in / osmosis; starch not lost /diffuse from cell; starch not react in cell; Total 8 marks. (a) sweat evaporates; using / loss of body heat / removes body heat; vasodilation; blood vessels (NOT capillaries) get wider / eq; (more) blood to skin / surface; heat lost from skin / surface; radiation / convection; water content (of blood) decreases; (more) ADH released; kidney / nephron / collecting duct; (more) water reabsorbed / increases permeability; water into blood; less water lost from body / more concentrated urine produced; 4 homeostasis is keeping conditions / substances / levels constant; temperature control / glucose control / ph of blood / eq; Total marks

11 4. (a) shoot has grown/bent towards the light; (positive) phototropism; more (auxin) on dark side; growth / cell elongation; (positive) geotropism; obtain water; obtain minerals/nutrients / name mineral/nutrient; anchorage idea; Total 7 marks 5. (a) fertilisers contain minerals/salts / named mineral/salt; e.g. nitrate for amino acids/protein or magnesium for chlorophyll; advantage less crop is destroyed / more crop growth; disadvantage affects other organisms / affects food chain / pollutes environment / needs reapplication / pest resistance; biological control; living organism/predator that eats insects/pests; example e.g. ladybirds eating aphids; A restriction; B plasmid / virus; C virus / plasmid; D - ligase; 4 advantage: higher crop yield / better food quality; disease resistant / pest resistant / herbicide resistant; less pesticide/herbicide use / less pollution; disadvantage: not accepted by public; long term effects unknown / effect on food chains / environment; gene transfer to other species / reduces variation; 4 Total 4 marks PAPER TOTAL 0 MARKS

12 Paper. A; F; C; B; Total 4 marks. (a) (iv) table correctly filled in;; 70; W: axes correct way; S: scales at least half and linear; U: axes labelled with units (% germinated / age in years); P: points accurate;; not to use seeds / use younger seeds; they will not germinate / less chance of germination; 5 time; water / moisture / humidity; temperature / warmth; light (intensity); number; oxygen / air; variety / type; size / mass; ph; use more seeds / repeat; NOT using seeds of different ages to original experiment Total marks. (a) equal numbers both sides / 5 seen / maggots evenly spread / equal areas/half of apparatus covered and uncovered; 5; 5; 4 / 4-6; cover not used / even light intensity / not left long enough; all dish uncovered / clear / covered / dark; swap / rotate cover; Total 6 marks

13 4. (a) measuring cylinder; correct line; stop oxygen or air (NOT gas) getting in / keeps anaerobic; count bubbles / amount of bubbles / volume of gas; reference to time; method for changing temperature of water bath; increases; peak / optimum / 45 C; decreases; molecules move slower at low temps / low kinetic energy / few collisions; optimum temperature /eq; enzymes denatured / destroyed by high temperatures; (d) smaller range / more readings; NOT repeats above and below or around 45 C / optimum temperature; 5. (a) heading with distance moved by bubble in mm; columns with still air and wind; four readings listed in each column; average present; added up four numbers / all numbers; divided by four / all numbers; OR as a sum 6 4 Total marks 4 obtain more results; range of windy conditions e.g. less distance between plant & fan; use different types of plant / leaves; Total 9 marks 6. C : tea and no tea / range of tea concentrations / before and after tea; O : same person / age / sex / weight; R : several people / several cups of tea / several times; M : heart rate / pulse rate in set time; : how measured; S : same temperature; : same concentration / volume / brand; : same level of activity; 5 Total 5 marks PAPER TOTAL 50 MARKS

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