Animal tissues, organs and organ Systems

Transcription

1 Animal tissues, organs and organ Systems Mark Scheme Level GCSE (9-) Subject Biology Exam Board AQA Topic 4.2 Organisation Sub-Topic Animal tissues, organs and organ systems Difficulty Level Bronze Level Booklet Mark Scheme Time Allowed: 59 minutes Score: /57 Percentage: /00 Page

2 M. (a) to show the experiment was more repeatable (b) (circle) 0.0 at 20 C (c) ignored it / did not use it ignore repeated it (d) increases the rate of reaction up to 30 C (e) 60 C (f) do the experiment at 30 C, 35 C and 40 C (g) Level 2 (3 4 marks): A detailed and coherent plan covering all the major steps is provided. The method is set out logically taking into account control variable and appropriate measurements. The plan could be repeated by another person to determine the effect of ph on breakdown of starch by amylase. Level ( 2 marks): Simple statements relating to relevant apparatus or steps are made but they may not be in a logical order. The plan would not allow another person to determine the effect of ph on breakdown of starch by amylase. 0 marks: No relevant content. Page 2

3 Indicative content range of at least 3 ph values / use of buffer solutions control variables / keep amount or concentration of starch and amylase the same keep temperature the same using water bath / electric heater use iodine test to make qualitative observations observe colour changes at different temperatures do repeats at each ph 4 [0] Page 3

4 M2. (a) (Type 2) diabetes / heart disease / deficiency disease / named allow a relevant health problem ignore obesity or over / under weight / anorexia (b) (i) provides more (energy / sugar) than is used idea of sugar being high in / having a lot of energy eg contains a lot of calories allow it is turned to fat or stored (as fat) fat (c) (i) C no health problems allow as others (may) have (possible) health problems ignore reference to sweetness (iii) idea of informed choice eg in case you have health problems / allergies allow legal requirement ignore diabetes [6] Page 4

5 M3.(a) (i) A = (cell) membrane B = cytoplasm do not accept cytoplast To control the activities of the cell (b) extra lines cancel 3 [6] Page 5

6 M4.(a) extra line from any drug cancels that mark 4 (b) (i) any one from: (live) animals accept named examples, eg mice ignore people / volunteers cells tissues do not allow plants to check that the drug works to find the best dose to use (iii) only scientists at the drug company (c) (i) 420 Page 6

7 statin(s) (iii) any one from: side effects allow cost other medication allow patient choice other (medical) conditions allow family history or age [] Page 7

8 M5.(a) (i) alveoli / alveolus allow air sacs allow phonetic spelling any one from: protection (of lungs / heart) help you breathe / inflate lungs. (b) (i) diffusion capillaries (iii) any two from: (have many) alveoli allow air sacs large surface / area thin (exchange) surface or short diffusion pathway accept only one / two cell(s) thick good blood supply / many capillaries allow (kept) ventilated or maintained concentration gradient. 2 [6] Page 8

9 M6.(a) (i) a catalyst (iii) protein salivary glands (b) extra lines from any enzyme cancels that mark 3 [6] Page 9

10 M7. (a) 300 (b) suitable scale on y-axis label y-axis 4 bars drawn correctly allow mark for 3 correct bars 2 (c) increases from 50 to 500 then decreases from 500 to 0 (d) carbohydrates broken down / digested into sugars broken down by carbohydrase or amylase (e) absorption of glucose into blood Page 0

11 by active transport allow diffusion [2] Page

12 Animal tissues, organs and organ Systems Mark Scheme Level GCSE (9-) Subject Biology Exam Board AQA Topic 4.2 Organisation Sub-Topic Animal tissues, organs and organ systems Difficulty Level Silver Level Booklet Mark Scheme Time Allowed: 58 minutes Score: /58 Percentage: /00 Page

13 M. (a) 55% 2 marks for correct answer alone accept / 0 00 alone gains mark 2 (b) any three from: amino acids antibodies antitoxins carbon dioxide cholesterol enzymes fatty acid glucose glycerol hormones / named hormones ions / named ions proteins urea vitamins water. ignore blood cells and platelets ignore oxygen max named example of each for ions and hormones allow minerals 3 (c) Marks awarded for this answer will be determined by the Quality of Communication (QC) as well as the standard of the scientific response. Examiners should also refer to the information in the Marking Guidance and apply a best-fit approach to the marking. 0 marks No relevant content. Level ( 2 marks) There is a description of pathogens with errors or roles confused. or the immune response with errors or roles confused. Level 2 (3 4 marks) There is a description of pathogens and the immune response with some Page 2

14 errors or confusion or a clear description of either pathogens or the immune response with few errors or little confusion. Level 3 (5 6 marks) There is a good description of pathogens and the immune response with very few errors or omissions. Examples of biology points made in the response: bacteria and viruses are pathogens credit any ref to bacteria and viruses they reproduce rapidly inside the body bacteria may produce poisons / toxins (that make us feel ill) viruses live (and reproduce) inside cells (causing damage). white blood cells help to defend against pathogens by: ingesting pathogens / bacteria / (cells containing) viruses credit engulf / digest / phagocytosis to destroy (particular) pathogen / bacteria / viruses producing antibodies to destroy particular / specific pathogens producing antitoxins to counteract toxins (released by pathogens) credit memory cells / correct description this leads to immunity from that pathogen. 6 [] Page 3

15 M2. (a) any three from: parts of organisms have not decayed accept in amber / resin allow bones are preserved conditions needed for decay are absent accept appropriate examples, eg acidic in bogs / lack of oxygen parts of the organism are replaced by other materials as they decay accept mineralised or other preserved traces of organisms, eg footprints, burrows and rootlet traces allow imprint or marking of organism 3 (b) (i) teeth for biting (prey) must give structure + explanation claws to grip (prey) accept sensible uses wing / tail for flight to find (prey) any two from: new predators new diseases better competitors catastrophe eg volcanic eruption, meteor changes to environment over geological time accept climate change allow change in weather prey dies out or lack of food allow hunted to extinction 2 [8] Page 4

16 M3. (a) (i) sucrose fructose is sweeter than sucrose can use less fructose (for same sweetness) cheaper / can use in slimming food allow less calories accept better for diabetics (b) (i) carbohydrases denatured / shape changed ignore inactivated allow enzyme / shape destroyed (iii) faster reaction so more product made / product made in shorter time allow 60 C will kill microorganisms (c) any two from: enzyme can be re-used / not wasted constant-flow system can be automated product (= food) not contaminated by enzyme / enzyme may give allergic reaction / no need to separate P from E allow people do not want to eat enzymes 2 Page 5

17 (d) any three from: volume is smaller so costs less to heat / to maintain temperature / to build temperature is cooler so costs less to heat / to maintain temperature / loses less heat to surroundings reaction time is shorter so reduces running costs (re. heating / stirring) or can make more product in time -stage product refining c.f. 4 stages, leading to reduced labour / time cost need to qualify each point with respect to how it lowers costs 3 (e) (i) 4500 correct answer = 2 marks allow mark for: 500 x 3 2 enzyme used for longer / less enzyme needed less money spent on enzyme [7] Page 6

18 M4. (a) (i) glycerol pancreas / small intestine accept duodenum / ileum ignore intestine unqualified (b) any two from: type of milk volume / amount of milk vol. bile equals vol. water volume of lipase concentration of lipase temperature ignore time interval ignore solution unqualified do not allow ph ignore starting ph ignore volume / amount of bile / water ignore concentration of bile accept amount of lipase if neither volume nor concentration given 2 (c) (i) fatty acid (production) (iii) faster reaction / digestion (with bile) or ph decreases faster (with bile) or takes less time (with bile) or steeper fall / line (with bile) allow use of data ignore easier all fat / milk digested or same amount of fatty acids present or (lower ph) denatures the enzyme / lipase allow all reactants used up ignore reference to neutralisation Page 7

19 allow enzyme won t work at low ph do not allow enzyme killed [7] Page 8

20 M5. (a) Marks awarded for this answer will be determined by the Quality of Communication (QC) as well as the standard of the scientific response. Examiners should also refer to the information in the Marking guidance and apply a best-fit approach to the marking. 0 marks No relevant content. Level ( 2 marks) The method described is weak and could not be used to collect valid results, however does show some understanding of the sequence of an investigation. Level 2 (3 4 marks) The method described could be followed and would enable some valid results to be collected, but lacks detail. Level 3 (5 6 marks) The method described could be easily followed and would enable valid results to be collected. Examples of the points made in the response: bean seedlings of same age cut material from same part of each organ (for repeats) e.g. top cm of stem / a whole cotyledon / seed equal mass of each organ accept weight for mass grind / homogenise in equal amounts of water / buffer equal volumes of hydrogen peroxide solution equal concentrations of hydrogen peroxide solution same temperature temperature maintained in water bath quantitative measure of gas production eg height of foam in mm / collect gas in graduated syringe in cm 3 for same time period repetitions (3+ times) calculate mean for each. 6 (b) (i) correct answer: 40 mark for 45 as the anomalous result has been included in the calculation or mark for or 2 vertical axis correctly labelled: Enzyme activity in arbitrary units Page 9

21 allow ecf from (b)(i) points plotted correctly ± mm deduct mark for each incorrect plot suitable line of best fit not feathery, not point to point 2 (iii) 6.0 / 6 allow ± 0. if 6.0 not given, allow correct for candidate s graph ± 0. (iv) in range 0 to 4 units allow correct for candidate s graph (v) enzyme denatured / enzyme (active site) shape changed allow substrate no longer fits (active site) ignore reference to temperature do not allow enzyme dies [5] Page 0

22 Animal tissues, organs and organ Systems Mark Scheme Level GCSE (9-) Subject Biology Exam Board AQA Topic 4.2 Organisation Sub-Topic Animal tissues, organs and organ systems Difficulty Level Gold Level Booklet Mark Scheme Time Allowed: 58 minutes Score: /57 Percentage: /00 Page

23 M.(a) stomach and pancreas correctly labelled (b) bacteria not killed (by stomach acid / HCl) and so they damage mucus lining so acid / HCl damages stomach tissue / causes an ulcer allow bacteria infect stomach tissue (c) if the cancer is malignant (cancer) cells can spread to other organs via the blood forming a secondary tumour do not award marking points 2 or 3 without marking point (d) add Biuret reagent to food sample allow sodium / potassium hydroxide (solution) + copper sulfate(solution) mauve / purple colour shows protein present (e) damaged villi reduce surface area for absorption (of food molecules) Page 2

24 (therefore) fewer amino acids and glucose absorbed with less glucose transfer of energy from respiration is reduced and fewer amino acids available to build new proteins [2] M2. (a) any two from: diet ignore exercise Page 3

25 accept any reasonable reference to diet do not accept salt / blood pressure ignore age / gender / HDL / LDL heredity / genes / genetic makeup reference to cholesterol production by liver 2 (b) (i) Blood cholesterol concentration is only one of several factors affecting death from all causes accept [4] \ M3. (a) (substance / chemical) that affects body chemistry / chemical reactions in the body Page 4

26 (b) statin / aspirin / neither recommended no mark, may be implied. If no recommendation or implication, max 4 marks answers should be comparative any five from: argued evaluation in favour of aspirin or statin or neither answers could include reference to accept converse for statins / aspirin but not as advantage of one and disadvantage of other for statins: more people in studies so data / findings more repeatable accept reliable for repeatable ignore accurate / precise reduces cholesterol but aspirin doesn t allow reduces cholesterol but no evidence about aspirin aspirin (may) causes bleeding / poor clotting but statins do not allow aspirin causes bleeding / poor clotting but no evidence about statins smaller (total) percentage suffer side-effects monitored by doctor, aspirins not for aspirin: cheaper can be bought over the counter rather than prescribed statins cause serious damage / muscle damage / kidney failure but aspirins do not similarities: both have similar effect on reducing (non-fatal) heart attacks incidence of side-effects low in both allow (for aspirin) higher reduction of risk of heart attack 5 [6] Page 5

27 M4. (a) (concentration high) in the hepatic portal vein is blood with glucose absorbed from the intestine Page 6

28 concentration is lower in the hepatic vein because insulin (has caused) glucose to be converted into glycogen or allows glucose into liver cells (b) (i) (after 6 hours) most of the glucose has been absorbed from the intestine or from food into the blood because glucagon (made in the pancreas) causes if biological terms incorrectly spelt they must be phonetically accurate do not accept glucagon made / produced by the liver glycogen to be converted into glucose glucose released into blood allow the liver maintains the correct / constant level of glucose in the blood [7] M5.(a) stomach is acidic / has low ph allow any ph below 7 ignore stomach is not alkaline Page 7

29 lactase works best / well in alkali / high ph / neutral / non-acidic conditions allow any ph of 7 and above accept works slowly in acid conditions allow figures from table with a comparison ignore reference to temperature (b) any three from: (below 40( C)) increase in temperature increases rate / speed of reaction reference to molecules moving faster / colliding faster / harder / more collisions enzyme optimum / works best at 40 C allow value(s) in range ignore body temperature unless qualified high temperatures (above 40 C) / 45 C / 50 C enzyme denatured allow synonyms for denaturation, but do not allow killed denaturation at high and low temperature does not gain this mark ignore references to time / ph 3 (c) any two from: acid neutralised or conditions made neutral / alkali accept bile is alkaline (allow) emulsification / greater surface area (of lipid / fat) allow description of emulsification eg fat broken down / broken up into droplets do not accept idea of chemical breakdown lipase / enzymes (in small intestine) work more effectively / better allow better for enzymes ignore reference to other named enzymes 2 [7] Page 8

30 M6. (a) (i) mitochondrion / mitochondria must be phonetically correct carbon dioxide / CO 2 Page 9

31 water / H 2O in either order accept CO2 but not CO 2 accept H2O or HOH but not H 2 O (iii) diffusion high to low concentration allow down a concentration gradient through (cell) membrane or through cytoplasm do not accept cell wall (b) ribosomes make proteins / enzymes using amino acids part A / mitochondria provide the energy for the process allow ATP do not accept produce or make energy [9] M7.A + B most effective (treatment) ignore descriptions of LDL levels Page 0

32 D is (the most) effective (treatment) D is the best single (treatment) neither A nor B (alone) are effective allow increase risk of heart disease instead of not effective can t tell if C is effectiveora + C is not effective [4] M8. (a) (i) diaphragm accept phonetic spelling (because) the volume (inside the jar) increases maximum two marks if no reference to correct part of model Page

33 (causing) the pressure to decrease (and) air enters the balloon allow oxygen (b) (i) (so it moves by) diffusion do not allow osmosis or active transport from a high concentration (of oxygen) to a low concentration allow down its / oxygen concentration gradient from the air or to the blood or (because) there is a high(er) concentration (of oxygen) in the air or there is a low(er) concentration of oxygen in the blood ignore reference to amount of oxygen many gill filaments must be in the correct pairs to gain 2 marks (give a) large surface / area do not allow surface area to volume ratio or thin (so) short diffusion pathway or good blood supply (to) maintain the concentration gradient or water continually flows over them / continually ventilated (to) maintain the concentration gradient [8] Page 2

34 Plant tissues, organs and organ Systems Mark Scheme Level GCSE (9-) Subject Biology Exam Board AQA Topic 4.2 Organisation Sub-Topic Plant tissues, organs and organ systems Difficulty Level Bronze Level Booklet Mark Scheme Time Allowed: 56 minutes Score: /56 Percentage: /00 Page

35 M. (a) (i) wind temperature answers in either order ignore weather different plants have different sizes / different numbers of leaves / different sizes of leaves / different plants take up different amounts of water ignore reference to validity allow different plants need different amounts of water (b) in table, in sequence: C all 3 correct = 2 marks B A all 3 correct = 2 marks 2 correct = mark 0 or correct = 0 mark 2 (c) transpiration [6] Page 2

36 M2. (a) (i) root hairs if clear which word then allow xylem if clear which word then allow (iii) stomata if clear which word then allow (iv) storage organs in this order phloem (b) (i) 23.2 loss of water (from flask with plant) from leaves / plant via transpiration / via evaporation if no other marks allow used in photosynthesis for one mark [8] Page 3

37 M3. (a) transpiration (b) increase then decrease maximum rate at ( C ) / (grams per day) any figure in these ranges (c) (i) reduce water loss / prevent wilting allow stops water loss C [5] Page 4

38 M4. (a) transpiration (b) (i) 200 correct answer with or without working if answer incorrect: allow mark for 8 25 or allow mark for answer from candidate s count 25 2 R allow P or Q if candidate s answer to (b)(i) nearer to value for one of those do not allow R if the answer to (b)(i) would give an answer of P or Q allow R if (b)(i) is blank (iii) few stomat allow no stomata on upper surface / all stomata on lower surface little / less transpiration or little / less water (vapour) loss / enable water to be retained allow no water loss from upper surface [6] Page 5

39 M5. (a) (i) water / H 2O accept oxygen allow H 2O do not allow H 2 O or H2O (iii) the mineral ions are absorbed by active transport the absorption of mineral ions needs energy have (many root) hairs (which) give a large surface area (for absorption) (b) carbon dioxide in or oxygen out or control water loss accept gas exchange ignore gases in and out ignore gain / lose water (c) (i) guard cells (stomata are) closed allow there is no gap / space (iii) plant will wilt / droop ignore die [9] Page 6

40 M6. (a) xylem and phloem either order allow words ringed in box allow mis-spelling if unambiguous (b) (i) movement / spreading out of particles / molecules / ions / atoms ignore names of substances / gases from high to low concentration accept down concentration gradient ignore along / across gradient ignore with gradient oxygen / water (vapour) allow O 2 / O2 ignore O 2 / O allow H 2O / H2O ignore H 2 O [4] Page 7

41 M7. (a) (i) wind answers in either order temperature ignore weather different plants have different sizes ignore reference to validity / different numbers of leaves / different sizes of leaves / different plants take up different amounts of water / different number of stomata / different surface area allow different plants need different amounts of water (b) in table, in sequence: C B A all 3 correct = 2 marks 2 correct = mark 0 or correct = 0 marks max 2 (c) transpiration [6] Page 8

42 M8. (a) (i) xylem phloem (iii) transpiration (iv) stomata (b) (i) any one from: reduce / prevent evaporation of water from flask holds plant shoot in place prevent damage to the plant same surface area or number of leaves (because if they used larger / smaller size shoots) there would be a larger / smaller surface area or a larger/ smaller number of leaves allow same number of stomata from which (the same amount of) water evaporates (and therefore) more / less water would escape allow from which water escapes (iii) 4.5 look for answer written in table (iv) increasing temperature / heat increases (rate of) water loss / evaporation Page 9

43 (v) having moving air / a fan increases (rate of) water loss / evaporation (c) (i) 0.3 g plastic bag reduces air flow across leaves or air is humid around the leaves allow plastic bag stops water (vapour) leaving allow air (in plastic bag) becomes saturated (with water) [2] Page 0

44 Plant tissues, organs and organ Systems Mark Scheme Level GCSE (9-) Subject Biology Exam Board AQA Topic 4.2 Organisation Sub-Topic Plant tissues, organs and organ systems Difficulty Level Silver Level Booklet Mark Scheme Time Allowed: 52 minutes Score: /5 Percentage: /00 Page

45 M. (a) active transport (b) by transpiration stream / pull in xylem (c) any three in the correct order from: mount epidermis on a slide count stomata in one area repeat in four more areas repeat method on other surface of leaf calculate mean allow nail varnish film 3 (d) allow numbers written out in a line with middle number circled (e) ( ) / 5 = allow 4 with no working shown for 2 marks allow 4.2 for mark (f) less water lost Page 2

46 so it does not wilt [] Page 3

47 M2. (a) guard cells (b) (i) any one from: species / plant length of time ignore temperature and size of leaves 20 correct answer = 2 marks accept or for mark 2 (c) less water loss / transpiration / evaporation (d) hot ignore bright / sunny conditions dry / low humidity wind(y) [8] Page 4

48 M3.(a) A - atrium ignore references to right / left B - ventricle (b) (i) muscular push blood accept pump / force (c) arrows approx as indicated arrow(s) showing flow from A to B from B out / up / to artery (d) (i) male 65 and over fatty deposits / material in (coronary) arteries allow correct points made about heart attacks Page 5

49 narrows / blocks / reduces flow decreases oxygen supply (to heart muscle) [] Page 6

50 M4. (a) to kill virus or to prevent virus spreading (b) take (stem) cells from meristem or tissue culture allow take cuttings (c) use Benedict s solution glucoses turns solution blue to orange (d) Level 2 (3 4 marks): A detailed and coherent explanation is provided. The student makes logical links between clearly identified, relevant points that explain why plants with TMV have stunted growth. Level ( 2 marks): Simple statements are made, but not precisely. The logic is unclear. 0 marks: No relevant content. Indicative content less photosynthesis because of lack of chlorophyll therefore less glucose made so less energy released for growth because glucose is needed for respiration and / or therefore less amino acids / proteins / cellulose for growth because glucose is needed for making amino acids / proteins / cellulose 4 [8] Page 7

51 M5. (a) (i) 5.0 (5 0.8) or 4 allow ecf from distance 0.4 allow ecf from 0-min volume increased (rate of uptake) more transpiration / evaporation (b) correct scales allow reversed axes correctly labelled axes with units correct points one plot error = max mark curved line of best fit allow correct straight line 2 (c) leaves wilt because plants lose too much water (by evaporation) through the stomata or because cells become plamolysed or stomata close controlled by guard cells to prevent wilting [3] Page 8

52 Plant tissues, organs and organ Systems Mark Scheme Level GCSE (9-) Subject Biology Exam Board AQA Topic 4.2 Organisation Sub-Topic Plant tissues, organs and organ systems Difficulty Level Gold Level Booklet Mark Scheme Time Allowed: 30 minutes Score: /30 Percentage: /00 Page

53 M. (a) (i) guard (cells) allow phonetic spelling any one from: ignore reference to cells allow carbon dioxide to enter allow control loss / evaporation of water or control transpiration rate allow oxygen to leave. allow gaseous exchange (b) (i) 200 correct answer gains 2 marks with or without working allow mark for = 0.0 (mm 2 ) 2 more / a lot of / increased water loss allow plant more likely to wilt (in hot / dry conditions) (c) (i) 0.2 the lower surface has most stomata stomata are now covered / blocked (by grease) so water cannot escape / evaporate from the stomata ignore waterproof to gain credit stomata must be mentioned at least once [9] Page 2

54 M2. (a) guard cell ignore stoma / stomata (b) Species A : allow converse points for species B stomata open in dark / at night or close in light / in day stomata closed during warm(est) period or open when cool(er) heat (energy) /warmth increases evaporation / transpiration must give explicit link between heat and transpiration reduces water loss / evaporation / transpiration ignore photosynthesis [5] Page 3

55 M3. (a) guard (cell) ignore stoma / stomata (b) Species A: stomata open in dark / at night or close in light / in day stomata closed during warm(est) period or open when cool(er) heat (energy) / warmth increases evaporation / transpiration must give explicit link between heat and transpiration reduces water loss / evaporation / transpiration ignore photosynthesis allow converse points for species B [5] Page 4

56 M4. (a) solution in soil is more dilute (than in root cells) concentration of water higher in the soil (than in root cells) so water moves from the dilute to the more concentrated region so water moves down (its) concentration gradient or water moves from a high concentration of water to a lower concentration concentration of ions in soil less (than that in root cells) so energy needed to move ions or ions are moved against concentration gradient the direction of the concentration gradient must be expressed clearly accept correct reference to water potential or to concentrations of water (b) any three from: movement of water from roots / root hairs (up stem) via xylem to the leaves (water) evaporates via stomata 3 (c) (i) 0.67/0.7 accept 0.66, or ⅔ or 0.6 Page 5

57 correct answer gains 2 marks with or without working if answer incorrect allow evidence of do not accept 0.6 or 0.70 for mark 2 during the first 30 minutes any one from: it was warmer it was windier it was less humid there was more water (vapour) in the leaves so there was more evaporation ignore water loss or stomata open during first 30 minutes or closed after 30 minutes () so faster (rate of) evaporation in first 30 min or reducing (rate of) evaporation after 30 min () [] Page 6