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Q1.The effect of watering tomato plants with sodium chloride solution on the mass of tomatoes??Type oftomato plantWatered withMean mass of tomatoes / g?fresh massdry mass?NormalDistilled water115.96.5?NormalSodium chloride solution?87.86.6?GMDistilled water101.36.4?GMSodium chloride solution?57.46.5(a) ????What conclusions can you draw about the effects of watering plants with sodium chloride solution on the mass of tomatoes?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b) ????Use your knowledge of water potential to suggest how watering plants with sodium chloride solution affects the fresh mass of the tomatoes.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(Extra space) .................................................................................................................................................................................................................................................................................................................................................(3)(Total 5 marks)Q2.????????? The diagram shows a carrot.A group of students investigated the effect of sucrose concentration on the length of cylinders cut from a carrot.(a)???? The students used a cork borer to cut cylinders from the carrot. Describe how the students should cut these cylinders to make sure that this was a fair test and would produce reliable results.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)???? They measured the initial length of each cylinder then placed the cylinders into test tubes containing different concentrations of sucrose solution. Bungs were placed in the tubes and the tubes were left overnight. Explain why the bungs were placed in the tubes.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(c)???? The students then measured the final lengths of the carrot cylinders. Their results are shown in the table.?Concentration of sucrose / mol dm–30.01.40.21.40.41.20.61.10.80.9(i)????? The students used these results to find the concentration of sucrose that has the same water potential as the carrot cylinders. Describe how they could have done this.....................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)???? Was it important in this investigation that the carrot cylinders had the same initial length? Explain your answer........................................................................................................................................................................................................................................................................................................................................(1)(Total 7 marks)??Q3.????????? The diagram shows a cholera bacterium. It has been magnified 50 000 times.?(a)???? Name A.......................................................................................................................(1)(b)???? Name two structures present in an epithelial cell from the small intestine that are not present in a cholera bacterium.1 ...................................................................................................................2 ...................................................................................................................(2)(c)???? Cholera bacteria can be viewed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).(i)????? Give one advantage of using a TEM rather than a SEM...........................................................................................................................................................................................................................(1)(ii)???? Give one advantage of using a SEM rather than a TEM........................................................................................................................................................................................................................................................................................................................................(1)(d)???? Calculate the actual width of the cholera bacterium between points B and C.Give your answer in micrometres and show your working.???.................................. ?m(2)(e)???? An outbreak of cholera occurred in London in 1849. The graph shows the relationship between the number of deaths from cholera and the height at which people lived above sea level.?Describe the relationship between the number of deaths from cholera and the height at which people lived above sea level...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 9 marks)?Q4.????????? A student investigated the effect of putting cylinders cut from a potato into sodium chloride solutions of different concentration. He cut cylinders from a potato and weighed each cylinder. He then placed each cylinder in a test tube. Each test tube contained a different concentration of sodium chloride solution. The tubes were left overnight. He then removed the cylinders from the solutions and reweighed them.(a)???? Before reweighing, the student blotted dry the outside of each cylinder. Explain why.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)The student repeated the experiment several times at each concentration of sodium chloride solution. His results are shown in the graph.?(b)???? The student made up all the sodium chloride solutions using a 1.0 mol dm–3 sodium chloride solution and distilled plete the table to show how he made 20 cm3 of a 0.2 mol dm–3 sodium chloride solution.??Volume of 1.0 mol dm–3 sodium chloride solutionVolume of distilled water???(1)(c)???? The student calculated the percentage change in mass rather than the change in mass. Explain the advantage of this...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(d)???? The student carried out several repeats at each concentration of sodium chloride solution. Explain why the repeats were important...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(e)???? Use the graph to find the concentration of sodium chloride solution that has the same water potential as the potato cylinders............................... mol dm–3(1)(Total 8 marks)?Q5.????????? (a)???? Give two ways in which active transport is different from facilitated diffusion.1 .........................................................................................................................................................................................................................................2 .........................................................................................................................................................................................................................................(2)Scientists investigated the effect of a drug called a proton pump inhibitor. The drug is given as a tablet to people who produce too much acid in their stomach. It binds to a carrier protein in the surface membrane of cells lining the stomach. This carrier protein usually moves hydrogen ions into the stomach by active transport.The scientists used two groups of people in their investigation. All the people produced too much acid in their stomach. People in group P were given the drug. Group Q was the control group.The graph shows the results.?(b)???? (i)????? The scientists used a control group in this trial. Explain why...........................................................................................................................................................................................................................(1)(ii)???? Suggest how the control group would have been treated.....................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(c)???? Describe the effect of taking the drug on acid secretion...................................................................................................................................................................................................................................................................................................................................................................(1)(Total 6 marks)?Q6.????????? Scientists use optical microscopes and transmission electron microscopes (TEMs) to investigate cell structure. Explain the advantages and the limitations of using a TEM to investigate cell structure.......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(Total 5 marks)Q7.????????? The diagram shows a cell cycle.?(a)???? In prophase of mitosis, the chromosomes become visible. Describe what happens in(i)????? metaphase.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)???? anaphase..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)???? (i)????? Cells lining the human intestine complete the cell cycle in a short time. Explain the advantage of these cells completing the cell cycle in a short time........................................................................................................................................................................................................................................................................................................................................(1)(ii)???? The time required for a cell to complete the cell cycle was 4 hours 18 minutes.Calculate the time required in minutes for this cell to multiply to produce eight cells.Show your working.?????Answer .....................................................(2)(c)???? Mikanolide is a drug that inhibits the enzyme DNA polymerase. Explain why this drug may be effective against some types of cancer...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 9 marks)?Q8.????????? Yeast is a single-celled eukaryotic organism. When yeast cells are grown, each cell forms a bud. This bud grows into a new cell. This allows yeast to multiply because the parent cell is still alive and the new cell has been formed.Scientists grew yeast cells in a culture. They counted the number of cells present and measured the total concentration of DNA in the culture over a period of 6 hours. Their results are shown in the graph.?(a)???? Use your knowledge of the cell cycle to explain the shape of the curve for the number of yeast cells(i)????? between 1 and 2 hours..........................................................................................................................................................................................................................(1)(ii)???? between 3 and 4 hours...........................................................................................................................................................................................................................(1)(b)???? Use the curve for the concentration of DNA to find the length of a cell cycle in these yeast cells. Explain how you arrived at your answer.Length of cell cycle ......................................................................................Explanation ....................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 5 marks)?Q9.Scientists investigated the effect of bromelain on cancer cells. They took cells from skin cancers in mice and added them to a liquid growth medium in two dishes.Four hours later they added a solution of bromelain to one of the dishes. They left the other dish as a control. They also added a substance to both dishes that is turned purple by respiring cells.Both dishes were placed in an incubator. The scientists measured the intensity of the purple colour at intervals over a period of 100 hours.?(a) ????The scientists put the same number of skin tumour cells in each dish at the start of this investigation. Explain why it was important to put the same number of cells in each dish.................................................................................................................................................................................................................................................(1)(b) ????The scientists concluded that bromelain did not kill cancer cells but stopped them dividing. Does the graph support this conclusion? Explain your answer.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(c) ????An article in a newspaper claimed that these data show that bromelain can be used to treat cancer.Give three reasons why we should be careful about accepting this claim.1 .............................................................................................................................................................................................................................................2 .............................................................................................................................................................................................................................................3 .............................................................................................................................................................................................................................................(3)(d) ????The rate of cell division is important in investigations into cancer. Suggest why.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(e) ????Scientists have investigated the effects of bromelain on cancer growth in humans. Suggest why they gave bromelain in addition to, rather than instead of, the usual treatment.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 10 marks)Q10.????????? The diagram shows a cell cycle.(a)???? The table shows the number of chromosomes and the mass of DNA in different nuclei.All the nuclei come from the same animal. Complete this table.?NucleusNumber of chromosomesMass of DNA / arbitrary unitsAt prophase of mitosis2660At telophase of mitosis??From a sperm cell??(4)(b)???? If the DNA of the cell is damaged, a protein called p53 stops the cell cycle.Mutation in the gene for p53 could cause cancer to develop. Explain how.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)???? Drugs are used to treat cancer. At what phase in the cell cycle would each of the following drugs act?(i)????? A drug that prevents DNA replication.............................................................................................................(1)(ii)???? A drug that prevents spindle fibres shortening.............................................................................................................(1)(Total 9 marks)???M1.(a)???? No effect on dry mass / small increase in dry mass;Decrease in fresh mass;Ignore reference to figures.2(b)???? Water potential inside tomato plant becomes higher / less negative;Water drawn out of tomato plants / more difficult for tomato plants to take up water;By osmosis;Most of the fresh mass is (mass of) water;3 max[5]M2.????????? (a)???? Lengthways / down the root;Through one tissue only / through same part / same proportion of tissues;2(b)???? To prevent the water from evaporating / prevent evaporation;Changing the concentrations / water potential (of solution);2(c)???? (i)??????Plot data on a graph;Find (sucrose concentration) from the graph where the ratio is 1;2(ii)?????No, because the results are given as a ratio / as a proportion of initial length;1[7]M3.????????? (a)???? (Plasma / cell) membrane;Reject: nuclear membrane1(b)???? Nucleus / nuclear envelope / nuclear membrane / nucleolus;Accept: membrane-bound organelles only if an example has not been givenMitochondrion;(Smooth / rough) ER;Lysosome;Microvillus / brush border;Neutral: villiGolgi;Linear / non-circular DNA / chromosome;Neutral: DNA strands80S / denser / heavier / larger ribosomes;Neutral: ribosomes2 max(c)???? (i)??????Higher resolution / higher (maximum) magnification / higher detail (of image);ORAllows internal details / structures within (cells) to be seen / cross section to be taken;Accept: ‘better’ instead of ‘higher’Neutral: shorter wavelengthReject: longer wavelengthReject: can be used on living specimensQ Do not accept ‘clearer’ image1(ii)?????Thin sections do not need to be prepared / shows surface of specimen / can have 3-D images;Accept: can be used on thick(er) specimensReject: can be used on living specimensNeutral: refs. to staining / preparation / artefacts / colour1(d)???? Two marks for correct answer of 0.42 – 0.46;;One mark for incorrect answers in which candidate clearly divides measured width by magnification;Correct answer = 2 marks outrightAccept: 0.4 or 0.5 only if working is correct for 2 marksDo not award a mark for 0.4 or 0.5 if there is no working outIgnore rounding up2(e)???? As height increases, the number of deaths decrease / inversely proportional / negative correlation;Correct reference to increase / decrease at 14-30m;Accept: converse statementMust give a trend and not simply give individual pointsDo not penalise for ‘more likely to get cholera’2[9]M4.????????? (a)???? Water will affect the mass / only want to measure water taken up or lost;Amount of water on cylinders varies / ensures same amount of water on outside;Neutral: removes waterAccept: ‘(sodium chloride) solution’ for waterDo not accept ‘sodium chloride’Neutral: refs. to fair testing2(b)???? 4 cm3 (of 1.0 mol dm–3 sodium chloride solution) and 16 cm3 (of distilled water);Reject: factors and multiples of these figures e.g. 2 cm3 and 8?cm3, as final volume should be 20 cm31(c)???? Allows comparison / shows proportional change;Idea that cylinders have different starting masses / weights;Reject: if comparison is in context of the start and final mass of the same cylinderNeutral: different massesNeutral: different starting sizes2(d)???? (Allows) anomalies to be identified / ignored / effect of anomalies to be reduced / effect of variation in data to be minimised;Makes the average / mean / line of best fit more reliable / allows concordant results;Accept: ‘outliers’ instead of anomaliesQ Reject: abnormalitiesReject: idea of not recording anomalies / preventing anomalies from occurringAccept: ‘cancels out anomalies’ as bottom line responseQ Reject: makes the average / mean more accurateNeutral: makes the average / mean more validNeutral: makes ‘it’ / results / conclusion more reliable2(e)???? 0.35 (mol dm–3)1[8]M5.????????? (a)???? 1.??????Uses energy / ATP;2.??????Against concentration gradient / low to high concentration;3.??????Does not use channel proteins / only uses carrier proteins;Assume “it” refers to active transport.1. Facilitated diffusion is passive - neutral2. Along / across concentration gradient - neutralAccept up / down concentration gradientAccept AT does not need concentration gradient.2 max(b)???? (i)????? To see the effect of the drug / effect not due to anything else in the tablet;Neutral “to compare results”1(ii)???? Placebo / dummy drug / tablet without drug;(Otherwise) treated the same;No drug - neutralAccept: Example e.g. tablet given at same time2(c)???? Decrease for 3 hours;Accept decreases from 1 - 4 hours1[6]M6.????????? Advantages:1?????? Small objects can be seen;2?????? TEM has high resolution as wavelength of electrons shorter;Accept betterLimitations:3?????? Cannot look at living cells as cells must be in a vacuum / must cut section / thin specimen;4?????? Preparation may create artefact5?????? Does not produce colour image;[5]M7.????????? (a)???? (i)????? Spindle formed / chromosome / centromere / chromatidsattaches to spindle;Chromosomes / chromatids line up / move to middle / equator(of cell);Do not award second mark for answers referring to chromosomes ‘pairing up’.Ignore reference to homologous chromosomes unless context suggests pairing which negates second mark.Neutral: Details on nuclear membrane.Accept: Diagram for second marking point.2(ii)???? Chromosome / centromere splits / chromatids / ‘chromosomes’ separate / pulled apart;To (opposite) sides / poles / centrioles (of cell);Reject: Homologous chromosomes separate for first marking point.Accept: Diagram for second marking point.Chromatids / ‘chromosomes’ move to poles / sides / centrioles = 2 marks.2(b)???? (i)????? Form / replace cells quickly / rapidly / divide / multiply / replicate rapidly;Neutral: Repair cells.Answers must convey idea of ‘speed’.1(Ii)???? Correct answer = 774 minutes / 12 hours 54mins = 2 marks;;Incorrect answer but indicates 3 cell cycles involved = one mark;2(c)???? Prevents / slows DNA replication / doubling / prevents / slows mitosis;New strand not formed / nucleotides (of new strand) not joinedtogether / sugar-phosphate bonds not formed;First marking point must be in context of DNA replication not cell replication.Do not negate first marking point if role of DNA polymerase is described incorrectly e.g. Reject: ‘joins bases / strands together’.Role of DNA polymerase must be correct for last marking point.2[9]M8.????????? (a)???? (i)??????Cells are in interphase;Accept G phase / S phase.1(ii)?????Cells undergoing mitosis / in telophase / cytokinesis;Accept all named stages but reject prophase, metaphase or anaphase on their own.1(b)???? 1.????? 3 hours;2.????? Time between beginnings / endings DNA replication / Increases / levelling outs of DNA concentration / for shape (of curve for replication) to be repeated;3.????? (DNA) replication takes place once per cell cycle;Allow close approximation where candidate attempts to be more accurate.PrincipleWhat is shown on the graph3[5]M9.(a)???? To ensure the colour is the same at the start;1(b) ????Yes – curve on graph with bromelain present remains approximately constant / rises very slightly;Would decrease if killing of cells occurred / would increase if cells still dividing;2(c) ????Use of mouse cells (rather than human);(Carried out) in vitro / not in living organisms;Only tested on one type of cancer;Not possible to predict effect on humans (as no data collected);3 max(d) ????The faster the rate of division the faster the cancer would grow;By measuring rate of cell division you could see how effective the treatment was;2(c) ????Not ethical to replace conventional treatment;As life of patient is at risk (if bromelain not effective);2[10]M10.????????? (a)???? NucleusNumber of chromosomesMass of DNA / arbitrary unitsAt telophase of mitosis26;30;From a sperm cell13;15;4(b)???? Cancer cells often have faulty / damaged DNA;Protein / p53 faulty / not made;Cell (with faulty / DNA) divides / completes cell cycle;Uncontrolled division produces cancer;p53 refers to the protein so do not accept reference to p53 mutating.3(c)???? (i)??????Interphase / S phase / synthesis phase;1(ii)?????Anaphase / A;1[9] ................
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