Cambridge A Level Biology 9700 — 2016 May/June Paper 4 · Variant 1

This document consists of 22 printed pages and 2 lined pages. DC (NF/FD) 108514/3 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 0 2 6 7 3 9 8 2 2 1 * BIOLOGY 9700/41 Paper 4 A Level Structured Questions May/June 2016 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Section A Answer all questions. Section B Answer one question. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

2 9700/41/M/J/16 © UCLES 2016 Section A Answer all the questions. 1 (a) ATP and NAD both play important roles in respiration. Both compounds are nucleotides. Fig. 1.1 represents the molecular structures of ATP and NAD. ATP NAD Fig. 1.1 Using Fig. 1.1, compare the structures of ATP and NAD. … … … … … … … … … … [3]

3 9700/41/M/J/16 © UCLES 2016 [Turn over (b) ATP provides an immediate energy source for metabolic processes such as anabolic reactions. State two examples of anabolic reactions in a mammal that require ATP as an energy source. 1 … 2 … [2] (c) Name the type of chemical reaction by which ATP is made during the Krebs cycle. … [1] (d) Outline the roles of NAD in the cytoplasm of a cell. … … … … … [2] (e) Carbohydrates and lipids are used as respiratory substrates. Table 1.1 shows the energy values of carbohydrates and lipids. Table 1.1 respiratory substrate energy value / kJ g−1 carbohydrate 15.8 lipid 39.4 Explain why lipids have a higher energy value than carbohydrates. … … … … … … [2] [Total: 10]

4 9700/41/M/J/16 © UCLES 2016 2 The concentration of carbon dioxide in the atmosphere and the light intensity often limit the rate of photosynthesis. (a) Explain what is meant by a limiting factor in relation to photosynthesis. … … … … … [2] (b) Investigations were carried out in Florida, USA, into the effect of different concentrations of atmospheric carbon dioxide and of light intensity on the rate of photosynthesis of soybean plants. Plants were grown from seed in outdoor, computer-controlled growth chambers at different concentrations of carbon dioxide. The upper parts of the chambers were transparent so that the plants received natural sunlight. After the seedlings emerged, the air in the soil was separated from the air around the leaves by a gas-tight seal in each chamber. Suggest why the air in the soil and the air around the leaves of the plants were separated. … … … … … … [2] (c) In one investigation, two sets of plants, A and B, were grown from seed at different concentrations of carbon dioxide: • A – normal atmospheric concentration of carbon dioxide (0.033%) • B – normal atmospheric concentration of carbon dioxide ×2 (0.066%). Then, keeping each set of plants in its particular concentration of carbon dioxide, measurements were made of their rates of photosynthesis at different light intensities. The results are shown in Fig. 2.1 on page 5.

5 9700/41/M/J/16 © UCLES 2016 [Turn over 0 0 1 2 3 mean rate of photosynthesis per unit area of leaf / arbitrary units 4 2 4 light intensity / arbitrary units 6 8 10 set B set A Fig. 2.1 With reference to Fig. 2.1: (i) describe and explain, in terms of limiting factors, the results from the plants in set A … … … … … … … … [3] (ii) explain the difference between the results of set A and set B at high light intensities. … … … … … [2]

6 9700/41/M/J/16 © UCLES 2016 (d) In a second investigation, two sets of plants, C and D, were grown from seed, as before, in different carbon dioxide concentrations: • C – normal atmospheric concentration of carbon dioxide (0.033%) • D – normal atmospheric concentration of carbon dioxide ×2 (0.066%). When the plants matured, conditions in the growth chambers were changed to investigate the rate of photosynthesis of each set of plants in different concentrations of carbon dioxide. The results are shown in Fig. 2.2. 0 0 1 2 3 4 mean rate of photosynthesis per unit area of leaf / arbitrary units 5 2 concentration of carbon dioxide / arbitrary units 4 6 set D set C Fig. 2.2

7 9700/41/M/J/16 © UCLES 2016 [Turn over Suggest explanations for the higher rate of photosynthesis per unit area of leaf shown by the plants in set D compared with those in set C. … … … … … … … … … … [4] [Total: 13]

8 9700/41/M/J/16 © UCLES 2016 3 Malaria is a serious and often fatal infectious disease caused by Plasmodium. Drugs such as chloroquine are widely used to decrease the risk of getting malaria and also to treat people who have become infected. However, in many parts of the world, Plasmodium populations have become resistant to chloroquine. Sequencing the genome of Plasmodium and the application of bioinformatics has provided several new targets for the development of anti-malarial drugs. (a) (i) Define the term bioinformatics. … … … … … [2] (ii) Outline how sequencing the genome of Plasmodium and the use of bioinformatics can suggest new targets for anti-malarial drugs. … … … … … … … [3]

9 9700/41/M/J/16 © UCLES 2016 [Turn over (b) In parts of the world where Plasmodium is resistant to chloroquine, one of the most effective anti-malarial drugs currently in use is artemisinin. Artemisinin works by binding to an enzyme in Plasmodium called PfATP6, acting as an inhibitor. A substance called curcumin, which has long been used as a spice and yellow food colouring in India and other countries, is also known to act against chloroquine-resistant Plasmodium. A group of researchers predicted that curcumin acts by binding to the same enzyme as artemisinin. In order to test this hypothesis, and to try to find similar substances that might work even better than curcumin, the researchers used theoretical modelling to: • look at the chemical structures of various molecules with a similar structure to curcumin (curcumin analogues) • generate a three-dimensional model of the structure of the enzyme PfATP6 • investigate whether each curcumin analogue could bind to PfATP6. The researchers predicted that several of the curcumin analogues would bind more strongly than curcumin to PfATP6. (i) Suggest advantages of using theoretical models in this research, rather than testing possible drugs in the laboratory. … … … … … … … [3] (ii) Suggest why theoretical modelling cannot completely replace laboratory trials in the search for new drugs. … … … … … … [2] [Total:10]

10 9700/41/M/J/16 © UCLES 2016 4 Maize is an important food crop that has been improved both by selective breeding and by genetic modification. (a) Outline how selective breeding has been used to improve maize. … … … … … … … … … … [4]

11 9700/41/M/J/16 © UCLES 2016 [Turn over (b) Fig. 4.1 shows part of a maize cob. The cob is made up of many individual seeds called kernels. Each kernel results from a separate fertilisation of a male and a female gamete. Some kernels are yellow and some are purple. yellow kernel purple kernel Fig. 4.1 Name the type of variation shown in Fig. 4.1. Suggest a genetic explanation for this pattern of variation in colour. type of variation … explanation … … … … … … … [3]

12 9700/41/M/J/16 © UCLES 2016 (c) Maize and other crops have been genetically modified since 1996 to produce the Bt toxin to kill insect pests. Fig. 4.2 shows the area of Bt crops grown (plotted points) and the number of insect pest species in which resistance to Bt has been reported (bars). 0 year 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 area of Bt crops grown / million hectares 10 20 30 40 50 60 70 Bt crops resistant species 0 number of resistant pest species 1 2 3 4 5 6 7 Fig. 4.2

13 9700/41/M/J/16 © UCLES 2016 [Turn over (i) Describe and suggest an explanation for the relationship between the area of Bt crops grown and the number of resistant pest species. … … … … … … … … … … [4] (ii) Suggest one social advantage and one environmental advantage of growing this Bt maize. social advantage … … environmental advantage … … [2] [Total: 13]

14 9700/41/M/J/16 © UCLES 2016 5 Fig. 5.1 shows a water vole, Arvicola amphibius. This species is native to Great Britain. Fig. 5.1 The numbers of water voles are estimated to have fallen by 94% in the last century. This is thought to be due to habitat fragmentation and also to extensive predation by mink, Neovison vison, shown in Fig. 5.2. Mink originated in North America but were brought to Great Britain for fur farming. Some escaped or were released into the wild, where their numbers rapidly increased. Fig. 5.2 (a) Name and describe a method for estimating the abundance of water voles in a local area. … … … … … … … … … [4]

15 9700/41/M/J/16 © UCLES 2016 [Turn over (b) Both water voles and mink are classified as class Mammalia, phylum Chordata, kingdom Animalia. Outline two features of the cells of members of the kingdom Animalia that distinguish them from the cells of other multicellular eukaryotes. 1 … … 2 … … [2] (c) (i) Discuss the reasons why alien species should be controlled. … … … … … … … [3] (ii) Suggest one way of controlling mink numbers in Great Britain. … … … [1] [Total: 10]

16 9700/41/M/J/16 © UCLES 2016 6 The fruit fly, Drosophila melanogaster, has eyes, a striped abdomen and wings longer than its abdomen. This is called a ‘wild-type’ fly. Mutation has resulted in many variations of these features. Table 6.1 shows diagrams of a wild-type fly and three other flies, each of which shows one recessive mutation. Table 6.1 H\HV DEGRPHQ ZLQJGHVFULSWLRQ present striped long present black long absent striped long present striped short (a) Using appropriate symbols, complete the genetic diagram below. symbols … … … … parental phenotypes with eyes black abdomen X no eyes striped abdomen parental genotypes gametes offspring genotypes offspring phenotypes with eyes black abdomen no eyes black abdomen with eyes striped abdomen no eyes striped abdomen [4]

17 9700/41/M/J/16 © UCLES 2016 [Turn over (b) State how you would carry out a test cross. … … [1] (c) A cross was carried out between a fly heterozygous for striped abdomen and long wings and a fly with a black abdomen and short wings. The results are shown below in Table 6.2. Table 6.2 offspring number striped abdomen long wing 86 black abdomen long wing 87 striped abdomen short wing 81 black abdomen short wing 78 total 332 A chi-squared test (χ2) was carried out on these data. Complete Table 6.3 and calculate the value of χ2. Table 6.3 observed number (O) expected number (E) O − E (O − E)2 (O − E)2 E 86 … … … … 87 … … … … 81 … … … … 78 … … … … 332 332 χ2 = Σ (O − E)2 E Σ = sum of... χ2 … [3]

18 9700/41/M/J/16 © UCLES 2016 (d) Table 6.4 shows χ2 values. Table 6.4 degrees of freedom probability 0.50 0.20 0.10 0.05 0.02 0.01 0.001 3 2.37 4.64 6.25 7.82 9.84 11.34 16.27 Using Table 6.4, explain what conclusions can be made about the results of the χ2 test. … … … … … [2] [Total: 10] 7 (a) An important function of control systems in mammals is homeostasis. Explain what is meant by the term homeostasis. … … … [1] (b) Insulin plays a part in homeostasis. It affects muscle and liver cells to bring about a decrease in blood glucose concentration, particularly after a meal. (i) Insulin is composed of two polypeptides which are made in β cells in the pancreas. State precisely where in β cells polypeptide molecules are synthesised. … [1] (ii) Name the process by which insulin is secreted from β cells. … [1]

19 9700/41/M/J/16 © UCLES 2016 [Turn over (iii) Describe the effects of insulin on muscle cells. … … … … … … … [3] (c) During periods of stress or extreme exercise more glucose needs to be released into the blood. The hormone adrenaline is released and binds to receptors on the cell surface membranes of liver cells. Describe how the effect of adrenaline on liver cells results in an increase in blood glucose concentration. … … … … … … … … … … … [5] [Total: 11]

20 9700/41/M/J/16 © UCLES 2016 8 (a) Fig. 8.1 is a diagram of a sensory neurone and some receptor cells. % & $ ' P\HOLQVKHDWK UHFHSWRUFHOO Fig. 8.1 Name the parts of the neurone labelled A, B, C and D. A … B … C … D … [4] (b) Explain how the myelin sheath increases the speed of conduction of nerve impulses. … … … … … … [2]

21 9700/41/M/J/16 © UCLES 2016 [Turn over (c) Fig. 8.2 shows the changes in the membrane potential of a sensory neurone when the receptor cells are stimulated. –90 –50 time / ms 0 membrane potential / mV 50 Fig. 8.2 Fig. 8.3 shows the strength of the stimuli applied to these receptor cells. strength of stimulus time / ms Fig. 8.3 With reference to Fig. 8.2 and Fig. 8.3, describe the relationship between the strength of the stimulus and the resulting action potential. … … … … … … [2] [Total: 8]

22 9700/41/M/J/16 © UCLES 2016 Section B Answer one question. 9 (a) Outline how ATP is synthesised by oxidative phosphorylation. [8] (b) Describe respiration in yeast cells in anaerobic conditions. [7] [Total: 15] 10 (a) Describe the behaviour of chromosomes during meiosis. [9] (b) Outline the differences between structural and regulatory genes. [6] [Total: 15] … … … … … … … … … … … … … … … … … … …

23 9700/41/M/J/16 © UCLES 2016 [Turn over … … … … … … … … … … … … … … … … … … … … … … … … … … … …

24 9700/41/M/J/16 © UCLES 2016 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. … … … … … … … … … … … … … … … … … … … … … … … …

® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 10 printed pages. © UCLES 2016 [Turn over] Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level BIOLOGY 9700/41 Paper 4 A Level Structured Questions May/June 2016 MARK SCHEME Maximum Mark: 100 Published This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2016 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 Mark scheme abbreviations: ; separates marking points / alternative answers for the same point R reject A accept (for answers correctly cued by the question, or by extra guidance) AW alternative wording (where responses vary more than usual) underline actual word given must be used by candidate (grammatical variants accepted) max indicates the maximum number of marks that can be given ora or reverse argument mp marking point (with relevant number) ecf error carried forward I ignore AVP alternative valid point (examples given as guidance)

Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 1 (a) both have ribose (sugars) ; R ribulose ATP has 1, ribose / pentose / sugar, NAD has 2 ; I ref. to additional hexose both have, adenine / purine (base) ; I adenosine NAD has, nicotinamide / pyrimidine (base) ; ATP has 3 phosphates, NAD has 2 ; [max 3] (b) accept synthesise / produce / convert to, for ‘make’ for all mp make (named), protein / polypeptide / peptides ; A protein synthesis / translation make (named), disaccharide / oligosaccharide / polysaccharide / glycogen ; R non- mammalian examples such as starch or cellulose make (named), triglycerides / lipids / phospholipids / steroids / cholesterol ; A glycogenesis make, nucleotide / polynucleotide / nucleic acid / DNA / RNA ; A transcription / DNA replication AVP ; e.g. named example of, polymerisation / condensation A phosphorylation example [max 2] (c) substrate-linked / substrate-level, phosphorylation ; I condensation reaction [1] (d) hydrogen, carrier / acceptor ; A gets reduced or gains H / H+ and electrons I donates R H2 / hydrogen molecules (acts as a) coenzyme ; A enables dehydrogenases to work ref. to glycolysis / respiration in anaerobic conditions ; A anaerobic respiration I aerobic [max 2] (e) ‘more’ needed once plus implied for second mp 1 more, C-H bonds / hydrogen(s) / reduced ; I C-C bonds R more hydrogen bonds R hydrocarbons accept produces / gives / results in for ‘makes’ in mp 2 and mp3 2 (makes) more reduced NAD ; 3 makes more ATP per, gram / molecule / mole / unit mass ; A releases / results in / gives, more energy per, g / etc. 4 more, aerobic respiration / electron transport chain (ETC) / oxidative phosphorylation / chemiosmosis ; A higher rate of for ‘more’ [max 2] [Total: 10] 2 (a) at lowest value / in shortest supply ; I insufficient supply / not enough (the) one factor of several that affects rate ; A one factor of several prevents increase in rate [2] (b) to keep out unwanted CO2 (in air around leaves) ; A to stop CO2 increasing / entering (upper chamber) ref. to respiration of soil organisms ; A respiration of bacteria / fungi / seeds ref. to respiration of plant roots ; [max 2]

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 (c) (i) I ref. to set B throughout I time references at low(er) light intensity / light intensity up to a figure in range 6 – 7 au 1 rate increases as light intensity increases ; 2 light intensity is (main) limiting factor ; mp1 and mp 2 need to be in correct context at high light intensity / light intensity above a figure in range 6 – 7 au 3 rate, levels off / reaches plateau / remains constant ; A rate unaffected (by light intensity) 4 another (named) factor / not light intensity, is limiting ; A CO2 concentration / temperature mp3 and mp4 need to be in correct context [max 3] (ii) more CO2 available in B / less CO2 in A ; A CO2 concentration in B is double that of A ref. to fixation / Calvin cycle / light independent reactions ; A description, e.g. CO2 combines with RuBP CO2 concentration is limiting factor in set A ; A CO2 concentration is limiting at a higher light intensity in B [max 2] (d) accept ora throughout 1 D, adapted to high CO2 / can use more CO2 (per unit leaf area) ; A plants in D have, adjusted / accommodated, to high CO2 2 D have more, chloroplasts / chlorophyll ; 3 D have more, rubisco / RuBP ; 4 D have more stomata ; 5 D have thinner leaves ; 6 AVP ; e.g. ref. to diffusion of CO2 [max 4] [Total: 13] 3 (a) (i) database(s) ; computer (programs) / software ; analysis of, data / biological information / sequences ; A compare, genes / genomes [max 2] (ii) 1 identify / recognise, gene(s) ; A find where genes are 2 predict, primary structure / amino acid sequences, of proteins ; 3 predict 3D structure of proteins ; A tertiary 4 identify / predict, functions of proteins (from 3D structure) ; 5 ref. to drug to, bind with / block activity of / disrupt structure of, protein / enzyme ; A drug specific to protein I denature, protein / enzyme 6 drug prevents, transcription / expression, (of gene) ; I gene editing [max 3] (b) (i) cheaper ; A more economic(al) faster / can try many different drugs in a short period of time ; A time-saving can try out changes to, model / drug structure, to see if more effective ; no need for, laboratories / equipment ; I uses less labour (initially) no need for tests on, animals / humans ; A fewer ethical issues [max 3]

Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 (ii) functionality / to test that drug, actually works / is effective ; A cannot assume predictions are correct I efficiency safety ; A ref. to clinical trials / side effects dosage ; A theoretical modelling will not give information on doses [max 2] [Total: 10] 4 (a) 1 best / desirable, plants crossed ; A cross-pollinated R cross with other (maize) species 2 repeatedly / every generation ; 3 detail of cross-pollination ; e.g. ref. to male tassels and female silks 4 example of desirable characteristic ; A more kernels / big kernels / high yield / ref. to kernel colour / fast-growing / cold-tolerant 5 hybridisation / two inbred (named) lines crossed / F1 hybrids formed ; A description, e.g. cross two, homozygous parents / parents from two pure- bred lines 6 gives more, vigorous / uniform, plants ; A heterosis 7 ref. to dwarf maize / mutant alleles for gibberellin (synthesis) ; [max 4] (b) 1 discontinuous ; max 2 for mp2–6 2 one gene / single locus / monogenic, inheritance ; A monohybrid 3 two alleles ; 4 dominant and recessive ; 5 1:1 ratio purple to yellow ; A 50% purple, 50% yellow 6 test cross / Aa × aa ; [max 3] (c) (i) 1 as, Bt crops / area, increases the number of resistant, pests / species, increases ; A the more (the area of) Bt crops grown, the more (the) resistant species 2 figures quote ; (2 years, area with units once) 3 figures quote ; (2 years, no. resistant pest species) 4 mutation(s) (in pest species) ; 5 chance / random / spontaneous (mutations) ; 6 pests evolve resistance / natural selection for resistant pests ; 7 AVP ; e.g. plateau in resistance, 2002–2005 / 2009–2011 first 6 years / 1996–2001, no resistant species [max 4] (ii) social increased yield / more food / cheaper food / AW ; environmental decreased insecticide use / few hazards to humans / Bt only targets pest species ; A no / less pesticide used R herbicide [2] [Total: 13]

Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 5 (a) 1 mark-release-recapture / AW ; A catch, mark, return, catch A mark-and-recapture description (max 3) 2 detail of trapping ; e.g. Longworth / Sherman / live / small mammal 3 detail of marking ; e.g. felt tip pen / clipping fur / not to have adverse effects 4 detail of timing of second trapping ; e.g. not too soon or mixing will not occur / not too long after as migration may occur / after 24 hours / 1 day (any number of days up to two weeks) 5 detail of calculation ; e.g. Lincoln Index / Petersen index or number marked time 1 × no. captured time 2 number of marked individuals recaptured time 2 A symbols in equation if key is given [max 4] (b) glycogen ; centrioles / centrosomes ; (may have) cilia / flagella / microvilli ; no cell wall ; no, large / central / permanent, vacuole ; A no tonoplast [max 2] (c) (i) 1 reduce, other organisms’ abundance / biodiversity ; A endanger, rare species / water voles A causes extinction 2 alter food, chains / webs ; 3 due to predation ; 4 due to competition ; 5 due to spreading disease ; 6 may change habitat ; e.g. create shade, change soil pH 7 may be toxic / threaten human health ; [max 3] (ii) culling / hunting / trapping ; contraceptive measures ; biological control disease agent ; I introduce new mink-eating predator I biological control alone [max 1] [Total: 10] 6 (a) key to 4 chosen symbols ; A any two lettered pairs (e.g. E/e and A/a) identified I symbols for wing length no eyes and black abdomen must be lower case (e, a) with eyes and striped abdomen must be upper case (E, A) allow ecf to max 3 if error in symbols parents genotypes Eeaa × eeAa ; gametes Ea ea × eA ea ; A each gamete written twice F2 genotypes Eeaa eeaa EeAa eeAa ; [4] (b) cross with, homozygous recessive / black no-eyes, fly ; A double recessive / aaee (or own symbols) / organism showing recessive characters or phenotype [1]

Page 7 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 (c) observed number (O) expected number (E) O – E (O – E)2 (O – E)2 E 86 83 3 9 0.11 87 83 4 16 0.19 81 83 –2 4 0.05 78 83 –5 25 0.30 332 332 ;; χ2 = 0.65 ; A fractions in last column A 3 s.f. in last column [3] (d) no significant deviation from expected / difference not significant ; A (95% probability that) difference is due to chance A data is a good fit / match A null hypothesis (no significant difference between O and E) R comment on significance of results R ‘the value’ is not significant probability (of this deviation) is over 0.05 / χ2 is less than 7.82 ; A χ2 / results (of χ2 test), less than value at probability 0.05 ref. to critical value ; ecf reverse arguments if answer from 6(c)is over 7.82 ref. to independent assortment / AW ; [max 2] [Total: 10] 7 (a) maintaining a constant internal environment ; AW R external I body conditions [1] (b) (i) ribosomes / rough endoplasmic reticulum / RER ; [1] (ii) exocytosis ; [1] (iii) causes glucose uptake / increases permeability to glucose ; adds transport proteins to cell (surface) membrane ; A in sarcolemma A GLUT(4), proteins / channels / carriers more glucose respired / increase in respiration rate ; glucose converted to glycogen / glycogenesis ; [max 3]

Page 8 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 (c) accept stimulates / stimulated, for activates / activated throughout 1 (adrenaline) receptor shape change ; 2 G-proteins activated ; A description of G protein releases (α) subunit 3 adenylyl cyclase activated ; A adenyl(ate) cyclase 4 cyclic AMP made ; 5 (cAMP is) second messenger ; 6 activates / phosphorylates, kinase ; 7 ref. to enzyme cascade / cascade of reactions ; 8 glycogenolysis / hydrolysis of glycogen, stimulated / AW ; A break down glycogen 9 AVP ; gluconeogenesis / ref. to glucose transport proteins A description / glucose from, amino acids / lipids A GLUT(2) channels / carriers [max 5] [Total: 11] 8 (a) A – dendrite(s) ; B – dendron / (sensory) axon ; C – cell body (of neurone) / soma / centron ; D – axon (membrane) ; A terminal axon [4] (b) myelin insulates (axon) ; action potentials / depolarisation, only at nodes (of Ranvier) ; local circuits set up between nodes ; I local circuits at nodes action potentials / impulses, ‘jump’ from node to node or saltatory conduction ; [max 2] (c) only, stimulus / depolarisation / receptor potential / potential difference, that reaches threshold produces an action potential ; ora A -50mV for threshold A generator for receptor idea that the action potential is the same size no matter how strong the stimulus ; ref. to all-or-nothing (law) ; I all-and-nothing [max 2] [Total: 8]

Page 9 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 9 (a) accept proton / hydrogen ion / H+ / H ion as equivalent throughout 1 reduced, NAD / FAD ; A NADH / NADH2 / NADH + H+ for reduced NAD 2 passed to ETC ; 3 inner membrane / cristae ; 4 hydrogen released (from reduced, NAD / FAD) ; R H2 5 split into electrons and protons ; A released as electron and proton 6 electrons pass along, carriers / cytochromes ; A electrons pass along proteins of, ETC / carrier chain 7 energy released pumps protons into intermembrane space ; 8 proton gradient is set up ; A concentration gradient of protons is created A full description 9 protons diffuse, (back) through membrane / down gradient ; A protons diffuse into matrix 10 ATP synthase / stalked particles / protein channels ; A ATP synthetase R ATPase 11 (ATP produced from) ADP and (inorganic) phosphate ; A context for ‘final’ 12 idea of oxygen as final electron acceptor ; 13 addition of proton (to oxygen) to form water / (oxygen) reduced to water ; [max 8] (b) 1 pyruvate formed by glycolysis ; 2 reduced NAD formed by glycolysis ; 3 pyruvate decarboxylated / AW ; 4 ethanal produced ; 5 pyruvate decarboxylase ; 6 ethanal is, hydrogen acceptor / reduced ; A gains H or gains H+ and e– 7 from / by, reduced NAD ; 8 ethanol formed ; 9 ethanol / alcohol, dehydrogenase ; 10 not reversible reaction ; 11 NAD, regenerated / can now accept hydrogen atoms ; A reduced NAD oxidised 12 so glycolysis can continue ; [max 7] [Total: 15]

Page 10 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9700 41 © Cambridge International Examinations 2016 10 (a) I ref. to nuclear envelope I names of stages meiosis I 1 chromosomes, condense / thicken / spiralise ; 2 homologous chromosomes pair / bivalents form ; 3 crossing over / described ; 4 chiasma(ta) ; 5 spindle fibres / microtubules, attach to / pull, centromeres / kinetochores ; allow once in mp5 or in meiosis II 6 bivalents line up on, equator / mid-line ; A pairs of homologous chromosomes 7 independent assortment (of homologous pairs) / described ; A random assortment 8 chromosomes move to, two ends of cell / poles ; A (pairs of) homologous chromosomes separate meiosis II 9 (individual) chromosomes / pairs of chromatids, line up on, equator / mid-line ; 10 at right angles to first equator ; 11 centromeres divide ; 12 chromatids separate ; A chromatids move to (opposite) poles 13 ref. to haploid / chromosome number halved / one set of chromosomes ; A n for haploid [max 9] (b) I polypeptide throughout structural gene 1 structural protein / enzyme / rRNA ; A any named protein other than a transcription factor (e.g. transporter / receptor / named hormone / immunoglobulin / haemoglobin / etc.) R if any of these are identified as product of regulatory gene 2 named, structural protein / other protein / enzyme, or tRNA ; R named protein if function wrongly described 3 idea that needed for, structure / function, of cell ; regulatory gene 4 (product) controls, gene expression / transcription ; A promote / prevent / start / stop, gene expression or transcription 5 (codes for) transcription factor / DNA-binding protein ; 6 binds to, promoter / operator / DNA response element ; 7 stops / allows, binding of RNA polymerase ; 8 ref. to repressor / repressible ; A silencer 9 ref. to inducer / inducible ; A activator / enhancer 10 named example of regulatory gene ; A lac repressor / DELLA repressor / homeobox or homeotic or Hox gene [max 6] [Total: 15]