GCE Biology B H022/02: Biology in depth Advanced Subsidiary GCE Mark Scheme for November 2020

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GCE Biology B H022/02: Biology in depth Advanced Subsidiary GCE Mark Scheme for November 2020 Oxford Cambridge and RSA Examinations GCE Biology B H022/02: Biology in depth Advanced Subsidiary GCE... Mark Scheme for November 2020Oxford Cambridge and RSA Examinations OCR (Oxford Cambridge and RSA) is a leading UK awarding body, providing a wide range of qualifications to meet the needs of candidates of all ages and abilities. OCR qualifications include AS/A Levels, Diplomas, GCSEs, Cambridge Nationals, Cambridge Technicals, Functional Skills, Key Skills, Entry Level qualifications, NVQs and vocational qualifications in areas such as IT, business, languages, teaching/training, administration and secretarial skills. It is also responsible for developing new specifications to meet national requirements and the needs of students and teachers. OCR is a not-for-profit organisation; any surplus made is invested back into the establishment to help towards the development of qualifications and support, which keep pace with the changing needs of today’s society. This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. It shows the basis on which marks were awarded by examiners. It does not indicate the details of the discussions which took place at an examiners’ meeting before marking commenced. All examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes should be read in conjunction with the published question papers and the report on the examination. © OCR 2020H022/02 Mark Scheme November 2020 Annotations Annotation Meaning DO NOT ALLOW Answers which are not worthy of credit IGNORE Statements which are irrelevant ALLOW Answers that can be accepted ( ) Words which are not essential to gain credit __ Underlined words must be present in answer to score a mark ECF Error carried forward AW Alternative wording ORA Or reverse argumentH022/02 Mark Scheme November 2020H022/02 Mark Scheme November 2020 Subject-specific Marking Instructions INTRODUCTION Your first task as an Examiner is to become thoroughly familiar with the material on which the examination depends. This material includes: • the specification, especially the assessment objectives • the question paper • the mark scheme. You should ensure that you have copies of these materials. You should ensure also that you are familiar with the administrative procedures related to the marking process. These are set out in the OCR booklet Instructions for Examiners. If you are examining for the first time, please read carefully Appendix 5 Introduction to Script Marking: Notes for New Examiners. Please ask for help or guidance whenever you need it. Your first point of contact is your Team Leader.H022/02 Mark Scheme November 2020 5 Question Answer Mark AO element Guidance 1 (a) (i) hydrogen  1 AO1.2 1 (a) (ii) phosphate (group) AND deoxyribose  1 AO1.2 Both required for 1 mark. 1 (b) X has deoxyribose not ribose  X has 1 phosphate group not 3  X has sulphur atom  2 max AO2.1 ACCEPT ORA throughout 1 (c) Nucleotide base Percentage of each base in DNA strand 1 (%) Percentage of each base in DNA strand 2 (%) A 21 26 C 11 15 G 15 11 T 26 21 X 18 9 Y 9 18   2 AO2.8H022/02 Mark Scheme November 2020 6 Question Answer Mark AO element Guidance 1 (d) DNA helicase  cannot unzip the DNA / hydrogen bonds not broken  bases not exposed  idea of nucleotides unable to bind  cannot copy whole strand  4 max AO1.2 1 (e) P1 blend (all samples) for same (length of) time / at the same speed  P2 same volume of cold water  P3 same mass of table salt  P4 same volume/concentration of protease enzyme  E1 idea that sample needs to have similar surface area / similar cell wall breakage  E2 idea that the dilution should be the same  E3 idea that DNA should have similar solubility  E4 idea that unwanted proteins should be removed equally  2 max 2 max AO3.3 Explanations must match the chosen precautions TOTAL: 10H022/02 Mark Scheme November 2020 7 Question Answer Mark AO element Guidance 2 (a) (i) more cases of cervical cancer caused by HPV16 and 18  fewer caused by HPV 31/33/45/52  could be caused by another / named factor  no comparison to see if healthy women have HPV  2 max AO3.1 ACCEPT no control group 2 (a) (ii) (unpaired) T-test  because means are being compared  unpaired because the strains of HIV are unrelated  2 max AO2.8 Question Answer Mark AO element Guidance 2 (b)* Summary of instructions to markers: Read through the whole answer. (Be prepared to recognise and credit unexpected approaches where they show relevance.) Using a ‘best-fit’ approach based on the science content of the answer, first decide which of the level descriptors, Level 1, Level 2 or Level 3, best describes the overall quality of the answer. Then, award the higher or lower mark within the level, according to the Communication Statement (shown in italics): o award the higher mark where the Communication Statement has been met. o award the lower mark where aspects of the Communication Statement have been missed. • The science content determines the level. • The Communication Statement determines the mark within a level.H022/02 Mark Scheme November 2020 8 Level 3 (5–6 marks) Provides a comprehensive list of the types of antigenic material used and a detailed description of the problems faced in developing a vaccine. There is a well-developed line of reasoning which is clear and logically structured and uses scientific terminology at an appropriate level. All the information presented is relevant and forms a continuous narrative. Level 2 (3–4 marks) Provides a list of the types of antigenic material used and a description of the problems faced in developing a vaccine. There is a line of reasoning presented with some structure and use of appropriate scientific language. The information presented is mostly relevant. Level 1 (1–2 marks) Provides a named type of antigenic material and a problem faced in developing a vaccine. The information is communicated with only a little structure. Communication is hampered by the inappropriate use of technical terms. 0 marks No response or no response worthy of credit 6 AO1.1 AO2.1 Indicative scientific points may include: types of antigenic material whole live organism attenuated organism dead pathogen preparation of antigens toxoid biological problems in producing vaccines mutation rates antigen variability incubation/storage of vaccine remote area distribution general health of the target group risk of disease from live vaccine Total: 10H022/02 Mark Scheme November 2020 9 Question Answer Mark AO element Guidance 3 (a) (i) 35%  2 AO2.8 ALLOW 1 mark for (17-23) = 6 ALLOW 1 mark for Ans/ 17 x 100 3 (a) (ii) idea that (net) movement of water would have been measurable  1 AO3.2 ACCEPT water loss in lower concentrations would be slow ACCEPT idea that time needed to reach equilibrium 3 (a) (iii) all carrot extracts lost water  carrot extracts had a higher water potential (than NaCl sol.) more water loss into more concentrated NaCl solutions both 0.8 & 1.0 had stopped (net) loss of water  2 max AO3.2 3 (a) (iv) more values 0-0.4  more intervals  draw graph of distance moved against concentration  read off where the line crosses x-axis  3 max AO3.3 3 (a) (v) record the distance moved at regular time intervals plot a graph of distance against time and calculate, gradient of steepest part / tangent  OR record the distance moved by the meniscus in the first hour  calculate distance/time  idea of using volume of cylinder formula (πr2d) to calculate volume of water  2 max AO3.1 ACCEPT suitable time (15-30 minutes) ACCEPT volume plotted against time ACCEPT suitable time (30 minutes -2 hours) ACCEPT volume/timeH022/02 Mark Scheme November 2020 10 Question Answer Mark AO element Guidance 3 (b) (i) could have more/less sugar / starch  extract could have a lower / higher water potential  less / more water leaves by osmosis  meniscus move down less / more  1 max 1 max AO3.2 ACCEPT correct refs to reducing g and non-reducing sugars MP 2 - 4 must be correct description of MP1 3 (b) (ii) sugar might be sucrose which is not detected by the Benedict’s test  idea that a positive test for Benedict’s is orange-red same as the carrot extract  idea that the concentration of sugar may be too low to give a positive test  1 max AO1.2 ALLOW test is subjective Total 13H022/02 Mark Scheme November 2020 11 Question Answer Mark AO element Guidance 4 (a) (i) 0.66  dm-3 s-1  2 max AO2.8 (4.8-1.5)/5 = 0.66 4 (a) (ii) allows a comparison  1 AO3.1 4 (b) reduced lung capacity  less recoil / force of exhalation  2 AO2.5 4 (c) age  BMI  gender  smoker  2 max AO3.1 4 (d) (i) the squamous epithelium becomes scar tissue/ thicker  increased diffusion distance  alveolar walls damaged/absent  lower surface area of alveoli  2 max AO2.1 ACCEPT ref to alveoli 4 (d) (ii) less oxygen supplied to muscle (cells)  reduced (aerobic) respiration / energy release / ATP production  tiredness / lethargy  decreased activity  2 max AO2.1 Total: 11H022/02 Mark Scheme November 2020 12 Question Answer Mark AO element Guidance 5 (a) (i) 2 million (per year)  2 AO2.1 ALLOW 1 mark for (8-24) = 16 ALLOW 1 mark for Answer/ 8 5 (a) (ii) deaths falling (since 2004)  new diagnoses falling (since 1996)  2 AO2.1 5 (a) (iii) not all countries have accurate records on cause of death  1 AO2.1 (b) antibiotics cannot destroy (HIV) virus  can kill opportunistic (bacterial) pathogens  2 AO2.1 ACCEPT named example of an opportunistic pathogen that is killed Question Answer Mark AO element Guidance 5 (c)* Summary of instructions to markers: Read through the whole answer. (Be prepared to recognise and credit unexpected approaches where they show relevance.) Using a ‘best-fit’ approach based on the science content of the answer, first decide which of the level descriptors, Level 1, Level 2 or Level 3, best describes the overall quality of the answer. Then, award the higher or lower mark within the level, according to the Communication Statement (shown in italics): o award the higher mark where the Communication Statement has been met. o award the lower mark where aspects of the Communication Statement have been missed. • The science content determines the level. • The Communication Statement determines the mark within a level.H022/02 Mark Scheme November 2020 13 Question Answer Mark AO element Guidance Level 3 (5–6 marks) Provides a comprehensive description of the biological, ethical and economic factors and how factors may differ between developing and developed countries. There is a well-developed line of reasoning which is clear and logically structured and uses scientific terminology at an appropriate level. All the information presented is relevant and forms a continuous narrative. Level 2 (3–4 marks) Provides a detailed description of the biological, ethical and economic factors. There is a line of reasoning presented with some structure and use of appropriate scientific language. The information presented is mostly relevant. Level 1 (1–2 marks) Provides a brief description of the biological or ethical / economic factors. The information is communicated with only a little structure. Communication is hampered by the inappropriate use of technical terms. 0 marks No response or no response worthy of credit 6 AO1.1 AO2.1 Indicative scientific points may include Ethical problems encouraging use of contraception discouraging breast feeding contact tracing encouraging testing religious objection stigma Economic problems cost of education cost of contraception cost of health facilities / medical staff cost of tests cost of treatments Biological problems high mutation rate of virus hides / evades immune cells symptomless carriers easily transmitted Differences access to medical services access to education cultural practices and beliefs Total 14H022/02 Mark Scheme November 2020 14 Question Answer Mark AO element Guidance 6 (a) (i) 5  1 AO1.2 6 (a) (ii) we share a common ancestor with Pan paniscus more recently than with Gorilla gorilla  1 AO1.2 ACCEPT 5 million years ago compared with over 7 million years ago 6 (b) (i) moves further under the skull/AW  allows the species to walk upright  2 AO2.1 6 (b) (ii) increased cranial capacity / cavity  larger skull  1 AO2.1 IGNORE bigger brain as this is not seen in Fig 6.2 6 (b) (iii) complete fossils not found / only pieces of fossils found  (similarities in) behaviour cannot be observed  unknown if viable (hybrid) offspring have been produced  idea that not all tissues fossilise  1 AO2.1 6 (c) deoxyribose (nucleotide)  ribose nucleotide  amino acid  3 AO1.2 Total 9OCR (Oxford Cambridge and RSA Examinations) The Triangle Building Shaftesbury Road Cambridge CB2 8EA OCR Customer Contact Centre Education and Learning Telephone: 01223 553998 Facsimile: 01223 552627 Email: general.qualifications@ocr.org.uk [Show More]

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